Chapter 7I Agilent 10717A Wavelength Tracker
Contents
1. Chapter 71 Agilent 10717A Wavelength Tracker Installation and Alignment Installation and Alignment Pre installation checklist In addition to reading chapters 2 through 4 and Chapter 15 Accuracy and Repeatability complete the following items before installing a laser positioning system into any application g Complete Beam Path Loss Calculation see Calculation of signal loss in Chapter 3 System Design Considerations of this manual g Provide for aligning the optics laser head and receiver s on the machine g Besureto allow for transmitted beam offset of beam splitters Agilent 10700A and Agilent 10701A in your design See the offset specifications under the Agilent 10717A Wavelength Tracker Specifications and Characteristics section at the end of this subchapter Alignment aid To help in aligning the Agilent 10717A Wavelength Tracker an Alignment Aid Agilent Part Number 10706 60001 is included This is the same alignment aid used on the Agilent 10706A Plane Mirror Interferometer and Agilent 10715A Differential Interferometer Procedure This procedure describes the installation and alignment of the wavelength tracker axis The two units that require alignment are the Agilent 10717A Wavelength Tracker and the Agilent 10780C or Agilent 10780F Receiver The wavelength tracker unit itself is prealigned at the factory and requires nointernal alignment The Wavelength Tracking Compensation syst2. 2002 Agilent Technologies Printed in U S A 07 02 This is a chapter from the manual titled Laser and Optics User s Manual For complete manual order Paper version p n 05517 90045 CD version p n 05517 90063 This chapter is p n 05517 90116 User s Manual
3. Agilent 10717A Wavelength Tracker _ MEASUREMENT PATH fp Aperture A Aperture B Pa a pA Plate Front Rear A Y H Mirror _ _____ Mirror To Agilent J 7 Ys Receiver lt Q hg m m m m m m m m m f 5 LA B h E From Laser be ma am G mu mu am prz ay R mR mre m G a m m m m R Y qa am Tr Prd J m m m mb ml K I fB Y Al Ree Z p I 1 ETALON 1 4 Plate Lv ay Fixed Optical Path ar Lu m Agilent 10715A Differential Interferometer Top View Agilent 10717A Wavelength Tracker COMPOSITE fa and fp Aperture A Aperture B P Lda Arias Front Rear A y H Mirror Mirror To Agilent a B E Receiver lt lt F From Laser gt gt m m m m mhd m m m m m va Head S sak erdwweeee gt gt E i ETALON 14 Plate Yy Lo u Fixed Optical Path io S Agilent 10715A Differential Interferometer Top View Agilent 10717A Wavelength Tracker LEGEND a fy Qa gt fp lt gt faand fg f P Rounded corners are used to help you trace paths Figure 71 2 Agilent 10717A Wavelength Tracker laser beam path User s Manual 71 3 Chapter 71 Agilent 10717A Wavelength Tracker Description The Agilent 10717A Wavelength Tracker provides a higher degree of accuracy than environmental sensors such as the Agilent 10751C or Agilent 10751D Air Sensor thereby improving the laser system measurement performance F or a more detailed comparison of compensation methods see WOL Compensatio
4. Mounting Clearance Required Etalon Length 127mm 5 inches nominal 3 mm 0 12 inch around perimeter Optical Efficiency Calibration none required Typical 36 NOTE If an Agilent Automatic Compensation Board is not Worst Case 25 used system measurement repeatability may be calculated as Angular Adjustment Range at nominal position follows Pitch 1 R 127 0 028 ppm AT 0 06 ppm C Yaw l AP 0 002 ppm mm Hg Translational Adjustment Range at nominal position sie ation i Vertical 3 mm 0 12 inch electronics resolution in nm 5 nm for Agilent Automatic Compensation Boards Horizontal 3 mm 0 12 inch k 79 25 mm 3 120 7 39 62 mm 1 560 30 10 mm La 5 1 185 30 10 mm 1 185 Mounting Holes 3 x 10 32 UNF 2A x 13 mm 0 5 DP 260 35 mm 10 25 177 80 0 25 mm 7 00 010 Y 15 88 mm Centerline of laser beam 0 625 Output beam to receiver tT 67 0 mm 2 63 1 y 32 0 mm 12 70 mm 1 25 0 500 Figure 7l 7 Agilent 10717A Wavelength Tracker dimensions User s Manual 71 15 Input beam from laser Customer mounting surface a Chapter 71 Agilent 10717A Wavelength Tracker Installation and Alignment 71 16 Product specifications and descriptions in this document subject to change without notice Copyright C
5. not remove red tape and hitch pin clips at this time 2 Engage three to four threads of the three mounting screws see Figure 71 4 by rotating each screw three to four revolutions using the hex ball driver supplied WAVELENGTH TRACKER ADJUSTMENT HARDWARE Rear Mirror Mounting Screw hidden tit A Mounting Screw Pitch Adjustment Screw A Input Aperture 0 L N Ar Mounting Screw Vertical Translator Adjustment Screw Figure 7I 5 Agilent 10717A Wavelength Tracker adjustment hardware 3 Remove the three hitch pin clips by pulling on the red tape 4 Tighten the front mounting screw Figure 71 5 until slight resistance is sensed 5 Placea piece of translucent tape over the differential interferometer s A input aperture see Figure 71 4 Flatten the tape tightly against the input A aperture to produce a high resolution outline of the input aperture You should see a well defined laser pattern on the tape 71 10 User s Manual NOTE 10 11 12 Chapter 71 Agilent 10717A Wavelength Tracker Installation and Alignment Rotate the vertical translator adjustment screw see Figure 71 5 until the input beam is vertically centered about the input aperture At the same time move the tracker horizontally to center the laser beam horizontally Tighten the front mounting screw see Figure 71 5 finger tight when the laser beam is centered on the input aperture Remove
