AxoScan TM Mueller Matrix Polarimeter

Transcription

1 103 Quality Circle, Suite 215 Huntsville, AL Phone: (256) Fax: (256) Website: AxoScan TM Mueller Matrix Polarimeter OPERATOR S HARDWARE MANUAL 2014 All rights reserved. AxoScan, AxoView, Axometrics and the Axometrics logo are trademarks of

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3 Please read these instructions completely and carefully before operating the Mueller Matrix Polarimeter. If you have any questions, or experience any difficulties, please contact Axometrics or the representative from whom the instrument was purchased. iii

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5 CONTENTS 1 Introduction to the Instrument Optical Heads Control Unit SpectroPolarimeter Option Automated XY Scan Table Option Automated Out-of-Plane Measurement Fixture (Tip-Tilt Table Option) Temperature Controller Unpacking and Setup Shipment Contents Setting Up the Instrument Setting up the fiber-coupled source Instrument Details Instrument Heads Polarization State Generator (PSG) Polarization State Analyzer (PSA) Cables Control Unit Temperature Controller Software Polarimeter operation AxoScan Engine AxoScan Configuration AxoView Basic Operational Controls Polarimeter Coordinate System General Safety Electrical Replacing Fuses Mechanical Optical Laser Safety Warranty

6 1 INTRODUCTION TO THE INSTRUMENT The AxoScan TM Mueller Matrix Polarimeter (MMP) is an optical instrument for measuring all of the polarization properties of samples in a fraction of a second. A sequence of intensity measurements are acquired as retarders rotate within the Polarization State Generator and the Polarization State Analyzer heads. Then a very accurate Mueller matrix is determined and displayed which characterizes all of the polarization transformations for that sample, at the operating wavelength and angle of incidence. A single or sequence of Mueller matrices can be saved to a file for analyzis in other computer programs. From the Mueller matrix, the retardance parameters are calculated and displayed on the Poincaré sphere. From the Mueller matrix, the diattenuation and polarizance parameters (properties of polarizers and partial polarizers) and depolarization parameters are determined. All of these polarization parameters can be saved to disk or put into AxoScan generated reports which can be easily exchanged as digital files. Please read this Operator s Manual carefully in order to obtain the best results from your AxoScan system. 1.1 Optical Heads All AxoScan systems consist of two optical heads, the Polarization State Generator (PSG) and the Polarization State Analyzer (PSA). There are different optical source options for the PSG. Depending on the system ordered, your system will have one of the following configurations: 1. Integral thermo-electrically stabilized diode laser. 2. FC or SMA adapter with collimating lens allowing the use of fiber-coupled optical source. Additionally, AxoScan is supplied with one of the following mounting schemes: 1. Horizontal mounting feet to attach to a standard optics table with ¼ -20 threaded holes on 1 centers. 2. Vertical mounting post with extension arms, sample table, and base plate inch pillar mounting system for users who intend to mount the polarimeter to a standard 1/4-20 optical table in a vertical configuration. This option is compatible with the 1.5 diameter pillar mounting systems available from most major opto-mechanics vendors. AxoScan systems can be calibrated by the user for use at any wavelength across a range of optical wavelengths. Please see the enclosed SPECIFICATIONS FORM for detailed information on your polarimeter. Dimensioned drawings of these options are contained in the MECHANICAL DRAWINGS section near the end of this manual. 1.2 Control Unit The AxoScan also includes a Control Unit that controls the polarimeter, analyzes the data, and provides the graphical user interface. The Control Unit contains a computer running a Microsoft Windows operating system. The AxoScan Control Unit must be handled with extreme caution. As with any computer system, moving the Control Unit while it is turned on can result in damage to the hard drive. Carefully avoid dropping or hard shocks to the Control Unit as damage may occur. Refer to the enclosed SPECIFICATIONS FORM for details pertaining to the operating system and software version present on your system. 2

