Fast Steering Mirror User`s Manual
Contents
1. 1 10th wave p v depends on mirror substrate Useable aperture 0 94 SON ORR Model OIM102 Mirror key features v 2 glass mirror mounted to gimbal using low out gassing RTV Y Mirror coating to customer requirements v Wave front quality wave rms Y Useable aperture 1 95 Model OIM102 3 Mirror key features 2 1 x 3 glass mirror mounted to gimbal using low out gassing RTV v Mirror coating to customer requirements v Wave front quality 14 wave rms Y Useable aperture 1 95 viewed 45 degrees incident angle Page 4 of 11 Drive Motors All mirror models are driven by a push pull configuration of voice coils similar to speaker coil magnet arrangement However unlike a speaker the FSM is configured with a moving magnet instead of a moving coil This arrangement has several advantages The first being that since the coil is stationary the wires do not have to move which adds greater overall reliability The second advantage is that the heat generated by the mirror coils is conducted to the mirror housing away from the optical mirror substrate This prevents thermal distortions of the mirror wavefront quality Proper heatsinking of the coils prevent coil damage when the mirror is overdriven Mirror Suspension The mirror is flexurally suspended in two axes The flexure is designed for an infinite fatigue life under normal operation the absence of high levels of external vibration The mirror rotates in both directions ar2. in a remote enclosure connected to the FSM via a 6 foot cable Mirror commands are input to the controller through a 25 socket D sub miniature connector The commands are differential signals representing the x and y mirror positions scaled to the 10 volt range For example the X command can be grounded and the X command can go from 10volts to 10volts The input impedance of the command signals is 10K ohms Monitor signals are provided for the actual mirror positions error signals feedback error between commanded position and actual position The PID gain of the controller may be set from the controller front panel potentiometers See fig 1 amp a v axis foo al _ or EO Qa ov Figure 1 Adjustable PID The potentiometers that are accessible from the controller front panel set the mirror proportional gain P CCW is increasing gain The other adjustment potentiometers are mounted to the controller board to access these pots the front 4 cover screws must be removed The photo in figure 1 shows the front panel slid forward to allow access to the integral 1 and derivative gain potentiometers CCW to increase gain on both these pots The controller card is attached to another card via a ribbon cable which is hidden inside the controller box The mirror can be driven while this card is pulled forward allowing the user to optimize the PID values for a given step requirement while Page 6 of 11 monito
3. Fast Steering Mirror User s Manual OIM100 series FSM Models OIM101 OIM102 OIM102 3 Optics October 11 2008 Motion Revision D Product Warranty Optics In Motion LLC warrants this product to be free from defects in material and workmanship for a period of 1 year from the date of shipment If the product is found to be defective during the warranty period the product will either be repaired or replaced at Optics In Motion s option This warranty does not apply to defects resulting from modifications or misuse of any product or part Optics In Motion LLC shall not be held liable for any indirect special or consequential damages caused by the use of the product Table of Contents Page NUR QN IG oh ahs a care 2 COMMS 3 Fast Steering Mirror Description i Aeneane a eTA Ka EASAC SEIO VAEA SE SAN ENA Ya 4 Fast Steering Mirror Models 4 oo E Do s Pas y boy P P wig bone 5 MIPROFSUSDSTISIOFIS A A t Bou eue eu te Ou en 5 Mirror Angular Position tu bie ole ae Fe n 5 Mirror Controllers 6 Figure 1s Adjustable Dre Fat ed as 6 Mirror Power Supply eere mehr ite he redo fno as dab gt db ge 7 Figure 2 Controller Front View cola nla or e aca RR t oo mea Quee emer or nes REN eu ms 8 Figure 3 Controlle
4. Steering Mirror Block Diagram X ERROR SERVO X COMMAND CONTROLLER INT EXT SWITCH X POSITION LOCAL X POSITION EXT X POSITION OUTPUT Figure 6 Block diagram for X axis control Page 11 of 11
