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Model VSL-337ND-S - Spectra

1. Notes 3 Model VSL 337ND S Air Cooled Nitrogen Laser Notes 4 Notes Notes 5 Model VSL 337ND S Air Cooled Nitrogen Laser Notes 6 Report Form for Problems and Solutions We have provided this form to encourage you to tell us about any difficul ties you have experienced in using your Spectra Physics instrument or its manual problems that did not require a formal call or letter to our service department but that you feel should be remedied We are always interested in improving our products and manuals and we appreciate all suggestions Thank you From Name Company or Institution Department Address Instrument Model Number Serial Number Problem Suggested
2. le ll 1 1 Triggered by SYNC Output l Oscilloscope Oscilloscope Triggered by the OPTOSYNC Output ji ij y Figure 5 6 Laser pulses captured using the SYNC input top versus the OPTOSYNC triggering input bottom The disadvantage of OptoSync triggering is that it follows the laser pulse by 50 ns or less For some applications this delay is unimportant Other applications may lend themselves to data collection techniques that com pensate for this delay Some digital data collection instruments such as digitizing oscilloscopes include a pre triggering feature that can be use Model VSL 337ND S Air Cooled Nitrogen Laser 5 8 ful in this regard In this case data is stored until the arrival of the trigger pulse that initiated the event and marks the temporal relationship of the two It can also prove useful to place a delay line between the detected signal and the digitizer so that the OPTOSYNC signal can catch up to the detected pulse This is illustrated in Figure 5 7 Here an extra length of coaxial cable has been inserted between the optical detector and the oscil loscope The delay constant for RG 58 type cable is given Experiment Detector VSL 337ND S Laser OPTOSYNC Digitizing Oscilloscope 00000 Extra Coaxial Cable Delay Constant for RG 58 1 6 ns ft Trigger Signal Figure 5 7 Example of
3. 000 ete eee 2 7 CE CDRH Warning Labele 2 8 Label Translations 2 2 220 nenne nennen een 2 9 CE Declaration of Conformity o ooooccocc een een ern 2 10 Sources for Additional Information 22 222 sense nennen een een en 2 11 Laser Safety Standards 2 11 Equipment and Training 2 12 vii Model VSL 337ND S Air Cooled Nitrogen Laser Chapter 3 Laser Deserlption ENEE o SN ee 3 1 A Brief Review of Laser Theory 3 1 Emission and Absorption of Lob 3 1 Population Inversion 222 oa E ne a aa e GapA een ren 3 2 Nitrogen as a Laser Medium 3 3 The Optical CV ssi doo eaae ne en ee ale nn a a El 3 4 The VSL 337ND S Nitrogen Laser 3 5 lte TI EE 3 6 Beam Cross Section 3 6 High Voltage Power Supply 3 7 Trigger Contre ee ER a re ehe 3 8 Output Synchronization 3 8 Specifications 52 2 ead ee IR a A i eS 3 9 Replaceable Plasma Cartridge 0 0 ccc eee 3 10 Outline Drawing 3 11 Chapter 4 Controls Indicators and Connections ssss na nanaannnnnns 4 1 elle LN 4 1 e Lie 4 1 Rear Panel nn ne a nae ET A deng ple Se we dee a EEA 4 1 Controls rte ds A A A dad 4 2 Indicators EE 4 2 Connections u ee IN her ee ee eege AE amp 4 2 Chapter 5 Operation NI EE EN NEIER 5 1 Precautions oya d rege Eed en a ee EEN EEN de Neen 5 1 Basie Operation due ri ea a ee A ee 5 1 Burst Control dares moan er Br Re A De Burner 5 2 PUISG Gating 2 pe A a ans en aa e
4. 3 9 Model VSL 337ND S Air Cooled Nitrogen Laser Table 3 3 Mechanical and Electrical Specifications AC power input Power requirements 100 to 240 Vac 10 50 60 Hz single phase 1 5 A 110 Vac 1 0 A 220 Vac Size W x H x L Weight Air flow Environmental operating temperature 46 2 x 19 4 x 11 7 cm 18 2 x 7 6 x 4 6 in 7 3 kg 16 Ib 24 CFM 4 40 C 40 105 F Table 3 4 Fuse Rating Supply Voltage Rating Type 100 240 Vac 50 60 Hz 1 8 A F 250 V Replaceable Plasma Cartridge 3 10 The VSL 337ND S features a Spectra Physics user replaceable plasma car tridge that allows the user to regain the performance of a new laser at a fraction of the cost The patented design ensures minimal downtime because no alignment of the laser cavity is necessary to return it to fully specified performance The plasma cartridge is warranted to maintain at least 70 of the listed energy value i e 210 uJ for 20 million pulses or two years whichever comes first Outline Drawing Laser Description 18 20 7 60 gt gt le 17 20 193 0 s 436 9 gt 354 al o 0 4 62 Laser Output Port amp H 117 4 o O o A 0 31 7 9 Y U U L 1 72 A dE ne Dimensions given in inches OAT er 0 94 29 Fi 249 mm 11 9 l 239 1 y O 1 10 y d d Y e Da Ka EEE G
5. Ge Figure 4 5 Oscilloscope trace of the trigger pulse the laser pulse and OPTOSYNC output AC power connector provides attachment for an IEC ac power cable to the internal power supply Although the power supply itself is auto switch ing there are two separate models to accommodate power receptacles for different utility service Model 33201 00 accommodates 1 5 A at 100 120 Vac 50 60 Hz Model 33201 01 accommodates 1 0 A at 200 240 Vac 50 60 Hz 4 5 Model VSL 337ND S Air Cooled Nitrogen Laser 4 6 Chapter 5 Precautions Danger Laser Radiation AA Eyewear 0 Required Basic Operation Operation Please read this entire chapter and Chapter 2 on laser safety before using your laser for the first time The Spectra Physics VSL 337ND S laser is a Class IIIb Medium Power Laser whose beam is by definition a safety and fire hazard Take precautions to prevent accidental exposure to both direct and reflected beams Diffuse as well as specular reflections of the invisible ultraviolet radiation can cause severe eye or skin damage Note that at low pulse repetition rates the laser is fully charged and ready to fire a considerable time before the arrival of a trigger pulse Although unlikely it is possible that some perturbation electrical noise or perhaps a cosmic ray particle may trigger the laser to emt a pulse spontaneously during this time See the descript
6. Table 6 1 Replacement Parts Description Part Number High Voltage Power Supply SA1387S Pulse Transformer AA1307 05S Trigger Board BD1001 00S Low Voltage Power Supply 4004 0790 Keyswitch 250005 Interlock Switch internal 250004 Fan 090003S Service Warranty Maintenance and Service At Spectra Physics we take great pride in the reliability of our products Considerable emphasis has been placed on controlled manufacturing meth ods and quality control throughout the manufacturing process Neverthe less even the finest precision instruments will need occasional service Our instruments have excellent service records compared to competitive prod ucts and we strive to provide excellent service to our customers in two ways by providing the best equipment for the price and by servicing your instruments as quickly as possible Spectra Physics maintains major service centers in the United States Europe and Japan Additionally there are field service offices in major United States cities When calling for service inside the United States dial our toll free number 1 800 456 2552 To phone for service in other coun tries refer to the Service Centers listing located at the end of this section Order replacement parts directly from Spectra Physics For ordering or shipping instructions or for assistance of any kind contact your nearest sales office or service center You will need your instrument model and serial number
7. CE CDRH Warning Labels oocoocccccccco tne 2 8 Figure 3 1 Electrons occupy distinct orbitals in an atom or molecule Two different distributions are shown 3 1 Figure 3 2 A typical four level transition scheme 3 3 Figure 3 3 The long lifetimes of the lower molecular energy levels are responsible for the pulsed nature of the nitrogen laser output 22m sonen een nenn 3 4 Figure 3 4 VSL 337ND S Internal Components ooccccccoc c seen nn 3 5 Figure 3 5 Typical output pulse VSL 337ND S ococcccccccccc nennen nennen nn nn 3 6 Figure 3 6 Typical profile of the VSL 337ND S laser beam 3 6 Figure 3 7 A representation of the VSL 337ND S laser cavity 00000 cece eee 3 7 Figure 3 8 Outline Drawing for the VLS 337ND S Laser 0000 cece eee nennen nenn 3 11 Figure 4 1 VSL 337ND S Front Panel 4 1 Figure 4 2 VSL 337ND S Rear Control Panel 4 1 Figure 4 3 Remote Interlock Connector 4 3 Figure 4 4 The timing between the trigger signal the laser pulse and OPTOSYNC output 4 4 Figure 4 5 Oscilloscope trace of the trigger pulse the laser pulse and OPTOSYNC output 4 5 Figure 5 1 Gating of 30 Hz Pulses Using the Burst Gong 5 2 Figure 5 2 Pulse Energy vs Repetition Rate 5 3 Figure 5 3 HVPS Recharge Noise 5 5 Figure 5 4 The Noise Spectrum With above and Without below the HVPS Recharging Delay 5 5 Figure 5 5 Pulse Attenuation vs BURST Low Duration o ooo
8. Class B digital devices pursuant to Part 15 of the FCC rules and it uses a power supply that is a UL recognized ULR com ponent 1 Although the power supply is auto switching there are two separate models of the VSL 337ND S to accommodate differences in utility receptacles Model 337201 00 accommodates 100 120 Vac 50 60 Hz Model 337201 01 accommodates 200 240 Vac 50 60 Hz Chapter 2 Warning Danger Laser Radiation Eyewear Per 2 Required Note Hazards Y A B Laser Safety This user information is in compliance with section 1040 10 of the CDRH Laser Products Performance Standards from the Health and Safety Act of 1968 The use of controls or adjustments or the perfor mance of procedures other than those specified herein may result in hazardous radiation exposure The Spectra Physics VSL 337ND S air cooled nitrogen laser is a Class IIIb Medium Power Laser whose beam is by definition a safety haz ard Take precautions to prevent accidental exposure to both direct and reflected beams Diffuse as well as specular beam reflections can cause severe eye or skin damage The 337 nm UV output from the laser is invisible and therefore especially dangerous This safety section should be reviewed thoroughly prior to operating the VSL 337ND S laser system and the safety precautions listed herein should be followed carefully The CE certification described in this chapter applies to standard models
9. Delay Compensation Using Coaxial Cable Experimental results are shown in Figure 5 8 The top trace shows the OptoSync output The middle and bottom traces show the detected pulse The middle trace has the cables for the OptoSync output and the detector equal in length while the bottom trace includes an extra 48 feet of coaxial cable between the detector and the oscilloscope This extra cable length produces an additional delay of approximately 70 ns placing the detected pulse beyond the leading edge of the OptoSync signal scales are 200 mV and 25 0 ns OPTOSYNC No Delay PRT AA Delay Added Figure 5 8 OPTOSYNC Delay Compensation Using Coaxial Cable Chapter 6 Maintenance and Service Replacing the Plasma Cartridge Required Tools Procedure The Plasma Cartridge includes in one integrated assembly all the laser components that are expected to require replacement as a result of normal operation Although replacing the Plasma Cartridge is a straightforward procedure it is important to follow these instructions carefully The war ranty is void if damage results from improper installation The following tools are required to change the cartridge e a Phillips screwdriver e a 32 in hex ball driver e a o4 in hex ball driver e a ie in nut driver 1 Disconnect the laser ac power cord 2 Remove all the screws from the housing then slide th
