Hinds Instruments PEM200 User Manual Download

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PEM200

PHOTOELASTIC MODULATOR

USER MANUAL

Hinds Instruments, Inc.

P/N: 010-0000-095 UM Rev B

Summary of Contents for PEM200

Page 1: ...PEM200 PHOTOELASTIC MODULATOR USER MANUAL Hinds Instruments Inc P N 010 0000 095 UM Rev B ...

Page 2: ...nished by Hinds Instruments Inc is believed to be accurate and reliable however no responsibility is assumed by Hinds Instruments Inc for its use nor for any infringements of patents or other rights of third parties which may result from its use No license is granted by implication or otherwise under any patent rights of Hinds Instruments Inc In all respects the English version of this manual is c...

Page 3: ... II ZS50 ZS42 Optical Heads 10 Series II ZS37 Optical Heads 11 1 Introduction 12 Overview 12 2 PEM 200 Controller 13 PEM 200 Controller Front Panel 13 PEM 200 Controller Rear Panel 14 PEM 200 Controller Rear Panel Buttons 14 PEM 200 Controller Rear Panel Connections 14 PEM 200 Controller Rear Panel LEDs 15 PEM 200 Controller Dimensions 15 3 Modulator Head Assembly 16 Optical Head 16 Controller Err...

Page 4: ...n 48 Calibration Theory 48 Light Sources for Modulator Calibration 50 Calibration Using an Oscilloscope 51 Multiple Reflection Techniques 53 Static Waveplate Techniques 54 Bessel Function Zero Methods 54 Bessel Function Ratio Methods 56 Parallel Polarizer Calibration at a Single Wavelength 57 B Specifications 61 General Controller 61 Parameter Specifications 61 Input Output Specifications 61 Envir...

Page 5: ... or practices that could result in personal injury or loss of life CAUTION statements identify conditions or practices that could result in damage to the equipment or other property NOTICE statements identify conditions or practices that are important in proper use of the equipment to get the expected results PEM 200 Controller Labels CE The CE certification label is located at the top right corne...

Page 6: ...t for communication with any Windows 7 or newer computer ON OFF The ON OFF engraving is above the power switch Ensure the power is off before connecting or disconnecting SMA cables from HV outputs to optical head More details below WARNING HARZARDOUS VOLTAGE USB ON OFF CE Label 24V DC ...

Page 7: ...a DC power source at 24 VDC The main power input is 90 264VAC 47 63 Hz 1 7A A protective ground connection by way of the grounding connector in the power cord is required for safe operation Power line requirements are listed in the specifications section The power cord provided with this instrument is less than 3 meters in length Use only the power cord and connector specified for your product to ...

Page 8: ...rsonnel Operating Space Hinds Instruments suggests leaving 2 3 inches 5 8cm minimum of space around the PEM 200 controller to allow for safe connection and disconnection of all cables Keep liquids of all types away from PEM200 especially if flammable Integration Special Conditions The integration of the PEM into a measurement system by a customer doesn t involve any change or modification to the P...

Page 9: ... User Manual 5 Not Required To operate the PEM200 there no requirements for Safety Equipment Accessories Pollution Degree Ventilation Flow of air or cooling liquid Permanently connected equipment Sound level ...

Page 10: ...h If the shipment receives handling rough enough to trigger the shock watch the watch will turn red 3 Open the container and inspect the contents Do not throw away the container or any damaged parts Try to keep all items in the same condition as originally received 4 Notify the Transport Company immediately in writing preferably by facsimile or email about the shipping damage 5 Wait for the transp...

Page 11: ...1 PEM200 Photoelastic Modulator in Shipping Case Packaging Overview The PEM200 packaging is separated into four sections Power Supply Unit Optical Head SMA Cable Assembly Power Cable PEM 200 Controller Unpacking the PEM Optical Head ...

Page 12: ...I FS50 PEM optical head Ensure the work surface is clean and free of dust Using a 1 Phillips screwdriver remove the shipping disk The alternate side of the Optical Head is covered by tape to prevent dust and other particles from entering the enclosure This can be easily removed by hand Please save the shipping disk screws and white cover in the event the PEM needs to be transported Shipping Disk Q...