7 Three programs are installed on your system for operating the AxoScan: 1. The AxoView TM program operates the polarimeter, provides real time data viewing, logging of data to disk, and generate reports. 2. The MMP Alignment Utility is used to align the optical heads and check optical power levels 3. The MMP Calibration Utility performs a calibration of the AxoScan, necessary for accurate operation. The polarimeter has been calibrated at the factory. If (1) the optical wavelength of the source is changed, or (2) the AxoScan heads have been remounted or moved, then the AxoScan requires re-calibration. 1.3 SpectroPolarimeter Option AxoScan systems can be optionally ordered with the SpectroPolarimeter option for measuring polarization properties as a function of wavelength. The SpectroPolarimeter option includes a monochromator and Axometrics proprietary achromatic polarization optics. The software for SpectroPolarimeter operation is integrated with the AxoView control and analysis software. With the SpectroPolarimeter Option comes an additional SpectroPolarimeter Supplemental Operator s Manual which contains important safety information, details regarding the tunable optical source, and instructions for the spectral analysis features in the AxoView software. 1.4 Automated XY Scan Table Option Axometrics offers an automated XY Scan Table for mapping spatial variations of polarization properties across samples. These Scan Table Polarimeter systems are intended for automated quality control applications. The scan table is seamlessly integrated with either the AxoScan single-wavelength Mueller Matrix Polarimeter or with the AxoScan Mueller Matrix SpectroPolarimeter. With the XY Scan Table comes an additional XY Scan Table Supplemental Operator s Manual which contains important safety information, hardware details, and a description of the XY mapping features in the AxoView software. 1.5 Automated Out-of-Plane Measurement Fixture (Tip-Tilt Table Option) The Automated Tip-Tilt Table is optional hardware for measuring the polarization properties as a function of angle of incidence. The Tip-Tilt table is seamlessly integrated with either the AxoScan singlewavelength Mueller Matrix Polarimeter or with the AxoScan Mueller Matrix SpectroPolarimeter. With the Tip-Tilt Table comes an additional Tip-Tilt Table Supplemental Operator s Manual which contains details regarding the hardware and describes the automated Tip-Tilt measurement features in the AxoView software. 1.6 Temperature Controller In order to stabilize the calibration, the internal temperatures of the AxoScan heads are held constant at 35 C (95 F) using a resistive heater element that is controlled using the AxoScan Control Unit. If the heads are started from room temperature there is a 30 minute warm-up time until the calibration is fully stabilized. This Controller is located on the front panel of the AxoScan Control Unit. 3

8 2 UNPACKING AND SETUP 2.1 Shipment Contents The AxoScan system has been shipped in one or more boxes. Axometrics recommends retaining these boxes in case the AxoScan Polarimeter system needs to be shipped in the future. The items below are included with the Axometrics AxoScan Mueller Matrix Polarimeter system: 1. This Operator s Manual 2. Polarization State Generator (PSG) head 3. Polarization State Analyzer (PSA) head 4. Mounting hardware (brackets, post, etc.) 5. Instrument Control Unit 6. Documentation and software for the computer inside the Instrument Control Unit (for backup purposes) 7. CD with Axometrics software and drivers (for backup purposes) 8. One or two BNC-to-SMA coaxial cables 9. Two push-pull locking cables 10. One 68-pin SCSI-3 ribbon cable 11. Two AC input power cords 12. Flat panel monitor with power supply and video cable 13. Keyboard and mouse 14. Hex-key wrenches for all adjustment and assembly bolts 15. Reference retarder, CAL-VIS (Optional) Additional SpectroPolarimeter hardware and manual 17. (Optional) Additional XY Scan Table hardware and manual 18. (Optional) Additional Tip-Tilt Table hardware and manual 2.2 Setting Up the Instrument Refer to the INSTRUMENT DETAILS section of this manual for photographs and additional information regarding the AxoScan. The AxoScan should be setup in the following order: 1. The PSG and PSA instrument heads may have been shipped with the mounting hardware already attached. If not, attach the PSG and PSA heads to the stand using the supplied bolts. Each head has two mounting holes. There may be additional holes on the bottom of the PSG 4