10. Solution s Mail To FAX to Spectra Physics Inc Attention Quality Manager SSL Quality Manager 650 961 7101 1335 Terra Bella Avenue M S 15 50 Post Office Box 7013 Mountain View CA 94039 7013 U S A E mail sales splasers com www spectra physics com
11. eyewear is available from suppliers listed in the Laser Focus World Lasers and Optronics and Photonics Spectra buyer s guides Consult the ANSI and ACGIH standards listed at the end of this section for guidance Maintain a high ambient light level in the laser operation area so the eye s pupil remains constricted reducing the possibility of damage To avoid unnecessary radiation exposure keep the protective cover on the laser head at all times Avoid looking at the output beam even diffuse reflections are hazard ous And because the beam is invisible the laser can appear to be off even when it is not Avoid blocking the output beam or its reflections with any part of the body Establish a controlled access area for laser operation Limit access to those trained in the principles of laser safety Post prominent warning signs near the laser operating area Figure 2 1 Set up experiments so that the laser beam is either above or below eye level Provide enclosures for beam paths whenever possible Set up shields to prevent any unnecessary specular reflections Set up a beam dump to capture the laser beam and prevent accidental exposure Figure 2 2 INVISIBLE LASER RADIATION AVOID DIRECT EXPOSURE TO BEAM 337 nm 8 mW MAX AVG POWER 400 pJ MAX ENERGY PULSE CLASS IIIb LASER PRODUCT Figure 2 1 These CE and CDRH standard safety warning labels would be appropriate for use as entry warning signs EN 60825 1 A
12. from 100 ns to 1 ms The maximum allowable pulse rate is 30 Hz continuous or up to 60 Hz when combined with the BURST input Even at low repetition rates the energy storage capacitor is usually charged and the laser is ready for a trigger signal Since the laser is ready to be fired at any time precautions should be taken to avoid accidental exposure should the laser trigger unexpectedly To operate the VSL 337ND S using an external trigger source place the trigger selection switch in EXTERNAL and apply an positive edge triggered TTL pulse gt 1 us The laser output pulse is emitted lt 1000 ns later with temporal jitter about this mean of 7 ns or less The maximum allowable pulse rate is 30 Hz when the laser is operated con tinuously For higher repetition rates refer to the BURST connector below To minimize EMI RF interference an opto isolator is used to protect the trigger input REMOTE INTERLOCK connector 3 pin allows the user to stop laser operation by activating opening a user supplied safety switch such as a doorway entry switch The system is provided with a shorting jumper Controls Indicators and Connections installed on this connector that must be left in place if the interlock is not used However it can be replaced with a similar plug to wire to a normally closed relay or switch Only two pins are used Figure 4 3 When pins J and J are shorted the current flowing through them is 24 mA When these
13. gain laser pulses is relatively broad The VSL 337ND S Nitrogen Laser The major components of the laser are shown in Figure 3 4 Plasma Low Voltage Control and Cover Interlock Cartridge Fan Power Supply Trigger Board Switch DANGER HIGH VOLTAGE Shutter Output Coupler HR Mirror Trigger High Voltage Slide Assembly Mount Transformer Power Supply Figure 3 4 VSL 337ND S Internal Components Model VSL 337ND S Air Cooled Nitrogen Laser Output Pulse Beam Cross Section 3 6 The VSL 337ND S nitrogen laser is designed specifically for generating ultraviolet UV pulses at 337 nm that have very low angular beam diver gence without compromising their high pulse energy The full beam diver gence angle is less than 0 3 mrad This is accomplished by placing the gain medium the nitrogen plasma tube between specially designed mirrors of an optical cavity In addition to increasing the efficiency of light output the optical cavity optimizes beam quality Population inversion is achieved through a high voltage discharge that is transverse to the axis of the output beam The pulsed discharge is applied in the nanosecond time scale needed to match the lifetime of the nitrogen laser transition The characteristics of the nitrogen gas at the low pressure used in the VSL 337ND S result in output pulses typically greater than 300 microjoules in energy and less than 4 nanoseconds in duration and that can be repeated at rates of up to 30 Hz
14. is ever needed Service and Repair is intended to help you guide your Spectra Physics field service engineer to the source of any problems Do not attempt repairs yourself while the unit is still under warranty instead report all problems to Spectra Physics for warranty repair This section includes instructions for the replacement of the laser plasma cartridge which is engineered for easy servicing in the field This product has been tested and found to conform to Low Voltage Directive 72 23 EEC governing product safety using standards EN 60950 1992 with Amendment 14424 Safety of information technology equipment including electrical business equipment including Amendment 1 1993 Amendment 2 1994 Amendment 3 1996 Amendment 4 1997 and Amendment 11 1997 and IEC 60825 1 1993 Safety of Laser Products Part 1 Equip ment classification requirements and user s guide including Amendment A1 1997 and Amendment A2 2001 This product also conforms to Directive 89 336 EEC governing electromagnetic compatibility using stan dard EN 61326 1 1997 Electrical equipment for measurement control and laboratory use EMC requirements including Amendment 1 1998 and Amendment 2 2000 as listed in the official Journal of the European Com munities Refer to the CE Declaration of Conformity document in Chapter 2 for a complete list of directives to which this system complies Model VSL 337ND S Air Cooled Nitrogen Laser This product conf
15. nitrogen laser output Lasers with relatively modest gain use a resonant optical cavity to pass the light back and forth though the gain medium a number of times sufficient to overcome absorption and internal losses As with other amplifiers the signal strength in this case the light intensity increases until it reaches a steady state condition where the gain saturates becomes unity The resonant optical cavity is most often two mirrors that reflect light that is parallel to the cavity axis through the gain medium Both cavity mirrors are coated to reflect the wavelength of interest while transmitting all others One of the mirrors the output coupler transmits a fraction of the energy circulating within the cavity which becomes the output beam of the laser The situation changes when the gain of the laser medium is very high as it is for nitrogen lasers In the limiting case of super radiance no resonant cavity is necessary at all as the device will produce laser light with a single pass through the nitrogen gas discharge It is typical of these types of lasers which include semiconductor lasers to produce a beam of compara tively lower spatial and spectral quality Laser Description The mechanism that excites the gain often plays an important role in the shape of the laser beam in such devices as it forms a profile within the gain medium where laser light is produced This usually requires that extra mea sures be taken in the de
16. not expressly approved by Spectra Physics could void your right to operate the equipment This product conforms to the requirements of 21 CFR 1040 10 CDRH Table of Contents Preface Drag iii Environmental Specifications 00s V CE Electrical Equipment Requirements aaan v Environmental Specifications v FCC Regulations u nne as deg Ra Re Ep Rn v CDRH Be UE TEE v Warning Conventions 2 e cia EE NEE CR xi Standard Units tirita ia ii a A xiii el ue TEE EE ieee Re RN a Se Sele eee XV Unpacking and Inspection 2 00 cece eee xvii Chapter 1 Introduction os os hb a ae 1 1 Key Features as er ara en ie Rn caer outed Magis Ale DEE 1 2 CE CDRH and FCC Compliance and Certification 1 2 Chapter 2 Laser Safety mas a ae 2 1 ele Sua aaa A ED een A Ee ats 2 1 Precautions For The Safe Operation Of Class ID Medium Power Lasers 2 2 Maximum Emission Levels and Protective Eye Wear 2 3 Safety Devices un an a A weiner a ARO nal ae ie A 2 3 Interlock Keyswitch 2 3 Emission and Power Indicator 2 4 El CEET 2 4 Remote Interlock 2 4 Interlocks Defeat Indicator 222m onen een 2 5 External Trigger Connector ooccccc nennen een 2 5 Burst Input Connector 2 5 Cover Safety Interlock 2 5 Maintenance Necessary to Keep this Laser Product in Compliance with Center for Devices and Radiological Health CDRH Regulations 2 6 CE CDRH Radiation Control Drawing
17. 1 708 0 Fax 49 06151 79102 Japan East Spectra Physics KK East Regional Office Daiwa Nakameguro Building 4 6 1 Nakameguro Meguro ku Tokyo 153 Telephone 81 3 3794 5511 Fax 81 3 3794 5510 Japan West Spectra Physics KK West Regional Office Nishi honmachi Solar Building 3 1 43 Nishi honmachi Nishi ku Osaka 550 0005 Telephone 81 6 4390 6770 Fax 81 6 4390 2760 e mail niwamuro O splasers co jp United Kingdom Telephone 44 1442 258100 United States and Export Countries Spectra Physics 1330 Terra Bella Avenue Mountain View CA 94043 Telephone 800 456 2552 Service or 800 SPL LASER Sales or 800 775 5273 Sales or 650 961 2550 Operator Fax 650 964 3584 e mail service O splasers com sales O splasers com Internet www spectra physics com And all European and Middle Eastern countries not included on this list And all non European or Middle Eastern countries not included on this list Model VSL 337ND S Air Cooled Nitrogen Laser 6 10 Notes Notes 1 Model VSL 337ND S Air Cooled Nitrogen Laser Notes 2 Notes
18. E ir 97 d ome S 50 0 3 S EA A O O A 0 47 A 11 9 2x 8 32 x V 0 19 4x M4 thru Do not break thru Front Plate Laser Output Accessory Mounting Holes Detail FA 5 M2o o Cl O gt O c3 O O F2 O O o o oo c2 20 n Oo O o Mio output beam 3 O H a O ps O 9 o o y X S Base Plate Dimensions position inches position mm size D y D y hole QI a o E Only the indicated holes are c2 0 28in 1550 2 32 393 7 58 9 C3 1550 532 397 1351 suitable for mounting the laser F1 0 75 1 32 19 1 33 5 The use of other holes in the F2 x 20 0 75 4 32 191 109 7 base plate for mounting may F3 15 75 1 32 400 1 33 5 F4 1575 632 4001 1605 result in loss of performance Mi M6 1575 1 78 400 1 45 2 or damage to the laser M2 15 75 5 72 400 1 145 33 Figure 3 8 Outline Drawing for the VLS 337ND S Laser 3 11 Model VSL 337ND S Air Cooled Nitrogen Laser 3 12 Chapter 4 Controls Indicators and Connections Front Panel Push Pull o o Shutter Slide o o Shutter Beam Aperture e O U Figure 4 1 VSL 337ND S Front Panel Controls Shutter is hand operated by means of the push pull slide on the side Rear Panel INTERLOCKS ON OFF DEFEATED REPETITION Keyswitch Indicator RATE Control LASER On TRIGGER Indicator INTERLOOKS REPETTON Input BURST Input SYNC AC Power Output Input OPTOSYNC Output REMOTE Trigger Interlock Selection Switch Figure 4 2 VSL 337ND S Rear C