Page 13: ...ging the optical assembly Series II FS Optical Heads 1 Remove the 4 lid screws using the provided screwdriver 2 Gently pull the yellow clip out Grab the provided tabs on the lower half of the clip There is a split in the clip under the transducer Separate the clip and lift it out from around the transducer Take care when removing a clip near transducer wires Save clips for future return or transpo...

Page 14: ...clip out Grab the provided tabs on the lower half of the clip There is a split in the clip under the transducer Separate the clip and lift it out from around the transducer Take care when removing a clip near transducer wires Save clips for future return or transportation of unit NOTE DO NOT TURN OPTICAL HEAD OVER WHILE LID IS OFF OPTICS WILL FALL OUT 3 Replace lid Extra screws are provided ...

Page 15: ...b the provided tabs on the lower half of the clip There is a split in the clip under the transducer Separate the clip and lift it out from around the transducer Take care when removing the clip near transducer wires Save clips for future return or transportation of unit NOTE DO NOT TURN OPTICAL HEAD OVER WHILE LID IS OFF OPTICS WILL FALL OUT 3 Replace lid Extra screws are provided Split ...

Page 16: ...otoelastic effect in which a mechanically stressed sample exhibits birefringence proportional to the resulting strain Photoelastic modulators are resonant devices each producing oscillating birefringence at a fixed frequency in the low frequency ultrasound range 20 kHz to 82 kHz These factors result in a number of very useful advantages which are unique to the PEM including wide acceptance angle l...

Page 17: ...0 controller is off or disconnected from power when making any connection with these SMA ports Order does not matter when connecting SMAs from HV output to optical head inputs See Operators Safety Summary for more detail Ref Out The Ref Out SMA will give a 3 3V TTL signal at the PEM s selected harmonic frequency for any triggering needs Trig Out Trig Out is a second reference SMA reserved for futu...

Page 18: ...wer Switch The PEM 200 powers using the I O switch Push the selector to the I position to power ON and O to power OFF PEM 200 Controller Rear Panel Connections USB Type B Connection The USB 2 0 Type B connector interface allows communication to a PC PEM200 software runs on Windows 7 or 10 24V Barrel Input The barrel connection is the input for a 24VDC power brick USB Type B Input ON OFF Power Togg...

Page 19: ...ill illuminate if the controller is attempting to detect connection with the PEM optical head or if the optical head connected is inappropriate match for the controller hardware Error Error red will illuminate when the PEM controller reaches a limit of drive voltage PEM will go into idle state if connected and error occurs To recover the PEM from an error state cycle the power on the PEM 200 contr...

Page 20: ... to the same frequency This assembly oscillates and produces the time varying birefringence which is the basis of operation of the PEM This assembly consisting of the optical head controller and the cables which connects them is a single circuit It is not intended to operate unless all three elements are together CAUTION Operation of the controller without the optical head attached may result in d...

Page 21: ...PEM200 User Manual 17 Figure 3 2 Model II FS42 II FS47 II FS50 Optical Head Figure 3 3 Model II FS55 II FS60 Optical Head ...

Page 22: ...PEM200 User Manual 18 Figure 3 4 Model II FS74 II FS84 Optical Head Figure 3 5 Model II ZS37 II ZS42 II ZS50 Optical Head ...

Page 23: ... required for the modulator More detailed set up information can be found at our website s applications menu The most common optical and electronic setup for checkout and calibration of the modulator is shown in figure 4 1 This shows a monochromatic light source such as a laser or multi wavelength source with a wavelength selection device e g monochromator Figure 4 1 Block Diagram for Oscilloscope...

Page 24: ... connected to the oscilloscope trigger input Figure 4 2 Oscilloscope Waveform for PEM Set to 0 25 Wave Retardation Between Crossed Polarizers and PEM 1f Reference Signal The detector circuitry deserves some special comment Care must be taken to ensure adequate frequency response typically several times the PEM operating frequency Pre amplified photo detectors are available from Hinds Instruments t...

Page 25: ...e computer that will control the PEM200 After the download has completed be sure to unzip the software package before installing The Graphical User Interface GUI is downloaded with a provided Windows Installer msi file Click on the Pem200ControllerSetup msi file After running the file a destination folder prompt will appear This is where the software will be saved on the computer Figure 5 1 PEM200...

