Dr. Michael Gully-Santiago Profile

Dr. Michael Gully-Santiago

Graduate Research Assistant

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Publications (14)

Proceedings Article | 13 December 2020 Poster + Paper

Precise blaze angle measurements of lithographically fabricated silicon immersion gratings

Emily Lubar, Daniel Jaffe, Cynthia Brooks, Sierra Hickman, Gregory Mace, Michael Gully-Santiago

Proceedings Volume 11451, 114515I (2020) https://doi.org/10.1117/12.2561128

KEYWORDS: Silicon, Wet etching, Fabrication, Spectrographs, Exoplanets, Observatories, X-ray lithography, X-rays, Crystallography, Lithography

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Proceedings Article | 3 August 2016 Paper

300 nights of science with IGRINS at McDonald Observatory

Gregory Mace, Hwihyun Kim, Daniel Jaffe, Chan Park, Jae-Joon Lee, Kyle Kaplan, Young Sam Yu, In-Soo Yuk, Moo-Young Chun, Soojong Pak, Kang-Min Kim, Jeong-Eun Lee, Christopher Sneden, Melike Afsar, Michael Pavel, Hanshin Lee, Heeyoung Oh, Ueejeong Jeong, Sunkyung Park, Benjamin Kidder, Hye-In Lee, Huynh Anh Nguyen Le, Jacob McLane, Michael Gully-Santiago, Jae Sok Oh, Sungho Lee, Narae Hwang, Byeong-Gon Park

Proceedings Volume 9908, 99080C (2016) https://doi.org/10.1117/12.2232780

KEYWORDS: Telescopes, Infrared spectroscopy, Infrared spectroscopy, Observatories, Stars, Silicon, Spectrographs, Sensors, K band, Electronics, Spectral resolution

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The Immersion Grating Infrared Spectrometer (IGRINS) is a revolutionary instrument that exploits broad spectral coverage at high-resolution in the near-infrared. IGRINS employs a silicon immersion grating as the primary disperser, and volume-phase holographic gratings cross-disperse the H and K bands onto Teledyne Hawaii-2RG arrays. The use of an immersion grating facilitates a compact cryostat while providing simultaneous wavelength coverage from 1.45 - 2.5 μm. There are no cryogenic mechanisms in IGRINS and its high-throughput design maximizes sensitivity. IGRINS on the 2.7 meter Harlan J. Smith Telescope at McDonald Observatory is nearly as sensitive as CRIRES at the 8 meter Very Large Telescope. However, IGRINS at R≈45,000 has more than 30 times the spectral grasp of CRIRES* in a single exposure. Here we summarize the performance of IGRINS from the first 300 nights of science since commissioning in summer 2014. IGRINS observers have targeted solar system objects like Pluto and Ceres, comets, nearby young stars, star forming regions like Taurus and Ophiuchus, the interstellar medium, photo dissociation regions, the Galactic Center, planetary nebulae, galaxy cores and super novae. The rich near-infrared spectra of these objects motivate unique science cases, and provide information on instrument performance. There are more than ten submitted IGRINS papers and dozens more in preparation. With IGRINS on a 2.7m telescope we realize signal-to-noise ratios greater than 100 for K=10.3 magnitude sources in one hour of exposure time. Although IGRINS is Cassegrain mounted, instrument flexure is sub-pixel thanks to the compact design. Detector characteristics and stability have been tested regularly, allowing us to adjust the instrument operation and improve science quality. A wide variety of science programs motivate new tools for analyzing high-resolution spectra including multiplexed spectral extraction, atmospheric model fitting, rotation and radial velocity, unique line identification, and circumstellar disk modeling. Here we discuss details of instrument performance, summarize early science results, and show the characteristics of IGRINS as a versatile near-infrared spectrograph and forerunner of future silicon immersion grating spectrographs like iSHELL² and GMTNIRS.³