19. Model VSL 337ND S Pulsed UV Air Cooled Nitrogen Laser System User s Manual S Spectra Physics 1335 Terra Bella Avenue Mountain View CA 94043 Part Number 0000 318A Rev A May 2004 Preface This manual contains information required to safely install operate main tain and service your VSL 337ND S pulsed ultraviolet nitrogen laser sys tem The system comprises a single self contained unit that includes the laser resonator power supply and control circuitry The Introduction contains a brief description of the laser system and available accessories Following that section is an important chapter on safety The VSL 337ND S is a Class IIIb laser and as such emits laser radiation that can permanently damage eyes and skin This section contains information about these haz ards and offers suggestions on how to safeguard against them To minimize the risk of injury or expensive repairs be sure to read this chapter then carefully follow these instructions Laser Description contains a short section on laser theory relevant to nitrogen lasers It is followed by a more detailed description of the laser system and concludes with system specifications The next few chapters describe the VSL 337ND S controls then guide you through its installation and operation The last part of the manual covers service and includes a replacement parts list and a list of world wide Spectra Physics service centers to call if help
20. NSI 4 3 10 1 Figure 2 2 Folded Metal Beam Target N Caution I Danger W Laser Safety Use of controls or adjustments or performance of procedures other than those specified herein may result in hazardous radiation exposure Operating this laser without due regard for these precautions or in a manner that does not comply with recommended procedures may be dangerous At all times during installation maintenance or service of your laser avoid unnecessary exposure to laser or collateral radiation that exceeds the accessible emission limits listed in Performance Stan dards for Laser Products United States Code of Federal Regulations 21CFR1040 10 d Follow the instructions contained in this manual to ensure proper installa tion and safe operation of your laser Maximum Emission Levels and Protective Eye Wear Safety Devices Interlock Keyswitch It is recommended that laser safe eye wear be worn at all times when the VSL 337ND S nitrogen laser is on The table below shows the maximum emission level possible for this product Use this information for selecting appropriate laser safety eyewear and implementing appropriate safety pro cedures This value does not imply actual system power or specifications Emission Wavelength Maximum Power 337 nm laser output wavelength 7 2 mW During normal operation the operator will not be exposed directly to other hazardous emissions However removing the
21. Note Suppression is not needed when internal triggering is used When exter nal triggering is used the Burst signal must be driven synchronously and at the same repetition rate as the external trigger signal In non Burst operation at low pulse repetition rates the laser is fully charged and ready to fire for a considerable time before the arrival of a trig ger pulse Although unlikely it is possible that some external impulse electrical noise or even a cosmic ray particle may trigger the laser to emit a pulse spontaneously during this time period This can be prevented by combining the trigger signal with the Burst input The Burst input can be used to prevent the laser from recharging and thus eliminating the possibility of a spontaneous pulse Operating in this mode requires that BURST be driven high immediately following the Trigger signal leading edge which triggers the laser pulse and held high until ready for laser output BURST is then sent low prior to the next leading edge of the Trigger signal with sufficient time to allow the HVPS to fully recharge the laser The HVPS requires at least 15 ms to fully charge the laser Note that this mode of operation is only available when external triggering is used When internal triggering is used an internal inhibit signal is gener ated that always prevents the HVPS from recharging until it is required by the next internal trigger signal which is determine
22. Pulse Energy lt 400 uJ Pulsenergig lt 400 y q Pulse Duration lt 4 nanoseconds Pulsdaver lt 4 nanosekunden Wavelength 337 nm Wellenlange 337 nm EN 60825 1 2001 EN 60825 1 2001 Eviter l exposition au faisce Produit laser de classe 3B Lissance moyenne de7 2mW 8 30h EN 60825 1 2001 International CE Label 8 Internal Labels LDANGERS HIGH VOLTAGE Y CE Electrical System Ground Danger High Voltage Label Warning Label Label Figure 2 6 CE CDRH Warning Labels 2 8 Laser Safety Label Translations For safety the following translations are provided for non English speak ing personnel The number in parenthesis in the first column corresponds to the label number listed on the previous page Table 2 1 Label Translations Label No French German Spanish Dutch Danger Attention Vorsicht Peligro Gevaar Laser Rayonnement laser Unsichtbare Laser Radiaci n l ser invisi Onzichtbare laser stral Radiation invisible Exposition strahlung Bestrahlung ble Evitar la exposici n ing Vermijd blootstell Label dangereuse au rayon von Auge oder Haut directa o dispersa ing aan ogen of huid 2 nement direct ou dif durch direkte oder 337 nm door directe of gere fus 337 nm Streustrahlung ver Potencia maxima pro flecteerde straling Puissance moyenne meiden 337 nm Mit medio 8 mW Energ a 337 nm Maximaal uit de 8 mW Energie tlere Leistung 8 MW maxima del pulso tredend vermogen maximum p
23. URST low to 15 ms will return the pulses to full energy and varying this duration between 15 ms and 10 ms will vary the pulse energy between 100 and 50 in a fairly linear fashion see Figure 5 5 See Burst Control on page 2 for a description of how to vary the BURST low state BURST can be employed this way using either internal or exter nal triggering but it should be synchronized to the trigger signal If the recharge time is reduced below 10 ms laser operation will become erratic Note that using this technique to attenuate laser energy also results in other laser specifications being altered In particular laser temporal jitter will become worse as will the synchronization to the SYNC output and energy stability will degrade 100 90 80 70 60 50 40 Pulse Energy Remaining Burst LOW Width ms Figure 5 5 Pulse Attenuation vs BURST Low Duration Operation Using the OPTOSYNC Output The OptoSync trigger described in Chapter 4 provides an alternative to the Sync output where the latter is derived from the trigger pulse that starts the nitrogen discharge The advantage of using the OPTOSYNC signal for data collection is illustrated in Figure 5 6 The top display shows an overlay of 100 pulses captured using the SYNC trigger while the lower display com pares 100 pulses using the OPTOSYNC trigger Jitter reduction is obvious
24. ad ne 5 2 Burst Output a ne ta Sale he E A naeh 5 3 Suppression of Spontaneous Pulses 5 4 Noise Suppression 0 nennen etn eee teens 5 4 Electronic Control of Laser Energy 5 6 Using the OPTOSYNC Output 5 7 Chapter 6 Maintenance and Service 00 cece eee eee eee eee 6 1 Replacing the Plasma Cartridge 0 00 cece eee 6 1 Required TOONS ENEE 6 1 Procedure urn 2a Er lipase he a pe e o a ps 6 1 Troublesh oting vue its Vela ted a ea ambien ae ae emu hand iii 6 6 ACCOSSOMOS a ii Sey dre MOGs nie Wee Vee EE 6 6 Replacement Parts Zeien teg a ober nn et ee AE pad Dre 6 6 TEE Renae hae ead eae oath wohne dew wide SAT belie were cag dda 6 7 Warranty Ascii cued fot aie hd Se MUR AE AAA A SA toes Me Oo RE 6 7 Returning the Instrument for Repair 0 0 00 ce eae 6 8 Service Centers Notes Report Form for Problems and Solutions viii Table of Contents List of Figures Figure 1 1 The VSL 337ND S Nitrogen Laser 1 1 Figure 2 1 These CE and CDRH standard safety warning labels would be appropriate for use as entry warning signs EN 60825 1 ANGIA3 1m0m eee seen 2 2 Figure 2 2 Folded Metal Beam Target 2 2 Figure 2 3 The VSL 337ND S laser showing the location of the safety devices on the front upper figure and rear lower figure panels 0 00 ernennen 2 4 Figure 2 4 Remote Interlock Connector 2 4 Figure 2 5 CE CDRH Radiation Control Drawing 2 7 Figure 2 6
25. anoseconds or less in duration The pulse repetition rate can be varied from less than one pulse per second up to 60 Hz The pulse energy is typi cally 300 uJ with a peak pulse power of about 75 kW Average output power is approximately 7 mW at a pulse repetition rate of 20 Hz The VSL 337ND S emits a near diffraction limited collimated beam with excellent homogeneity for this type of device The beam can be focused to a spot less than 3 um in diameter resulting in very high peak power density and an energy density of 4 5 kJ cm The VSL 337ND S nitrogen laser features flexible triggering and control features for pulse gating or command charging applications which simpli fies the synchronization of the laser output to the timing of complex exper iments Both internal and external triggering is available as well as a burst mode that allows higher repetition rates and broader control of pulse tim ing A unique OptoSync output trigger provides a high synchronization low delay and low jitter signal All the sensitive components of the nitrogen laser the energy storage capacitor the spark gap switching element the plasma tube the electrodes the pre ionizers and the pre aligned resonator mirrors are contained in the integrated laser plasma cartridge module 1 1 Model VSL 337ND S Air Cooled Nitrogen Laser Note Key Features The plasma cartridge is polymer encapsulated and engineered for simple field replacement The factory ali
26. ar impul Maximale Pulsenergie 400 uJ 8 mW Maximaal sion 400 uJ Appareil 400 uJ LaserKlasse Producto l ser Clase Pulsenergie 400 pJ laser de classe 3b 3b 3b Klasse 3b laser produkt Aperture Ouverture Laser Austritt von sichtbarer Evite la exposici n Por Vanuit dit apertuur Label Exposition Dan und unsichtbarer esta abertura se emite wordt zichtbare en 3 gereuse Un Rayon Laserstrahlung radiaci n l ser visible e onzichtbare laserstral nement laser visible et Bestrahlung ver invisible ing geemiteerd invisible est emis par meiden Vermijd blootstelling cette ouverture CE Inter Attention Rayonne Vorsicht beim ffnen Peligro Radiaci n Gevaar Zichtbare en locked ment Laser Visible et Austritt von sichtbarer l ser visible e invisible onzichtbare laserstral Cover Label Invisible en Cas und unsichtbarer existe al abrir el dispos ing vermijd blootsteling 5 D Ouverture et lor Laserstrahlung wenn _itivo de seguridad aan huid of oog aan sque la securitc est Sicherheitsverrie Evite que los ojos y la disecte straling of neutralis e Exposi gelung berbr ckt piel queden expuestos weerkaatsingen tion Engereuse de Bestrahlung von Auge a la radiaici n directa o l oeil ou de la Peau au oder Haut durch direkte dispersa Refiera servi Rayonnement Direct oder Streustrahlung cio solamente a per ou Diffus R f rez vermeiden Wenden sonal calificado vous l entretien au Sie sich mit Wartung personnel qualifie sa
