Agilent 10716A High-Resolution Interferometer
Contents
1. plate from the measurement side of the interferometer by loosening one cap screw and removing the other Block the measurement beam and select the small aperture on the laser head Insert the Alignment Aid Agilent Part Number 10706 60202 between the now exposed glass beam splitter and the reference reflector the one with the four adjustment cap screws and two springs See Figure 7H 8 This will allow the reference beam to autoreflect back toward the small aperture on the laser head Return light will now be visible from this reflector near the laser output aperture Now adjust TWO of the small cap screws on the housing so that this return beam autoreflects back into the small output aperture of the laser GENTLY snug the other two cap screws while observing the return beam on the output aperture Preserve the beam alignment Remove the alignment aid Agilent Part Number 10706 20202 and replace the Plane Mirror Converter Unblock the measurement beam Verify autoreflection of the measurement beam by attaching the magnetic alignment aid to the output measurement side of the interferometer and observing the autoreflected beam on the laser aperture Remove the magnetic alignment aid Verify that you now see four unclipped spots in a rectangular pattern on the face of the measurement plane mirror The room lights may have to be dimmed to see these weak spots of scattered light Install the Agilent 10780C or Agilent 10780F2. Chapter 14 Principles of Operation and Chapter 15 Accuracy and Repeatability in this manual Provide for aligning the optics laser head and receiver s on the machine Ideally you want to be able to translate beam in two directions and rotate beam in two directions for each interferometer input This typically takes two adjustment optics with proper orientations User s Manual 7H 5 Chapter 7H Agilent 10716A High Resolution Interferometer Alignment Besureto allow for transmitted beam offset of beam splitters Agilent 10700A and Agilent 10701A in your design See the offset specifications under the Specifications and Characteristics section at the end of this subchapter Alignment The objective of these instructions is to align the Agilent 10716A to make measurements with 1 minimal cosine error and thermal drift and 2 maximum signal strength at the Agilent 10780C Agilent 10780 Agilent E1708A or Agilent E1709A receiver The procedure below assumes that the plane mirror reflector is the movable optic and has been installed perpendicular to the axis of travel see the Agilent 10724A installation procedure for details Before proceeding with the alignment procedures details on interferometer configurations and alignment aids are covered Configurations The two configurations available for the High Resolution Interferometer allow flexibility in optical layout of a measurement system They
3. High Resolution Interferometer Alignment AGILENT 10716A WITH GAGE BLOCK Gage Block Figure 7H 6 Agilent 10716A with gage block attached AGILENT 10716A USING 10706 60001 ALIGNMENT AID Bee Alignment Aid Part Number 10706 60001 Measurement Beam Figure 7H 7 Agilent 10716A with alignment aid attached over measurement beam 8 Select the small aperture on the front turret of the laser head The return beam from the moving plane mirror may not autoreflect back to the small aperture of the laser head as it did in step 5 This must be corrected Adjust the laser beam until the laser beam is perpendicular to the measurement mirror This step requires pitching and yawing the laser head beam benders or beam splitters depending on optical layout 9 If substantial adjustment of the laser beam was required in step 8 the interferometer will have to be repositioned so that the beam goes through the center of the input aperture Repeat steps 1 through 5 and secure the interferometer to its mount 7H 10 User s Manual NOTE 10 11 12 16 17 19 20 Chapter 7H Agilent 10716A High Resolution Interferometer Alignment The Agilent 10716A High Resolution Interferometer is now aligned for minimum cosine error The final steps 10 through 23 will align the reference reflector for minimum thermal drift coefficient and maximum signal strength Remove the Plane Mirror Converter assembly e the quarter wave