6. the translucent tape from the differential interferometer input aperture Install the quarter waveplate alignment aid so the primary measurement beam passes through the hole in it see Figure 71 6 Standard input aperture for the wavelength tracker is A positive sense If the input beam goes to aperture B the direction sense changes negative sense See Special Considerations section in this subchapter and Table 71 1 for wavelenght tracker direction sense change details Select the small aperture of the laser head Rotate the pitch adjustment screw see Figure 71 5 until the laser beam autoreflected back to the laser head is centered vertically about the output beam Y aw the baseplate back and forth until the autoreflected beam is concentric with the laser head aperture Tighten all three mounting screws alternately see Figure 71 5 until finger tight Now tighten the screws by applying a torque of 0 9 Newton meter 8 inch pounds Maintain proper autoreflection as the screws are tightened Correct for any change by readjusting the wavelength tracker in pitch and yaw until the laser beam is autoreflected back into the laser head This insures proper angular alignment User s Manual 7I 11 Chapter 71 Agilent 10717A Wavelength Tracker Installation and Alignment INSTALLATION OF ALIGNMENT AID Laser Beam D Alignment Aid O E Figure 7I 6 Installation of alignment
7. J Agilent 10717A Wavelength Tracker Chapter 71 Agilent 10717A Wavelength Tracker Description Description The Agilent 10717A Wavelength Tracker see Figure 71 1 uses one axis of a laser measurement system to report wavelength of light changes not changes in position displacement The Agilent 10717A Wavelength Tracker s output can be used to correct displacement values reported via other measurement axes in the system Since the wavelength of the laser light is the length standard used in Agilent laser measurement systems being able to track these changes helps to make more accurate measurements The Agilent 10717A Wavelength Tracker consists of an optical reference cavity called an etalon and an Agilent 10715A Differential Interferometer Both components are mounted on a common metal baseplate and prealigned at the factory Built in baseplate adjustments simplify installation and alignment to the laser system Agilent 10717A Wavelength Tracker Figure 7I 1 Agilent 10717A Wavelength Tracker 71 2 User s Manual Chapter 71 Agilent 10717A Wavelength Tracker Description REFERENCE PATH fa 2 4 Plat Aperture A Aperture B E J e Front Rear D Mirror _____ Mirror To Agilent fa Y A Receiver lt gt Yj Y From Laser gt Ss 7 Head eA l Wa L A yy E T E stakes E ETALON 14 Plate i lei Fixed Optical Path Agilent 10715A Differential Interferometer Top View
8. aid NOTE Tightening the mounting screws unevenly or exceeding the specified torque specification will disrupt alignment and degrade overall system performance 13 Remove the alignment aid 14 Return the laser head turret to its larger aperture Two parallel unclipped beams should now exit the differential interferometer 15 Check for a circular unclipped laser beam As long as the two beams are not clipped the wavelength tracker alignment is adequate 71 12 User s Manual 16 17 19 20 21 Chapter 71 Agilent 10717A Wavelength Tracker Installation and Alignment Alignment of the receiver is accomplished by moving it or its sensor head from side to side and pitching and yawing it to center the beam on its lens Coarse beam alignment is performed using the snap on Alignment Target fixture Agilent Part Number 10780 40003 or Agilent Part Number 10780 40009 supplied with the receiver see Chapter 8 Receivers in this manual For the wavelength tracker this target is used only to align the receiver or its sensor head to the incident beam To check the final optical alignment of the Wavelength Tracking Compensation system place a rectangular gage block over the lens of the receiver and pressed against the receiver s case or its sensor head s input face and autoreflect the beam back toward the differential interferometer of the wavelength tracker When the receiver or its sensor head is mounted properly
