HIRMES is a far-infrared spectrometer that was chosen as the third generation instrument for NASA's SOFIA airborne observatory. HIRMES promises background limited performance in four modes that cover the wavelength range between 25 and 122 μm. The high-spectral resolution (R ≈105) mode is matched to achieve maximum sensitivity on velocity-resolved lines to study the evolution of protoplanetary disks. The mid-resolution (R≈12,000) mode is suitable for high sensitivity imaging of galactic star formation regions in, for example, the several far-infrared fine structure lines. The low-resolution (R≈2000) imaging mode is optimized for spectroscopic mapping of far-infrared fine structure lines from nearby galaxies, while the low resolution (R≈600) grating spectrometer mode is optimized for detecting dust and ice features in protostellar and protoplanetary disks. Several Transition Edge Sensed (TES) bolometer arrays will provide background limited sensitivity in each of these modes. To optimize performance in the various instrument modes, HIRMES employs eight unique fully-tunable cryogenic Fabry-Perot Interferometers (FPIs) and a grating spectrometer. Here we present the design requirements and the mechanical and optical characteristics and performance of these tunable FPI as well as the control electronics that sets the mirror separation and allows scanning of the FPIs.
CCAT-prime will be a 6-meter aperture telescope operating from sub-mm to mm wavelengths, located at 5600 meters elevation on Cerro Chajnantor in the Atacama Desert in Chile. Its novel crossed-Dragone optical design will deliver a high throughput, wide field of view capable of illuminating much larger arrays of sub-mm and mm detectors than can existing telescopes. We present an overview of the motivation and design of Prime-Cam, a first-light instrument for CCAT-prime. Prime-Cam will house seven instrument modules in a 1.8 meter diameter cryostat, cooled by a dilution refrigerator. The optical elements will consist of silicon lenses, and the instrument modules can be individually optimized for particular science goals. The current design enables both broad- band, dual-polarization measurements and narrow-band, Fabry-Perot spectroscopic imaging using multichroic transition-edge sensor (TES) bolometers operating between 190 and 450 GHz. It also includes broadband kinetic induction detectors (KIDs) operating at 860 GHz. This wide range of frequencies will allow excellent characterization and removal of galactic foregrounds, which will enable precision measurements of the sub-mm and mm sky. Prime-Cam will be used to constrain cosmology via the Sunyaev-Zeldovich effects, map the intensity of [CII] 158 μm emission from the Epoch of Reionization, measure Cosmic Microwave Background polarization and foregrounds, and characterize the star formation history over a wide range of redshifts. More information about CCAT-prime can be found at www.ccatobservatory.org.