27. at the desired rate At the same time supply a TTL input to the Burst connector to reduce the duty cycle of the laser BURST should be driven high and kept high to disable the HVPS at the appropriate intervals between groups of pulses BURST should be held low before the next group of pulses is to be emit ted long enough gt 15 ms to allow the HVPS to fully recharge It is critical to limit the Burst mode duty cycle to avoid serious damage to the laser Both the duration of a group of Burst mode pulses and the time between groups of Burst mode pulses must be in agreement with Table 5 1 Table 5 1 Burst Mode Duty Cycles Pulse Rep Rate Maximum duration of Minimum interval pulse group between pulse groups 3 45 Hz 10 seconds 20 seconds 45 60 Hz 10 seconds 30 seconds As might be expected as the frequency of pulses is increased the energy available in each individual pulse decreases This pulse energy roll off as a function of repetition rate relative to energy at 10 Hz operation is shown in Figure 5 2 Note that other pulse characteristics may change as well such as the duration of individual pulses 100 90 80 70 60 Pulse Energy 50 40 0 10 20 30 40 50 60 Pulse Rep Rate Hz Figure 5 2 Pulse Energy vs Repetition Rate 5 3 Model VSL 337ND S Air Cooled Nitrogen Laser Suppression of Spontaneous Pulses Noise Suppression 5 4 Note
28. d by the repetition rate When Internal mode is used the HVPS is always inhibited in the most opti mum way Burst mode still operates with Internal triggering however the internally generated inhibit delay sets the minimum length of time for which the HVPS is prevented from recharging The following method of operation is only applicable when using exter nal triggering The Burst input must be driven synchronously and at the same repetition rate as the external trigger signal In this application the BURST signal is again used to prevent the laser from recharging immediately Although the laser itself generates very little EMI some applications are sensitive to the low level noise generated by the HVPS when it is recharg ing This noise is at the HVPS switching frequency of 38 kHz and at its harmonics In some applications it may be advantageous to use the BURST signal to delay HVPS recharging until after the period of sensitive data col lection Figure 5 3 shows the effects on the noise output of the HVPS by using the Burst signal The weak switching noise output was detected by an antenna Operation The top trace displays the amplified antenna pickup while the lower trace displays the TTL Burst input As can be seen when BURST is high e inhibiting HVPS recharging the noise level is reduced When BURST sig nal is low the HVPS is allowed to recharge and there is a jump in the noise level following a 500
29. dent on its power supply which must be capable of switching gt 15 kV with a very fast rise time The VSL 337ND S power supply consists of a 38 kHz switching module that charges a parallel capacitor to about 17 kV The supply fully charges the capacitor within about 15 milliseconds This capacitor voltage is held off by the nitrogen tube itself which acts as an insulator until the gas discharge is initiated by a spark gap transformer triggered either inter nally or externally to pre ionize the gas At this point the capacitor fires fully discharging and ionizing the nitrogen gas in less than a few nanosec onds After the laser has fired the power supply is prevented from immediately recharging the capacitor This minimizes the possibility that in certain con ditions the laser will prematurely emit a pulse before receiving a trigger signal Although rare this spontaneous pulse emission can occur when the nitrogen gas is pre ionized by some random event and then can no longer hold off the fully charged capacitor thus causing the laser to fire prema turely The duration of this recharge delay varies by operating mode For internal triggering the power supply does not begin a recharge cycle until 1 ms before it is required to prepare for the next laser pulse For external trigger ing the power supply is delayed from recharging the capacitor for approxi 3 7 Model VSL 337ND S Air Cooled Nitrogen Laser Trigger Control mately 2 m
30. diately to Es If E is metastable i e atoms that occupy E have a relatively long life time the population will grow rapidly as excited atoms cascade from above Laser Description E4 A E3 A v2 vi Eo Ey Figure 3 2 A typical four level transition scheme For many materials the atom can decay to E by stimulated emission of a photons of frequency v Note however that the atom can also be re excited to E by the absorption of a photon of the same energy However if E atoms return rapidly to the ground state E the population of E is kept small and the rate of absorption of v is reduced In this way the population of E is kept large and that of E remains low thus establishing a population inversion between E and E Under these conditions light is amplified as it is emitted by one excited atom encoun ters another where it stimulates emission which stimulates emission of other excited atoms and so on The greater the population inversion the greater the amplification or gain The dynamics of lasing action depends in a critical way on the relative life times of the energy levels For example if the E level is slow to empty that is if it has a lifetime that is relatively long compared to the upper laser level E its population will soon exceed that of E and laser action will be extinguished However if a mechanism can be devised to quickly excite the higher levels transitory or pulsed laser am
31. e cover back towards the control panel and then lift it up Take care not to damage the shutter 3 Detach the connector from the OptoSync detector using the 32 in hex ball driver see Figure 6 1 AN b e ptoSync Assembly _ a 3 Mounting Screw a ge Figure 6 1 Detach the OptoSync detector 6 1 Model VSL 337ND S Air Cooled Nitrogen Laser 4 Disconnect the Trigger Transformer cable from the Plasma Cartridge Figure 6 2 Trigger Wire Connector High Voltage Connection 6 2 Maintenance and Service 6 Using a 7 64 in hex ball driver unscrew the 4 retaining screws that fas ten the Plasma Cartridge to the Base Plate Figure 6 4 Plasma Cartridge Retaining Screws x 4 e Figure 6 4 Unfasten the Plasma Cartridge Retaining Screws 4 a 7 Using a ite in nut driver remove the ground nut and slide off the black wire that grounds the Plasma Cartridge to the Base Plate Leave the smaller ground connections for the HVPS and Trigger Transformer in place Figure 6 5 Ground Connections ad Figure 6 5 Ground Connections 6 3 Model VSL 337ND S Air Cooled Nitrogen Laser 8 Carefully lift out the Plasma Cartridge Figure 6 6 Plasma Cartridg Figure 6 6 Remove the Plasma Cartridge 9 If the Pulse Counter option is used disconnect the lead at the back of the Plasma Cartridge Figure 6 7 Pulse Counter Connector CC 33 ari SA Fi
32. eci 10 d nano 10 n giga 10 G centi 10 c pico 1077 p mega 10 M mill 10 m femto 10715 f kilo 10 k micro 10 y atto 10 a xiii Abbreviations The following is a list of abbreviations used in this manual ac ACGIH ANSI AOM AR CDRH CE CW dc E O IEC FHG FWHM HR LBO Nd YAG Nd YLF Nd YVO OC RF SCFH SHG TEM THG UV alternating current American Conference of Governmental and Industrial Hygienists American National Standards Institute acousto optic modulator antireflection Center for Devices and Radiological Health Conformite Europeenne continuous wave direct current electro optic International Electrotechnical Commission fourth harmonic generation full width at half maximum high reflector infrared lithium triborate neodymium doped yttrium aluminum garnet neodymium doped yttrium lithium fluoride neodymium doped Vanadate output coupler radio frequency standard cubic feet per hour second harmonic generation transverse electromagnetic mode third harmonic generation ultraviolet wavelength XV Unpacking and Inspection Your VSL 337ND S nitrogen laser was packed with great care and its con tainer was inspected prior to shipment it left Spectra Physics in good con dition The laser in the shipping container has been tested for Shock and Vibration and found compliant to International Safe Transit Association Standard ISTA 2 A Upon receiving your las
33. egulations Chapter 1 subchapter J parts 1040 10 and 1040 11 as applicable To maintain compliance with these regulations once a year or whenever the product has been subjected to adverse environmental condi tions e g fire flood mechanical shock spilled solvent etc check to see that all features of the product identified on the CDRH Radiation Control Drawing found later in this chapter function properly Also make sure that all warning labels remain firmly attached 1 Verify that removing the jumper from or if implemented opening the interrupt switch connected to the INTERLOCK connector on the laser control panel Figure 2 1 prevents laser operation 2 Verify that the laser can only be turned on when the keyswitch is in the ON position and that the key can only be removed when the switch is in the off position 3 Verify that the emission indicator s provides a visible signal when the laser emits accessible laser radiation that exceeds the accessible emis sion limits for Class I 4 Verify the time delay between turn on of the emission indicator s and the start of the laser it must give enough warning to allow actioto avoid exposure to laser radiation 5 Verify that the beam attenuator mechanical shutter actually blocks exposure to laser radiation If any of the above items fail to operate as noted and you cannot correct the error please call your Spectra Physics service representative for assistance A list
34. er immediately inspect the outside of the shipping container If there is any major damage holes in the containers crushing etc insist that a representative of the carrier be present when you unpack the contents and before unpacking take a photograph of the container for use if a claim must be filed Carefully inspect your laser system as you unpack it If any damage is evi dent such as dents or scratches on the covers or broken connectors etc immediately notify the carrier and your Spectra Physics sales representa tive Keep the shipping container If you file a damage claim you may need it to demonstrate that the damage occurred as a result of shipping If you need to return the system for service at a later date the specially designed con tainer assures adequate protection If the instrument has to be returned to Spectra Physics for repair it must be sent in the shipping container with the original packing materials When unpacking and carrying the laser lift 1t by the bottom base plate not the cover The VSL 337ND S nitrogen laser is shipped in a single box Any accesso ries ordered with the laser system e g a dye laser attachment are shipped in their own separate containers xvii Chapter 1 Introduction Figure 1 1 The VSL 337ND S Nitrogen Laser The VSL 337ND S is a highly reliable self contained nitrogen laser that emits pulsed ultraviolet light at a wavelength of 337 nm with output pulses of 4 n
