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PSM Application Notes

Aligning a Parabola to an Autocollimating Flat Mirror (ABSTRACT)

ABSTRACT: An autostigmatic microscope is a perfect way of aligning an autocollimating flat mirror to a parabola. This notes descibes the simple two step process of positioning the PSM objective focus coincident with the focus of the parabola.

Aligning Optical Elements to a Common Axis (ABSTRACT)

ABSTRACT: It is sometimes necessary to align a series of optical elements, lenses and mirrors, to a single, straight optical axis. This note describes a method using an autostigmatic microscope (ASM) where the ASM is moved along a straight line relative to the axis of the bench in which the elelemts are mounted so the centers of curvature of the elements can be adjusted to lie on the line or axis of the system.

Measurement of Radius of Curvature (ABSTRACT)

ABSTRACT: The most common use of the Point Source Microscope (PSM), or any autostigmatic microscope, is the precision measurement of the radius of curvature of spherical surfaces. This note describes the procedure for doing so and defines confocal and Cat's eye focus.

Measuring Wedge in a Window (ABSTRACT)

ABSTRACT: One of the easier measurements to make with the Point Source Microscope (PSM) is determining the wedge in a nominally plane, parallel window by removing the PSM microscope objective and using the PSM as an autocollimator to view the wedge between the surfaces.

The Autostigmatic Microscope (ABSTRACT)

ABSTRACT: This relatively recent (1983) paper by W. H. Steel of CSIRO is the only paper found in the archival literature to describe an autostigmatic microscope (ASM) and its most common use, the measurement of radii of curvature, in this case, the radii of contact lenses. The Point Source Microscope (PSM) is a modern version of this classical instrument.

What is a Point Source Microscope? (ABSTRACT)

ABSTRACT: As opposed to a bright field, reflecting microscope that produces an image of a microscopic object, a point source, or autostigmatic, microscope uses pinhole illumination to produce a diffration limited spot at the objective focus and that spot diverges as a nearly perfect spherical wavefront. This note describes many useful applications of the Point Source Microscope (PSM), a modern version of the classic autostigmatic microscope, that also includes a bright field imaging option and is useful as an autocollimator.