9 and PSA heads, however, the two mounting holes are easily identified by their stainless steel inserts. The other holes are used to access fasteners that secure internal components in the polarimeter heads. Do not loosen the fasteners in these other holes under any circumstance. 2. Attach the BNC-SMA coaxial cable(s) and the two push-pull locking cables to the instrument control box and to the instrument heads. Labels indicate the appropriate connection ports on the rear of the instrument control box. 3. Connect the top and bottom portions of the Control Unit with the 68-pin SCSI-3 ribbon cable. 4. If your system contains an integral diode laser, attach the laser power cable to the Control Unit and the laser. The cable has connector that connects to the AUX jack on the back of Control Unit and a 16-pin rectangular connector that attached to the laser. White dots painted on the laser and on the 16-pin connector indicate the proper orientation. Installing this cable backwards will not damage the laser, but will prevent the laser from turning on when the Control Unit is powered up. 5. Attach AC input power cords to both instrument control box inputs, then insert into a 120 VAC outlet. 6. Turn on the computer of the Control Unit by pressing the bottom power button. 7. Once the computer has booted up, turn on the electronics of the Control Unit by pressing the square green power button on the upper unit. CAUTION: Only turn on the electronics module (top portion of the Control Unit) when the computer (bottom portion) is already on. When powering up, turn on the computer and then the electronics. When powering down, turn off the electronics and then the computer. If the electronics are turned on while the computer is off, you may notice the motors in PSG and PSA pulsating. In this case, simply turn off the electronics module. Leaving the system in this state (pulsating motors) for extended periods may damage the motors and motor control electronics. 8. If your system includes an FC or SMA adapter for use with an external fiber-coupled source, attach the source and turn it on. You will need to collimate and align the beam so it can pass through both optical heads unobstructed. See next section for details. 9. (Option) Run the MMP Alignment Utility 2.0 to align the PSG and PSA heads. Refer to Section 6.1 for details. 10. (Option) Run the MMP Calibration Utility 2.0 to calibrate the instrument. Refer to Section 6.2 for details. 11. Run the program AxoView 2.0 to start the system. A shortcut to this program can be found on the Windows Desktop. 2.3 Setting up the fiber-coupled source If an external fiber-coupled source is used, use the following procedure to couple the source into the optical heads. 1. The supplied fiber optic cable has SMA connectors with ferrules attached to each end. Insert one of the ferrules (leaving the fiber optic attached) into the output port of the light source. 2. The ferrule on the other end of the fiber is inserted into a sleeve that contains a collimating lens. (See the figure below) By loosening the Thumbscrew in the sleeve, the ferrule can be moved back and forth, thus focusing the beam emerging from the collimator. You can adjust the 5

10 collimation as desired, but keep in mind that the beam should remain less than 10 mm diameter in order to pass unobstructed through both of the AxoScan heads. thumbscrew Fiber optic with SMA ferrule installed in the collimator sleeve. You can adjust the beam collimation by loosening the thumbscrew and moving the fiber back and forth. 3. Insert the collimating sleeve into the adapter on the back of the AxoScan polarization state generator (PSG). Lock the sleeve in place with the thumbscrew. locking screw collimating sleeve adjustment screw screw thumbscrew 4. Now, the beam of light should be clearly visible coming out the front of the PSG head. The beam needs to be well-centered on the output window of the PSG. If the beam is not well centered, try loosening the thumbscrew and readjusting or rotating the collimator sleeve. Generally, this is enough adjustment and the next step can be skipped. 6

11 5. If you are unable to get the beam centered in the PSG output window by readjusting the collimating sleeve, you will need to adjust the tip and tilt of the adapter plate on the PSG input. Do this by loosening all three locking screws and then turning the adjustment screws until the beam is centered in the output window of the PSG. Tighten the locking screws. You might need to repeat this process a few times. 6. Once the beam is emerging from the center of the PSG output window, the final step in the alignment is to position the PSG and PSA heads such the beam enters the center of the PSA input window and the PSA and PSG are coaxial. The following illustration shows a good alignment (left) and a poor alignment (poor). In the poorly aligned system, the optical beam is centered on the PSA entrance window, however the beam strikes the internal apertures of the polarimeter. While this system may appear to be operating correctly, measurement accuracy will be reduced. A properly aligned polarimeter (left) and a poorly aligned polarimeter (right) If the polarimeter heads are mounted to a vertical mounting fixture (such as the XY Scan Table option), it is often useful to first align the polarimeter with a PSA head removed. As shown in the following figure, removing the PSA head allows the PSG head to be aligned to the PSA mounting bracket. This way, it is easier to see if the optical beam is properly centered. The beam should be centered approximately 34 mm above the mounting bracket, and should be aligned along the mounting bolts on the bracket. Also, the fiber-optic collimator should be focused so that the beam diameter is not much more that 10 mm diameter at the PSA location. Once this step is finished, attached the PSA head and adjust it to center the beam on the input window. 7

