Our Operating Funding Partners Recent Design Improvements to the Canadian Light Source (CLS)...
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Our Operating Funding Partners www.lightsource .ca Recent Design Improvements to the Canadian Light Source (CLS) Recent Design Improvements to the Canadian Light Source (CLS) Optical Metrology Facility Long Trace Profilometer Optical Metrology Facility Long Trace Profilometer Brian Yates Brian Yates * * , Alan Duffy , Alan Duffy * * , Shawn Carriere , Shawn Carriere * * (* CLS) (* CLS) A design upgrade was recently initiated for the long trace A design upgrade was recently initiated for the long trace profilometer (LTP) at the Canadian Light Source that allows profilometer (LTP) at the Canadian Light Source that allows radius of curvature measurements, on large mirror benders, radius of curvature measurements, on large mirror benders, as a function of bending force prior to beamline as a function of bending force prior to beamline installation. The LTP vertical clearance can now handle installation. The LTP vertical clearance can now handle mirror benders up to approximately 500 mirror benders up to approximately 500 mm mm in height. A in height. A decoupled external enclosure reduces air convection current decoupled external enclosure reduces air convection current effects, and vertical adjustment of the main beam can be effects, and vertical adjustment of the main beam can be safely performed by one person, with no realignment of the safely performed by one person, with no realignment of the LTP reference light beam. Design criteria and recent LTP reference light beam. Design criteria and recent stability scan results will be discussed. stability scan results will be discussed. Motivation Motivation The need arose from two CLS hard x-ray beamlines that use The need arose from two CLS hard x-ray beamlines that use relatively large mirror bender mechanisms in their designs. relatively large mirror bender mechanisms in their designs. There was a requirement prior to installation to measure There was a requirement prior to installation to measure these mirror bender systems to determine the radius of these mirror bender systems to determine the radius of curvature as a function of bending force, and to verify curvature as a function of bending force, and to verify that the overall slope error (mirror plus bender) met that the overall slope error (mirror plus bender) met specifications. A design that provides adequate vertical specifications. A design that provides adequate vertical clearance between the LTP optical head and the mirror clearance between the LTP optical head and the mirror bender system was required. Fig. 1 shows the LTP prior to bender system was required. Fig. 1 shows the LTP prior to the system upgrade. the system upgrade. Discussion Discussion • Mirror bender mechanisms up to 500 mm in height should be Mirror bender mechanisms up to 500 mm in height should be measurable. measurable. • More rigid support of the LTP main beam to achieve sub- More rigid support of the LTP main beam to achieve sub- microradian microradian stability. stability. • Eliminate realignment issues of the reference light beam Eliminate realignment issues of the reference light beam with a change in with a change in LTP main beam height. LTP main beam height. • An external enclosure that is decoupled from the LTP and An external enclosure that is decoupled from the LTP and vibration vibration isolation table to reduce air convection currents. isolation table to reduce air convection currents. • All operations of the LTP should be directly viewable and All operations of the LTP should be directly viewable and accessible from accessible from the front access doors. the front access doors. • Vertical adjustment of the LTP main beam can be safely Vertical adjustment of the LTP main beam can be safely performed by one performed by one person. person. A series of stability tests were carried out as a function of A series of stability tests were carried out as a function of scan duration time to estimate our “noise floor”, keeping the scan duration time to estimate our “noise floor”, keeping the LTP position fixed. For this test essentially “identical” LTP position fixed. For this test essentially “identical” super-polished silicon mirrors from General Optics (Catalogue super-polished silicon mirrors from General Optics (Catalogue Number GO-S100-1) were used for both the reference beam and Number GO-S100-1) were used for both the reference beam and the sample. Fig. 5 shows the LTP stability test with scan the sample. Fig. 5 shows the LTP stability test with scan duration times ranging from 30 to 600 seconds. duration times ranging from 30 to 600 seconds. It is interesting to note that although the average sample It is interesting to note that although the average sample beam slope error contribution is 83 nrad RMS, the beam slope error contribution is 83 nrad RMS, the “bottleneck” appears to lie more with the reference beam “bottleneck” appears to lie more with the reference beam which