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1. 4 rtisan tisan Technology Group is your source for quality Femoog Ge new and certified used pre owned equipment FAST SHIPPING AND SERVICE CENTER REPAIRS WE BUY USED EQUIPMENT DELIVERY Experienced engineers and technicians on staff Sell your excess underutilized and idle used equipment TENS OF THOUSANDS OF at our full service in house repair center We also offer credit for buy backs and trade ins IN STOCK ITEMS www artisantg com WeBuyEquipment EQUIPMENT DEMOS HUNDREDS OF InstraV ea REMOTE INSPECTION LOOKING FOR MORE INFORMATION MANUFACTURERS Remotely inspect equipment before purchasing with Visit us on the web at www artisantg com 7 for more our interactive website at www instraview com 7 information on price quotations drivers technical LEASING MONTHLY specifications manuals and documentation RENTALS ITAR CERTIFIED aed Contact us 888 88 SOURCE sales artisantg com www artisantg com POLARIMETER OPERATING MANUAL 135 MODELS PA410 PA410 EC PA430 PA430 EC PA450 PA450 EC PA460 PA460 EC 2052 a IN 435 Route 206 P O Box 366 Newton NJ 07860 SALES 973 579 7227 FAX 973 383 8406 www thorlabs com COPYRIGHT THORLABS INC 1998 2127 D03 Rev B 4 4 01 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Table of Contents Section 1 SpeclfiCatiohs iius deed teinte Ee Pa Dee Ede e REL t eaten2. 8X Cancel Reset Defaults OK Illustration 3 Gain Control Window Of particular interest are the first two entries in the Gain Control list box These two entries labeled Polr and Pre represent the gain stages for the Polarimeter input channel and the Pre Amp gain stage in the optical head The selections for the pre amp gain are coded as P1 P2 P3 and P4 These values equate to the following gain Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com P1 1X P2 16X P3 256X P4 4096X It should also be noted that these first two entries have a right most selection labeled AUTO Choosing this option the Polarimeter software automatically chooses the best gain combination for the incident beam power This operation takes place each time a voltage signal is returned from the data acquisition routines while the Main Control Loop is active The current gain selection for a given entry is indicated by a blue box with white lettering In the case of having selected AUTO the AUTO selection will be highlighted in blue with white lettering while the actual gain selected by the auto gain algorithm will be highlighted in orange with white lettering As indicated in previous sections each time the gain is changed from this window the Vo constant displayed in the Control Console will change according to the new gain combination Changing the gain values of any
3. DELIVERY Experienced engineers and technicians on staff Sell your excess underutilized and idle used equipment TENS OF THOUSANDS OF at our full service in house repair center We also offer credit for buy backs and trade ins IN STOCK ITEMS www artisantg com WeBuyEquipment EQUIPMENT DEMOS HUNDREDS OF InstraV ea REMOTE INSPECTION LOOKING FOR MORE INFORMATION MANUFACTURERS Remotely inspect equipment before purchasing with Visit us on the web at www artisantg com 7 for more our interactive website at www instraview com 7 information on price quotations drivers technical LEASING MONTHLY specifications manuals and documentation RENTALS ITAR CERTIFIED aed Contact us 888 88 SOURCE sales artisantg com www artisantg com
4. 0 0000 Aux 3 0 0000 Aux 4 0 0000 Sample Rate Normal C Turbo Sample Length Sets Delay su i Cancel Stop Pause Record Illustration 10 Data Logger Window As shown in Illustration 10 the Data Logger Window includes a check box for each data channel which may be recorded and a check box next to each numeric display These allow the user to independently activate the channels to be recorded and activate numeric displays to be viewed during data acquisition The display windows are updated with the first data point for each data set Specifically each channel s data set includes 32 data points The display window is updated with the first of the 32 data points A numeric display may be activated or de activated at any time during data acquisition without effecting the data acquisition routine Cancel Button Clicking Cancel will close the window Stop Button Stop will abort the recording process without closing the Data Logger window Pause Button Pause will temporarily halt the recording operation Pressing the Pause button again will activate the recording process Record Button The Record button initiates the recording process While the data acquisition routines are recording the number of sets specified in Sample Length a completion gauge will display the percent complete 26 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE
5. De SER ER ER ME E pu 2 Section 2 Software ite meet Le ue pue ane 3 Section Installing the Data Acquisition Board sssssssssssssssseeeeeenneenene nnne 3 Section 4 Installing and Configuring the Polarimeter Software sss 4 AV EEE E L M 4 4 2 Running the Program for the First Time een ener nnns 4 AS MDI Frame WIndOW E m 4 Section 5 The User 6 5 1 Control Console WindOW aguante xa 6 5 2 Data Acquisition Controls idis deer eaa eae Re HEBR aee and A A ek edad 6 Calibration Controls sss rerit Fe ERREUR aee 7 54 Gain Control sisi UE 9 5 5 SCOPE WINKOW wise EE 10 Section 6 System Calibration ou cecccccceceeseceeeeeseeeeeeaaeeeeneeceaeeeeaeeeeaaeseeaeecaeeesaaeseeaaeeseeeseaeesaesseaaeesenees 12 6 1 Preparing Input Polarization States ener nennen trennen 12 6 2 The System Calibration ncen a anth nain tenentes tasas aa 13 Section 7 Display WindOWS cott ett teint ent ra uL Eee od Ended Rx ru aac 16 Properties Dese Cer net ved e buo Dena banc e 16 7 3 Numerical Display Windows se
6. The Ellipticity window enables the user to examine characteristics specific to the Polarization ellipse The measurements are displayed in degrees The following values are displayed Orientation Measured orientation angle of the major axis with respect to the horizontal axis in degrees Ellipticity Measured minor to major ellipticity C 7 4 Graphical Display Windows There are two windows which fall under this category they are the Poincare Sphere and Polarization Ellipse windows These windows much like the Numerical Display windows possess all of the same functionality as described for the Display Windows However the right button pop up menu will not be activated by right clicking inside the drawing region of these Display windows The drawing region is the area in which all the graphic sketching takes place 7 4 1 Poincare Sphere The Poincare Sphere window is the most complex and typically the most often viewed of the display windows Based on a pseudo 3D appearance a viewer can quickly approximate the effective state of polarization exhibited by the incident beam With the numerous adjustable parameters the display can be modified to suit a wide range of needs One special feature that exists only with this window is the ability to have up to five Poincare Sphere windows open on the desktop simultaneously This will allow the user to adjust each sphere to display a different viewing perspective in order to track varying polariz
7. calibration input box has both an up and down arrow button located at its far right Clicking the up and down arrows will increment and decrement the values in the input box by the amount specified in Adjustment Value respectively Using the up and down arrows will immediately place the new value in the measurement calculations Manually typing new values into the input box will require the user to click the Set button This button is only activated when the content of any input box is changed via the keyboard This button will deactivate itself after it has been clicked and the new values assigned Manual Calibration Adjustm ME Ea Illustration 2 Manual Calibration Adjustments window 8 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com The three remaining buttons at the bottom of the Manual Calibration Adjustments window have the following functions Cancel will restore the calibration values to their settings prior to opening the window This will also close the window Reset will restore the calibration input boxes to their settings prior to opening the window This will not close the window Accept will save the values in the input boxes as the new calibration constants Pitfalls Using Auto Gain with Manual Adjustments One must pay particular attention to the gain settings prior to launching the Manual Adjustment window The V value is determined by th
