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Resume of Steven M. Arnold



Ph.D. The University of Rochester (1979)
Major fields: Physics and Astronomy

M.S. The University of Rochester (1975)
Major field: Physics

B.A. summa cum laude, Hamline University (1973)
Major fields: Mathematics and Physics

Professional Experience

Diffraction International Ltd.
President and Founder, 1993 to present

APA Optics, Inc.
Staff Scientist, 1987–1992

Honeywell Corporate Research Center
Principal Research Scientist, 1980–1986

Honeywell Avionics Division
Senior Scientist, 1979

Industrial Nucleonics Corporation (Accuray)
Sensor Engineer, 1978

Research and Publications

V. John Chambers, Ronald G. Mink, Raymond G. Ohl, Joseph A. Connelly, J. Eric Mentzell, Steven M. Arnold, Matthew A. Greenhouse, Robert. S. Winsor, Johh W. MacKenty, “Optical testing of diamond machined, aspheric mirrors for ground-based, near-IR astronomy,” in Instrument Design and Performance for Optical/Infrared Ground-based Telescopes, SPIE Vol. 4841, 689–701 (2003).

Abstract: The Infrared Multi-Object Spectrometer (IRMOS) is a facility-class instrument for the Kitt Peak National Observatory 4 and 2.1 meter telescopes. IRMOS is a near-IR (0.8–2.5 µm) spectrometer and operates at ~80 K. The 6061-T651 aluminum bench and mirrors constitute an athermal design. The instrument produces simultaneous spectra at low- to mid-resolving power (R = λ/Δλ = 300–3000) of ~100 objects in its 2.8×2.0 arcmin field.

We describe ambient and cryogenic optical testing of the IRMOS mirrors across a broad range in spatial frequency (figure error, mid-frequency error, and microroughness). The mirrors include three rotationally symmetric, off-axis conic sections, one off-axis biconic, and several flat fold mirrors. The symmetric mirrors include convex and concave prolate and oblate ellipsoids. They range in aperture from 94×86 mm to 286×269 mm and in f-number from 0.9 to 2.4. The biconic mirror is concave and has a 94×76 mm aperture, Rx=377 mm, kx=0.0778, Ry=407 mm, and ky=0.1264 and is decentered by -2 mm in X and 227 mm in Y. All of the mirrors have an aspect ratio of approximately 6:1. The surface error fabrication tolerances are < 10 nm RMS microroughness, “best effort” for mid-frequency error, and < 63.3 nm RMS figure error.

Ambient temperature (~293 K) testing is performed for each of the three surface error regimes, and figure testing is also performed at ~80K. Operation of the ADE PhaseShift MicroXAM white light interferometer (micro-roughness) and the Bauer Model 200 profilometer (mid-frequency error) is described. Both the sag and conic values of the aspheric mirrors make these test challenging. Figure testing is performed using a Zygo GPI interferometer, custom computer generated holograms (CGH), and optomechanical alignment fiducials.

Cryogenic CGH null testing is discussed in detail. We discuss complications such as the change in prescription with temperature and thermal gradients. Correction for the effect of the dewar window is also covered. We discuss the error budget for the optical test and alignment procedure. Data reduction is accomplished using commercial optical design and data analysis software packages. Results from CGH testing at cryogenic temperatures are encouraging thus far.

S. M. Arnold, A. P. Stuart and L. Koudelka, “CGH-LUPI Interferometer for Aspheric Figure Metrology,” in Optical Manufacturing and Testing II, SPIE Vol. 3134, 390–397 (1997).

Abstract: We have designed and built a phase-measuring LUPI interferometer to use pre-aligned custom CGH nulls for high accuracy figure metrology of deep aspherics. The CGH nulls operate in double pass, first producing an aspheric test wavefront ant then recollimating the return wavefront. This eliminates any need to locate the CGH at an image of the test pupil. The CGH is common to both test and reference paths, allowing use of photomask quality substrates. To enable the CGH-LUPI to test a wider variety of aspheres, we have designed and built a set of 100 mm aperture optics for use in combination with CGH nulls. These accessory optics consist of five singlets, each approximately F/3, which may be kinematically stacked in numerous combinations and permutations to produce test wavefronts ranging from nearly collimated to F/0.75. A CGH null compensates for asphericity of the test optics and design aberrations of the accessory optics. The interferometer and accessory optic designs permit independent verification of all aspects of system accuracy and calibration without the need for disassembly. Designing a custom CGH null involves raytracing the accessory optics but not the interferometer mainframe optics. Depending on the phase measuring algorithm selected, known system aberrations due to manufacturing tolerances may be software compensated in real time.

S. M. Arnold and R. Kestner, “Verification and Certification of CGH Aspheric Nulls,” in Optical Manufacturing and Testing, SPIE Vol. 2536, 117–126 (1995).

Abstract: Computer Generated Holograms (CGHs) are an alternative to refractive or reflective null optics when testing aspheric optical components. A key attraction is that the difficulty of designing and fabricating a CGH null is largely independent of the detailed shape of the test asphere. CGH nulls have been used quite successfully in a number of high profile programs, but certification issues have limited their more widespread acceptance as a primary testing means. This is due largely to unfamiliarity with appropriate verification and certification methods. We here discuss specification and tolerancing of CGH nulls and present a comprehensive methodology for verification and certification.

S. M. Arnold, L. C. Maxey, J. E. Rogers and R. C. Yoder, “Figure metrology of deep general aspherics using a conventional interferometer with CGH null”, in Optical Manufacturing and Testing, SPIE Vol. 2536, 106–116 (1995).