Page 26: ...200 User Manual 22 Figure 5 2 PEM 200 Software Installer Loading Setup Running After selecting Next the setup installs the necessary files onto the computer The progress is shown through a green status bar ...

Page 27: ...will prompt you to select Finish indicating the software has been successfully installed on the computer The PEM Control Software is now installed There will be a shortcut placed on your desktop with the following icon Figure 5 3 PEM 200 Software Installer Finish ...

Page 28: ...llows before attempting to use the PEM Control Software 1 Make sure the PEM 200 has power 2 Connect the USB 2 0 B cable to the PEM 200 controller and to the PC 3 Once connected the PEM 200 should connect to a COM port on the target computer View this on the computers Device Manager 4 In the Device Manager select the Ports COM LPT dropdown If there are multiple ports open you can disconnect and rec...

Page 29: ...unication with the PEM 200 Controller 1 Open the PEM Control Software icon from the computer desktop Upon opening the following COM port dialog box will appear 2 Use the dropdown to select the computer COM port number used by the PEM200 Controller then press OK to open the main window Figure 6 2 COM port dialog box ...

Page 30: ...ew wavelength using the keyboard 2 Click on the up or down arrow to the right of the wavelength display to adjust the wavelength setting by single digits Wavelength Units The wavelength units field displays the selected wavelength unit Wavelength units can be set to display in nanometers nm micrometers µm and wavenumbers 1 cm To change the wavelength unit click on the arrow to the right of the wav...

Page 31: ...ation unit click on the arrow to the right of the retardation units field and click on the desired retardation unit The retardation displayed will adjust accordingly Frequency The frequency field displays the first 1f harmonic operating frequency of the head set being used Update Frequency Press the Update button Scan Panel The scan panel will display additional fields to set up a wavelength scan ...

Page 32: ...ays 1 Double click the number of steps displayed to highlight the setting and then enter a new number of steps using the keyboard 2 Click on the up or down arrow to the right of the number of steps display to adjust the number of steps setting by single digits Step Delay The delay in seconds taken between each step in the wavelength sweep Entering a different step delay can be accomplished two way...

Page 33: ...ctly interacting It also serves as a tool to see what commands are being used to properly set up the PEM for unique experiments or software where the user will communicate through the serial port Select the View tab and select Show Debug Panel to open the debug panel on the window Figure 6 6 Accessing PEM200 Control Debug Panel Figure 6 7 PEM200 Control Debug Panel ...

Page 34: ...ual 30 Themes The PEM Control Software offers both a light and dark theme Select the View tab and select Use Light Dark Theme to switch themes Figure 6 8 PEM200 Control Light Theme Figure 6 9 PEM200 Control Dark Theme ...

Page 35: ...and select Serial Port to change the COM port number to the PEM200 Controller The serial port dialog box will appear Use the dropdown to select the appropriate COM port Figure 6 10 PEM200 Control Serial COM Port Access Figure 6 11 PEM200 Control COM Port Selection ...

Page 36: ...s for Programmable Instruments SCPI protocol SCPI protocol is a standard syntax for controlling programmable devices The protocol outlines a common syntax command structure and data format Commands are text strings sent to the device as either set operations eg MODulator VOLTage 0 25 or get operations MODulator VOLTage Set operations are often followed by a text string containing numerical or stri...

Page 37: ...urn arguments Sent upon successfully parsing and applying the command Some returns are instant Others may take a moment to return as the unit is setting internal systems Argument format Arguments usually consist of a single floating point number These are parsed by the device as standard floats eg 0 01 or as scientific notation eg 1e 2 for 0 01 Arguments can also be a simple integer eg 1 Arguments...

Page 38: ...RMonics Set Set the harmonics measured by the synchronous detection system INTegration Set Set the integration time of the synchronous detector INTegration Get Get the integration time of the synchronous detector FORMat Set Set the XY or magnitude angle format FORMat Get Get the XY or magnitude format Measure Get Take a measurement and return data as set by FORMat MeasureDC Get Take a measurement ...

