Mr. Andrew S. Hauser Profile

Andrew S. Hauser

at Univ of Wisconsin-Madison

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Author

Publications (5)

Proceedings Article | 13 December 2020 Presentation + Paper

SDSS-V local volume mapper instrument: overview and status

Nicholas Konidaris, Niv Drory, Cynthia Froning, Anthony Hebert, Pavan Bilgi, Guillermo Blanc, Alicia Lanz, Charles Hull, Juna Kollmeier, Solange Ramirez, Stefanie Wachter, Kathryn Kreckel, Soojong Pak, Eric Pellegrini, Andrés Almeida, Scott Case, Ross Zhelem, Tobas Feger, Jon Lawrence, Michael Lesser, Tom Herbst, José Sanchez-Gallego, Matthew Bershady, Sabyasachi Chattopadhyay, Andrew Hauser, Michael Smith, Marsha Wolf, Renbin Yan

Proceedings Volume 11447, 1144718 (2020) https://doi.org/10.1117/12.2557565

KEYWORDS: Telescopes, Spectrographs, Spectroscopes, Stars, Solar system, Lanthanum, Observatories, Clouds, Spectral resolution, Atmospheric sciences

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Proceedings Article | 13 December 2020 Poster + Paper

Development and characterization of a precisely adjustable fiber polishing arm

Michael Smith, Sabyasachi Chattopadhyay, Andrew Hauser, Joshua Oppor, Matthew Bershady, Marsha Wolf

Proceedings Volume 11451, 114516W (2020) https://doi.org/10.1117/12.2563201

KEYWORDS: Polishing, Surface finishing, Astronomy, Spectrographs, Inspection, Matrices, Near infrared, Spectral calibration, Calibration, Interfaces

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SPIE Journal Paper | 27 June 2020 Open Access

Fiber positioning in microlens-fiber coupled integral field unit

Sabyasachi Chattopadhyay, Matthew Bershady, Marsha Wolf, Michael Smith, Andrew Hauser

JATIS, Vol. 6, Issue 02, 025002, (June 2020) https://doi.org/10.1117/12.10.1117/1.JATIS.6.2.025002

KEYWORDS: Etching, Semiconducting wafers, Microlens, Photoresist materials, Optical lithography, Silicon, Photomasks, Telescopes, Near field, Spectrographs

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A generic fiber positioning strategy and a fabrication path are presented for microlens-fiber-coupled integral field units (IFUs). It is assumed that microlens-produced microimages are carried to the spectrograph input through a step-index, multimode fiber, but our results apply to micropupil reimaging applications as well. Considered are the performance trades between the filling percentage of the fiber core with the microimage versus throughput and observing efficiency. A merit function is defined as the product of the transmission efficiency and the étendue loss. For a hexagonal packing of spatial elements, the merit function has been found to be maximized to 94% of an ideal fiber IFU merit value (which has zero transmission loss and does not increase the étendue) with a microlens-fiber alignment (centering) tolerance of 1-μm RMS. The maximum acceptable relative tilt between the fiber and the microlens face has been analyzed through optical modeling and found to be 0.3 deg RMS for input f-ratio slower than f / 3.5, but it is much more relaxed for faster beams. From the acceptable tilt, we have deduced a minimum thickness of the fiber holder to be 3 mm for 5 μm clearance in hole diameter relative to the fiber outer diameter. Several options of fabricating fiber holders have been compared to identify cost-effective solutions that deliver the desired fiber positioning accuracy. Femto-second laser-drilling methods from commercial vendors deliver holes arrayed on plates with a relative position accuracy of ±1.5-μm RMS, similar diameter accuracy, and with an aspect ratio of 1:10 (diameter:thickness). One commercial vendor combines femtosecond laser-drilling with photolithographic etching to produce plates with thickness of 5 mm, but with similar (±1-μm RMS) positioning accuracy and conical entry ports. Both of these techniques are found to be moderately expensive. A purely photolithographic technique performed at Wisconsin Center for Advanced Microelectronics (a facility at the University of Wisconsin, Madison), in tandem with deep reactive ion etching, has been used to produce a repeatable recipe with 100% yield. Photolithography is more precise (0.5-μm RMS) in terms of hole positioning and similar diameter accuracy (1-μm RMS) but the plate can only have a thickness of 250 μm.

