We installed the next-generation automated laser adaptive optics system, Robo-AO-2, on the University of Hawaii 2.2-m telescope on Maunakea in 2023. We engineered Robo-AO-2 to deliver robotic, diffraction-limited observations at visible and near-infrared wavelengths in unprecedented numbers. This new instrument takes advantage of upgraded components, manufacturing techniques and control; and includes a parallel reconfigurable natural guide star wavefront sensor with which to explore hybrid wavefront sensing techniques. We present the results of commissioning in 2023 and 2024.
The Diffraction-Limited Near Infrared Spectropolarimeter (DL-NIRSP) is a facility instrument of the U.S. National Science Foundation’s Daniel K. Inouye Solar Telescope (DKIST). DL-NIRSP was originally commissioned with a birefringent fiber optic image slicer for high resolution observations of the solar atmosphere to support contiguous 2D-spatial, spectral, and polarimetric measurements in three channels between 500 and 1800 nm with very high spectral resolution over narrow bandpasses. During commissioning, we found temporal variations of the flat field and other fiber-related issues limited instrument performance. To resolve these various problems, we replaced the existing fiber-based image slicer with the high resolution Machined Image Slicer Integral Field Unit with 36 micrometer wide slicer mirrors (MISI-36). We report on the implementation and optical testing of MISI-36.
This paper describes Flare Sentinel, a compact integral field spectrograph (IFS) for the study of the hydrogen Balmer series spectrum from 350 to 450 nm of solar flare from space. Flare Sentinel IFS is based on a new Machined Image Slicer Compact Spectrograph Array (MICS) design. MICS consists of an image slicer that divides a continuous 2D spatial field formed by an imaging system into multiple narrow slices, and an array of miniature spectrographs, each forming the spectra of one of the slices of the 2D field. The spectra formed by all the miniature spectrographs can be projected on a common 2D focal plane to be recorded by an image sensors. The spectra can also be distributed to multiple focal planes and recorded simultaneously by multiple sensors to increase the instantaneous hyperspectral field of view of the instrument. New image slicers with slit width of 36 um and 20 um have been successfully fabricated using Canon Inc.’s ultra-precision diamond-cutting CNC mill. This capability is enabling design and fabrication of IFSs with imaging format of 102 × 102 , and spectral resolution between 100 < R < 10, 000 in a very compact package. We will present the optical design and the optical hardware of a prototype IFS that has been fabricated.
Canon has the world's most advanced cutting machine and has provided the world's first CdZnTe1 and InP2 immersion gratings to the market. Cutting gratings on brittle materials is very delicate, and nm-accurate processing can be achieved by cutting alone. Using this technology, we have fabricated the machined image slicer integral field unit (MISI) for the Diffraction-Limited near-IR Spectropolarimeter (DL-NIRSP) 3 of the Daniel K. Inouye Solar Telescope (DKIST) 4 . The MISI-36 we produced is consists of 112 36μm×1.3mm micro slicer mirrors, a parabolic collimator, a monolithic flat mirror array consists of 112-fold mirrors, and a monolithic spherical mirror array consists of 112 spherical mirrors. This paper presents the latest high precision machined and fabricated ultra-compact IFU/ MISI-36.
With the advancements of ultra-high-precision micro-optics fabrication technologies, it is now possible to fabricate integral field units (IFUs) with slicer mirror width of 30 m or less. This paper describes a 36-um machined image slicer IFU (MISI-36) for the Diffraction-Limited near-IR Spectropolarimeter (DL-NIRSP) of the Daniel K. Inouye Solar Telescope (DKIST). MISI-36 has a unique 2-section image slicer design, and is consists of a monolithic image slicer block with 112 micro slicer mirrors, a parabolic collimator, a monolithic flat mirror array consists of 112 fold mirrors, and a monolithic spherical mirror array consists of 112 spherical mirrors. We have successfully fabricated a prototype device using Canon Inc.’s diamond-cutting CNC, and conducted a preliminary performance evaluation using an experimental bench-top spectrograph similar to the spectrograph of DL-NIRSP. We will present the optical design and optical performances of the MISI-36 prototype.
With the recent advancement of ultra-high-precision micro-optics fabrication technologies, it is now possible to fabricate IFUs based on machined image slicers with slicer width of 30 um or less. We have developed a machined image slicer IFU (MISI) to replace the BiFOIS IFU of the DL-NIRSP Instrument, one of the first light instrument for the DKIST Telescope. Overall, the IFU contains a total of 336 micro mirrors and a common collimator. The large number of micro optical elements of MISI present a great challenge to the optical and mechanical design process of the IFU. Typical design method that model and position each optical element manually would result in a tedious and lengthy mechanical design process.
This paper describes the CAD design process of MISI using Solidworks macros that were developed to automatically generate all the optical surfaces based on the ZEMAX model data output and also simulating the tool shape and path to generate a precise model of the IFU.
iSHELL is 1.10-5.3 μm high spectral resolution spectrograph being built for the NASA Infrared Telescope Facility on Maunakea, Hawaii. Dispersion is accomplished with a silicon immersion grating in order to keep the instrument small enough to be mounted at the Cassegrain focus of the telescope. The white pupil spectrograph produces resolving powers of up to R=75,000. Cross-dispersing gratings mounted in a tilt-able mechanism allow observers to select different wavelength ranges and, in combination with a slit wheel and Dekker mechanism, slit lengths ranging from 5ʺ″ to 25ʺ″. One Teledyne 2048x2048 Hawaii 2RG array is used in the spectrograph, and one Raytheon 512x512 Aladdin 2 array is used in a slit viewer for object acquisition and guiding. First light is expected in mid-2016. In this paper we discuss details of the construction, assembly and laboratory testing.
iSHELL is 1.15-5.4 μm high spectral resolution spectrograph being built for the NASA Infrared Telescope Facility on
Mauna Kea, Hawaii. Dispersion is accomplished with silicon immersion gratings in order to keep the instrument small
enough to be mounted at the Cassegrain focus of the telescope. The white pupil spectrograph is designed to produce
resolving powers of up to R=70,000. Cross-dispersing gratings mounted in a tilt-able mechanism at the second pupil
allow observers to select different wavelength ranges and, in combination with a slit wheel and dekker mechanism, slit
lengths ranging from 5″ to 25″. One Teledyne 2048x2048 Hawaii 2RG array is used in the spectrograph, and one
Raytheon 512x512 Aladdin 2 array is used in a slit viewer for object acquisition, guiding, and imaging. About $4 million
in funding has been provided by NSF, NASA and the University of Hawaii. First light is expected in about 2015. In this
paper we discuss the science drivers, instrument design and expected performance.
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