8. can be displayed with the Preview on parent option enabled If for example the current color scheme for the parent window has been set to Color adjusting the monochromatic pens will obviously not have an effect on the display 7 2 4 Reset Color Control Clicking the Reset Color control will return the currently selected color to its value at the time the selection was made 7 2 5 Cancel Reset All Defaults OK The control buttons located at the bottom of the Edit Colors window perform the following actions 18 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Cancel returns all color settings to their values prior to opening the window then closes the window Reset All returns all color settings to their values prior to opening the window but does not close the window Defaults assigns all color settings to values predefined by Thorlabs in the program code assigns the color settings to the values specified in this window then closes the window 7 3 Numerical Display Windows There are four 4 Numerical Display windows They are the Voltage Stokes Polarization and Ellipticity windows Illustration 7 depicts three of the Numerical Display windows Stokes 0 Ellipticity Stokes 1 Orientation Stokes 2 Stokes 3 Illustration 7 Numerical Display Windows 7 3 1 Voltages Window The largest of the display windows the Voltages window enabl
9. display output Each window will have its own specialized color schemes Rather than discuss the specific color pens of each window we will discuss the general functionality of the controls present on the window reference Illustration 6 Edit Colors E E E 75 Cancel ResetAl Defaults Illustration 6 Edit Colors Window 7 2 1 Select Color Control The Select Color list box contains all the adjustable pen colors available to the parent window When a color is selected from this control the Color Preview box will display the current color setting Additionally the Red Green and Blue slide bars will adjust to match the color representation 7 2 2 Red Green Blue Sliders All colors displayed on a computer monitor are represented by varying the intensity of the three primary colors red green and blue By adjusting the intensity of these color components the overall appearance of the color will change The higher the color value indicated by the numerical value on the right of the control the brighter the color component For example a color scheme of Red 255 Green 0 Blue 255 would yield a bright purple color By contrast the color scheme Red 0 Green 255 Blue 0 would yield a bright green color 7 2 3 Preview On Parent Checking this option will cause the parent window to be redrawn each time a color value is adjusted Keep in mind that only the colors belonging to the currently selected color scheme
10. minute The state of the Turbo mode is indicated by the status LED located directly above the Turbo button When the Turbo On mode is active the LED is illuminated green When inactive the LED is dark black Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Control Console 2 Manual Adj Illustration 1 Control Console Start and Stop The Start and Stop buttons located at the bottom of the Data Acquisition Control window are used to initiate and cancel the Polarimeter s Main Control Loop Only one button is active at any time If both buttons are inactive grayed refer to Appendix A Troubleshooting Clicking Start will initiate the Main Control Loop The data acquisition board will acquire the number of voltage sets entered in the Samples Average input box average them into one voltage set process the data and update the appropriate display windows with the new measurement data Clicking Stop at any time during the process will cease all operations and terminate the Main Control Loop returning the Polarimeter to a ready state Reading and Updating Status LED s Used primarily to verify operation of the Main Control Loop the status LED s indicate the current state of the Main Control Loop of which there are two primary operations Reading acquiring voltage data Updating updating re drawing display windows 5 3 Cali
11. of the parent window The result of selecting this option will be described in the following section 7 1 Properties Window Each Display window has an associated Properties window that allows the user to adjust any changeable parameter of the parent window Properties ranging from color scheme to Main Control Loop activity can be altered within this window Illustration 5 depicts a minimum set of properties available for any Display window Most Display windows will contain more attributes specific to their displays These specific adjustments will be discussed for each window The common adjustments available to all Display windows will now be discussed 16 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Stokes Properties xc 2 Cancel Reset Defaults ok Illustration 5 Common Display Window Properties 7 1 1 Choosing a Color Scheme All Display windows allow the user to select from a few standard color schemes Each of these color schemes has configurable pen colors that relate to the specific display being adjusted These adjustments can be made in the Edit Colors window discussed later The following are the available color schemes Monochromatic one background color and one drawing color Reverse Mono Monochromatic colors are swapped Color Multiple colors can be used to create the display 7 1 2 Active Option Checking this option has the same ef
12. often useful to view them simultaneously Reference Illustration 9 The Polarization Ellipse window offers several customizable parameters effecting the graphical display Each serves to more easily interpret the displayed information 23 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Boundary Enabling the Boundary parameter will draw a circle in the display window This circle has a radius a few pixels larger than the major axis of the polarization ellipse This circle enables the viewer to quickly compare the polarization ellipse to the boundary An ellipse whose ellipticity measures 1 00 would be a perfect circle easily comparable to the boundary Deviations from the perfect circle are visually detectable Polarization Ellipse Illustration 9 Polarization Ellipse Window Boundary Fill Enabling the Boundary fill parameter will paint a solid boundary border which extends to the boundaries of the parent window With proper color selection this option improves the visual distinction between the boundary and the polarization ellipse Boundary Axis Checking the Boundary Axis parameter draws orthogonal axes through the Polarization Ellipse display If the Boundary parameter is also enabled the axis will extend only to the boundary If no boundary is present the axis will extend to the boundaries of the parent window This aids in visually appro
13. the default view which is discussed below in the section titled Define Reset View Step Values The step values represent in degrees the rotational increment induced by clicking the double arrow increment buttons located at each end of the X and Y axis rotation scroll bars Tracer Pop Up Option Selecting this option from the right mouse button s pop up menu will toggle the tracer on and off When this menu item is check marked the tracer is enabled This has an identical effect to checking the Tracer parameter described above Define Reset View Pop Up Option If a particular orientation of the Poincare sphere seems to be especially useful selecting Define Reset View from the right mouse button pop up menu will record the current orientation values These are the same values that can be set in the Reset Values section of the Poincare Sphere Properties window One additional function of selecting this option is that the zoom focus location will also be recorded As mentioned previously in Reset Values clicking the Reset View button will always return the sphere to this newly saved orientation 7 4 3 Polarization Ellipse The Polarization Ellipse window graphically displays the numerical data viewed in the Ellipticity window Though the Ellipticity and Polarization Ellipse windows will work independently which means that they do not both need to be active for proper operation However it is
14. www artisantg com Appendix A Troubleshooting System Message Default settings have been enforced message appears at program launch This message is displayed when the polar ini file is either missing from the Polarimeter working director or has been corrupted by a system crash or other mishap In either case the software will write a new file when the program is exited If this is a consistent problem check to ensure that the Working directory specified by the program icon matches the settings specified during installation Start Stop and Calibrate buttons on the Control Console are disabled grayed During the Polarimeter initialization which is performed each time the program is executed the software attempts to communicate with the data acquisition board If an error occurs while attempting this communication an error message will be displayed Consulting the Keithley Metrabyte user s manual will help identify the cause of this error Regardless of the cause the software was unable to establish any interface with the board Because the data acquisition board is not under program control tasks such as System Calibration and Main Control Loop execution cannot occur For this reason they are unavailable to the user Reading and Updating LED s do not act in expected manner There are several possible reasons why this might be observed So that the potential problem might be addressed more easily this problem has been br