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Proceedings Article | 6 July 2018 Paper

A Near Infrared Integral Field spectrograph (NIR) for the Southern African Large Telescope (SALT): mechanical design

Michael Smith, Marsha Wolf, Matthew Bershady, Douglas Adler, Kurt Jaehnig, Ron Koch, Mark Mulligan, Joshua Oppor, Jeffrey Percival, Nelli Aydinyan, Andrew Hauser, Elijah Ruder

Proceedings Volume 10702, 107023C (2018) https://doi.org/10.1117/12.2313906

KEYWORDS: Spectrographs, Near infrared, Telescopes, Collimators, Control systems, Space telescopes, Large telescopes, Mechanical engineering, Astronomy, Spectroscopy

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Washburn Astronomical Laboratories in the University of Wisconsin-Madison Astronomy Department is developing a near infrared (NIR) integral field spectrograph for the 11-meter Southern African Large Telescope (SALT). This instrument will extend SALT’s capabilities into the NIR, providing medium resolution spectroscopy over the wavelength range of 0.8 to 1.7 microns. Formerly known as RSS-NIR, this spectrograph was originally designed to mount at the prime focus of SALT and share a common collimator and spaceframe structure with the visible wavelength Robert Stobie Spectrograph (RSS-VIS). However, to maximize performance of both the instrument and telescope, its configuration has been changed into a fiber fed instrument located in the spectrometer room below the telescope7. This change necessitated the addition of several new components, including a separate collimator; a fiber integral field unit (IFU); a means to inject light from the telescope into the fibers; and a cooled enclosure to house the spectrograph, collimator, and pseudo-slit end of the fiber cable. The new collimator consists of four refractive elements, one of which is calcium fluoride, and requires a new lens barrel and support structure. The new fiber system incorporates a hexagonally arranged 217-fiber IFU and two mini-bundles containing 15 sky fibers each. The IFU is fabricated out of a two-part clam-shell stainless steel ferrule. The existing SALT fiber instrument feed (FIF) mechanism is adapted to position the IFU and sky bundles on sky, while a slave motion on flexure pivots ensures that the fibers remain telecentric. A 42-m protected fiber cable spans the distance between the telescope prime focus and the pseudo-slit in the spectrometer room. The cable is constructed out of four 25mm outer diameter flexible conduits. Within the conduit, each fiber is individually protected in its own Teflon tube. The route of the fiber cable through the telescope requires careful accommodation of controlled bending. The pseudo-slit comprises a line of mini v-groove blocks attached to the slit plate. The slit, collimator, and spectrograph are housed inside a 40 cold enclosure in the SALT spectrometer room. The cooling system, developed by Norlake Scientific to our specifications, carefully controls against thermal shock and humidity. This paper describes the design, integration, and laboratory verification of the reconfigured spectrograph system, as well as our experiences operating in a -40 ambient pressure environment.

Proceedings Article | 6 July 2018 Paper

A near infrared integral field spectrograph for the Southern African Large Telescope (SALT)

Marsha Wolf, Douglas Adler, Matthew Bershady, Kurt Jaehnig, Ron Koch, Mark Mulligan, Joshua Oppor, Jeffrey Percival, Michael Smith, Nelli Aydinyan, Andrew Hauser, Elijah Ruder

Proceedings Volume 10702, 107022O (2018) https://doi.org/10.1117/12.2312792

KEYWORDS: Near infrared, Collimators, Optical fibers, Galactic astronomy, Spectrographs, Diffraction gratings, Telescopes, Sensors, Spectroscopy, Cameras

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