Proceedings Article | 4 August 2014 Open Access

The first SPIE software Hack Day

S. Kendrew, C. Deen, N. Radziwill, S. Crawford, J. Gilbert, M. Gully-Santiago, P. Kubánek

Proceedings Volume 9152, 915202 (2014) https://doi.org/10.1117/12.2075357

KEYWORDS: Astronomy, Observatories, Visualization, Telescopes, Databases, Astronomical telescopes, Stellar astronomy, Physics, Roads, Software development

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Proceedings Article | 28 July 2014 Paper

New metrology techniques improve the production of silicon diffractive optics

Cynthia Brooks, Michael Gully-Santiago, Michelle Grigas, Daniel Jaffe

Proceedings Volume 9151, 91511G (2014) https://doi.org/10.1117/12.2057468

KEYWORDS: Silicon, Ultraviolet radiation, Etching, Semiconducting wafers, Photoresist materials, Photomasks, Error analysis, Plasma etching, Optical lithography, Diffraction gratings

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Silicon immersion gratings and grisms offer significant advantages in compactness and performance over frontsurface gratings and over grisms made from lower-index materials. At the same time, the high refractive index of Si (3.4) leads to very stringent constraints on the allowable groove position errors, typically rms < 20 nm over 100 mm and repetitive error of <5 nm amplitude. For both types of devices, we produce grooves in silicon using photolithography, plasma etching, and wet etching. To date, producers have used contact photolithography to pattern UV sensitive photoresist as the initial processing step, then transferred this pattern to a layer of silicon nitride that, in turn, serves as a hard mask during the wet etching of grooves into silicon.

For each step of the groove production, we have used new and sensitive techniques to determine the contribution of that step to the phase non-uniformity. Armed with an understanding of the errors and their origins, we could then implement process controls for each step. The plasma uniformity was improved for the silicon nitride mask etch process and the phase contribution of the plasma etch step was measured. We then used grayscale lithography, a technique in which the photoresist is deliberately underexposed, to measure large-scale nonuniformities in the UV exposure system to an accuracy of 3-5%, allowing us to make corrections to the optical alignment. Additionally, we used a new multiple-exposure technique combined with laser interferometry to measure the relationship between UV exposure dose and line edge shift. From these data we predict the contribution of the etching and photolithographic steps to phase error of the grating surface. These measurements indicate that the errors introduced during the exposure step dominate the contributions of all the other processing steps. This paper presents the techniques used to quantify individual process contributions to phase errors and steps that were taken to improve overall phase uniformity.

Proceedings Article | 28 July 2014 Paper

GMTNIRS (Giant Magellan Telescope Near-Infrared Spectrograph): optimizing the design for maximum science productivity and minimum risk

Daniel Jaffe, Stuart Barnes, Cynthia Brooks, Michael Gully-Santiago, Soojong Pak, Chan Park, Insoo Yuk

Proceedings Volume 9147, 914722 (2014) https://doi.org/10.1117/12.2057084

KEYWORDS: Spectrographs, Telescopes, Optical design, Adaptive optics, Space telescopes, Sensors, Silicon, Neodymium, Optical instrument design, Astronomy

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Proceedings Article | 28 July 2014 Paper

High performance Si immersion gratings patterned with electron beam lithography

Michael Gully-Santiago, Daniel Jaffe, Cynthia Brooks, Daniel Wilson, Richard Muller

Proceedings Volume 9151, 91515K (2014) https://doi.org/10.1117/12.2056912

KEYWORDS: Electron beam lithography, Silicon, Distortion, Prototyping, Photomasks, Lithography, Optical lithography, Wavefronts, Interferometry, Ultraviolet radiation