15. Optic Adapter 1 Polarimeter User s Manual Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Section 2 Software Manual By using a PC running the Polarimeter software a user can take full advantage of the powerful tools this package has to offer We will begin by first installing the data acquisition board and related software Next we will install the Polarimeter software When this is completed we will be ready to operate the new System for the first time Section 3 Installing the Data Acquisition Board To install the data acquisition board follow the instructions provided in Chapter 2 Setup and Installation in the Keithley Metrabyte DAS 1700 User s Manual provided with the data acquisition board Do not install the DriverLINX software CD ROM While several disks are supplied with the data acquisition board only two are required by the polarimeter software These two disks labeled DAS Support Software Disk 10f2 and DAS Support Software Disk 2 of 2 contain the files DISK1 EXE and DISK2 EXE respectively must be installed by the user This requires only a minor effort from the user Please follow and execute the following steps 1 Using either the Windows Explorer or a DOS prompt create a temporary directory on the computer s hard drive 2 Copy DISK1 EXE and DISK2 EXE into this temporary directory from the above mentioned disks 3 While in the temporary direct
16. The above example lists the parameters common to all display windows We ll discuss each in turn Class This parameter specifies the display window type This should not ever be changed Caption Determines the text displayed in the caption bar of the window This can be changed to any valid text string provided there is only one set of quotation marks If the default descriptions are not adequate change them to fit your needs Coords defines the outer boundary of the window formatted left top right bottom Parenthesis must be included Create A value of 1 will display the window at start up A value of 0 will allocate the window memory but not display the window unless it is called upon via the Display menu Minimized A value of 1 will display the window in icon form whereas 0 will display the window using the coordinates specified in Coords Status Specifies system properties understood by the software This should never be changed CirMonoDraw Specifies the monochromatic drawing pen color in format Red Green Blue CirMonoBack Specifies the monochromatic background pen color APU Specifies the Averages Per Update value Precision Defines the output values which appear on the display window The format is as follows n d where nindicates the total number of digits displayed dindicates the number of decimal places Adjusting System Parameters 29 Artisan Technology Group Quality Instrumentation G
17. ar circular states is due to the Fresnel reflections and absorption this should be minimal associated with the QWP Generating a Linear Horizontal State To best align the linear state of polarization with the linear analyzer in the optical head it is easiest to use the Scope Window described earlier To start the Scope Window ensure the Main Control Loop is inactive by clicking the Stop button or ensuring the Stop control is inactive on the Control Console Open the Scope window by selecting File Scope from the frame s main menu Ensure Polarimeter is selected in the Channel A list box Click Start and begin adjusting the Channel A gain as required to reach a suitable signal With the linear polarization state input to the system rotate the linear state of polarization until the signal level reaches its minimum value One will notice that a linear state of polarization produces four 4 cycles of a sinusoidal signal in the Scope window One will also notice that the offset and phase of the sinusoid will vary as the linear polarization state is rotated It will help to increase the gain until the signal is saturated and only the troughs of the signal are evident to best detect the minimum of the signal Once this is found rotate the linear state of polarization precisely 90 degrees The linear state of polarization will then be aligned with the transmission axis of the linear analyzer Select the gain combination that yields the maxi
18. are operating under Windows 95 start by clicking on the My Computer icon and then follow the path of icons to the directory where you installed the polarimeter software typically the path will be My Computer C Polar4 Click on the Polar4 exe icon to start the software In Windows 95 it is recommended to create a shortcut from the Desktop to save time A welcome window will appear on the screen displaying an animated Poincare sphere as well as the revision information If any data acquisition board errors occur message windows titled MetraByte Error will appear For explanations of these errors consult the Keithley MetraByte operator s manual After the data acquisition board has been tested and configured the Polarimeter software will begin searching for set up information in its working directory If the polar ini file is not located in the same directory as the executable code polar4 exe the program will not detect set up information A message window will appear displaying System Message Default settings have been enforced Rest assured that this message is expected and that no problems will arise as a result of this Clicking OK will close this warning window and continue the software start up process Upon exiting the program the polar ini information file will be created Please note if the head1 ini file is also not present the software will create a new headl ini file Some critical coefficients in the head1 ini file specifi
19. at different wavelengths following the same procedure as above and save the calibration values to a different file To switch between one set of calibration values to another first click on Stop in the Control Console or Scope window if the unit is running Then select File Load Calibration A window will open up prompting the user to select the file containing the desired calibration values Select the desired file and click Ok Then click on Start in the Control Console window to begin running the unit with the new calibration values 14 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Note The current calibration constants are saved in the head1 ini file when the Polarimeter software is exited These will be the default values the next time the Polarimeter software is started 15 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Section 7 Display Windows To add flexibility to the display configuration the various measurements are grouped and displayed in separate windows The display windows may be activated de activated positioned and sized individually It is important to note that similar to the calibration constants all display window configurations are saved to the polar ini file upon exiting of the Polarimeter software The following explains some of the common attributes associated with all display wind
20. ation states without the need for constantly adjusting the sphere s orientation To gain a better understanding of this window s versatility the tools available directly in the Poincare window will be described then the customizable parameters found in the Properties and Edit Colors dialog boxes will be discussed Reference Illustration 8 20 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Poincare Sphere Illustration 8 Poincare Sphere Window Rotation Located on the left bottom and right sides of the Poincare Sphere window are scroll bars controlling the X axis rotation Y axis rotation and Zoom magnification respectively By dragging the bottom scroll bar to the left and to the right rotates the Poincare Sphere The rotation is real time it occurs as the scroll bar is moved This scroll bar rotates the sphere about the Y axis By dragging the left scroll bar upward and downward the Poincare sphere rotates about the X axis The X axis rotation the left scroll bar rotates the sphere about a fixed X axis This means no matter how the sphere is oriented sliding the left scroll bar will rotate the sphere about an axis parallel to the bottom of the desktop The Y axis rotation the bottom scroll bar rotates the sphere about a variable Y axis The reason the Y axis isn t fixed to a parallel with the side of your desktop is because this axis is rotated along with