35. er s Guide Laser Focus World Penwell Publishing 10 Tara Blvd 5 Floor Nashua NH 03062 Tel 603 891 0123 Lasers and Optronics Buyer s Guide Lasers and Optronics Gordon Publications 301 Gibraltar Drive P O Box 650 Morris Plains NJ 07950 0650 Tel 973 292 5100 Photonics Spectra Buyer s Guide Photonics Spectra Laurin Publications Berkshire Common PO Box 4949 Pittsfield MA 01202 4949 Tel 413 499 0514 Chapter 3 Laser Description A Brief Review of Laser Theory Emission and Absorption of Light Laser is an acronym derived from Light Amplification by Stimulated Emis sion of Radiation Radiant emission and absorption take place within the arrangement of the electrons in the atomic or molecular structure of materi als Each electron occupies a unique orbital that has a distinct energy Fig ure 3 1 Together the energies of the electrons in their orbitals make up the energy state of an isolated atom Figure 3 1 Electrons occupy distinct orbitals in an atom or molecule Two different distributions are shown The level with the lowest possible energy at a given temperature is the ground state in which each electron is in the least energetic orbital avail able to it Higher energy levels are called excited states where some elec trons occupy orbitals farther from the nucleus The same considerations are also true of molecules with the additional complication that the individual atoms are in moti
36. ghout this manual to draw your attention to situations or procedures that require extra attention They warn of hazards to your health damage to equipment sensitive procedures and exceptional circumstances All messages are set apart by a thin line above and below the text as shown here Laser radiation is present Condition or action may present a hazard to personal safety Condition or action may present an electrical hazard to personal safety Condition or action may cause damage to equipment Action may cause electrostatic discharge and cause damage to equip ment Condition or action may cause poor performance or error Text describes exceptional circumstances or makes a special refer ence Do not touch Appropriate laser safety eyewear should be worn during this opera tion Refer to the manual before operating or using this device xi Standard Units The following units abbreviations and prefixes are used in this Spectra Physics manual Quantity Unit Abbreviation mass kilogram kg length meter time second Ss frequency hertz Hz force newton N energy joule J power watt W electric current ampere A electric charge coulomb C electric potential volt V resistance ohm Q inductance henry H magnetic flux weber Wb magnetic flux density tesla T luminous intensity candela cd temperature celcius C pressure pascal Pa capacitance farad F angle radian rad Prefixes tera 10 T d
37. gnal Control of the HVPS using the BURST signal provides several ways to modify the pulsed laser output These include e gating the pulsed laser output e producing pulsed laser output at repetition rates up to 60 Hz e suppression of spontaneous pulses at low repetition rates e suppression of HVPS switching frequency noise e Jaser attenuation via remote control Figure 5 1 shows an oscilloscope trace that demonstrates the use of the BURST signal to produce a gated output of groups of pulses The top trace shows the SYNC OUT signal with the laser internally triggered at a repeti tion rate of 30 Hz The middle trace displays the TTL level signal applied to the Burst connector from an external signal generator The lower trace displays detection of the pulsed laser output The combination of laser trig gering and the BURST signal results in the gating of 9 laser pulses spanning about 330 ms at a duty cycle around 50 Pulse gating can be used with the laser triggered either internally or exter nally and the BURST signal can be synchronous or asynchronous with TRIGGER 30 Hz Internal J H Trigger TTL Burst Input Gated Pulsed Laser Output Figure 5 1 Gating of 30 Hz Pulses Using the Burst Signal Burst Output Operation To operate the laser between 30 and 60 Hz place the Trigger Selection Switch in External Mode and supply a TTL external trigger
38. gned resonator mirrors are an integral part of the plasma cartridge which eliminates the need to align the laser The plasma cartridge is warranted to maintain at least 70 of its energy for twenty million pulses or two years whichever occurs first The laser is fac tory sealed air cooled and requires no warm up period The auto switch ing power supply automatically matches your line voltage Spectra Physics offers a fiber optic adapter a variety of optical fibers modular holders for filters attenuators energy meters and other optical components for the most common nitrogen laser applications This versa tile laser may also be mated with either of two available dye lasers to obtain tunable output from the infrared to the ultraviolet A list of available accessories including Spectra Physics part numbers is provided in Chapter 6 The VSL 337ND S includes the following features e flexible output control e modular design for long life and high reliability e uniform beam profile e single compact metal unit auto switching power supply e CE certification CE CDRH and FCC Compliance and Certification 1 2 The VSL 337ND S design incorporates RFI EMI shielding and the system complies with CE requirements for low radiated emissions and low volt age The directives to which this system has been certified are listed in the Declaration of Conformity statement in Chapter 2 The system also com plies with the limits for
39. gure 6 7 Pulse Counter Connector 10 Place the new Plasma Cartridge unto the Base Plate Warning W Maintenance and Service 11 If the Pulse Counter option is used attach the counter lead to the con nector on the back of the new Plasma Cartridge 12 Reconnect the black ground wire from the Plasma Cartridge to the ground terminal Figure 6 5 Failure to reconnect the black ground wire from the plasma cartridge to the base plate will result in a serious electrical shock hazard Damage may also result to electrical components 13 Attach the four retaining screws that fasten the Plasma Cartridge to the Base Plate Be sure to orient the spacers correctly between the screws and the Base Plate see Figure 6 8 BER i E Mounting Spacer Orientation Figure 6 8 Spacer Orientation 14 Connect the cables from the HVPS and the Trigger Transformer to the Plasma Cartridge 15 Separate the HVPS and trigger cables from each other to minimize the possibility that noise will trigger spontaneous laser pulses 16 Install the cover on the laser and connect the ac power cord 17 The laser is now ready for use The new Plasma Cartridge should not need alignment If after the Plasma Cartridge has been replaced the laser performs poorly contact your Spectra Physics representative 6 5 Model VSL 337ND S Air Cooled Nitrogen Laser Troubleshooting Accessories Replacement Parts The VSL 337ND S generally has t
40. in a continuous duty cycle Figure 3 5 100 kW 50 kW u gt lt Ans FWHM Figure 3 5 Typical output pulse VSL 337ND S Before any appreciable divergence occurs the cross section of the output of the VSL 337ND S is a square 7 mm on a side with a smaller square cut out of one of its corners that is about 3 mm x 3 mm as shown in Figure 3 6 ra anny Figure 3 6 Typical profile of the VSL 337ND S laser beam Laser Description This beam shape is determined by the approximately square cross section of the transverse electrical discharge combined with the blocking effect caused by the output coupler mirror of the optical cavity Figure 3 7 High Reflector TRANS VE Fann Output Coupler Figure 3 7 A representation of the VSL 337ND S laser cavity This mirror is a 90 circular segment with a convex surface oriented towards the plasma tube The mirror segment intercepts with its 90 edge a fraction of the laser beam 20 in order to supply the optical feedback into the amplifying medium that is the nitrogen gas discharge in the plasma tube Actually it is not the convex mirror but the lack of this mirror surface that allows the beam to exit from the optical cavity The concave high reflector at the rear of the cavity prevents the loss of about half the laser energy that would occur in its absence High Voltage Power Supply The performance of any nitrogen laser is critically depen
41. ions and examples of Burst mode for suggestions on how to minimize this possibility So for safety treat the laser as though it is constantly emitting pulses whenever it is on In addition note that whenever the laser is fully charged changing from external to internal triggering or vice versa produces a laser output pulse It is recommended that the laser first be shut down or the shutter be closed before changing the trigger mode After plugging in the ac power cord the most direct method of operating the laser is to use Internal mode as follows 1 2 3 4 au Close the shutter Set the Trigger Selection switch to INTERNAL Turn the keyswitch to ON Laser emission will begin in 3 to 5 seconds Open the shutter Fluorescence from the pulsed UV output is readily visible on a sheet of white paper Adjust the Repetition Rate control knob to the desired pulse frequency Turn off the laser by turning the keyswitch to the OFF position 5 1 Model VSL 337ND S Air Cooled Nitrogen Laser Burst Control Pulse Gating 5 2 Applying a TTL input to the Burst connector controls the duty cycle of the laser by disabling the High Voltage Power Supply HVPS When BURST is low or left floating laser operation proceeds as normal When BURST is TTL high the HVPS is halted from charging as long as the BURST sig nal remains high The trigger signal is logically ANDed with an inverted version of the BURST si
42. is warranty is extended only to the equipment manufactured by Spectra Physics This warranty also does not apply to equipment or components that upon inspection by Spectra Physics is found to be defective or unworkable due to abuse mishandling misuse alteration negligence improper installa tion unauthorized modification damage in transit or other causes beyond the control of Spectra Physics Model VSL 337ND S Air Cooled Nitrogen Laser This warranty is in lieu of all other warranties expressed or implied and does not cover incidental or consequential loss This warranty is valid for units purchased and used in the United States only Products shipped outside the United States are subject to a warranty surcharge Returning the Instrument for Repair Contact your nearest Spectra Physics field sales office service center or local distributor for shipping instructions or an on site service appointment You are responsible for one way shipment of the defective part or instru ment to Spectra Physics Use the original packing boxes to secure instruments during shipment If shipping boxes have been lost or destroyed order new ones Instruments can be returned only in Spectra Physics containers Service Centers Maintenance and Service Benelux Telephone 31 40 265 99 59 France Telephone 33 1 69 18 63 10 Germany and Export Countries Spectra Physics GmbH Guerickeweg 7 D 64291 Darmstadt Telephone 49 0615