has a much higher average slope error contribution of which has a much higher average slope error contribution of 270 nrad RMS. Typically when measuring a mirror the two 270 nrad RMS. Typically when measuring a mirror the two signals are either added or subtracted from one another signals are either added or subtracted from one another (phasing depends on the setup) to correct for the (phasing depends on the setup) to correct for the fluctuations in the straightness of the LTP main beam. As a fluctuations in the straightness of the LTP main beam. As a result an actual mirror measurement is currently limited to result an actual mirror measurement is currently limited to this noise floor of ~300 nrad. A series of test fans was set this noise floor of ~300 nrad. A series of test fans was set up to mix the air through which the reference beam passes, to up to mix the air through which the reference beam passes, to break up convection cells and avoid air stratification, but break up convection cells and avoid air stratification, but the stability tests were either unchanged or slightly worse the stability tests were either unchanged or slightly worse than that shown in Fig. 5. In order to further reduce the than that shown in Fig. 5. In order to further reduce the LTP noise floor we are looking into improving our room LTP noise floor we are looking into improving our room temperature stability (from ±0.1 to ±0.01 degrees temperature stability (from ±0.1 to ±0.01 degrees centigrade), and replacing the main LTP aluminum beam with a centigrade), and replacing the main LTP aluminum beam with a ceramic beam from Coorstek, Inc., with substantially better ceramic beam from Coorstek, Inc., with substantially better flatness of ~5 μrad RMS, higher stiffness, and lower flatness of ~5 μrad RMS, higher stiffness, and lower coefficient of thermal expansion. coefficient of thermal expansion. The design used extruded aluminum The design used extruded aluminum beams from MK Profile [1] to build a beams from MK Profile [1] to build a rigid support system for the main rigid support system for the main LTP beam and enclosure. The LTP beam and enclosure. The surrounding enclosure is isolated surrounding enclosure is isolated from the vibration isolation table from the vibration isolation table and LTP main beam by a small and LTP main beam by a small clearance gap. The enclosure has clearance gap. The enclosure has three floor-mounted support legs and three floor-mounted support legs and a fourth support at the back wall. a fourth support at the back wall. Transparent 0.25” polycarbonate Transparent 0.25” polycarbonate sheets enclose the top and side sheets enclose the top and side panels of the external isolated panels of the external isolated enclosure, using rubber grommets for enclosure, using rubber grommets for additional vibration isolation. Fig. additional vibration isolation. Fig. 2 shows the LTP and enclosure with a 2 shows the LTP and enclosure with a mirror bender under test, and Fig. 3 mirror bender under test, and Fig. 3 shows a back view of the LTP. shows a back view of the LTP. The two aluminum towers supporting The two aluminum towers supporting the LTP main beam were precision the LTP main beam were precision machined from solid aluminum 4”x4” machined from solid aluminum 4”x4” bar (Type 6061-T6), with thirty five bar (Type 6061-T6), with thirty five precisely drilled holes in each, precisely drilled holes in each, allowing LTP beam height adjustments allowing LTP beam height adjustments over a total range of 510 over a total range of 510 mm mm , to , to within 15 within 15 mm mm . An expanding pin is . An expanding pin is used to align both sides of the main used to align both sides of the main beam to equal height, to better than beam to equal height, to better than 1 mrad levelness. Once level the 1 mrad levelness. Once level the two bolts beside each expanding pin two bolts beside each expanding pin are tightened to lock the LTP main are tightened to lock the LTP main beam down, and the expanding pins beam down, and the expanding pins removed. The reference mirror is removed. The reference mirror is mounted fixed relative to the main mounted fixed relative to the main beam, eliminating reference mirror beam, eliminating reference mirror readjustments. Fig. 4 shows an readjustments. Fig. 4 shows an expanding pin locked in one of the expanding pin locked in one of the hole. hole. A removable worm gear hand winch A removable worm gear hand winch (McMaster-Carr Part. No. 3205T16, (McMaster-Carr Part. No. 3205T16, load capacity of 2000 lbs.) was used load capacity of 2000 lbs.) was used to lift the main LTP beam using to lift the main LTP beam using 3/16” stainless steel braided 3/16” stainless steel braided cables. The hand winch employs a cables. The hand winch employs a 41:1 gear ratio and is of a “no back 41:1 gear ratio and is of a “no back drive” design so a single person can drive” design so a single person can raise or lower the LTP main beam. raise or lower the LTP main beam. Two cables are employed on the