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Infrared spectrographs employing silicon immersion gratings can be significantly more compact than spectro- graphs using front-surface gratings. The Si gratings can also offer continuous wavelength coverage at high spectral resolution. The grooves in Si gratings are made with semiconductor lithography techniques, to date almost entirely using contact mask photolithography. Planned near-infrared astronomical spectrographs require either finer groove pitches or higher positional accuracy than standard UV contact mask photolithography can reach. A collaboration between the University of Texas at Austin Silicon Diffractive Optics Group and the Jet Propulsion Laboratory Microdevices Laboratory has experimented with direct writing silicon immersion grating grooves with electron beam lithography. The patterning process involves depositing positive e-beam resist on 1 to 30 mm thick, 100 mm diameter monolithic crystalline silicon substrates. We then use the facility JEOL 9300FS e-beam writer at JPL to produce the linear pattern that defines the gratings. There are three key challenges to produce high-performance e-beam written silicon immersion gratings. (1) E- beam field and subfield stitching boundaries cause periodic cross-hatch structures along the grating grooves. The structures manifest themselves as spectral and spatial dimension ghosts in the diffraction limited point spread function (PSF) of the diffraction grating. In this paper, we show that the effects of e-beam field boundaries must be mitigated. We have significantly reduced ghost power with only minor increases in write time by using four or more field sizes of less than 500 μm. (2) The finite e-beam stage drift and run-out error cause large-scale structure in the wavefront error. We deal with this problem by applying a mark detection loop to check for and correct out minuscule stage drifts. We measure the level and direction of stage drift and show that mark detection reduces peak-to-valley wavefront error by a factor of 5. (3) The serial write process for typical gratings yields write times of about 24 hours- this makes prototyping costly. We discuss work with negative e-beam resist to reduce the fill factor of exposure, and therefore limit the exposure time. We also discuss the tradeoffs of long write-time serial write processes like e-beam with UV photomask lithography. We show the results of experiments on small pattern size prototypes on silicon wafers. Current prototypes now exceed 30 dB of suppression on spectral and spatial dimension ghosts compared to monochromatic spectral purity measurements of the backside of Si echelle gratings in reflection at 632 nm. We perform interferometry at 632 nm in reflection with a 25 mm circular beam on a grating with a blaze angle of 71.6°. The measured wavefront error is 0.09 waves peak to valley.

Proceedings Article | 8 July 2014 Paper

Design and early performance of IGRINS (Immersion Grating Infrared Spectrometer)

Chan Park, Daniel Jaffe, In-Soo Yuk, Moo-Young Chun, Soojong Pak, Kang-Min Kim, Michael Pavel, Hanshin Lee, Heeyoung Oh, Ueejeong Jeong, Chae Kyung Sim, Hye-In Lee, Huynh Anh Nguyen Le, Joseph Strubhar, Michael Gully-Santiago, Jae Sok Oh, Sang-Mok Cha, Bongkon Moon, Kwijong Park, Cynthia Brooks, Kyeongyeon Ko, Jeong-Yeol Han, Jakyoung Nah, Peter Hill, Sungho Lee, Stuart Barnes, Young Sam Yu, Kyle Kaplan, Gregory Mace, Hwihyun Kim, Jae-Joon Lee, Narae Hwang, Byeong-Gon Park

Proceedings Volume 9147, 91471D (2014) https://doi.org/10.1117/12.2056431

KEYWORDS: Sensors, Spectrographs, Cameras, K band, Spectral resolution, Infrared spectroscopy, Cryogenics, Mirrors, Optical design, Telescopes

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Proceedings Article | 18 December 2012 Paper

Alignment based on a no adjustment philosophy for the Immersion Grating Infrared Spectrometer (IGRINS)

Jeong-Yeol Han, In-Soo Yuk, Kyeongyeon Ko, Heeyoung Oh, Jakyoung Nah, Jae Sok Oh, Chan Park, Sungho Lee, Kang-Min Kim, Moo-Young Chun, Daniel Jaffe, Soojong Pak, Michael Gully-Santiago

Proceedings Volume 8550, 85501B (2012) https://doi.org/10.1117/12.981169

KEYWORDS: Mirrors, Infrared radiation, Spherical lenses, Infrared spectroscopy, Temperature metrology, Refractive index, Infrared imaging, Spectroscopy, Cameras, Interferometers