Page 39: ...Purpose Identify the unit Reports the firmware version Input example IDN Output example IDN Hinds PEM 200 controller V01 Command MODulator DRiVe Short command MOD DRV Type Get Set Purpose Sets the voltage to the modulator on an arbitrary range of 0 0 lowest modulation amplitude to 1 0 highest modulation amplitude Input example MOD DRV 0 1325 Output example DRIVE 1 325000E 1 Command MODulator AMPli...

Page 40: ...MP 316 5 Output example AMP 3 165000E 2 Command MODulator AMPRange Short command MOD AMPR Type Get Purpose Reports the modulation amplitude range in nanometers Input example MOD AMPR Output example AMPR 1 000000E 1 5 50000E 2 Command MODulator FREQuency Short command MOD FREQ Type Get Purpose Reports the frequency of modulation in Hz Input example MOD FREQ Output example FREQUENCY 5 01930899E 4 ...

Page 41: ... MOD STABLE Output example STABLE 1 Command DETector SampleFREQuency Short command DET SFREQ Type Get Set Purpose Sets the sampling frequency of the synchronous detector in Hz The valid range is 1MHz 1e6 to 10MHz 1e7 Suggested and default sample frequency is the suggested 10MHz Input example DET SFREQ 1e6 Output example SCLOCK 1 000000E 6 ...

Page 42: ...lectable gain levels and the closest option will be chosen and returned Input example DET G 20 Output example GAIN 4 000000E 2 Command DETector HARMonics Short command DET HARM Type Get Set Purpose Select the channel and harmonic of interest to measure when the synchronous detector is activated The range of the harmonic is 1 to 5 Input example DET HARM 1 2 Channel 1 2f Output example HARMONIC 1 2 ...

Page 43: ... command DET M Type Get Purpose Starts the synchronous detection system and returns the magnitude of the harmonic components as set by DET FORM Input example DET M Output example MXY 1 314652E0 3 623624E 1 2 1465E 1 1 02436E 4 9 21565E 5 Command DETector MeasureDC Short command DET MDC Type Get Purpose Quickly measure the DC amplitude of the input optical signal Returns mean and standard deviation...

Page 44: ...4652E0 Command DETector HARMTrig Short command DET HARMT Type Set Purpose Set the trigger out signal to different harmonics 1f enter 0 to 4f enter 3 Input example DET HARMT 1 Output example HARMT 1 Command DETector DETActive Short command DET DETA Type Set Purpose Set channel detector active 0 off 1 on Input example DET DETA 1 0 Channel 1 off Output example DETACT 1 0 ...

Page 45: ...utput example DDBG 0 13546 0 321654 0 212384 0 874654 0 32158 0 386546 0 87951 0 365 47 0 9874160 0 3658745 Command SYStem PEMOutput Short command SYS PEMO Type Set Purpose Sets modulator active inactive on off Input example SYS PEMO 1 Output example PEMOUT 1 Command SYStem IDLE Short command SYS IDLE Type Set Purpose Set the PEM to an idle mode where PEM will stop dynamically stabilizing Input ex...

Page 46: ...200 User Manual 42 Command SYStem CPError Short command SYS CPE Type Get Purpose Get current error and phase error as a percentage 0 1 scale Input example SYS CPE Output example CPE 2 500000E 4 1 670000E 3 ...

Page 47: ... communication please contact sales hindsinstruments com or call 1 503 690 2000 for assistance Only remove optical head cover as instructed in unpacking instructions below and when initially unpacking Do not remove cover of optical head for any other reason Ensure the optical head is disconnected from any SMA cables before removing cover High voltages can be present otherwise Do not remove cover f...

Page 48: ...n may be easily observed using an oscilloscope as described in the Calibration appendix Even when other reference points are used this method should be regarded as the coarse adjustment on the modulator calibration The peak retardation calibration of the modulator is adjusted by adjusting modulation drive MOD DRV and fitting appropriate firmware points Please contact Hinds Instruments for assistan...

Page 49: ...portant to use the proper cleaning solution for specific optic materials Failure to use the proper cleaning solution may scratch or damage the optical surface Coated Uncoated Non ZnSe Optics The non ZnSe optics are coated with a hard durable dielectric material and may be cleaned like an uncoated optical surface The optic may be cleaned with uncontaminated acetone Coated Uncoated ZnSe Optics The Z...