21. ative to the center horizontal grid line If you look at the center grid line you ll notice a value written at the far right This value indicates the voltage represented by that line The horizontal voltage scale is 2 0 volts per division Dragging this vertical scroll bar will adjust the center grid line voltage level between 6 000 volts and 6 000 volts This will allow the scope display to cover the full range of the data acquisition board Start Control Located at the bottom of the Scope window is a button labeled Start Clicking this button will initiate data acquisition Once this button is clicked its caption changes to Stop Clicking the button while in the Stop state will end the data acquisition It is important to note here that the Scope will only allow data acquisition while the Main Control Loop directed through the Control Console is inactive 11 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Section 6 System Calibration With the knowledge of the Control Console and the Gain Control windows the System Calibration may now be addressed During the calibration routine various system parameters are characterized These parameters include the angles between the systems horizontal axis and the fast axis of the quarter wave plate and the linear analyzer the optical phase retardance of the quarter wave plate at the operating wavelength and the electronic offset
22. bration Controls Located on the right hand side of the Control Console are all the System Calibration controls and constants As we will see shortly these constants are instrumental in making accurate polarization calculations Four calibration constants are displayed in the Calibration pane They indicate the following y angular difference between the defined linear horizontal input and the linear analyzer transmission axis in radians angular difference between the defined linear horizontal input and the quarter wave fast axis in radians Phase Retardance of the quarter wave plate in radians measured DC offset value for current gain arrangement in volts Low signal and Bad calib Status LED s During the measurement calculations several parameters are checked to ensure the system is operating within defined limits which assure accurate measured results If the system is operating outside these limits a warning indication will be displayed Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com The first check occurs immediately after the data acquisition routine returns voltages for analysis If the signal is too low the Low signal LED will become illuminated red This situation can be remedied by either increasing the gain or increasing the optical power of the incident beam The second check occurs after the calculations have been made The measurement result
23. c to the optical head will be set to zero These will have to be manually adjusted if the original head1 ini file is not available Reference Appendix B for the print out of the polar ini file 4 3 MDI Frame Window Now that the software has been completely loaded the main window called a frame window will appear on the screen This window is the controlling agent for all Polarimeter display windows which are often referred to as children windows Ultimately any child window displayed on this frame window is bounded by the frame s coordinates This means that no child window can ever be found outside the boundaries of the frame window Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com This boundary is not a serious limitation however The frame window exhibits the full functionality of a Multiple Document Interface MDI commonly seen in word processing and database applications The MDI frame has the ability to represent a surface area much greater than what is visible on the screen Any children who lie either partially or completely outside the visible region of the MDI frame can be reached via horizontal and vertical scroll bars that appear on the bottom and right of the frame as required These scroll bars allow the user to pan their view port across the entire range of the frame s virtually sized surface defined by the extreme coordinates of the outermost child windows This virtuall
24. ctory dictates every adjustable parameter available in the system While it should be a rare circumstance that a user would need to edit this file a working knowledge of its functionality is important If adjustments are required open polar ini with any standard text editor such as MS DOS Edit or Notepad It is important to not use word processing applications such as MS Word as they add special formatting characters that would not be well received by the Polarimeter The top of the file lists each window opened or closed that the user has accessed the last time they executed the software Note however that only window s whose Save on exit control was enabled will appear in this file In order to distinguish between the identical parameters on the many different windows each entry is prefixed with the format childn parameter The n value represents the order in which the windows will be created Adjusting Display Windows The functionality of most of the settings should be easily identifiable by their parameter names Of the many available parameters there are two that should never be adjusted namely Class and Status All others can be easily adjusted A common listing should appear as follows child3 class stokes child child3 Caption Stokes child3 Coords 722 104 864 217 child3 Create 1 child3 Minimized 0 child3 Status 67 child3 clrMonoDraw 0 0 0 child3 clrMonoBack 255 255 255 child3 APU 1 child3 Precision 6 4f
25. dded perspective the radius and brightness of the locator will adjust in proportion to the views Z axis in exactly the same manner observed by the polarization vector 22 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Locator Radius Parameter The full sized radius of the locator is an arbitrary value which can easily be set in the input box labeled Radius Tracer Parameter Enabling the Tracer option causes a history line to be drawn from one polarization state to the next This line will be continuously drawn until this option is again disabled In order to gain better perspective on the tracer line the brightness of the line is proportional to the viewers Z axis operating in exactly the same manner as the polarization vector and locator NOTE The software does not internally track the previous polarization states If the Poincare sphere window needs to be redrawn or is adjusted with its scroll bars the tracer data is lost Reset Values The Reset Value button is located at the top of the Poincare sphere window It looks like the Poincare sphere Clicking this button will set the sphere to a pre defined orientation That orientation is defined in the Reset Values The X axis and Y axis reset values are designated in degrees ranging 360 The Zoom reset value ranges from 100 to 400 representing the range 1X to 4X There is also an alternative approach to setting
26. e gain combination at the time the window is opened When Accept is clicked the current DC offset value is assigned the amount specified in the Vor input box If the gain combination changes from the time the window is launched to the time the new values are accepted the DC offset value will be incorrectly adjusted overriding the wrong gain combination DC offset value It is highly recommended that the user select a fixed gain combination rather than the AUTO option discussed in section 5 4 Gain Control 5 4 Gain Control To make accurate and precise measurements it is important to utilize as much of the dynamic range of the data acquisition board as possible The Gain Control window allows the user to control and monitor the gain values at any time To activate the Gain Control window select File Gain Control from the frame window main menu The Gain Control window pictured in Illustration 3 is a versatile visually intuitive tool used to adjust the values of the various gain stages The main Gain Control display consists of a specialized list box which contains all the channels available to the data acquisition board via the Control Unit If this window is resized to a height that prevents viewing all the gain channels at once a vertical scroll bar will appear in the list box providing access to all of the entries Gain Control 1X 2X 8 P1 P3 P4 Temp 2X Aux 2X 4X 8X Aux2 2X AX 8X Aux3 2X 4X 8X Aux4 2 4