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Proceedings Article | 13 September 2012 Paper

Near-infrared metrology of high-performance silicon immersion gratings

Michael Gully-Santiago, Weisong Wang, Casey Deen, Daniel Jaffe

Proceedings Volume 8450, 84502S (2012) https://doi.org/10.1117/12.926434

KEYWORDS: Silicon, Interfaces, Mirrors, Metrology, Interferometry, Point spread functions, Prisms, Cryogenics, Refractive index, Aluminum

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Proceedings Article | 5 August 2010 Paper

NIRCam: development and testing of the JWST near-infrared camera

Thomas Greene, Charles Beichman, Michael Gully-Santiago, Daniel Jaffe, Douglas Kelly, John Krist, Marcia Rieke, Eric Smith

Proceedings Volume 7731, 77310C (2010) https://doi.org/10.1117/12.856615

KEYWORDS: James Webb Space Telescope, Sensors, Cameras, Coronagraphy, Fermium, Frequency modulation, Optical fabrication, Cryogenics, Image segmentation, Wavefronts

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Proceedings Article | 20 July 2010 Paper

High-performance silicon grisms for 1.2-8.0 um: detailed results from the JWST-NIRCam devices

M. Gully-Santiago, W. Wang, C. Deen, D. Kelly, T. Greene, J. Bacon, D. Jaffe

Proceedings Volume 7739, 77393S (2010) https://doi.org/10.1117/12.857568

KEYWORDS: Silicon, Antireflective coatings, James Webb Space Telescope, Coating, Surface finishing, Etching, Astronomy, Light scattering, Polishing, Interfaces

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Proceedings Article | 20 July 2010 Paper

Manufacturing of silicon immersion gratings for infrared spectrometers

Weisong Wang, Michael Gully-Santiago, Casey Deen, Douglas Mar, Daniel Jaffe

Proceedings Volume 7739, 77394L (2010) https://doi.org/10.1117/12.857164

KEYWORDS: Silicon, Manufacturing, Diffraction gratings, Spectral resolution, Spectrometers, Infrared spectroscopy, Infrared radiation, Lithography, Etching, Reactive ion etching

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Proceedings Article | 15 July 2010 Paper

GMTNIRS (Giant Magellan Telescope near-infrared spectrograph): design concept

Sungho Lee, In-Soo Yuk, Hanshin Lee, Weisong Wang, Chan Park, Kwi-Jong Park, Moo-Young Chun, Soojong Pak, Joseph Strubhar, Casey Deen, Michael Gully-Santiago, Jared Rand, Haingja Seo, Jungmi Kwon, Heeyoung Oh, Stuart Barnes, John Lacy, John Goertz, Won-Kee Park, Tae-Soo Pyo, Daniel Jaffe

Proceedings Volume 7735, 77352K (2010) https://doi.org/10.1117/12.857630

KEYWORDS: Spectrographs, Sensors, Silicon, Adaptive optics, Cameras, Telescopes, Spectral resolution, Space telescopes, Stars, Diffraction gratings

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Proceedings Article | 15 July 2010 Paper

Preliminary design of IGRINS (Immersion GRating INfrared Spectrograph)

In-Soo Yuk, Daniel Jaffe, Stuart Barnes, Moo-Young Chun, Chan Park, Sungho Lee, Hanshin Lee, Weisong Wang, Kwi-Jong Park, Soojong Pak, Joseph Strubhar, Casey Deen, Heeyoung Oh, Haingja Seo, Tae-Soo Pyo, Won-Kee Park, John Lacy, John Goertz, Jared Rand, Michael Gully-Santiago

Proceedings Volume 7735, 77351M (2010) https://doi.org/10.1117/12.856864

KEYWORDS: Spectrographs, Telescopes, K band, Cameras, Sensors, Space telescopes, Control systems, Optical design, Silicon, Astronomy

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Showing 5 of 14 publications

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