worm Two cables are employed on the worm gear – one to raise the right gear – one to raise the right portion of the LTP beam, the other portion of the LTP beam, the other to simultaneously raise the left to simultaneously raise the left portion through a longer cable and portion through a longer cable and adjustment turnbuckle. The adjustment turnbuckle. The turnbuckle allows the tension of the turnbuckle allows the tension of the two cables to be matched. Typically two cables to be matched. Typically the entire worm gear mechanism and the entire worm gear mechanism and cables are removed once the desired cables are removed once the desired Design Criteria Design Criteria Stability Tests Stability Tests Figure 3: Back view of the upgraded LTP showing the rigid support structure for the main beam (before external decoupled enclosure assembly). The worm gear hand winch (center portion) and wire/pulley system (middle-top portion) raises or lowers the main LTP beam to the desired height. Figure 2: Front view of the upgraded CLS Long Trace Profilometer (front doors open), showing adjustable height adjustment and external decoupled enclosure. Under measurement is a 1.1 m length vertically collimating mirror bender system mounted on an adjustable tip/tilt stage. Figure 4: Front view of the left tower support structure showing the wire/pulley system and anchor shackle/eyebolt that can be used to raise or lower the main LTP beam. Also visible are the precision drilled holes in the tower (15 mm spacing over a range of 510 mm) to which the height can be adjusted, and the lever/expanding pin that is used to align and level both sides to better than 1 mrad, before lock-down. Figure 5: LTP stability versus scan duration time. The sample and reference beam data have been shown separately for comparison purposes, and have had a best fit constant removed. The ±1s error bars shown were determined from seven measurements. Acknowledgements Acknowledgements • The CLS is supported by NSERC, NRC, CIHR, and the The CLS is supported by NSERC, NRC, CIHR, and the University of Saskatchewan. University of Saskatchewan. Figure 1: Front view of the CLS Long Trace Profilometer prior to the system upgrade shown with a small mirror under test. Motivation Motivation
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Transcript of Our Operating Funding Partners Recent Design Improvements to the Canadian Light Source (CLS)...
Our Operating Funding Partners
www.lightsource.ca
Recent Design Improvements to the Canadian Light Source Recent Design Improvements to the Canadian Light Source (CLS) Optical Metrology Facility Long Trace Profilometer(CLS) Optical Metrology Facility Long Trace Profilometer
Brian YatesBrian Yates**, Alan Duffy, Alan Duffy**, Shawn Carriere, Shawn Carriere** (* CLS) (* CLS)
A design upgrade was recently initiated for the long trace profilometer A design upgrade was recently initiated for the long trace profilometer (LTP) at the Canadian Light Source that allows radius of curvature (LTP) at the Canadian Light Source that allows radius of curvature measurements, on large mirror benders, as a function of bending force measurements, on large mirror benders, as a function of bending force prior to beamline installation. The LTP vertical clearance can now handle prior to beamline installation. The LTP vertical clearance can now handle mirror benders up to approximately 500 mirror benders up to approximately 500 mmmm in height. A decoupled in height. A decoupled external enclosure reduces air convection current effects, and vertical external enclosure reduces air convection current effects, and vertical adjustment of the main beam can be safely performed by one person, with adjustment of the main beam can be safely performed by one person, with no realignment of the LTP reference light beam. Design criteria and recent no realignment of the LTP reference light beam. Design criteria and recent stability scan results will be discussed.stability scan results will be discussed.
MotivationMotivation The need arose from two CLS hard x-ray beamlines that use relatively The need arose from two CLS hard x-ray beamlines that use relatively large mirror bender mechanisms in their designs. There was a requirement large mirror bender mechanisms in their designs. There was a requirement prior to installation to measure these mirror bender systems to determine prior to installation to measure these mirror bender systems to determine the radius of curvature as a function of bending force, and to verify that the the radius of curvature as a function of bending force, and to verify that the overall slope error (mirror plus bender) met specifications. A design that overall slope error (mirror plus bender) met specifications. A design that provides adequate vertical clearance between the LTP optical head and the provides adequate vertical clearance between the LTP optical head and the mirror bender system was required. Fig. 1 shows the LTP prior to the mirror bender system was required. Fig. 1 shows the LTP prior to the system upgrade.system upgrade.