43. length Spectral bandwidth Repetition rate Pulse width FWHM Pulse energy typical Pulse to pulse energy stability 10 Hz Peak power Average power 30 Hz Polarization Beam size area Beam divergence full angle 337 1 nm 0 1 nm continuous operation 0 30 Hz Burst Mode 0 60 Hz lt 4ns gt 300 uJ lt 4 standard deviation gt 75 kW gt 7 2 mW unpolarized 35 mm lt 0 3 mrad Due to our continuous product improvement program specifications are subject to change without notice Burst Mode operates at reduced duty cycles depending on the repetition rate See Chapter 6 for details Table 3 2 Trigger Specifications and Characteristics External trigger input pulse width optical pulse delay optical pulse temporal jitter OptoSync output drive impedance pulse width optical pulse temporal jitter optical pulse delay Sync output pulse width optical pulse temporal jitter Burst input TTL rising edge trigger 100 ns to 1 ms lt 1000 ns lt 40 ns standard deviation TTL rising edge trigger 50 Q 10 1 us lt 1 ns standard deviation lt 50ns TTL rising edge trigger 10 1 us lt 1 ns standard deviation TTL HI disable laser firing LO or float enable laser firing 1 Due to our continuous product improvement program specifications are subject to change without notice Optoisolated input 3 Available in both internal and external modes
44. mechanical housing cover during operation will not only invalidate the warranty but will also expose the operator to hazardous radiation There are several safety devices on this laser Figure 2 3 shows their loca tions Each is described in detail below The laser OFF ON keyswitch provides interlock safety to prevent unautho rized personnel from using the system when the key is turned to the OFF position and the key is removed Turning the key to the ON position closes the interlock and activates the laser The key can only be removed when the switch is in the OFF position Any electronic product radiation except laser radiation emitted by a laser product as a result of or necessary for the operation of a laser incorporated into that product Model VSL 337ND S Air Cooled Nitrogen Laser Push Pull o G Shutter Slide o o o Shutter Beam Aperture e e A U ON OFF INTERLOCKS DEFEATED Keyswitch Indicator LASEROn i e TRIGGER Indicator LASER E REPETITION O BURST or REMOTE SYNC INTERLOCK u INTERNAL AC Power Ih A O OPTOSYNC Input WR e REMOTE Interlock Figure 2 3 The VSL 337ND S laser showing the location of the safety devices on the front upper figure and rear lower figure panels Emission and Power Indicator When the red LASER indicator is on it means that ac power is applied to the unit and that lase
45. mission produces photons that have no directional or phase relation ship with one another The net absorption is the difference between the rates of emission and absorption The rate of excitation from E to E is proportional to the num ber of atoms in the lower level N Similarly the rate of stimulated emis sion is proportional to the population of the upper level N When a material is at thermal equilibrium most of its molecules are in the ground state The rate of absorption of photons exceeds that of emission with most of the absorbed energy dissipated in heating the material If enough light of frequency vis supplied the populations can be shifted until N N Under these conditions the rates of absorption and stimulated emission are equal and the absorption coefficient at frequency vis zero If the transition scheme is limited to two energy levels N can never exceed N because every upward transition is matched by one in the opposite direction However 1f three or more energy levels are employed it is possible to cre ate a population inversion where N gt N A model four level laser transition scheme is depicted in Figure 3 2 A photon of frequency v excites an atom from E to E for example the absorption of the photon causes one of the electrons of the atom to move to a higher energy orbital If the electron prefers to decay to E rather than E and if its lifetime at E is short the atom will decay almost imme
46. mples Output Synchronization 3 8 Sync Output A standard TTL rising edge signal derived from the trigger signal is avail able to synchronize the timing of applications to the pulsed laser output See Table 3 2 for characteristics of the TTL output pulses OptoSync Output A degree of delay and jitter between the trigger signal and the onset of ion ization is inherent in producing a rapid high voltage gas discharge As a result the interval between the trigger signal and the output of a laser pulse has a degree of unpredictability that may pose difficulty for some applica tions These effects may be minimized using the high speed TTL sync out put from the OPTOSYNC connector which is in extreme coincidence with the laser output pulse The OptoSync signal is derived from the detection of the laser pulse at the rear mirror of the laser cavity and it follows the laser output pulse by less than 50 ns The temporal jitter between the two is specified as less than 1 ns but is typically less than 500 ps Specifications Laser Description Since an OptoSync trigger pulse comes after a laser output pulse it may be necessary to introduce a delay in the data collection system to make the best use of this feature See Chapter 4 and Chapter 6 for further discussion and examples The OptoSync output signal is available in both internal and external trigger modes Table 3 1 VSL 337ND S Nitrogen Laser Output Characteristics Wave
47. n 3 Radiated radio frequency electromagnetic field immunity test EN 61000 4 4 1995 Electromagnetic compatibility EMC Part 4 Testing and mea surement techniques Section 4 Electrical fast transient burst immunity test EN 61000 4 5 1995 Electromagnetic compatibility EMC Part 4 Testing and mea surement techniques Section 5 Surge immunity test EN 61000 4 6 1996 Electromagnetic compatibility EMC Part 4 Testing and mea surement techniques Section 6 Immunity to conducted disturbances induced by radio frequency fields EN 61000 4 11 1994 Electromagnetic compatibility EMC Part 4 Testing and mea surement techniques Section 11 Voltage dips short interruptions and voltage vari ations immunity tests 73 23 EEC 1973 Low Voltage Directive EN60950 1992 with Amendment 1 1993 Amendment 2 1994 Amendment 3 1996 Amendment 4 1997 and Amnedment 11 1997 Safety of Information Tech nology Equipment including electrical business equipment EN60825 1 1993 with Amendments A1 1997 and A2 2001 Safety of laser prod ucts Part 1 Equipment classification requirements and users guide Bruce Craig Vice President Spectra Physics December 16 2003 2 10 Laser Safety Sources for Additional Information The following are some sources for additional information on laser safety standards safety equipment and training Laser Safety Standards Safe Use of Lasers Z136 1 1993 American National Standards I
48. nnector BNC provides a TTL rising edge signal derived from the trigger pulse to allow the user to synchronize individual laser pulses to an application or experiment This output is available with either internal or external triggering Unlike the OptoSync signal see below the SYNC signal is produced simultaneously with the trigger pulse so that the laser output pulse follows the SYNC output lt 1000 ns later When the VSL 337ND S is triggered internally SYNC provides a simulta neous TTL output pulse that is 10 us 1 us in duration to allow synchro nization of an application or experiment to individual laser pulses For external triggering SYNC output provides a buffered version of the external trigger input to allow daisy chaining of the trigger signal to other sys tems OPTOSYNC output connector BNC provides the preferred means of synchronizing applications and experiments to the pulsed laser output when feasible Unlike the SYNC signal see above the OPTOSYNC signal is derived from the actual detection of the laser pulse and operates at a high degree of temporal coincidence with the actual laser output However 4 3 Model VSL 337ND S Air Cooled Nitrogen Laser also unlike the SYNC output signal the OPTOSYNC signal follows the emis sion of the laser pulse Consequently in order to make good use of Opto Sync it is usually necessary to produce an artificial delay in data collection A degree of delay and ji
49. nstitute ANSI 11 West 42 Street New York NY 10036 Tel 212 642 4900 Occupational Safety and Health Administration Publication 8 1 7 U S Department of Labor 200 Constitution Avenue N W Room N3647 Washington DC 20210 Tel 202 693 1999 A Guide for Control of Laser Hazards 4th Edition Publication 0165 American Conference of Governmental and Industrial Hygienists ACGIH 1330 Kemper Meadow Drive Cincinnati OH 45240 Tel 513 742 2020 Internet www acgih org home htm Laser Institute of America 13501 Ingenuity Drive Suite 128 Orlando FL 32826 Tel 800 345 2737 Internet www laserinstitute org Compliance Engineering 70 Codman Hill Road Boxborough MA 01719 Tel 978 635 8580 International Electrotechnical Commission Journal of the European Communities EN60825 1 TR3 Ed 1 0 Laser Safety Measurement and Instrumentation IEC 309 Plug Outlet and Socket Coupler for Industrial Uses Tel 41 22 919 0211 Fax 41 22 919 0300 Internet http ftp iec c h Cenelec European Committee for Electrotechnical Standardization Central Secretariat rue de Stassart 35 B 1050 Brussels Document Center 1504 Industrial Way Unit 9 Belmont CA 94002 4044 Tel 415 591 7600 Model VSL 337ND S Air Cooled Nitrogen Laser Equipment and Training 2 12 Laser Safety Guide Laser Institute of America 12424 Research Parkway Suite 125 Orlando FL 32826 Tel 407 380 1553 Laser Focus World Buy
50. nts Environmental Specifications CE Electrical Equipment Requirements For information regarding the equipment needed to provide the electrical service listed in Specifications in Chapter 3 please refer to specification EN 309 Plug Outlet and Socket Couplers for Industrial Uses listed in the official Journal of the European Communities Environmental Specifications FCC Regulations CDRH Regulations The environmental conditions under which the laser system will function are listed below Indoor use Altitude up to 3000 m Temperatures 4 C to 40 C Maximum relative humidity 85 non condensing for temperatures up to 35 C Mains supply voltage do not exceed 10 of the nominal voltage Insulation category I Pollution degree 2 This equipment has been tested and found to comply with the limits for a Class B digital device pursuant to Part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment This equip ment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause harmful interference to radio communications Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense Modifications to the laser system
51. occcoccccco ern 5 6 Figure 5 6 Laser pulses captured using the SYNC input top versus the OPTOSYNC triggering input bottom 5 7 Figure 5 7 Example of Delay Compensation Using Coaxial Cable oococcoccoccoooo 5 8 Figure 5 8 OPTOSYNC Delay Compensation Using Coaxial Cable ooooooooooooooo 5 8 Figure 6 1 Detach the OptoSync detector 6 1 Figure 6 2 Detach the Trigger Connector ooo 6 2 Figure 6 3 Detach the HVPS Connector ooccccccccccc en 6 2 Figure 6 4 Unfasten the Plasma Cartridge Retaining Screws 3 6 3 Figure 6 5 Ground Connections 6 3 Figure 6 6 Remove the Plasma Cartridge o oocooocoococor een 6 4 Figure 6 7 Pulse Counter Connector 6 4 Figure 6 8 Spacer Orientation 6 5 List of Tables Table 2 1 Label Translations seen rennen een 2 9 Table 3 1 VSL 337ND S Nitrogen Laser Output Characteristics 3 9 Table 3 2 Trigger Specifications and Characteristics 3 9 Table 3 3 Mechanical and Electrical Specifications 3 10 Table 3 4 FUSE RAUNG as 4 2334 di a LA os 3 10 Table 5 1 Burst Mode Duty Cycles 5 3 Tabl6 6 2 ACCESSOS cio a EA A ra A e EE AA BB 6 6 Table 6 1 Replacement Parts 6 6 Model VSL 337ND S Air Cooled Nitrogen Laser Danger Laser Radiation Danger A Danger Warning Warning ESD N Caution Note Don t Touch Eyewear Required U d U d Y E A Warning Conventions The following warnings are used throu