27. entry besides the first two will have no impact on polarimetric measurements 5 5 Scope Window The Scope Window activated by selecting File Scope from the frame s main menu operates much like a simplified oscilloscope This window will display precisely the signal that is analyzed by the measurement calculations While a discussion about such a window would normally wait until later chapters it s the ability of this window to display the analyzed signal that makes it invaluable for the System Calibration in Section 6 Scope Window Channel Channel B Temperature Sets Displayed Set Start Illustration 4 Scope Window 10 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Selecting Display Signals When the Scope window is launched its appearance should be similar to that shown in Illustration 4 Located on the left side of the window are the controls that determine the display channels The Scope window has the ability to simultaneously display two signals each at different gains These signals are chosen from the list boxes labeled Channel A and Channel B while their respective gain settings are chosen from the main Gain Control window Note that only Channel A offers the Polarimeter as a selection This is because there are two gain stages that must be configured for this channel the pre amp gain and the DAS board gain If Polarimet
28. er is not chosen in the Channel A list box the pre amp gain selection has no effect on the displayed signal Sets Displayed Control Each time the Scope window calls the data acquisition routine two full data sets are retrieved The Scope display window has the ability to display either the first signal or both signals Selecting 1 in the Sets Displayed list box will show only the first of the two recorded voltage sets Selecting 2 will display two successive signals by halving the horizontal resolution Located on the bottom of the scope display is a horizontal scroll bar If only one data set is displayed on the window this scroll bar can be used to reposition the view so that the other signal in part or in whole can be viewed Only 32 points can be displayed at any time on the window while in this operating mode but the first of the 32 points is determined by the horizontal position of this scroll bar If two full data sets are being displayed on the scope window this scroll bar has no effect SPA Set SPA Control The SPA input box and the Set SPA button work in tandem identically to the Samples Average and Set SPA controls in the Control Console If you are unsure of how these controls work consult the Control Console portion of section 5 2 Data Acquisition Controls Vertical Scroll Bar Located to the left of the scope display is a vertical scroll bar This scroll bar adjusts the display offset rel
29. es the user to examine the voltages read from the optical head by the data acquisition board The voltages displayed in the window reflect the signal after the gain stages less the calibrated DC offset value This window does not show much useful information as it pertains to the input polarization state but it does allow the user to quickly identify low and saturated signal levels If a user wishes to manually adjust gain values via the Gain Control window the Voltages window or the Scope window should be used to assure an acceptable voltage level 7 3 2 Stokes Window The Stokes window enables the user to examine the normalized Stokes parameters measured during the polarization calculations Stokes values S1 S2 and S3 reflect the coordinates of the polarization vector located on the Poincare Sphere which is discussed below 7 3 3 Polarization Window The Polarization window enables the user to examine the varying degrees of polarization measured during the polarimetric calculations These measurements are displayed in terms of percentage with the labels indicating the following DOP Degree of Polarization DOLP Degree of Linear Polarization DOCP Degree of Circular Polarization Note that the sign of the measured DOCP determines its left or right handedness is right handed is left handed 19 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com 7 3 4 Ellipticity Window
30. fect as toggling the Active option on the parent window s pop up menu described in previous sections 7 1 3 Auto size Option Checking this option will allow the software to automatically size the window in such a way that the borders are only large enough to allow all the presentable data to be viewed on the window In the specific cases of the Poincare Sphere window and the Polarization Ellipse window Auto sizing will force the aspect ratio of the display to remain 1 1 7 1 4 Avr Update Control The Avr Update control specifies the reset value of the APU counter The value entered here is identical to updating the Averages option on the parent s pop up menu 7 1 5 Cancel Reset Defaults OK Controls Located at the bottom of every Property window are four control buttons These buttons perform the following tasks Cancel returns parameters to their settings prior to opening window then closes window Reset returns parameters to their settings prior to opening the window without closing window Defaults sets parameters to Thorlabs recommended values for normal operation OK assigns parameters to values currently specified in window then closes window 17 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com 7 2 Edit Colors Window In order to add flexibility to the Display windows the Edit Colors window allows the user to customize the drawing pens used to paint the
31. gger from the main frame menu Measurements File The Measurements file outputs a time stamp in milliseconds starting at time 0 and incrementing with each recorded set until the specified number of samples have been recorded Each time stamped line includes the calculated Stokes parameters Degree of Polarization Ellipticity and orientation in the following format Time stamp gt lt Stokes 0 3 gt lt DOP gt lt DOLP gt lt DOCP gt lt Ellipticity gt lt Orientation gt n Voltages File The Voltages file outputs a time stamp in milliseconds starting at time 0 and incrementing with each recorded set until the specified number of samples have been recorded Each time stamped line includes the voltages of the selected channels in the following format time stamp offset Polarimeter 0 31 gt lt Thermal 0 31 gt lt Aux 1 0 31 gt lt Aux 2 0 31 gt lt Aux 3 0 31 gt lt Aux 4 0 31 gt n Note that both ASCII files consist of float point comma delimited values with a n new line character at the end of each sample set These files may be directly imported into software packages such as MathCAD and Excel for further data analysis 25 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Data Logger FMeasuemems 3505 Browse Ss Browse Record Display Record Set up Polarimeter 0 0000 Thermal 0 0000 Aux 1 0 0000 Aux 2
32. ice that the first of four slides of the system calibration is titled Calibrate DC Offset The term slides refers to the different stages of the same window If one examines the bottom of the window several control buttons can be Seen Record Stop Control Each slide in the System Calibration requires different input parameters for the incident beam Once the proper input configuration is set the data may be collected by clicking the Record button This activates the data acquisition routine which reads the number of data sets specified in the Samples Average input box then averages them and stores them for use in the calibration routine To minimize the random noise in the data acquisition system it is recommended that a value between 15 and 30 be set in the Samples Average input box in the Control Console Immediately after the Record button is clicked the caption of this button changes to Stop At the same time all other controls on the window become temporarily deactivated Clicking Stop will immediately end the data acquisition routine which will return the averaged data up to the point of stopping This will also re enable the other controls as if the data acquisition routine had completed on its own Previous and Next Controls The flexibility of the System Calibration allows the user to click Previous or Next to traverse through the slides viewing or using any slide If for example
33. mum signal without signal saturation between 8V and 9V Note Aligning the linear horizontal polarization state to the transmission axis of the linear analyzer in the optical will yield an orientation of the linear polarization state along the horizontal axis of the optical head perpendicular to the mounting axis to within a couple degrees If the orientation of the linear horizontal 12 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com polarization state is known and the user would like to calibrate the Polarimeter to it this can be accomplished provided that it does not deviate from the transmission axis of the linear analyzer in the optical head by more that 25 Generating an Elliptical State With the horizontal polarization state set from the previous step a quarter wave plate may be used to generate an elliptical near circular state of polarization Using the Scope window to monitor the signal rotate the wave plate until two cycles of a sinusoidal signal are present This sinusoid should be approximately twice the amplitude of the sinusoid generated by the input linear state of polarization Once this is achieved you are ready to begin the System Calibration 6 2 The System Calibration The System Calibration routine is launched by clicking Calibrate on the Control Console This will launch the calibration window placing it in the center of the viewable screen You ll not