12 Aligning the PSG head to the PSA mounting bracket. The optical beam should be centered 34 mm from the bracket and lined up along the mounting bolts. 8

13 3 INSTRUMENT DETAILS 3.1 Instrument Heads The Mueller Matrix Polarimeter instrument includes two separate heads. PSG or Polarization State Generator head PSA or Polarization State Analyzer head The PSG can be identified by an additional extension on the side of the head which contains the reference photodiode. PSG Head PSA Head Each head has a flat surface that defines the bottom of the head. The bottom of each head has two mounting holes that accept #10-32 bolts. There may be additional holes on the bottom of the PSG and PSA heads, however, the two mounting holes are easily identified because they contain stainless steel inserts. The other holes are to access fasteners that secure internal components in the polarimeter heads. Do not loosen the fasteners in these other holes under any circumstance. Refer to the picture below for details: #10-24 mounting holes with stainless steel inserts These are NOT mounting holes. Do not loosen the fasteners that are in these holes. 3.2 Polarization State Generator (PSG) The PSG head includes the following components: Either an integral laser or a collimator for fiber-coupled sources Adjustment bracket for fine steering the optical beam 9

14 A stationary polarizer and high-speed motor with rotating retarder (waveplate) for generating polarization states Optional beamsplitter and reference detector. This option is only included when a fiber-coupled optical source is used. Removable front window. This window may be cleaned by the user as needed. If this window is removed, do not insert any object into the PSG head as you will run the risk of damaging the precision waveplate inside. 3.3 Polarization State Analyzer (PSA) The PSA head includes the following components: Removable front window. This window may be cleaned by the user as needed. If this window is removed, do not insert any object into the PSA head as you will run the risk of damaging the precision waveplate inside. A stationary polarizer and high-speed motor with rotating retarder (waveplate) for analyzing polarization states after they have interacted with the sample. Detector 3.4 Cables Electrical connections from each head to the instrument control box are made using two cables. BNC-SMA coaxial cable(s) for attaching the PSG and PSA heads to the Control Unit Push-pull locking cables for attaching the PSG and PSA heads to the Control Unit There is also a 68-pin SCSI-3 ribbon cable for attaching the top and bottom portions of the Control Unit to each other. On the AxoScan Control units, there are heater connectors that remain connected during shipping. There are labels on each of the six heater cables. They will be labeled PSA1H, PSA2H, PSA3H, PSG1H, PSG2H, and PSG3H. The numbering scheme for the AxoScan Controllers in the Operator Station from top to bottom is AxoScan 1, AxoScan 2, and AxoScan 3. See the figure below. 10

15 3.5 Control Unit Temperature Control Heater Cables The MMP Control Unit controls the instrument, analyzes data, and provides a graphical user interface for the user. It is enclosed in a 2U height box that can be mounted into most standard 19-inch racks with optional mounting brackets (contact Axometrics for details). The chassis contains the following: Power supplies Motor controllers Instrument computer The following photograph shows the rear panel of a typical Control Unit. Be sure to attach the cable between the Data Connection on the control electronics and the Data Connection on the computer. 11