4. dimension is 100 1mm 3 94 0 55 Figure 7H 9 Agilent 10716A High Resolution Interferometer and Agilent 10716A 001 Turned Configuration 7H 14 User s Manual Product specifications and descriptions in this Laser and Optics User s Manual document subject to change without notice Copyright C 2002 Agilent Technologies Printed in U S A 07 02 This is a chapter from the manual titled For complete manual order Paper version p n 05517 90045 CD version p n 05517 90063 This chapter is p n 05517 90115
5. 7H Agilent 10716A High Resolution nterferometer Chapter 7H Agilent 10716A High Resolution Interferometer Description Description The Agilent 10716A High Resolution Interferometer see Figure 7H 1 offers twice the resolution of conventional plane mirror interferometers and has the same excellent thermal characteristics as the Agilent 10706B interferometer typically only 0 04 micron of drift per degree C Measurement drift is typically 1 12 of that exhibited by a conventional plane mirror interferometer These features result in improved accuracy repeatability and positioning capability Although the Agilent 10716A interferometer is larger than the conventional plane mirror interferometer and the slew rate is halved the finer resolution of this optic allows laser measurement system measurement resolution of 2 5 nanometers 0 1 microinch with most Agilent laser electronics The Agilent 10716A interferometer can be used in the same applications as other Agilent plane mirror interferometers but with different alignment techniques A turned configuration Agilent 10716A 001 is available to turn the beam 90 degrees thereby eliminating the need for a beam bender Like other plane mirror interferometers the Agilent 10716A uses plane mirror reflectors such as the Agilent 10724A Plane Mirror Reflector or a suitable user supplied plane mirror Figure 7H 2 shows the optical schematic of the Agilent 10716A High Resolution interferome
6. Receiver so that light from the top aperture A aperture of the interferometer enters the center of the lens parallel to the optical axis of the lens User s Manual 7H 11 Chapter 7H Agilent 10716A High Resolution Interferometer Alignment 21 With a piece of translucent tape over the lens verify that the spots from Reference Measurement beams overlap adequately USING THE AGILENT 10706 60202 ALIGNMENT AID 22 23 Figure 7H 8 Using the Agilent 10706 60202 Alignment Aid If these spots do not overlap at the receiver the alignment should be rechecked It may be necessary to adjust the Reference Reflector adjustment screws to improve overlap Select the large aperture at the output of the laser head and traverse the full travel at the machine Verify that the LED indicator on the receiver is lighted through the full travel and the voltage measured at the receiver test point is between 0 6 and 1 3 Vdc 7H 12 User s Manual Chapter 7H Agilent 10716A High Resolution Interferometer Specifications and Characteristics Specifications and Characteristics Specifications describe the device s warranted performance Supplemental characteristics indicated by TYPICAL or NOMINAL are intended to provide non warranted performance information useful in applying the device Using electronic resolution extension the system resolution is increased significantly Depending on the system an additional resolution exte
7. are Standard Turned 10716 001 Figures 7H 3 and 7H 4 illustrate the location of the measurement beams for each configuration AGILENT 10716A BEAM LOCATIONS Adapter A IAJE 8 1 0 32 S 12 7 mm gt Le 0 50 Standard Configuration Figure 7H 3 Beam Locations for standard Agilent 10716A Interferometer 7H 6 User s Manual Chapter 7H Agilent 10716A High Resolution Interferometer Alignment Agilent 10716A 001 BEAM LOCATIONS 8 1mm gt lt 0 32 Adapter Turned Configuration Figure 7H 4 Beam Locations for Agilent 10716A 001 Turned Configuration Alignment Aids The Agilent 10716A High Resolution Interferometer is supplied with two of the alignment aids shown in Figure 7H 5 e Alignment Aid Agilent Part Number 10706 60001 e Alignment Aid Agilent Part Number 10706 60202 Alignment Aid Agilent Part Number 10706 60202 eases the autoreflection alignment for the high stability adapter to achieve minimal thermal drift and maximum signal strength It contains a quarter wave plate to reflect the reference beam back on itself and return it to the laser without offset Figure 7H 8 shows how the aid is positioned between the beam splitter and the high stability adapter during alignment User s Manual 7H 7 Chapter 7H Agilent 10716A High Resolution Interferometer Alignment ALIGNMENT AIDS FOR AGILENT 10716A Alignment Aid Ins