34. of the gain stages minus the DC offset voltage is scanned for its peak voltage level If that level falls below the value indicated by LowSigTrigger in the polar ini file this will be discussed in Appendix B INI Specifics The voltage level may be heightened by increasing the values of the gain stages or increasing the optical power of the incident beam If neither of these options is available to the operator be aware that the measurement calculates may not yield results as accurate or precise as would normally be expected Bad calib status LED is illuminated Among the most common causes for this LED to become illuminated is a low voltage level discussed in the previous paragraph Another reason why this might occur is if incorrect mis aligned or low intensity input beams were used for the System Calibration 27 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Errors occur during System Calibration Typically this is caused by incorrect mis aligned or low intensity input beams Entering a horizontal beam when an elliptical beam is expected would certainly cause such an error Ensure that the proper polarization states are entered at the appropriate times Also be sure that the wavelength of the input beam falls within the range specified for the optical head A Display window which was present at shutdown did not return at the next start up If a Display window which
35. oken down into its component symptoms The Heading LED is never illuminated This would most likely indicate that the Main Control Loop hasn t been initiated by clicking Start on the Control Console If the Start button is still active not grayed click Start The Updating LED never appears to be illuminated On very fast computers the display updates occur so rapidly that the observer may miss the brief instant the LED is illuminated If one can observe the display window measurement data updating this is most likely why the Updating LED is never seen illuminated The second cause for this behavior is if no display windows require updating This can be caused by a lack of any display windows or a lack of Active display windows refer to Section 3 Active Option The Heading LED is illuminated but no display windows appear to ever update As mentioned in the previous paragraph one reason this would occur is if none of the display windows are Active refer to Section 3 Active Option It is also possible that the Control Unit is not properly connected to either the optical head or the data acquisition card Check to ensure that all cables are firmly connected A final possibility is that either the optical head or the Control Unit have suffered electronic damage and are not operating properly If this is the case contact Thorlabs immediately Low signal status LED is illuminated The signal resulting from the output
36. one realizes on the last calibration slide that the DC offset voltages were recorded with the laser turned on one may click Previous until they return to the Calibrate DC Offset slide where the data may be recorded again Then the Next button may be pressed to return to the appropriate slide in the calibration routine to continue 6 2 1 Calibrate DC Offset To obtain accurate DC offset voltages the laser source should be turned off or the incident beam should be interrupted as close to the source as possible In the first slide of the calibration window the program will prompt the user to block the source and select the desired gain settings to read the DC offset voltages Located in a list box labeled Select Gain the four possible pre amp gains are listed along with their currently stored DC offset voltages Each selection can be chosen in turn and calibrated individually with the Record button In addition to the pre amp gains there is an Auto option which is the default selection With this option selected clicking Record will cycle through each pre amp gain with it s corresponding four Polr settings and will automatically and record the individual DC offset voltages When the DC offset calibration has completed click Next to continue with the calibration routine 13 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com 6 2 2 Calibrate Elliptical Allow
37. ory execute DISK1 EXE and upon its completion execute DISK2 EXE 4 Once step 3 has been completed the temporary directory will contain several new files While in the temporary directory execute the new file SETUP EXE Follow the set up instructions supplied by the set up software Once the installation has been completed a new file group will be automatically created called DAS 1800 Series Contained within this program group is an icon labeled DAS 1800 Configuration Execute this program A DOS window will appear prompting the user to Enter Number of boards to configure 1 2 or 3 Select 1 This will display a new configuration window The following settings must be selected to ensure proper functionality of the system Board Type DAS1802HR A D Mode Bipolar A D Config Differential The other settings Base Address A D DMA Chan IRQ Level must be configured to the specifics of the data acquisition board s dip switches and your computer s available DMA and IRQ channels Consult the Kiethley Metrabyte DAS 1700 User s Manual provided with the data acquisition board for assistance When all settings have been properly configured exit the configuration software by pressing the ESCape key Answer Y es when asked Update das1800 cfg This completes the data acquisition board set up requirements for the polarimeter software Artisan Technology Group Quality Instrumentation Guaran
38. ows Right Button Pop Up Menu Each Display window those windows which are activated from the Display menu has what is known as a pop up menu associated with it This menu is activated by right clicking the mouse while the pointer lies within the window display In general each window includes it s own list of options but there are some standard options displayed in all Pop Up windows which are listed below Active Option The first selection on each Display window s pop up menu is titled Active This menu item indicates whether the given window is updated during the Main Control Loop If a check mark appears next to this menu option each time the polarization measurements are taken this window s contents are updated Averages Option Each Display window contains a number known as the Averages Per Update APU value Selecting this option will display an input window requesting the user to enter an APU value This value indicates the number of averaged data sets to be taken prior to updating the window information As an example if a display window has an APU value equal to 5 the window would display only every fifth set of measurements NOTE the five 5 data sets are not averaged the values of the fifth data set are used to update the window Properties Option The last option on the pop up menu is labeled Properties Selecting this option will display a Properties window which allows the user to adjust any changeable attribute
39. r Enabling this option places polarization labels on the Poincare sphere These labels appear at each intersection point of the orthogonal axis The numerical values 0 45 90 135 represent linear polarization states in units of degrees The L and R represent left and right handed circular polarization respectively Vector Parameter Enabling this option will draw a polarization vector in the Poincare sphere originating at the center of the sphere and extending to the surface of the sphere This vector points to the measured state of polarization as it relates to the axis of the sphere It is important to note that the end location of the vector corresponds to the measured Stokes values with Stokes 1 Stokes 2 Stokes 3 representing X Y Z coordinates on the sphere The labels 0 and 90 represent the X axis The labels 45 and 135 represent the Y axis The labels L and R represent the Z axis For added perspective the brightness of the vector will adjust in proportion to the viewers Z axis Specifically when the vector is pointing out of the screen the vector will be at its brightest and when it points to the back of the monitor the vector will be at its darkest Locator Parameter As an added visual aid the polarization state can be represented by a circular locator whose center represents the Stokes coordinates as described above The locator can be displayed with or without the polarization vector being displayed For a