16 120 VAC PSG push-pull bulkhead Optional aux. power jack for laser systems PSG BNC PSA push-pull bulkhead PSA BNC Data connection 120 VAC RS-232 (COM1) RS-232 (COM2) If your system includes an integral diode laser, it will not have the PSG BNC connector shown in the illustration, and it will have a connector in the AUX position indicated for supplying power to the laser. Both of the 120 VAC connectors must be plugged in for the system to operate. The top 120 VAC connector has a toggle switch on the back panel that must be turned on. If this toggle switch is turned off, the green on/off button on the front panel will not operate. The Control Unit contains a fully functional computer running Microsoft Windows operating system. The MMP Control Unit must be handled with extreme caution. As with any computer system, moving the Control Unit while it is turned on can result in damage to the system s hard drive. Carefully avoid dropping or impacting the Control Unit as damage may occur. The following figure shows the front of the Control Unit. Ethernet Data connection Electronics Power Computer Power The top power switch provides power to the motors, detectors, and laser within the PSG and PSA Heads. The bottom power switch turns on the computer. If the operating system hangs up, the bottom power switch can be held in for 5 seconds to perform a hard reboot of the computer. The order in which the two units are powered up or powered down is important. When powering up, turn on the computer and then the electronics. When powering down, turn off the electronics and then the computer. If the electronics are turned on while the computer is off, you may notice the motors in the PSG and PSA pulsating. In this case, simply turn off the electronics module. Leaving the system in this state (pulsating motors) for extended periods may damage the motors and motor control electronics. 12

17 3.6 Temperature Controller The internal temperature of the AxoScan Heads is displayed on the front panel of the AxoScan Control Unit. Polarimeter Temperature Controller When the heater control unit is turned on it will require about one hour for the internal temperature of the Polarimeter heads to stabilize at 35 C. The temperature control system was designed such that the internal temperature of the AxoScan Heads will not exceed the damage threshold of 50 C. For normal day to day usage, the heater control unit can be left running continuously (The heaters remain operational regardless of whether the Electronics Power switch is turned on). Because the AxoScan heads are always kept at a constant temperature, a long warm-up of the AxoScan system is not necessary before beginning to make measurements. The front green power button puts the system in standby. The temperature controllers will be active if the power button is pressed. To turn off the temperature controllers, use the switch on the back of the power entry module. The green light on the front of the controller labeled CV1 will slowly blink on and off during operation. When CV1 is on, voltage is being applied to the heating element in the head. This light will be on constantly during initial startup. Because the temperature can drift by as much as 2 when the AxoScan system is first powered up, it is recommended that you allow approximately 5 minutes for the temperatures in the heads to re-stabilize. Important: Do not attempt to adjust the temperature set point on the heater control box. The AxoScan system was calibrated with the heads at a temperature of at 35 C. Attempting to change the temperature will invalidate the system calibration. 3.7 Software The following software has been installed on the Control Unit computer: Licensed copy of Microsoft Windows operating system Axometrics AxoView programs and files The Axometrics Mueller Matrix Polarimeter programs provided with the system are described in the SOFTWARE section of this manual. While installing additional software (such as data analysis software, word processors, etc.) on the dedicated Control Unit computer is unlikely to affect the polarimeter, Axometrics discourages installing additional software, especially software that may run background processes causing the instrument program to compete for system resources thereby degrading instrument performance. 13

18 In the event of a catastrophic computer problem it may be necessary to reinstall the operating system or reformat the hard drive. Please contact Axometrics for detailed instructions or assistance. 14

19 4 POLARIMETER OPERATION The program AxoView.exe is the Graphical User Interface (GUI) software for operating the instrument. A shortcut to this program can be found on the Windows Desktop. This program is described in the AXOVIEW SOFTWARE USER S MANUAL. Also included, AxoScan Engine.exe, is the software that manages the hardware and user requests for measurements and motion; start this program before any client software such as AxoView. To edit settings, use the program AxoScan Configuration.exe. 4.1 AxoScan Engine AxoScan Engine.exe runs the AxoScan Polarimeter and associated hardware. It acts as a server and is not the primary user interface. AxoScan Engine does have a few controls, mostly for viewing the status of the system. 15

20 First, under the Tools menu item the user can access the TCPIP Commands Log. From here the user can see any incoming command attempts and the response the engine sent back. This can be useful for users that want to develop their own client software to interface with the AxoScan Engine for debugging purposes. It is also helpful in troubleshooting large systems. 16