Page 50: ...he junction between the optical element and the transducer Figure 9 2 Junction between Optical Element and Transducer 1 Take a single piece of lint free lens tissue do not use Kimwipes and place it on the surface to be cleaned so it covers the entire surface 2 Using the recommended cleaning agent soak the lens tissue until the entire surface is damp not wet 3 Grasp two free corners of the lens tis...

Page 51: ...ture on the coated surface and assures a clean and long lasting coating This technique may be used regularly to keep residue from building up preventing damage and degradation to the optical surface When replacing the cover to the optics tighten screws Qty 4 until snug ...

Page 52: ...ods described later in this application note PEM 200 Calibration The PEM 200 has been designed to provide the same calibration for a narrow monochromatic light beam as compared to the PEM 100 For many applications the calibration built into the PEM 200 is sufficient retardation uncertainty 5 There are still cases where in situ calibration by the user is advisable or even mandatory These cases incl...

Page 53: ...sinusoidal retardation function B is the retardation magnitude of the waveplate and Ω is the angular frequency of the modulator The general expression for the intensity function is t A B t A B Ω Ω Ι cos sin sin cos cos cos 1 2 1 0 t A B Ω cos cos 1 2 1 0 1 For the majority of applications expansion of this expression using a Fourier Series is very useful 0 0 cos 1 2 1 A J B Ι DC 2 t A J B Ω cos si...

Page 54: ...when used with a monochromator or selected interference filters which match the spectral lines These allow calibration of the PEM over a range of wavelengths Interference effects should be negligible Systems based on interference filters may offer significantly better light throughput than monochromator systems White light sources may also be used with monochromators but here some caution is advis...

Page 55: ...cs including the oscilloscope should have a frequency bandwidth several times the frequency of the modulator Calibration can be done in many cases when this condition is not met but the waveforms will be distorted and the proper half wave condition will be more difficult to identify Referring to equation 3 interesting and distinctive waveforms on the oscilloscope occur whenever A0 is an integral m...

Page 56: ...onic configurations this display might appear inverted This feature is very distinctive and by adjusting the retardation at half wave to give the above waveform an accuracy of better than 1 can be achieved Figures A 4 and A 5 show waveforms for retardations slightly less and slightly more than half wave Figure A 4 Retardation 90 of Half wave ...

Page 57: ...r calibration The waveform for a retardation of four half waves is shown in figure A 6 Figure A 6 Waveform for a Retardation of Four Half waves Multiple Reflection Techniques Precise setting of the modulator peak retardation at levels less than half wave may be done by several different methods For integral fractions of a half wave the oscilloscope technique described above may be used by arrangin...

Page 58: ... static waveplate retardation and the modulator peak retardation is one half wave then a flat topped oscilloscope waveform will result The modulator retardation would then be half wave minus the retardation of the fixed waveplate The use of a calibrated Soleil Babinet Compensator would give a means of calibrating a modulator for continuous values of peak retardation Bessel Function Zero Methods An...

Page 59: ... function 0 J vanishes Figure A 8 Determining the Controller Settings for which J0 0 If a lock in amplifier is available and if the modulator is capable of providing adequate peak retardation then the AC signals can provide similar retardation calibration points Consider the second harmonic signal at twice the modulator frequency At a peak retardation or amplitude of 136 5 0 A radians 0 0 2 A J Th...

Page 60: ...retardations as shown in equation 5 2 0 2 1 0 2 2 0 2 1 0 2 2 0 2 1 0 2 2 2 1 2 2 cos 2 2 cos 2 A J A J t A J t A J A I A I V V f f f f Ω Ω 5 Assume that one of the retardation settings is the half wave calibration setting and the other setting is at somewhat less retardation Quarter wave retardation is a good example Equation 5 may be rewritten as equation 6 π π λ λ 2 2 2 2 2 2 4 J J V V f f 6 ha...