40. s are assessed to determine if the calibration constants are accurate This could be caused by several circumstances many of which will be covered in Appendix A Troubleshooting Calibrate Control The Calibrate button located at the bottom of the Control Console launches the System Calibration routine described in System Calibration We will discuss the details of this routine in Section 6 System Calibration The Calibrate button may be enabled only while the system is in the standby state After the calibration routine is completed and the new calibration values are accepted into the system the new calibration constants will be displayed within the control window Manual Adj Control Clicking Manual Adj will launch the Manual Calibration Adjustments window seen in Illustration 2 This window will allow the user to make adjustments to the calibration values while the Main Control Loop is operating The effect of adjusting values can be seen in real time during display updates We will discuss the operation of this window in the next section When this window is launched four input boxes are loaded with the current system calibration values Changing these values will effect the analysis measurements the next time the calculations are conducted though they won t become visible until the next time the display windows are updated Beneath the calibration input boxes lies a separate input box labeled Adjustment Value Each
41. sition controls 5 2 Data Acquisition Controls Located on the left hand side of the Control Console are all the major controls governing the data acquisition board At a glance several controls and indicators exist within this Control Console pane We ll discuss each in turn Samples Average and Set SPA Controls The Samples Average input box and the Set SPA button work in tandem Any time the value in the input box is changed Set SPA becomes enabled the text changes from gray to black When Set SPA is enabled it indicates that the value entered in the input box does not match the value currently being used by the software Clicking Set SPA will accept the new value into the system and the Set SPA button text will change back to gray The value entered into the Samples Average input box dictates the number of voltage sets the data acquisition board will acquire before averaging the result into a single data set This single data set will be passed to the software s main control loop for use in the polarization measurement calculations Turbo Control Directly to the right of the Set SPA control is the Turbo button Clicking this button toggles between Turbo On and Turbo Off modes The Turbo Off mode is the standard mode In this mode the quarter waveplate rotates at 10Hz In the Turbo On mode the quarter waveplate rotates at 30Hz It is recommended that this mode be used for only short durations less than one
42. ss een nennen 19 7 4 Graphical Display Windows sssssssssseseeeeeneeenne 20 7 5 Data Logging Windows Data Logger ssssssesseeeeeene nennen nnne 25 Appendix A Troubleshooting ionic irte ce eire de e tti eee Rue IER ee dO ede eau 27 Appendix B INI Fil Formal E 29 1 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Section 1 Specifications Performance Specifications Operating Wavelength Range PA410 PA430 PA450 PA460 Special Order Power Range Accuracy D O P Physical Properties Sensor PA410 PA430 PA450 PA460 PA410 PA450 Active Area PA430 PA460 Active Diameter General Operating Voltage Operating Temperature Size Optical Head Interface Box Accessories The Polarimeter comes with the following items 1 Optical Head 1 Interface Box 450 700nm 1100 1600nm 700 900nm 900 1100nm 30nW 3mW 1 0 Calibrated Wavelength 1 5 Over Operating Range Silicon Photodiode Germanium Photodiode Silicon Photodiode Germanium Photodiode 10 x 10mm 5 0mm 115VAC 230VAC EC models 50 60Hz 10 to 40 C amy 2 9 xat 115 5 x 2 2 1 Keithley DAS Data Acquisition Board with software and manuals 1 Thorlabs Polarimeter Software Diskette 2 DAS Support Software Diskettes 1 DAS Cable 2 Male Female Serial Cables 1 FC Fiber
43. teed 888 88 SOURCE www artisantg com Section 4 Installing and Configuring the Polarimeter Software 4 1 Installation The required files to run the polarimeter are included on one 3 1 2 diskette labeled Polarimeter Software The files included are polar4 exe polar ini and head1 ini file Create a directory called polar4 on the hard drive Copy the files from the 3 1 2 diskette into the new directory Copy the configuration file das1800 cfg from the directory that includes the DAS 1800 configuration files reference Section 3 into the polar4 directory following default settings during Step 4 of the data acquisition board instructions listed above will place the file as C DAS1800 ASOWIN DAS1800 CFG NOTE The 1 file includes calibration data that is unique to your optical head and interface box delivered along with the software diskette It is highly recommended to maintain a backup copy of this file 4 2 Running the Program for the First Time Now that all the necessary hardware and software have been properly installed we re ready for our first execution of the application We will initiate the Polarimeter software in much the same way any software application is launched through the standard Windows environment If you are operating Windows 3 1 double click the program group labeled Thorlabs Polarimeter and then double click the icon labeled Polarimeter Software If you
44. the elliptically polarized beam generated in section 6 2 to enter the optical head and click the Record button to collect and average the number of data sets specified in the Samples Average input box When the Elliptical calibration has completed click Next to continue with the calibration routine 6 2 3 Calibrate Horizontal Now allow the linearly polarized beam generated in section 6 2 to enter the optical head and click the Record button to collect and average the number of data sets specified in the Samples Average input box When the Horizontal calibration has completed click Next to continue with the calibration routine 6 2 4 Accept Values After the horizontal state of polarization is entered the calibration routine uses the data collected during the routine to make the calibration measurements The final slide shows the results of the calibration The following values are displayed y the angle in radians between the defined horizontal and the transmission axis of the linear polarizer 5 the angle in radians between the defined horizontal and the fast axis of the quarter wave plate the phase retardance of the quarter wave plate at the operating wavelength and V the displayed offset voltage is for the first pre amp gain P1 If these values appear to be reasonable click Accept 6 2 5 Save Load Multiple Calibration Values Whenever the polarimeter is to be operated at a new wavelength the system m
45. the sphere during X axis rotation This phenomenon known as gimbal lock is a common side effect of the three dimensional matrix rotations used by the Polarimeter software One additional feature to note regarding these two scroll bars is the step increment buttons located at the ends of each control These buttons allow the user to step past the range of the scroll bar If for example the sphere is oriented by dragging a scroll bar all the way to one extreme of its 360 range you can continue rotating by clicking the increment buttons These buttons may be clicked at any time They do not change the relative position of the scroll bar thumb box 21 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Zoom The third scroll bar located at the right of the window is the Zoom magnifier This slider incrementally ranges from 1X to 4X The user may zoom in on a selected focus point There are two ways in which the user may select the focus point The quickest way is to double click the left mouse button with the mouse pointer pointing to the location of the desired focus This causes two actions The first is to designate the indicated location as the new focus The second action is to magnify the current view by 4096 You ll notice that the Zoom scroll bar adjusts position each time you double click on a new location The second way to choose a focus point is to click the Pick Focus control but
46. ton located at the top of the Poincare Sphere window This button looks like a magnifying glass with small cross hairs in the looking glass When this has been pressed the next single click of the left mouse button inside the display area will place the focus at that spot This is indicated by cross hairs on the display Sliding the thumb box on the Zoom slide bar will quickly illustrate the manner in which the zoom algorithm works By progressively moving the focus point to the center of the display while increasing magnification a smooth transition occurs between normal 1X viewing and 4X magnification This focus location will be saved when exiting the software provided the Save on exit option is enabled for this window 7 4 2 Poincare Sphere Properties Window By right clicking inside the boundaries of the Poincare Sphere display and selecting Properties from the pop up menu the Poincare Sphere Properties window will appear centered on the monitor screen Along with standard configurations several new parameters specific to the Poincare Sphere also appear Solid Parameter Enabling this option gives the user a great sense of sphere orientation Two important actions occur when this option is enabled First a border is drawn around the sphere giving it a solid modeled look Second the hidden lines those lines which in a solid object would be obscured by the viewed surface are drawn in dotted lines Designators Paramete