Bibliography: Archival papers describing a variety of applications of the PSM

“A simple tool for alignment and wavefront testing”, W. P. Kuhn, Opt-E, Proc SPIE 66760F, doi: 10.1117/12.735477. Paper discusses methods of quantifying wavefront error using a PSM., Proc. SPIE 883804, doi:10.1117/12.2024599. Paper discusses the use of the MFT to take surface topography maps of window and lens surfaces.
“A simple tool for alignment and wavefront testing: experimental results”, W. P. Kuhn, Opt-E, Proc. SPIE 70680C, doi: 10.1117/12.798224. Paper shows experimental results of using a PSM and phase retrieval methods to measure wavefront error.
“A toolbox of metrology-based techniques for optical system alignment”, P. Coulter, NASA GSFC, Proc. SPIE 9951-7, Paper discusses many familiar optical alignment tools including the PSM.
“Alignment and use of the optical test for the 8.4 m off-axis primary mirrors of the Giant Magellan Telescope”, S. West, et. al., Steward Observatory and College of Optical Sciences, Univ. of Arizona, Proc. SPIE 77390N, doi:10.1117/12.857251. Paper shows several uses of the PSM in the alignment of the test optics for the GMT mirror metrology including a PSM permanently built into the test optics.
“Alignment of four-mirror wide field corrector for the Hobby-Eberly Telescope”, C. J. Oh, et. al., College of Optical Sciences, Univ. of Arizona, Proc. SPIE 884403, doi:10.1117/12.2023427. Papers shows the use of the PSM on the ram of a CMM for precise positioning of fiducial CGHs in alignment fixtures.
“Aspheric and freeform surfaces metrology with software configurable optical test system: a computerized reverse Hartmann test”, P. Su, et. al, College of Optical Sciences, Univ. of Arizona, Opt. Eng. 53, 031305, DOI: 10.1117/1.OE.53.3.031305. Paper shows the use of the PSM to precisely align the components of reflection deflectometry tests in conjunction with a CMM and a laser tracker.
“Centration of optical elements”, E. Milby & J. Burge, College of Optical Sciences, Univ. of Arizona, Proc. SPIE 812616, doi:10.1117/12.894126. Paper describes using the PSM in both the autostigmatic and autocollimation modes for centering lens elements on a rotary table.
“Delivery, Installation, On-sky Verification of the Hobby Eberly Telescope Wide Field Corrector”, H. Lee, et. al., Univ. of Texas at Austin, Proc. SPIE 990646, doi:10.1117/12.2231224. Paper shows of the use of PSM to align the mirrors within the Wide Field Corrector.
“Design and analysis of an alignment procedure using CGHs”, L. Coyle, M. Dubin & J. Burge, College of Optical Sciences, Univ. of Arizona, Opt. Eng. 52, 084104, doi: 10.1117/1.OE.52.8.084104. Paper shows use of the PSM in autostigmatic mode to find points in space produced by a CGH in reflection.
“Design and development of the fibre cable and fore optics of the HERMES Spectrograph for the Anglo-Australian Telescope (AAT)”, J. Brzeski, S. Case & L. Gers, Australian Astronomical Observatory, Proc. SPIE 812504, doi:10.1117/12.896389. Paper describes using the PSM to precisely position fibers that form the curved slit in the spectrograph.
“Design and implementation of a new time-delayed source and alignment considerations for a tangent ogive interferometer”, H. Durazo, et. al., Breault Research Organization, Proc. SPIE 730215, doi: 10.1117/12.818385. Paper shows the use of the PSM to align a multi-armed interferometer to a common point in space.
“Design of head-mounted binoculars utilizing freeform surfaces”, R. R. Boye, et. al., Sandia National Laboratory, Opt. Eng. 53, 031310, doi:10.1117/1.OE.53.3.031310. Paper describes using the PSM to help align the free form optics in the binoculars.
“Design of Wearable Binoculars with On-Demand Zoom”, R. R. Boye, et. al., Sandia National Laboratory, Proc. SPIE 88410H, doi: 10.1117/12.2024619 . Paper describes using the PSM to help align the free form optics in the binoculars.
“Development of surface metrology for the GMT primary mirror”, J. Burge, et. al., College of Optical Sciences, Univ. of Arizona, Proc. SPIE 701814, doi: 10.1117/12.790082. Paper describes using the PSM to alignment the null CGH in the null optics for the GMT primary mirror.
“Dynamic distortion calibration using a Diffracting Pupil”, E. Bendek, et. al., Steward Observatory, Univ. of Arizona and Lawrence Livermore National Laboratory, Proc SPIE 81510U, doi: 10.1117/12.893130. Paper describes the use of the PSM to align an off-axis parabola to a pinhole to give diffraction limited performance.
“Fabrication and testing of the first 8.4 m off-axis segment for the Giant Magellan Telescope”, H. Martin, et. al., Steward Observatory, Univ. of Arizona, Proc. SPIE 77390A, doi: 10.1117/12.857494. Paper shows how the PSM was an integral part of the alignment of the test optics for the GMT metrology.
“Final acceptance testing of the LSST monolithic primary/tertiary mirror”, M. Tuell, et. al., Steward Observatory, Univ. of Arizona and National Optical Astronomy Observatory, Proc. SPIE 91510W, doi:10.1117/12.2057076. Paper discusses the use of the PSM to measure the alignment of the optical axes of the two surfaces of the LSST primary/tertiary mirror.
“First light results from the High Efficiency and Resolution Multi-Element Spectrograph for Anglo-Australian Telescope”, A. Sheinis, et. al., Australian Astronomical Observatory, et. al., JATIS 035002, doi: 10.1117/1.JATIS.1.3.035002. Paper discusses the use of the PSM to bring the various arms of the spectrograph into alignment with each other.
“GMTIFS: The Adaptive Optics Beam Steering Mirror for the GMT Integral-Field Spectrograph”, J. Davies, et. al., Research School of Astronomy & Astrophysics, The Australian National University, Proc. SPIE 991217, doi:10.1117/12.2231560. Paper describes the use of the PSM to produce a pseudo guide star on which to align the spectrometer optics.
“Hermes – the engineering challenges”, J. Brzeski, S. Case & L. Gers, Australian Astronomical Observatory, Proc SPIE 84464N, doi:10.1117/12.924635. Paper discusses the centering of lenses within a barrel using the PSM and a rotary table. It also discusses using the PSM to locate the assembled lens within a fixture using a CMM.
“High Numerical Aperture Multimode Fibers for Prime Focus Use”, K. Zhang, J. Zheng & W. Sanders, Australian Astronomical Observatory and Nanjing Institute of Astronomical Optics and Technology, Proc SPIE 99125J, doi: 10.1117/12.2232131. Paper discusses using the PSM to center a diffraction limited spot in the center of a multimode optical fiber to less than one micrometer.