52. of service centers can be found in Customer Service at the end of this manual 0 39 uW for continuous wave operation where output is limited to the 400 to 1400 nm range Laser Safety CE CDRH Radiation Control Drawing Refer to the CE CDRH Warning Labels on the next page Cover Safety Interlock Internal Shutter Slide Figure 2 5 CE CDRH Radiation Control Drawing Model VSL 337ND S Air Cooled Nitrogen Laser CE CDRH Warning Labels Spectra Physics MODEL INVISIBLE LASER RADIATION NUMBER AVOID DIRECT EXPOSURE CE Aperture Label 2 en SERIAL NUMBER 337 nm 400 pd MAX ENERGYIFULSE MADE IN U S A E J CLASS IIb LASER PRODUCT Model Serial Identification Danger Laser Radiation Label 1 Label 4 CE Certification Label 3 DANGER VISIBLE AND INVISIBLE LASER RADIATION AV O D E X P O S U R E WHEN OPEN AND INTERLOCK DEFEATED 110 240 VAC AVOID EYE OR SKIN EXPOSURE TO DIRECT VISIBLE AND INVISIBLE LASER RADIATION 50 60 HZ 1 5A OR SCATTERED RADIATION REFER IS EMITTED FROM THIS APERTURE FUSE F 1 8A 250V REPLACE WITH SAME TYPE AND RATING SERVICING TO QUALIFIED PERSONNEL Aperture Label 5 Fuse Label 6 CE Interlocked Cover Label 7 Avoid Exposure To Beam utkontakt mit Strahl verme ider Class 3B Laser Product Laserprodukt der Klasse 3B Average Power 7 2mW 30 hZ ttlere Leistung 7 2mW bei 30h JAPAN LABEL
53. of the VSL 337ND S air cooled nitrogen laser OEM versions of this laser will carry CE marking when appropriate for the specific model Hazards associated with the use of ultraviolet lasers generally fall into the categories listed below At all times while working with these lasers please be aware of these potential hazards and act accordingly You are responsi ble for your health and the health of those working around you e Exposure to laser radiation can result in damage to the eyes or skin e Exposure to chemical hazards such as laser generated airborne con taminants can be health hazards when they are released as a result of laser material processing or as by products of the lasing process itself When these lasers are used to pump dye laser systems be aware that the dyes used can be extremely hazardous to your health if inhaled or in some cases even touched e Exposure to high voltage electrical circuits present in the laser power supply and associated circuits can result in shock or even death e Possible health risks are present if pressurized hoses cylinders liquids and gasses used in laser systems are damaged or misused 2 1 Model VSL 337ND S Air Cooled Nitrogen Laser Precautions For The Safe Operation Of Class lllb Medium Power Lasers 2 2 Wear protective eyewear at all times selection depends on the wave length and intensity of the radiation the conditions of use and the visual function required Protective
54. on relative to their molecular partners A molecule has different modes of vibration and rota tion depending on its shape If a molecule changes its vibrational or rota tional mode the distribution of its electrons will also change Light will be used to describe the portion of the electromagnetic spectrum from far infrared to ultraviolet Model VSL 337ND S Air Cooled Nitrogen Laser Population Inversion 3 2 A transition from one energy level to another happens when the atom or molecule either absorbs or emits energy Upward transitions can be caused by collisions with electrons or other atoms or molecules or by the absorp tion a photon A transition from a lower level E to a higher one E will only occur if the energy of the absorbed photon matches the energy differ ence between levels i e where h is Planck s constant and vis the frequency of the photon Likewise when an atom excited to E decays to E it loses energy equal to E E The atom may decay spontaneously emitting a photon with energy hv and wavelength A where he 2 EEN An atom excited to E can also be stimulated to decay to E by interacting with a photon of frequency v which is perhaps produced by the spontane ous emission from a neighboring atom This stimulated decay emits a pair of new photons that are identical to the absorbed one in phase frequency and direction This is known as stimulated emission In contrast spontane ous e
55. ontrol Panel Model VSL 337ND S Air Cooled Nitrogen Laser Controls Indicators Connections Danger Laser Radiation 4 2 Laser OFF ON interlock keyswitch provides interlock safety to prevent unauthorized personnel from using the system when the key is turned to the OFF position and the key is removed Turning the key to the ON position closes the interlock and activates the laser after a 3 to 5 second delay The key can only be removed when the switch is in the OFF position REPETITION RATE knob controls the repetition rate of the pulsed laser output from O to 30 Hz when the INTERNAL EXTERNAL trigger selection switch is set to INTERNAL INTERNAL EXTERNAL trigger selection toggle switch controls the repe tition rate of the laser through the Repetition Rate knob when it is in the INTERNAL position When in the EXTERNAL position the repetition rate is controlled by an external TTL trigger signal applied to the TRIGGER con nector LASER emission indicator red shows that power is supplied to the laser and that laser emission is present or imminent This indicator turns on 3 to 5 seconds before actual emission occurs INTERLOCKS DEFEATED indicator green indicates the laser is ready to fire i e that all the interlocks are closed TRIGGER connector BNC provides control of the pulsed laser output from an externally applied TTL trigger signal A laser pulse is fired on the rising edge of a TTL pulse rise time
56. orms to the requirements of 21 CFR 1040 10 and 1040 11 CDRH and uses a power supply that is a UL recognized ULR component It has also been designed and tested to comply with the limits for a Class B digital device pursuant to Part 15 of the FCC Rules The laser when in the shipping container has been tested for Shock and Vibration and been found to comply with International Safe Transit Associ ation Standard ISTA 2 A Should you experience any problems with any equipment purchased from Spectra Physics or are in need of technical information or support please contact Spectra Physics as described in Customer Service This chapter contains a list of world wide Spectra Physics service centers you can call if you need help Every effort has been made to ensure that the information in this manual is accurate All information in this document is subject to change without notice Spectra Physics makes no representation or warranty either express or implied with respect to this document In no event will Spectra Physics be liable for any direct indirect special incidental or consequential dam ages resulting from any defects in this documentation Finally if you encounter any difficulty with the content or style of this manual or encounter problems with the laser itself please let us know The last page of this manual is a form to aid in bringing such problems to our attention Thank you for your purchase of Spectra Physics instrume
57. pins are open the voltage across the them is 24 V maximum If a switch is used it must be certified for low voltage low current operation If the pins are not shorted the laser will not operate a Figure 4 3 Remote Interlock Connector BURST input connector BNC is used to allow the laser to output bursts of pulses at repetition rates from 30 Hz to 60 Hz by reducing the duty cycle so that the laser is not damaged The BURST TTL input signal over rides the trigger signal whether trigger ing is internal or external and modifies the laser duty cycle by controlling the charging of the high voltage power supply HVPS When BURST is low or floating laser operation and triggering proceeds normally no bursts When BURST is TTL high the HVPS is prevented from charging This feature is useful for gating the output of the laser whether triggered internally or externally into separate groups of pulses with a user specified interval between groups of pulsed output Another use of the BURST port is to selectively control when the HVPS is allowed to recharge after the previ ous laser pulse This is helpful in applications requiring low noise where the switching frequency of the HVPS might cause problems Burst mode can also be used in a number of different configurations that have separate requirements for internal or external triggering See Chapter 5 for more details on these and other Burst mode functions SYNC output co
58. plification may be possible This in fact is the case with the nitrogen laser The lower laser level is slow to decay so the population inversion is only sustainable for a few nanosec onds However a fast pulse of high voltage discharge is capable of exciting a large number of molecules to the upper level quickly enough so that an inversion is possible Nitrogen as a Laser Medium The nitrogen laser transition takes place between energy levels of the N nitrogen molecule Each mode of vibration of the molecule interacts with the orbitals causing many new and closely spaced levels to become avail able to the electrons Electrons are excited to a range of upper energy levels in one mode of vibration of the molecule and decay to a range of electronic levels in a lower energy vibrational mode Both the internal vibration of the molecular atoms and the energies of their electrons change simultaneously in what is called a vibronic transition 3 3 Model VSL 337ND S Air Cooled Nitrogen Laser The Optical Cavity 3 4 Upper Laser Level 10 337 1nm Lower Laser 8 VIN gt Level Intermediate Metastable State gt x Slow Decay o Cc gt ZS T u E 4 E ES xx Very Slow Decay D o Ss O 7 a Ground State Q 2 y 0 Separation between Atoms in N Molecule Figure 3 3 The long lifetimes of the lower molecular energy levels are responsible for the pulsed nature of the
59. r is usu ally charged and the laser is waiting for a trigger signal Since the laser is ready to be fired at any time all precautions should be taken to avoid acci dental laser exposure should the laser trigger unexpectedly Burst Input Connector A TTL level signal applied to this connector sets the laser to burst mode as explained in Chapter 6 Operation The maximum allowable pulse rate is 60 Hz in burst mode At low repetition rates burst mode control allows the laser power supply to be disabled Cover Safety Interlock Danger Y An interlock cover switch ensures that the VSL 337ND S nitrogen laser cannot be operated if the external sheet metal cover is not in place The switch is internal located toward the rear of the unit see Fig 3 7 The laser should not be opened by the user except to change the plasma car tridge and then only by someone trained in this procedure by Spectra Physics Do not operate the VSL 337ND S nitrogen laser with its cover removed except when necessary during required service Removing the cover may expose personnel to hazardous voltages and radiation It also increases the rate of optical surface contamination Model VSL 337ND S Air Cooled Nitrogen Laser Maintenance Necessary to Keep this Laser Product in Compliance with Center for Devices and Radiological Health CDRH Regulations 2 6 This laser product complies with Title 21 of the United States Code of Fed eral R