8. ert between Beam Splitter and High Stability reflector during autoreflection REMOVE TARGI AFTER ALIGNING HE Agilent Agilent Technologies P N 10706 60202 Alignment Aid P N 10706 60001 Alignment Aid P N 10706 60202 Figure 7H 5 Alignment Aids for the Agilent 10716A Interferometer Alignment Overview The alignment procedure is a five part process Alignment of the laser beam perpendicular to the plane mirror reflector using autoreflection Alignment of the Agilent 10716A Interferometer to the beam using a reflective gage block and autoreflection Realignment of the laser beam to correct for slight angular beam deviation caused by the interferometer Alignment of the reference reflector in the interferometer for minimum thermal drift and maximum signal strength Installation of the Agilent 10780C Agilent 10780F Agilent E1708A or Agilent E1709A receiver to properly receive the reference and measurement beams 7H 8 User s Manual NOTE Chapter 7H Agilent 10716A High Resolution Interferometer Alignment Alignment Procedure This alignment procedure is for the Standard Configuration with the laser beam entering the interferometer in aperture B The alignment procedure for the Turned Configuration is similar except it is more sensitive to angular alignment of the interferometer Either aperture A of the interferometer may be used as the input aperture The remaining apertu
9. ions Mounting Adjustable mounts The Agilent 10711A Adjustable Mount provides a convenient means of mounting aligning and securely locking the Agilent 10716A interferometer in position Since the mount allows some tilt and yaw adjustment the need for custom fixturing is minimized The mount allows the interferometer to be rotated about its centerline simplifying installation Fasteners The Agilent 10716A interferometer is supplied with English mounting hardware which is required to fasten it to its adjustable mount Installation Pre installation checklist In addition to reading chapters 2 through 4 and Chapter 15 Accuracy and Repeatability complete the following items before installing a laser positioning system into any application Complete Beam Path Loss Calculation see Calculation of signal loss in Chapter 3 System Design Considerations of this manual g You must supply the plane mirror reflectors if the Agilent 10724A Plane Mirror Reflector will not work for your installation See Chapter 15 Accuracy and Repeatability Chapter 6 Beam Directing Optics or Chapter 7 Measurement Optics in this manual for mirror specifications Determine the direction sense for each axis based on the orientation of the laser head beam directing optic and interferometer Enter the direction sense for each axis into the measurement system electronics See Chapter 5 Laser Heads
10. nsion factor of 32 for Agilent 10885A and 10895A or 256 for Agilent 10897B and 10898A is usually available Interferometer Fundamental Optical System Resolution 1 System Resolution 2 Resolution see NOTE see NOTE Agilent 10716A 2 8 79 1 3 1 pin 256 2 5 0 1 4 2048 0 31 0 012 pin NOTE The system resolution 1 is based on using 32X electronic resolution extension This is available with the Agilent 10885A and Agilent 10895A electronics The system resolution 2 is based on using 256X electronic resolution extension This is available with the Agilent 10897B and Agilent 10898A electronics User s Manual 7H 13 Chapter 7H Agilent 10716A High Resolution Interferometer Specifications and Characteristics Agilent 10716A High Resolution Interferometer and 10716A 001 Turned Configuration Specifications Weight 502 grams 1 11 pounds Dimensions see figure below Materials Used Housing 416 Stainless Steel and 6061 Aluminum Spacers Nylon Optics Optical Grade Glass Adhesives Low Volatility Vacuum Grade Optical Efficiency including a 98 efficient plane mirror reflector and the Reference Mirror Typical 30 Worst Case 25 Thermal Drift Error Change of indicated distance per degree C temperature change 0 05 micron C 1 6 pinch C typical Fundamental Optical Resolution A 8 Non linearity Error 1 nanometer 0 04 microinch Maximum Transmitted Beam Deviati