21 On the front-panel of the engine there is a Settings button. It is similar to the GUI seen in AxoScan Configuration.exe, which will be discussed later and is the best tool for changing settings. Should a setting need to change (common examples: changing COM ports, disabling the tilt and rotation motors, increasing or decreasing a filtering option) Axometrics recommends using AxoScan Configuration. Most of the tabs on this window should not be changed from the AxoScan Engine, without particular instructions or assistance from Axometrics. Some Settings on here will not be applied while the machine is operating. Some settings can not be changed from this window. Note:If you want to edit settings on here the password is ; the password is stored in AxoScan Polarimeter.ini and can be changed by editing the that file directly with the ini key shown below. [System] Config Password=

22 The AxoScan Status tab is where the user can see the current status of the machine. Ethernet Connections will display all clients with an active connection to AxoScan Engine. Signal Tower Status shows the general status of the machine; there is a Signal Tower purchasing option for users that want a hardware display of this status. Safety shows the status of the Safety Interlock input signal and Emergency Stop input signal. If the Safety Interlock is engaged the system will not move, and if it is tripped while a movement the error will need to be cleared by a user. If the Emergency Stop is engaged the system will shutdown with a settable delay, usually 15 seconds. 18

23 The Last Measurement tab displays the raw measurement information as a Mueller Matrix (not normalized), as well as Reduced Parameters. For the last measurement taken. 19

24 4.2 AxoScan Configuration AxoScan Configruation.exe is used to change the settings used by AxoScan Engine.exe. The machine shipped with settings that worked during manufacturing and factory testing. Axometrics recommends the user keep a copy of C:\AxoView\Current Version backed up incase of disaster; setting up a polarimeter without starting from a good initialization file is non-trivial. Should a setting need to change (common examples: changing COM ports, disabling the tilt and rotation motors, increasing or decreasing a filtering option) this is the software to use. The Initial Settings 1 Tab is has four sections: General, Acquisition Parameters, Ethernet Communication Ports, and Tunable Light Source. The items useful to the user under General are the Enable boxes for turning on or off stages and the tunable light source. Acquisition Parameters are used for controlling the hardware directly associated with the polarimeter heads and parameters used for calculating Mueller matrices. Some users want to set the wavelength the machine will set the light source to on startup, to do so use the Startup Wavelength parameter. Tunable Light Source has the parameters use to connect to and use the Axometrics tunable light source. If your system has multiple light sources and the type or COM port needs to be changed, the parameter is TLS Communication Port, COM1 is the default port. 20

25 Initial Settings 2 Tab has the controls to tune the motors, set hardware level digital filtering (this is only recommended in instances where the polarimeter is in an electrically noisy environment that is affecting the measurement, this is VERY rare) and change some timing parameters. Use the Enable Motors button to turn on the motors. If the motor error is more than 4%, it is recommended that the user use Auto Configure, which will adjust the motor speeds and associated parameters. Once the motor speed is acceptable turn off Auto Configure, close the Speed Error window, turn off Enable Motors and don t forget to Save Configuration. The indicators in the same section as Enable Motors are updated when the motors are running. 21

26 The Waveforms Tab can be used to watch raw data as the system operates. This is useful for troubleshooting. The PSG Slot Sensor should have at least two dips, as shown below. The PSG RPM should be around 2000, the PSA RPM should be around The PSG Detector should have at least 0.5 volts and only have Gaussian noise, no harmonics. If the PSG Detector is at 0 volts the fiber is likely not connected, the Light Source is off, or the shutter is closed on the light source. PSG Slot Sensor PSG RPMs PSA Slot Sensor PSA RPMs PSG Detector PSA Detector 4.3 AxoView The AxoView GUI is the main polarimeter control program which acquires data, provides real-time data visualization on the Poincaré sphere, streams the measurements to disk, and creates measurement reports. When the GUI runs, the motors within the PSG and PSA Heads are activated automatically and you should hear the whir of the motors as they begin to rotate. 22