60. r radiation is present or imminent This indicator turns on 3 to 5 seconds before actual emission occurs Shutter The mechanical shutter is hand operated by means of the push pull slide on the front panel Figure 2 3 Remote Interlock The REMOTE INTERLOCK allows the user to stop laser operation by the activation of a user supplied safety switch such as a doorway entry switch This connector is supplied with a connector jumper that must be installed if the interlock is not to be used If the REMOTE INTERLOCK con nector pins J and J are open the laser will not operate ri Figure 2 4 Remote Interlock Connector Laser Safety When these pins are shorted the current supplied through them is 24 mA When the interlock connector is open the voltage across them is 24 V max imum Chose an appropriate switch for low voltage low current service Interlocks Defeat Indicator When on this green light Figure 2 3 indicates all interlocks are closed and that the laser is ready to fire If it is off the laser will not operate External Trigger Connector Danger Laser Radiation It is possible to trigger this laser externally using a TTL level signal sup plied through the TRIGGER connector Operating the laser in this fashion is explained in Chapter 6 Operation The maximum allowable pulse rate is 30 Hz continuous or up to 60 Hz in burst mode Even when the laser is not firing the laser energy storage capacito
61. rbeiten an qualifi ziertes Personal Model VSL 337ND S Air Cooled Nitrogen Laser CE Declaration of Conformity We Spectra Physics 1335 Terra Bella Avenue Mountain View CA 94043 United States of America declare under our sole responsibility that the following products VSL 337ND S XXX XXX are numbers that denote Customer Specific Models manufactured after November 1 2003 meet the intent of EMC Directive 89 336 EEC for Electromagnetic Com patibility and Directive 73 23 EEC the Low Voltage Directive Compli ance was demonstrated to the following Specifications as listed in the official Journal of the European Communities 89 336 EEC 1989 EMC Directive EN61326 1997 A1 1998 A2 2000 Electrical equipment for measurement con trol and laboratory use EMC requirements EN 61000 3 2 1995 Electromagnetic compatibility EMC Part 3 Limits Section 2 Limits for harmonic current emissions equipment input current lt 16 A per phase EN 61000 3 3 1995 Electromagnetic compatibility EMC Part 3 Limits Section 3 Limitation of voltage fluctuation and flicker in low voltage supply systems for equip ment with rated current of lt 16 A EN 61000 4 2 1995 Electromagnetic compatibility EMC Part 4 Testing and mea surement techniques Section 2 Electrostatic discharge immunity test EN 61000 4 3 1995 Electromagnetic compatibility EMC Part 4 Testing and mea surement techniques Sectio
62. rouble free operation If the laser fails to produce output verify the following connections or settings Note that while this list appears elementary performing these checks results in the resolution of most problems typically referred to Spectra Physics and can save a service call e Verify the ac power cord is connected to the laser e Verify the keyswitch has been turned on e Verify the INTERLOCKS DEFEATED indicator is glowing green i e the interlocks are closed e Verify the shutter is open e Verify the REPETITION RATE knob is not set to zero If the laser still does not produce an output beam it is likely the Plasma Cartridge must be replaced Other symptoms that indicate the problem lies with the Plasma Cartridge are low power and the recurrence of untriggered pulses in EXTERNAL mode The following laser accessories are available Table 6 2 Accessories Description Part Number DUO Tunable Dye Laser 360 700 nm 3337220 00 DUO Tunable Dye Laser 600 960 nm 3337221 00 DUO Fixed Wavelength Dye Laser 360 950 nm 3 10 nm band 3337210 00 width Fiber Optic Coupler SMA Connector 337702 01 200 um diameter fused silica fiber SMA connectors 337710 01 400 um diameter fused silica fiber SMA connectors 337711 01 600 um diameter fused silica fiber SMA connectors 337712 01 1 mm diameter fused silica fiber SMA connectors 337714 01 The following parts may be purchased to replace broken components
63. s after a pulse The external triggering delay can be controlled using Burst Mode Refer to Chapter 6 for more information The duty cycle of the power supply is limited by the characteristics of the nitrogen laser excitation There is no advantage to building or paying for a power supply that can exceed the maximum repetition rate of the pulsed laser output Thus the upper limit of charging performance is 15 ms The laser may be triggered internally or externally The REPETITION RATE knob on the rear control panel provides internal pulse rate adjustment between 0 to 30 Hz External trigger control is available through the TRIG GER connector on the control panel which accepts TTL pulses with a ris ing edge from 100 ns to 1 ms and triggers a laser pulse less than 700 ns later Burst Mode By using the BURST input to reduce the duty cycle the VSL 337ND S can be operated at a repetition rate as high as 60 Hz This input signal also pro vides a flexible means of controlling laser output in a variety of ways including the gating of pulses in a grouped output and reducing power sup ply noise Input is a TTL level signal Burst mode functions by controlling the charging timing of the power sup ply In this sense Burst mode over rides the trigger signal suppressing the signal when the BURST signal is TTL high Burst mode operates with both internal and external triggering See Chapter 4 and Chapter 6 for detailed descriptions and exa
64. s available when you call Service data or shipping instruc tions will be promptly supplied To order optional items or other system components or for general sales assistance dial 1 800 SPL LASER in the United States or 1 650 961 2550 from anywhere else All parts and assemblies manufactured by Spectra Physics are uncondi tionally warranted to be free of defects in workmanship and materials for the period of time listed in the sales contract following delivery of the equipment to the F O B point Liability under this warranty is limited to repairing replacing or giving credit for the purchase price of any equipment that proves defective during the warranty period provided prior authorization for such return has been given by an authorized representative of Spectra Physics Spectra Physics will provide at its expense all parts and labor and one way return shipping of the defective part or instrument if required In warranty repaired or replaced equipment is warranted only for the remaining portion of the orig inal warranty period applicable to the repaired or replaced equipment This warranty does not apply to any instrument or component not manufac tured by Spectra Physics When products manufactured by others are included in Spectra Physics equipment the original manufacturer s war ranty is extended to Spectra Physics customers When products manufac tured by others are used in conjunction with Spectra Physics equipment th
65. sign of these lasers to create a beam of sufficiently useful quality Often the cavity mirrors provided are as much to shape the beam output as to enhance the amplification mechanism The shape of the laser output beam is very much dependent on the fre quency content of the beam This is determined by the width of the gain in frequency space around the transition frequency and by the design of the optical cavity The optical cavity supports a number of standing waves modes of the kind found in waveguides for RF systems Each mode has a different cross section and frequency The output beam is a superposition of the cross sections of these modes for its spatial character and of the mode frequencies for its spectral content For applications seeking maximum output power a cavity design that results in the creation of a number of these spatial or higher order modes is used so that the laser beam within the gain medium overlaps most of the volume of the excited molecules The optical design of the cavity must also produce a beam that allows the useful application of its power with charac teristics such as a smooth profile and a low divergence The duration or pulse width of the output is specified by plotting ampli tude as a function of frequency and measuring the width of the curve where the output has fallen to one half its maximum value full width at half maximum or FWHM As might be expected the spectral content of high
66. tter are inherent in producing a rapid high voltage gas discharge These effects can be minimized using the OptoSync signal a high speed TTL sync low jitter output signal 10 us 1 us in duration that is in extreme coincidence with the laser output pulse The detection of the laser pulse is by a photodiode at the rear mirror of the laser cavity The delay between the laser output pulse and the OPTOSYNC signal is specified as lt 50 ns while the temporal jitter between the two is specified as lt 1 ns and is typically lt 500 ps The OptoSync signal is available in both internal and external trigger modes and it has TTL 50 drive capabil ity Examples of employing the OptoSync feature are given in Chapter 5 The relationship between the triggering of the laser either internal or exter nal the production of a laser output pulse and the resulting production of an OptoSync pulse is shown in Figure 4 4 An oscilloscope representation shown in Figure 4 5 lt gt Laser Pulse Delay lt 1000 nS Trigger Signal D or SYNC output Laser Output Pulse gt Delay Jitter lt 7nso i A EA El i po gt i i lt OPTOSYNC Delay lt 50 ns e oi OPTOSYNC Y Output i gt OPTOSYNC Jitter lt 1 ns o Figure 4 4 The timing between the trigger signal the laser pulse and OPTOSYNC output Controls Indicators and Connections T i l l ee
67. us delay inherent in the HVPS Power Supply Switching Noise TTL Burst Input Figure 5 3 HVPS Recharge Noise As before using the Burst input for noise suppression still requires the HVPS be allowed to recharge fully for at least 15 ms before the next trigger pulse The reduction in the spectral content of the noise is shown in the FFT displays in Figure 5 4 38 kHz switching noise rene duh Au 1 IN Be Figure 5 4 The Noise Spectrum With above and Without below the HVPS Recharging Delay 5 5 Model VSL 337ND S Air Cooled Nitrogen Laser Electronic Control of Laser Energy It is possible to attenuate the energy of the laser pulses and the average power of the laser beam by using the BURST signal to reduce the time allowed for the HVPS to recharge the capacitor to less than the nominal 15 ms Because the HVPS will not have time to charge the capacitor to the 17 kV standard voltage before the laser is triggered the nitrogen gas that is sufficiently excited to provide laser amplification is reduced The result is lower energy output pulses By setting the BURST input signal to low 10 ms prior to triggering the laser a reduction of laser energy of approximately 50 can be achieved the exact duration will vary slightly from unit to unit Extending the dura tion of B

Model VSL-337ND-S - Spectra

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