11. on 30 minutes of arc Maximum Mirror Pitch Yaw Tolerance Depends on distance between mirror and interferometer 90 2 mm Typical values are 6 minutes for 152 mm 6 inches 3 minutes for 305 mm 12 inches 2 minutes for 508 mm 20 inches MEASUREMENT MIRROR RECOMMENDATIONS Reflectance 98 for 633 nanometers at normal incidence Flatness Depending on the application and accuracy requirements of the application mirror flatness may range from 2 4 to 4 20 i e 0 16 to 0 03 meters 6 to 1 2 pinches Optical Surface Quality 60 40 per Mil 0 13830 NOTE Flatness deviations will appear as measurement errors when the mirror is translated across the beam Mount should be kinematic so as not to bend mirror If accuracy requirements demand it mirror flatness might be calibrated scanned and stored in the system controller to be used as a correction factor Misalignment of interferometer to measurement mirror will degrade the Thermal Drift Coefficient ay Loo SYM Center Line gt lt gt 12 7 mm 3 55 See Note 0 50 E 85 9 Fo 9 3 38 8 1mm 0 32 6 32 UNC 4 Places Thru Clearance For 4 or2 5mm To From Mirrors 23 9 mm 0 94 y _ 28 4 1 12 From Laser 12 7 mm 0 50 6 A 5 38 1 5 1 50 4 Receiver Note For 10716A 001 this
12. re is the output Select the small aperture on the laser head The laser beam for each axis should be aligned perpendicular to the measurement mirror This is done by autoreflecting off this mirror and adjusting the laser head or beam bender until the reflected beam is centered in the small aperture on the laser head Move the interferometer so the laser beam enters the input aperture aperture B in this example Place a rectangular gage block over the input aperture so the laser beam is reflected back toward the laser See Figure 7H 6 Adjust the interferometer in pitch and yaw until the laser beam is autoreflected back into the laser head ensuring proper alignment It may be necessary to move the interferometer again to center the laser beam on the input aperture Use a piece of translucent tape to help observe the beam Remove the gage block Note that the autoreflection procedure above is used only to reduce clipping and is not as critical as the autoreflection procedure used to reduce cosine error As long as the four beams are not clipped the alignment of the interferometer is adequate The next steps refine the alignment to reduce cosine error Place the alignment aid Agilent Part Number 10706 60001 over the output aperture plane mirror converter on the interferometer such that the measurement beam passes through the aperture on the alignment aid See Figure 7H 7 User s Manual 7H 9 Chapter 7H Agilent 10716A
13. ter The unit consists of a cube corner a plane mirror converter a retroreflector a high stability adapter anda polarizing beam splitter 7H 2 User s Manual Chapter 7H Agilent 10716A High Resolution Interferometer Description Agilent 10716A High Resolution Interferometer Figure 7H 1 Agilent 10716A High Resolution Interferometer User s Manual 7H 3 Chapter 7H Agilent 10716A High Resolution Interferometer Description MEASUREMENT PATH fa Plates Measurement Mi lt High Reflector GY fat Af fa D we n Ess fat4Af fat44f fat3Af ala A A High Reflector Cube Corners Agilent 10716A Top View REFERENCE PATH fp Plates High Reflector AA Measurement Ht gt DI a een em mm em en fren mmm mm 22225 ig ao mm I A High Reflector i i High Reflector 2 I 2 Cube Corners Agilent 10716A Top View COMPOSITE f4 and fp High Reflector A EE Measurement Mirror i i lt fat Af fa DEA IECH f og fat Af 73 Zw High Reflector Cube Corners Agilent 10716A Top View LEGEND Gg gt fp mage 1 SQ and fg f r Rounded corners are used to help you trace paths Figure 7H 2 Agilent 10716A High Resolution Interferometer optical schematic 7H 4 User s Manual Chapter 7H Agilent 10716A High Resolution Interferometer Special Considerations Special Considerat
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