5. on input from external quad or similar position sensor 6 GND Output Ground Reference 7 15 VOLTS Output 15 VDC for external loads of less than 100ma 8 RESERVED 9 N C 10 Y EXTERNAL Input Y external mirror position High side of differential position input from external quad or similar position sensor 11 Y EXTERNAL Input Y external mirror position Low side of differential position input from external quad or similar position sensor 12 Y COMMAND Input Y mirror position command Low side of differential command input Range 10 Volts 13 Y COMMAND Input Y mirror position command High side of differential command input Range 10 Volts 14 X POSITION Output X mirror angular position readout from local position sensor referenced to ground 15 5 VOLTS Output 5 VDC for external loads of less than 100ma 16 GND Output Ground Reference 17 X EXTERNAL Input X external mirror position Low side of differential position input from external quad or similar position sensor 18 RESERVED 19 15 VOLTS Output 15 VDC for external loads of less than 100ma 20 GND Output Ground Reference 21 RESERVED 22 GND Output Ground Reference 23 Y POSITION Output Y mirror angular position readout from local position sensor referenced to ground 24 Y ERROR Output Y summing junction error voltage output difference between commanded and actual position referenced to ground 25 RESERVED Page 10 of 11 Fast
6. ound a single pivot point The pivot point for model OIM101 1 mirror is located 12mm behind the mirror surface and for model OIM102 2 mirror the pivot point is 9 5mm behind the mirror surface The OIM102 3 has a pivot point located 12 5mm behind the mirror surface Mirror Angular Position Local Position the mirror has a built in optical position sensor The position sensor provides mirror feedback information to the controller which can also be monitored by the user The local position sensor outputs a voltage which is proportional to the mirror angular position The position sensor scale factor is 10volts 1 5 degrees 26 2 mrad and has a range from 10 volts 1 5 degrees mechanical 3 0 degrees optical to 10 volts 1 5 degrees mechanical 3 0 degrees optical External Position the mirror controller has inputs for a user supplied control signals Typically these signals are from an external quadrant cell which is used to monitor the position of a beam reflected off the surface of the fast steering mirror These external signals x and y position angles are differentially input into the mirror command connector A TTL level high input to the command connector INT EXT switch controls the source of mirror feedback switching it from local to external position control In normal operation internal feedback mode these connections are left open Page 5 of 11 Mirror Controller The mirror controller electronics are housed
7. r Rear View cares hres eerie 8 Figure 4 Model OIM101 Mirror Head Front 9 Figure 5 Model OIM101 Mirror Head Rear View 9 Fast Steering Mirror Block Diagram 11 Figure 6 Block diagram for X axis control 11 Page 3 of 11 Fast Steering Mirror Description Voice coil driven Fast Steering Mirrors FSM have been used for several years in military and aerospace applications for target acquisition scanning and beam steering These mirrors were typically low volume high cost parts Optics In Motion has engineered a line of fast steering mirrors which have many of the attributes of the military versions low noise high pointing accuracy and high acceleration step speeds but are available at commercial prices Fast Steering Mirror Models The 100 series fast steering mirror product line consists of a one inch glass version with a user replaceable mirror sub mount and a two inch glass mirror version where the mirror is hard mounted to the mirror gimbal and a 2 1 x 3 elliptical version Model OIM101 Mirror key features Uses industry standard 1 x 0 25 or 1 x 6mm glass mirrors Mirror coating to customer requirements Mirror mounted into sub mount using low out gassing RTV Additional sub mount available for user installation of mirror Wave front quality
8. ring the position and error signals on a scope Also shown in the figure is our 25 pin D to BNC adapter that can be used for non OEM operation Mirror Power Supply The controller is powered by an external 15 volt power supply capable of 1 5 amps of current The external power supply is an air cooled tabletop supply which plug directly into a 110 or 220 volt wall socket Page 7 of 11 COMMAND CONNECTOR i 4 1 FAST STEERING MIRROR CONTROLLER Figure 2 Controller Front View TO MIRROR HEAD Figure 3 Controller Rear View Page 8 of 11 TO CONTROLLER Figure 5 Model OIM101 Mirror Head Rear View Page 9 of 11 25 Socket Sub miniature D Connector Command Connector Wiring Table Pin 1 0 Number Signal Name Type Description 1 X ERROR Output X summing junction error voltage output difference between commanded and actual position referenced to ground 2 INT EXT SWITCH Input Normally low TTL input High level switches the position feedback input from local to external used with input pins 10 11 and 17 5 3 X COMMAND Input X mirror position command Low side of differential command input Range 10 Volts 4 X COMMAND Input X mirror position command High side of differential command input Range 10 Volts 5 X EXTERNAL Input X external mirror position Low side of differential positi
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