9. em should be installed and aligned with the following considerations in mind e The wavelength tracker should be installed so that the air it samples is the same air through which the measurement axis beam passes e Thewavelength tracker should be aligned to obtain maximum laser beam signal at the receiver See multiaxis applications information in Chapter 3 System Design Considerations and elsewhere in this manual e TheAgilent 10780C 10780F E1708A or E 1709A receiver should be mounted in such a way that its LED indicator and gain adjustment potentiometer are accessible User s Manual 71 7 NOTE Chapter 71 Agilent 10717A Wavelength Tracker Installation and Alignment e TheAgilent 10780C 10780F E1708A or E 1709A receiver is properly aligned when 1 the laser beam is centered on its input aperture 2 the LED indicator on top is lighted and 3 the voltage at the its test point is greater than 0 7 Vdc A receiver alignment procedure is provided in Chapter 8 Receiver of this manual s Nomorethan six measurement axes are installed in addition tothe wavelength tracker Alignment starts at the laser head and moves out one component at a time laser head beam bending and beam splitting optics wavelength tracker and then receiver until the last component of the Wavelength Tracking Compensation system is aligned and the laser beam is centered on the receiver s aperture This alignment procedure has the lase
10. lignment steps 16 through 20 the voltage measured at the test point is still below 0 7 Vdc the entire alignment procedure must be repeated until the misalignment is corrected User s Manual 71 13 NOTE 22 Chapter 71 Agilent 10717A Wavelength Tracker Installation and Alignment Disconnect the voltmeter from the receiver s test point All alignment and adjustment procedures are now complete After the wavelength tracker and receiver have been properly aligned in the measurement system you should lock the vertical translator adjustment screw see Figure 71 5 in place This will prevent possible cosine error in the wavelength tracker due to thread clearance between the adjustment screw and the baseplate A suitable low strength wicking adhesive Locktite 425 is recommended In vibration free environments this precaution may not be necessary 71 14 User s Manual Chapter 71 Agilent 10717A Wavelength Tracker Installation and Alignment Agilent 10717A Wavelength Tracker Specifications and Characteristics Specifications describe the device s warranted performance Mounting Supplemental characteristics indicated by TYPICAL or NOMINAL are Three 10 32 UNF2A tapped holes hardware supplied intended to provide nonwarranted performance information useful in applying the device See drawings below Dimensions see figure below Mounting Screw Torque 0 9 Newton meter 8 inch pounds Weight 1 7 kg 3 7 pounds Minimum
11. n Method Comparison in Chapter 15 Accuracy and Repeatability of this manual The Agilent 10717A Wavelength Tracker s output must be directed to an Agilent 10780C Agilent 10780F Agilent E 1708A or Agilent E1709A receiver where a measurement signal is generated The laser measurement system electronics use this signal and the laser head s reference signal to monitor changes in the wavelength of light For maximum accuracy the etalon s length the number written on the end of the etalon must be used in the electronics Operation is straightforward The etalon consisting of two mirrors separated by a thermally stable spacer presents a fixed distance to the differential interferometer The interferometer monitors the optical path length between these two mirrors Any change in the wavelength of light that is changes in the air density or index of refraction within the etalon cavity causes an optical path length change which is detected as a phase shift in the measurement frequency The Agilent compensation electronics uses this phase information to update the compensation number for use by the rest of the system Maintaining the 0 20 ppm accuracy typical of this compensation technique requires that air within the etalon s cavity have the same temperature pressure and humidity as the air in the measurement paths To accomplish this the Agilent 10717A Wavelength Tracker should be mounted as close to the measurement area a