Page 61: ...tion Other methods such as the Bessel function zero method give retardation only at specific values of retardation e g 3 877 radians or 5 136 radians Another method of accurately measuring retardation at arbitrary values of modulator drive MOD DRV is much desired Calculating the ratio of V2f VDC is in principle a good approach However if calibration is being done with the PEM between crossed polar...

Page 62: ... of A0 3 radians and less It lacks sensitivity for retardation values near 3 5 radians but this is where the flat topped half wave waveform occurs π radians The graph is used in reverse for a given value of DC f V V2 A0 may be determined The method is conceived as a systematic calibration of retardation vs MOD DRV for a sequence of retardations beginning with low values Such a study should avoid a...

Page 63: ...tracted from the measured value of DC volts to give VDC There is another problem which is more subtle but just as important This method assumes that the responsivity and or gain if there is amplification are the same for DC or low frequencies as for 2f If this is the case then the following relationship should be valid 0 0 0 2 2 1 2 2 A J A J measured V measured V DC f 12 The factor of 2 results f...

Page 64: ... the value of K found may be generated and used for determining A0 Reference 1 Kemp James C Polarized Light and its Interaction with Modulating Devices Hinds International Inc 1987 2 Oakberg Theodore C Modulated Interference Effects in Photoelastic Modulators PEM Newsletter 8 Summer 1998 ...

Page 65: ...y Output 24DC Input 90 264VAC 47 63 Hz 1 7A Parameter Specifications Frequency f Display Range Resolution 37 kHz 74 kHz 1 dHz Display Accuracy 4 dHz Retardation Retardation Range See head set ratings in Appendix C Retardation Units Wavelength λ radian rad or degree o Input Output Specifications Head Connection Connector Style SMA Female RP SMA Female Reference Outputs Connector Style SMA Female Fe...

Page 66: ...erature 2 to 50 degrees C 36 to 122 degrees F Storage Temperature 40 to 65 degrees C 40 to 150 degrees F Humidity 95 RH non condensing Operating Altitude 3000 meters Overvoltage Category 40V overvoltage limit Wet Location NA Pollution Degree NA Approvals CE Approved for connection cables not exceeding 3 meters in length EMC Safety Standards EN 61326 FCC Class A EN 61010 1 ...

Page 67: ...m 170 nm 2 5 µm 22 mm II FS843 4 Fused Silica 84 kHz 200 nm 2 5 µm 200 nm 2 5 µm 13 mm II IS423 Infrasil 42 kHz 300 nm 3 5 µm 300 nm 3 µm 27 mm II IS843 4 Infrasil 84 kHz 300 nm 3 5 µm 300 nm 3 µm 13 mm II CF57 Calcium Fluoride 57 kHz 2 µm 8 5 µm 1 µm 5 5 µm 23 mm II ZS37 Zinc Selenide 37 kHz 2 µm 18 µm 1 µm 9 µm 19 mm II ZS42 Zinc Selenide 42 kHz 2 µm 18 µm 1 µm 10 µm 17 mm II ZS50 Zinc Selenide ...

Page 68: ...nstructions for one 1 year from the date of purchase subject to the provisions contained herein Our warranty shall extend to the original purchaser only and shall be limited to factory repair or replacement of defective parts Exclusions This warranty does not cover normal maintenance damage resulting from improper use or repair or abuse by the user This warranty extends only to repair or replaceme...

Page 69: ...optical and electronic heads and the controller Return For Repair Procedure If your unit ever does need repair please contact Hinds Instruments Inc before attempting repairs yourself or returning it to us We may be able to provide additional troubleshooting suggestions to help diagnose the problem In the event it is necessary to return the unit to us we will give it our prompt and professional att...

Page 70: ...the unit being shipped We are unable to accept COD shipments Return Shipping Address Customer Service Hinds Instruments Inc 7245 NE Evergreen Pkwy Hillsboro OR 97124 5850 U S A Shipping Costs If the unit is under warranty after repair or replacement has been completed we will pay the shipping costs to return the instrument to you via a carrier we choose to any destination within the continental Un...

Page 71: ...PEM200 User Manual 67 have been paid If you do not approve of our proceeding with the repair then your unit will be returned as is via UPS COD for the amount of the UPS COD freight charges ...

Page 72: ...PEM200 User Manual 68 ...

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