“High-accuracy aspheric x-ray mirror metrology using Software Configurable Optical Test System/deflectometry”, R. Huang, et. al., College of Optical Sciences, Univ. of Arizona and Brookhaven National Laboratory, Opt. Eng. 54, 084103, doi: 10.1117/1.OE.54.8.084103. Paper discusses use of the PSM to measure the locations of the camera and screen in a reflection deflectometry test setup.
“KOALA, a wide-field 1000 element integral-field unit for the Anglo-Australian Telescope: assembly and commissioning”, R. Zhelem, et. al., Australian Astronomical Observatory and Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, Proc SPIE 91473K, doi: 10.1117/12.2055588. Paper discusses using the PSM to align optical fibers to a micro-lens array.
“Low uncertainty alignment procedure using computer generated holograms”, L. Coyle, M. Dubin & J. Burge, College of Optical Sciences, Univ. of Arizona, Proc SPIE 81310B, doi: 10.1117/12.895237. Paper describes using the PSM to align two computer generated holograms to each other in transmission.
“Optical alignment with computer generated holograms”, J. Burge, R. Zehnder, C. Zhao, College of Optical Sciences, Univ. of Arizona, Proc SPIE 66760C, doi: 10.1117/12.735853. Paper discusses using computer generated holograms to create points in space for alignment purposes that can be viewed in reflection by a PSM or interferometer.
“Optomechanical design and tolerance of a microscope objective at 121.6 nm”, D. Keyes, College of Optical Sciences, Univ. of Arizona, Proc SPIE 957506, doi: 10.1117/12.2188803. Paper discusses using a PSM and rotary table to align the mirrors in a reflecting microscope objective.
“Progress in manufacturing the first 8.4 m off-axis segment for the GMT”, H. Martin, et. al., Steward Observatory and College of Optical Sciences, Univ. of Arizona, Proc SPIE 70180C, doi: 10.1117/12.789805. Paper shows how the PSM is an integral part the alignment of the optics used to test the GMT segments.
“Progress on the GMT”, M. Johns, Carnegie Observatories, Proc SPIE 701213, doi: 10.1117/12.788063. Paper points out the use of the PSM in the alignment of the test optics for the GMT mirrors.
“Research on the Measurement Technology of Effective Arm Length of Swing Arm Profilometer”, L. Chen, et. al., Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu, Proc SPIE 92800P, doi: 10.1117/12.2070673. Paper discusses using the PSM to measure the relationship of the swing arm probe tip to references on a coordinate measuring machine.
“Research on the relationship of the probe system for the swing arm profilometer based on the point source microscope”, M. Gao, et. al., Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu, Proc SPIE 96230N, doi: 10.1117/12.2186280. Paper discusses using the PSM to measure the relationship of the swing arm probe tip to laser tracker SMRs.
“Scanning pentaprism test for the GMT 8.4 m off-axis segments”, R. Allen, et. al, Steward Observatory and College of Optical Sciences, Univ. of Arizona, Proc SPIE 773911, doi: 10.1117/12.857901. Paper discusses using the PSM to measure the position of the camera detector array chip to SMRs mounted on the outside of the camera.
“SITELLE optical design, assembly, and testing”, D. Brousseau, et. al., Département de physique, génie physique et optique (COPL), Université Laval, Département de physique (CRAQ), Université de Montréal, Montréal, Proc SPIE 91473Z, doi: 10.1117/12.2055214. Paper discusses the use of the PSM to align the two halves of a Fourier Transform Spectrometer and to measure the point spread function of the instrument.
“Swing arm optical coordinate-measuring machine: high precision measuring ground aspheric surfaces using a laser triangulation probe:, Y. Wang, et. al., College of Optical Sciences, Univ. of Arizona, Opt. Eng. 51, 073603, doi: 10.1117/1.OE.51.7.073603. Paper discusses the use of the PSM to relate the focus of the triangulation sensor to laser tracker SMRs mounted to the sensor.
“Swing-arm optical coordinate measuring machine: modal estimation of systematic errors from dual probe shear measurements”, P. Su, et. al., College of Optical Sciences, Univ. of Arizona, Opt. Eng. 51, 043604, doi: 10.1117/1.OE.51.4.043604. Paper discusses the use of the PSM to measure the position of the fiber optic probe tips to laser tracker SMRs mounted on the swing arm.
“The deterministic optical alignment of the HERMES spectrograph”, L. Gers & N Staszak, Australian Astronomical Observatory, Proc SPIE 915113, doi:10.1117/12.2055574. Paper discusses using the PSM to define the optical axis of the spectrometer and to align the various arms of the spectrometer to a common axis.
“Use of a commercial laser tracker for optical alignment”, J. Burge, et. al., College of Optical Sciences, Univ. of Arizona, Proc SPIE 66760F, doi: 10.1117/12.736705. Paper discusses the use of the PSM to aid in locating nests for laser tracker SMRs relative to other features on optics or fixtures that need to be aligned.
“Using the Point Source Microscope (PSM) to find conjugates of parabolic and elliptical off-axis mirrors”, R. Parks & M. Borden, College of Optical Sciences, Univ. of Arizona, Proc. SPIE 81310A, doi:10.1117/12.894333. Paper discusses the use of the PSM to locate the tangential and sagittal centers of curvature of off-axis conic mirrors and the axes of rotation of toroidal mirrors and measure their radii of curvature.

Case Studies & Testimonials

Why is proper alignment so important?

Here is a case of a very happy customer due to better optics.

A few days ago an astronomer friend of mine commented that he had gotten the optics of his telescope improved and the improvement reduced the time it took to get data by a factor of 3. For an astronomer this is a dramatic improvement since observing time on large telescopes can cost thousands of dollars an hour.

My friend did not say how the optics had been improved, but the important point is that better optics, whether due to figure errors, mounting or alignment mean more productive optics. I generally think of better optics as a better product leaving the manufacturing facility without thinking about how much the better optics mean to the productivity of the customer.