KEYWORDS: Mirrors, Manufacturing, Surface roughness, Telescopes, Etching, Surface finishing, Short wave infrared radiation, Received signal strength, Temperature metrology, Optical simulations
The Fred Young Submillimeter Telescope (FYST) is a 6-meter diameter telescope with a surface accuracy of 10.7 microns, operating at submillimeter to millimeter wavelengths (100 GHz – 1.5 THz). It will be located at 5600 meters elevation on Cerro Chajnantor in the Atacama desert of northern Chile overlooking the ALMA site. Its novel optical “crossed-Dragone” design will deliver a high-throughput, wide field-of-view telescope capable of mapping the sky very rapidly and efficiently. This paper discusses the mirror panel production and its contribution to the overall half wave front error of the telescope. The first half details the panel manufacturing precision. The effect of panel production quality on the beam shape and beam quality is presented. The second half of the paper looks at the local surface roughness of a mirror panel. Surface roughness data for a machined panel with an etched surface are presented. Some non-ideal surface features for an etched panel are discussed.
The Fred Young Submillimeter Telescope (FYST) is a 6-meter diameter telescope currently being built by the CCAT-prime project that will observe at millimeter and submillimeter wavelengths. It will deliver a total wavefront error of less than 22 microns at the focal plane. The optics follow a modified crossed-Dragone configuration, yielding a 7.8° field of view across a ~2 meter diameter focal plane. The telescope will be located at 5600 meters on Cerro Chajnantor in the Atacama Desert. The demands of first-generation and future instruments significantly drove the design of the telescope. The telescope layout consists of multiple instrument bays, which provide the capacity to house a total of 11 tons of focal plane instrumentation across 23 square meters of floor space. The Yoke Traverse is divided into telescope servo, instrument electronics, and process spaces, and can support an additional 8 tons of instrument equipment. We discuss the final design and fabrication status of FYST.
The CCAT-prime telescope is a 6-meter aperture, crossed-Dragone telescope, designed for millimeter and sub-millimeter wavelength observations. It will be located at an altitude of 5600 meters, just below the summit of Cerro Chajnantor in the high Atacama region of Chile. The telescope’s unobscured optics deliver a field of view of almost 8 degrees over a large, flat focal plane, enabling it to accommodate current and future instrumentation fielding <100k diffraction-limited beams for wavelengths less than a millimeter. The mount is a novel design with the aluminum-tiled mirrors nested inside the telescope structure. The elevation housing has an integrated shutter that can enclose the mirrors, protecting them from inclement weather. The telescope is designed to co-host multiple instruments over its nominal 15 year lifetime. It will be operated remotely, requiring minimum maintenance and on-site activities due to the harsh working conditions on the mountain. The design utilizes nickel-iron alloy (Invar) and carbon-fiber-reinforced polymer (CFRP) materials in the mirror support structure, achieving a relatively temperature-insensitive mount. We discuss requirements, specifications, critical design elements, and the expected performance of the CCAT-prime telescope. The telescope is being built by CCAT Observatory, Inc., a corporation formed by an international partnership of universities. More information about CCAT and the CCAT-prime telescope can be found at www.ccatobservatory.org.
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