Abstract: We present a simple and general method of aspheric figure metrology using a CGH null mounted in the test beam of a conventional Fizeau or Twyman-Green interferometer. A “standard” reflective CGH is used to establish optical alignment with respect to the interferometer’s spherical test beam. This alignment is then mechanically transferred to a custom CGH null. The accuracy of the alignment transfer is readily verified. The test beam has been modeled by raytracing and verified experimentally by testing a perforated 8-inch F/1.5 on-axis paraboloid and a 50 mm F/2 off-axis paraboloid from their centers of curvature.

S. M. Arnold, “An interferometer for aspheric testing: calibration and error compensation,” presented at ASPE Spring Topical Meeting, Tucson, (April 1992).

S. M. Arnold and A. K. Jain, “An interferometer for testing of general aspherics using computer generated holograms,” SPIE Vol. 1396, (1990).

Abstract: An interferometer for aspheric testing (IAT) is under development at APA Optics for testing of general aspherics using inexpensive electron-beam written computer generated holograms (CGHs) as null compensators. This 152-mm aperture Twyman-Green interferometer is compatible with standards transmission spheres, fringe analysis software, and phase measuring accessories. Aspheric departures of up to several hundred waves can be measured using only standard interferometer accessories. Deeper aspheres may be tested using simple auxiliary optics. The interferometer configuration, methods of operation, and performance specifications are presented.

S. M. Arnold and A. K. Jain, “Sandwich Reflection Hologram (SRH) combiner for display applications,” SPIE Vol. 1211 (1990).

S. M. Arnold, “How to test an asphere with a computer generated hologram,” SPIE Vol. 1052, 191–197 (1989).

Abstract: The use of computer generated holograms (CGHs) in aspheric testing is reviewed in light of current capabilities of electron-beam written CGHs. Merits and limitations of various Twyman-Green and Fizeau interferometer configurations are discussed. Methods and guidelines for designing and specifying a CGH are presented.

S. M. Arnold, “Desktop computer encoding of electron-beam written holograms,” in Computer-Generated Holography II, SPIE Vol 884, 23–26 (1988).

Abstract: Computer algorithms for the encoding of electron-beam written holographic optical elements (HOEs), previously developed on a large main-frame computer, have been ported to a desktop computer and upgraded to use a more prevalent e-beam lithography system. Hardware requirements, encoding methods, and space-bandwidth limitations are discussed. Inasmuch as the inefficiency of the e-beam pattern description language in describing non-repetitive, non-rectilinear hologram patterns remains the prime limiter of hologram space-bandwidth product, the transition to a desktop computer has been accomplished without penalty.

S. M. Arnold and B. E. Cole, “Ion-Beam sputter deposition of low loss Al2O3 films for integrated optics,” Thin Solid Films 165, 1–9 (1988).

S. M. Arnold, “Electron beam fabrication of computer generated holograms,” Optical Engineering 24(5), 803–807 (1985).

S. M. Arnold, “E-beam fabrication of computer generated holograms,” SPIE Vol. 523, 285–291 (1985).

Abstract: We report here the development of an integrated capability for writing computer-generated holograms (CGHs) using either of two commercially available electron-beam lithography systems. These binary, chrome-on-glass holograms have been used extensively for aspheric optical testing and also have applications to the interferometric recording of holograms. Algorithms are described for encoding CGHs for e-beam writing. Limitations of e-beam CGH fabrication are discussed. A self-contact lithography and ion milling process is described for converting chrome-on-glass holograms into 40-percent efficient, environmentally durable, all-glass holograms.

S. M. Arnold and S. K. Case, “E-beam generated holographic masks for optical vector-matrix muliplication,” Optical Engineering 23, 79–82 (1984).

K. M. Leung, S. M. Arnold and J. C. Lindquist, “Using e-beam written computer-generated holograms to test deep aspheric wavefronts,” in Contemporary Methods of Optical Fabrication, SPIE Vol. 306, 161–167 (1981).

Abstract: The use of computer-generated holograms (CGHs) to test aspheric surfaces fabricated by modern optical methods such as diamond-turned machining has become increasingly important. The making of CGHs may, however, be limited in spatial resolution and space-bandwidth product provided by commercial optical recording devices. We will demonstrate that CGHs of high spatial resolution and large space-bandwidth product can be written directly on electron-resist using e-beam lithography. This approach not only reduces plotting errors normally introduced by optical recording devices, but also provides more than 106 distortion-free resolution picture elements in a synthetic hologram of correct size. In this paper, we will discuss how to make such a synthetic hologram by means of e-beam lithography. The performance of this CGH will be demonstrated by comparing with a non-rotationally symmetric aspheric wavefront of over 100 waves of spherical aberration using a concave mirror and plane parallel plate combination as the test piece.

S. M. Arnold, “Rapid photometry of cataclysmic variable stars,” doctoral thesis, The University of Rochester (1978).

S. M. Arnold, R. A. Berg and J. G. Duthie, “Eclipses of U Geminorum”, Astrophysical Journal 206, 790–794 (1976).

Abstract: Seven precise eclipse times for the cataclysmic variable star U Geminorum have been obtained during the 1974–1975 observing season. These, together with 65 others, have been used to re-evaluate the eclipse parameters. We have, with some selection of the eclipses used, found a statistically significant slowdown of the binary system. Using previously published masses for the components of U Gem, we infer a mass transfer rate of 8.1 x 10-8 Msolar yr-1 away from the primary. This direction of mass transfer is opposite to that required by current theoretical understanding of these systems.

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