DiscussionDiscussion
• Mirror bender mechanisms up to 500 mm in height should beMirror bender mechanisms up to 500 mm in height should be measurable. measurable.• More rigid support of the LTP main beam to achieve sub-microradianMore rigid support of the LTP main beam to achieve sub-microradian stability. stability.•Eliminate realignment issues of the reference light beam with a change inEliminate realignment issues of the reference light beam with a change in LTP main beam height. LTP main beam height.• An external enclosure that is decoupled from the LTP and vibrationAn external enclosure that is decoupled from the LTP and vibration isolation table to reduce air convection currents. isolation table to reduce air convection currents.• All operations of the LTP should be directly viewable and accessible fromAll operations of the LTP should be directly viewable and accessible from the front access doors. the front access doors.• Vertical adjustment of the LTP main beam can be safely performed by oneVertical adjustment of the LTP main beam can be safely performed by one person. person.
A series of stability tests were carried out as a function of scan duration time A series of stability tests were carried out as a function of scan duration time to estimate our “noise floor”, keeping the LTP position fixed. For this test to estimate our “noise floor”, keeping the LTP position fixed. For this test essentially “identical” super-polished silicon mirrors from General Optics essentially “identical” super-polished silicon mirrors from General Optics (Catalogue Number GO-S100-1) were used for both the reference beam and (Catalogue Number GO-S100-1) were used for both the reference beam and the sample. Fig. 5 shows the LTP stability test with scan duration times the sample. Fig. 5 shows the LTP stability test with scan duration times ranging from 30 to 600 seconds.ranging from 30 to 600 seconds.
It is interesting to note that although the average sample beam slope error It is interesting to note that although the average sample beam slope error contribution is 83 nrad RMS, the “bottleneck” appears to lie more with the contribution is 83 nrad RMS, the “bottleneck” appears to lie more with the reference beam which has a much higher average slope error contribution of reference beam which has a much higher average slope error contribution of 270 nrad RMS. Typically when measuring a mirror the two signals are either 270 nrad RMS. Typically when measuring a mirror the two signals are either added or subtracted from one another (phasing depends on the setup) to added or subtracted from one another (phasing depends on the setup) to correct for the fluctuations in the straightness of the LTP main beam. As a correct for the fluctuations in the straightness of the LTP main beam. As a result an actual mirror measurement is currently limited to this noise floor of result an actual mirror measurement is currently limited to this noise floor of ~300 nrad. A series of test fans was set up to mix the air through which the ~300 nrad. A series of test fans was set up to mix the air through which the reference beam passes, to break up convection cells and avoid air reference beam passes, to break up convection cells and avoid air stratification, but the stability tests were either unchanged or slightly worse stratification, but the stability tests were either unchanged or slightly worse than that shown in Fig. 5. In order to further reduce the LTP noise floor we than that shown in Fig. 5. In order to further reduce the LTP noise floor we are looking into improving our room temperature stability (from ±0.1 to ±0.01 are looking into improving our room temperature stability (from ±0.1 to ±0.01 degrees centigrade), and replacing the main LTP aluminum beam with a degrees centigrade), and replacing the main LTP aluminum beam with a ceramic beam from Coorstek, Inc., with substantially better flatness of ~5 ceramic beam from Coorstek, Inc., with substantially better flatness of ~5 μrad RMS, higher stiffness, and lower coefficient of thermal expansion.μrad RMS, higher stiffness, and lower coefficient of thermal expansion.