47. uaranteed 888 88 SOURCE www artisantg com At the end of the polar ini file a list of system parameters is defined Most of these options should be left since they can be adjusted by the Control Console and the Gain Control window There are however a few parameters adjusted so rarely that they don t warrant attention on any standard options window These parameters are as follows EnableLowSignal A value of 1 indicates the Low signal LED should actively monitor voltage levels indicating to the user when problems arise 0 disables this option EnableBadCalib A value of 1 indicates the Bad calib LED should actively monitor system calculations indicating to the user when problems arise 0 disables this option LowSigTrigger This value indicates the minimum voltage level used to compare against the inputted signal when determining whether or not the Low signal LED should illuminate DOP ErrBand When checking system calculations a DOP value exceeding the one specified here will trigger the Bad calib LED to illuminate Color Background This sets the background color of the software frame window in format Red Green Blue 30 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com 4 rtisan tisan Technology Group is your source for quality Femoog Ge new and certified used pre owned equipment FAST SHIPPING AND SERVICE CENTER REPAIRS WE BUY USED EQUIPMENT
48. ust be recalibrated and new calibration values recalculated Often the user might want to use the polarimeter at multiple wavelengths but does not want to recalibrate every time the wavelength is changed With the Polar4 exe version 4 25 the user now has the option of saving calibration values for different wavelengths allowing operation of the system at different wavelengths without having to recalibrate the system each time After clicking on Accept in the final slide during the calibration routine the user will have the option of saving the newly calculated calibration values to a file for future reference A window will open prompting the user to enter a file name in which to save the calibration values The file will be saved with the ini extension Once the name of the file has been entered either by typing in a new name or selecting an existing file click on Dk The new calibration constants will now be saved to the specified file as well as appearing in the Control Console window If the user does not save the calibration values at this time they may do so later assuming the unit has not been recalibrated since To save the calibration constants after the calibration routine has been completed select at the top menu bar File Save Calibration The same window will open as that after the calibration routine prompting the user to enter the filename to which the calibration values will be saved The user can then calibrate the unit
49. voltages of the detection circuit Attention Each Polarimeter is calibrated at Thorlabs at a specific wavelength and at room temperature Each polarimeter should be re calibrated by the customer especially under the working conditions of the application i e different wavelength or a temperature significantly warmer or cooler than room temperature 6 1 Preparing Input Polarization States The calibration routine is rather straightforward In summary it includes the following three steps 1 The input signal must be turned off or blocked so that the offset voltages of the detection circuit may be measured 2 An elliptical near circular state of polarization must be entered into the optical head 3 A linear state of polarization parallel with the linear analyzer in the optical head must then be entered Preparing these states of polarization prior to initializing the calibration routine will facilitate the calibration process lt is highly recommended that the intensities of the beams for each polarization state be approximately the same This ensures that the gain setting will not change during calibration One means of accomplishing this is to place a linear polarizer in the beam to generate the linear state of polarization Then with the linear polarizer in place a quarter wave plate QWP may be added down stream to generate the near circular elliptical state of polarization The only loss in intensity between the linear and ne
50. was present on the desktop during shutdown is not displayed at the next start up be sure the window s Save on exit parameter is checked in its respective Properties window Display updates occur very slowly Typically there are three main causes for such an occurrence Check the value entered into the Control Console s Samples Average edit control If this value is very high a large number of data sets must be collected sampled and passed back to the Main Control Loop Since the sample rate is fixed by the optical head the larger the Samples Average value the longer the software must wait to make calculations and update the display windows The second cause for this slowness could be the APU setting for the display windows If these values are high the display windows will skip several measurement sets before updating their displays A high SPA combined with a high APU could actually make the system appear to not function at all The final cause lies within the optical head itself If a problem exists where the drive motor is operating at slow speeds the data acquisition rate is proportionately slowed If this appears to be the situation contact Thorlabs immediately 28 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Appendix B INI File Format A key resource of the Polarimeter software lies within its polar ini file This file located in the software s working dire
51. ximating the orientation angle of the polarization ellipse s major axis Ellipse Axis Enabling the Ellipse Axis parameter draws both the major and minor axis of the polarization ellipse These axes extend only to the boundary of the polarization ellipse This combined with enabling the Boundary Axis offers the viewer more information about the orientation of the polarization ellipse Each of the above mentioned parameters has an associated color which can be adjusted through the Edit Colors dialog box 24 Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com 7 5 Data Logging Windows Data Logger Several windows which display measurement data in real time have been discussed However these windows do not allow the user to collect measurement data over time The Data Logging window is provided for this purpose By collecting all the voltage and measurement data in a file the user has the ability to import information into other software packages such as Excel and MathCAD to analyze and view the voltage data or measurements In order to capture polarization information for review in programs such as MathCAD the Data Logger offers a suitable solution Without interacting with any of the normal update routines the data logger captures voltage data and polarization measurements and logs them to two distinct ASCII files The Data Logger window is activated by selecting Data Data Lo
52. y expanding frame will allow the user to position the numerous children in many elaborate arrangements without being concerned with fitting the different children together like an intricate puzzle As an added feature discussed in Section 7 the Polarimeter software has the ability to record in the set up information file polar ini mentioned earlier the exact placement of children when exiting The next time the software is executed the layout from the previous set up will be restored Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com Section 5 The User Interfaces 5 1 Control Console Window The Control Console is the primary interface between the Polarimeter software and the electronic hardware Since this window controls everything from wave plate spin rates to data calculations and display updates the Control Console is present in the frame window at all times In order to take advantage of this property controls for the data acquisition card and the System Calibration along with several status lights can be found in one of the two panes which visually divide the window As you can see by referring to Illustration 1 the Control Console is grouped according to two major functions The left pane contains all the data acquisition controls while the right pane contains all the system calibration controls We ll begin our discussion of the Control Console by discussing the data acqui
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