27 4.3.1 BASIC OPERATIONAL CONTROLS For a detailed description of polarimeter operation, refer to the AXOVIEW SOFTWARE USER S MANUAL that came with your shipment. To test that your polarimeter is working properly Press the RUN ONCE button to perform a single measurement. That measurement will remain on-screen until a new measurement is acquired. NOTE: It is a good idea to start off a measurement sequence by hitting the RUN ONCE button and observing measurements made with NO sample between the PSG and PSA, i.e. a measurement of air. A measurement of air should result in very low diattenuation, polarizance and retardance values, and should also result in a transmittance of approximately 1.0. If the measurements appear to be random, check that the optical source is actually turned on, check that the instrument cables are properly hooked up, and ensure that the large green power switch on the Control Unit is on. To exit the program, press the EXIT button. This will ensure that the motors in the PSG and PSA stop rotating. NOTE: In the event of an abnormal program termination, the motors in the PSG and PSA may continue to rotate after the program has exited. To turn the motors off, simply run the program again and properly exit by pressing the EXIT button. The OPTICAL WAVELENGTH control must be set to the wavelength of your optical source. For systems with integral diode lasers, this value cannot be adjusted by the user. For systems that allow user- 23

28 supplied fiber-coupled sources, it is up to the user to set the wavelength control accurately to ensure proper system calibration. If you ordered a SpectroPolarimeter option, the OPTICAL WAVELENGTH control will also let you set the wavelength of your optical source. See your SpectroPolarimeter Operator s Manual for additional information. 4.4 Polarimeter Coordinate System It is imperative that the user understands the coordinate system used by all the Axometrics polarimeters. This coordinate system is standard throughout most of the polarization measurement community. If the AxoScan is mounted horizontally on an optics table, vertical polarization is defined to be parallel to the gravitational gradient. A line is scribed into the front window housing of each AxoScan head to approximately indicate horizontal. The true reference surface is the machined flat edge that attaches to the mounting bracket. The instrument s coordinate system is defined as follows: Horizontal is defined as zero degrees. Angles increase in the counter-clockwise direction when looking into the PSG head, as shown below. The measured 0 point is calibrated to within +/-0.5 of true horizontal as defined by the flat mounting edge of the PSG body. The 0 reference angle can be redefined as needed. See the Calibration manual for details on using the CAL-VIS-1 reference retarder to redefine the zero orientation of your system. 24

29 5 GENERAL SAFETY 5.1 Electrical The universal power inputs accept 110/220 VAC for operation. The instrument control box has no user serviceable parts inside. 5.2 Replacing Fuses A single fuse is accessible on the rear of the instrument control box. The fuse is located adjacent to the top on/off switch on the AC input receptacle. 5.3 Mechanical Avoid dropping, sudden shocks, or rough handling of the Mueller Matrix Polarimeter system since this may cause the instrument to lose its calibration and/or may destroy the mechanical components and optics. Verify that the instrument is properly assembled before operation. Do not move the instrument control box while it is powered. 5.4 Optical Do not touch any of the optical surfaces since the contact is likely to cause irreversible degradation through scratches and scatter. Remove the optical windows before cleaning them. Use only optical grade methanol as a cleaning solvent. Avoid rubbing the window with anything but a cotton swab (moist with methanol). Do not allow dust to enter the head while the window is removed for cleaning. 5.5 Laser Safety Polarimeters that ship with integral diode lasers have been adjusted at the factory such that the output beam from the PSG head meets the laser classification on the warning sticker applied to the PSG head. Follow all guidelines listed on the warning label. CAUTION: Never intentionally stare directly into any laser beam. For polarimeters which shipped with an integral diode laser, do not operate the laser if it has been removed from the MMP Polarization State Generator Head. The laser output power directly out of the laser may exceed the laser classification described on the warning label affixed to the PSG head. For polarimeters which shipped with a FC or SMA collimating lens, the user is responsible supplying a fiber-coupled optical source. Refer to the manufacturer of your optical source for details about its laser classification and safety precautions. 25

30 6 WARRANTY Axometrics warrants that all goods described in this manual shall be free from defects in material and workmanship for a period of one (1) year after delivery of goods to the buyer. Please contact Axometrics or your local agent if you are experiencing any difficulties. 26