The design used extruded aluminum beams The design used extruded aluminum beams from MK Profile [1] to build a rigid support from MK Profile [1] to build a rigid support system for the main LTP beam and system for the main LTP beam and enclosure. The surrounding enclosure is enclosure. The surrounding enclosure is isolated from the vibration isolation table and isolated from the vibration isolation table and LTP main beam by a small clearance gap. LTP main beam by a small clearance gap. The enclosure has three floor-mounted The enclosure has three floor-mounted support legs and a fourth support at the back support legs and a fourth support at the back wall. Transparent 0.25” polycarbonate sheets wall. Transparent 0.25” polycarbonate sheets enclose the top and side panels of the enclose the top and side panels of the external isolated enclosure, using rubber external isolated enclosure, using rubber grommets for additional vibration isolation. grommets for additional vibration isolation. Fig. 2 shows the LTP and enclosure with a Fig. 2 shows the LTP and enclosure with a mirror bender under test, and Fig. 3 shows a mirror bender under test, and Fig. 3 shows a back view of the LTP.back view of the LTP. The two aluminum towers supporting the LTP The two aluminum towers supporting the LTP main beam were precision machined from main beam were precision machined from solid aluminum 4”x4” bar (Type 6061-T6), solid aluminum 4”x4” bar (Type 6061-T6), with thirty five precisely drilled holes in each, with thirty five precisely drilled holes in each, allowing LTP beam height adjustments over a allowing LTP beam height adjustments over a total range of 510 total range of 510 mmmm, to within 15 , to within 15 mmmm. An . An expanding pin is used to align both sides of expanding pin is used to align both sides of the main beam to equal height, to better than the main beam to equal height, to better than 1 mrad levelness. Once level the two bolts 1 mrad levelness. Once level the two bolts beside each expanding pin are tightened to beside each expanding pin are tightened to lock the LTP main beam down, and the lock the LTP main beam down, and the expanding pins removed. The reference expanding pins removed. The reference mirror is mounted fixed relative to the main mirror is mounted fixed relative to the main beam, eliminating reference mirror beam, eliminating reference mirror readjustments. Fig. 4 shows an expanding readjustments. Fig. 4 shows an expanding pin locked in one of the hole.pin locked in one of the hole.
A removable worm gear hand winch A removable worm gear hand winch (McMaster-Carr Part. No. 3205T16, load (McMaster-Carr Part. No. 3205T16, load capacity of 2000 lbs.) was used to lift the capacity of 2000 lbs.) was used to lift the main LTP beam using 3/16” stainless steel main LTP beam using 3/16” stainless steel braided cables. The hand winch employs a braided cables. The hand winch employs a 41:1 gear ratio and is of a “no back drive” 41:1 gear ratio and is of a “no back drive” design so a single person can raise or lower design so a single person can raise or lower the LTP main beam. Two cables are the LTP main beam. Two cables are employed on the worm gear – one to raise employed on the worm gear – one to raise the right portion of the LTP beam, the other the right portion of the LTP beam, the other to simultaneously raise the left portion to simultaneously raise the left portion through a longer cable and adjustment through a longer cable and adjustment turnbuckle. The turnbuckle allows the turnbuckle. The turnbuckle allows the tension of the two cables to be matched. tension of the two cables to be matched. Typically the entire worm gear mechanism Typically the entire worm gear mechanism and cables are removed once the desired and cables are removed once the desired height has been achieved.height has been achieved.
[1] MK is the copyright for Maschinebau Kitz.[1] MK is the copyright for Maschinebau Kitz.
Design CriteriaDesign Criteria
Stability TestsStability Tests
Figure 3: Back view of the upgraded LTP showing the rigid support structure for the main beam (before external decoupled enclosure assembly). The worm gear hand winch (center portion) and wire/pulley system (middle-top portion) raises or lowers the main LTP beam to the desired height.
Figure 2: Front view of the upgraded CLS Long Trace Profilometer (front doors open), showing adjustable height adjustment and external decoupled enclosure. Under measurement is a 1.1 m length vertically collimating mirror bender system mounted on an adjustable tip/tilt stage.
Figure 4: Front view of the left tower support structure showing the wire/pulley system and anchor shackle/eyebolt that can be used to raise or lower the main LTP beam. Also visible are the precision drilled holes in the tower (15 mm spacing over a range of 510 mm) to which the height can be adjusted, and the lever/expanding pin that is used to align and level both sides to better than 1 mrad, before lock-down.
Figure 5: LTP stability versus scan duration time. The sample and reference beam data have been shown separately for comparison purposes, and have had a best fit constant removed. The ±1s error bars shown were determined from seven measurements.
AcknowledgementsAcknowledgements• The CLS is supported by NSERC, NRC, CIHR, and the University of The CLS is supported by NSERC, NRC, CIHR, and the University of Saskatchewan.Saskatchewan.
Figure 1: Front view of the CLS Long Trace Profilometer prior to the system upgrade shown with a small mirror under test.
MotivationMotivation