12. r beam entering the Agilent 10717A s differential interferometer through aperture A Donot remove the red tape and three hitch pin clips until instructed to do so in this procedure The clips make installation of the wavelength tracker easier The red tape and clips See Figure 71 4 item H4 keep the three mounting screws in place during installation and allow installation of the unit at any angle without having to physically hold the three mounting screws in place After installation is complete the clips are removed by pulling on the red tape If the red tape and mounting hardware are removed or lost prior to the wavelength tracker s installation refer to Figure 71 4 for an exploded view of the tracker s hardware and a listing of their respective Agilent part numbers 71 8 User s Manual Chapter 71 Agilent 10717A Wavelength Tracker Installation and Alignment WAVELENGTH TRACKER MOUNTING HARDWARE Reference Designator Description Agilent Part Number Screw HD cap 10 32 0 75 in lg 3030 0182 Washer spring 3050 1274 Washer flat 1 4 in 0 281 in lg 3050 0583 Hitch pin clip 1480 0694 Subplate 10717 20209 Washer 2 part spherical 3050 1272 Figure 7I 4 Wavelength tracker mounting hardware User s Manual 71 09 Chapter 71 Agilent 10717A Wavelength Tracker Installation and Alignment 1 Set the wavelength tracker over the tapped holes on your equipment NOTE Do
13. s possible Figure 71 3 shows an X Y stage application using a Wavelength Tracking Compensation system The components that comprise the Wavelength Tracking Compensation system are e Agilent 10717A Wavelength Tracker s Beam Bender or Beam Splitter e Agilent 10710B Adjustable Mounts for mounting beam bender or beam splitter e Agilent 10780C or Agilent 10780F receiver e Receiver Cable the cable used depends on the measurement system electronics used see Chapter 9 Accessories in this manual for a listing and description of the cables available 71 4 User s Manual Chapter 71 Agilent 10717A Wavelength Tracker Description e Automatic Compensation Board for the system electronics you are using Recommended see Automatic Compensation paragraphs in your electronics documentation for installation procedures X Y STAGE APPLICATION X Axis Differential Interferometer 10715 001 X Y STAGE gml Reference x Mirror Y Y MIRRORS X Axis A Receiver X Axis See Note Laser Beam Reference 33 Mirror Bear Y Axis K Laser Beam Splitter LO ty g Y Axis N E hH Differential IS VA gt 4 BI Interferometer Y Axis LT 10715 001 Y Beam Receiver Splitter See Note B E 7 lt aT Wavelength Tracker Wavelength Tracker Receiver See Note Note Beams pass under receivers to interferometers then return to receivers at receiver height Figure 7I 3 Two axis differen
14. tial interferometer with wavelength tracker User s Manual 71 5 Laser Head Agilent 5517A B C D F1 Horizontal F2 Vertical Chapter 71 Agilent 10717A Wavelength Tracker Special Considerations Special Considerations The orientation of the laser head with respect to the Agilent 10717A Wavelength Tracker and the selection of the input aperture on the wavelength tracker s differential interferometer affect the direction sense of the compensation output The correct direction sense of the wavelength tracker signal occurs when the compensation number gets larger as the wavelength of light increases Refer to Chapter 15 Accuracy and Repeatability in this manual for a discussion on atmospheric compensation The direction sense of the wavelength tracker signal may be changed on the Agilent 10896A VME Compensation Board by modifying the sign of the WRL value Refer to the appropriate electronics Users Manual for details Table 71 1 gives the correct sign of the WRL value for various system configurations Table 71 1 Agilent 10717A direction sense Laser Head Orientation Horizontal or Rolled 90 Agilent 10717A Input Aperture Agilent 10717A Orientation About Beam AorB Horizontal or Rotated 90 About Etalon Axis A Horizontal Horizontal Rotated 90 B Horizontal Rotated 90 A Horizontal Rotated 90 Rotated 90 B Horizontal Rotated 90 71 6 User s Manual
15. which occurs when the beam enters the receiver s or sensor head s input aperture parallel to its housing the autoreflected beam will be coincident on itself back to the laser head Refer to the receiver alignment procedures in Chapter 8 Receivers in this manual for more receiver alignment information After optical alignment of the receiver the gain of the receiver is adjusted This procedure ensures that the leakage signal from one of the beams isn t sufficient to turn on the receiver The following procedure sets the gain just below the optical leakage threshold Connect a fast responding voltmeter to the test pin on the receiver Block one of the two beams incident on the front etalon mirror see Figure 71 5 with a piece of paper Be sure to block only one beam at this time Observe the voltmeter reading If the reading is greater than 0 1 Vdc turn the gain adjustment screw counterclockwise until the voltage reads 0 1 Vdc Block one of the two beams incident on the rear etalon mirror see Figure 71 5 with a piece of paper Again be sure to block only one beam at this time If the measured voltage is greater than 0 1 Vdc turn the gain adjustment screw clockwise until the reads 0 1 Vdc Remove the beam blocking device The voltmeter should now read at least 0 7 Vdc If the measured voltage is below 0 7 Vdc the wavelength tracker or the receiver or both is not properly aligned If after repeating the receiver a
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