We report on the design, fabrication, and on-sky performance of the Florida Image Slicer for Infrared Cosmology and Astrophysics (FISICA) - a fully-cryogenic all-reflective image-slicing integral field unit for the FLAMINGOS near-infrared spectrograph. Designed to accept input beams near f/15, FISICA with FLAMINGOS provides R~1300 spectra over a 16x33-arcsec field-of-view on the Cassegrain f/15 focus of the KPNO 4-meter telescope, or a 6x12-arcsec field-of-view on the Nasmyth or Bent Cassegrain foci of the Gran Telescopio Canarias 10.4-meter telescope. FISICA accomplishes this using three sets of "monolithic" powered mirror arrays, each with 22 mirrored surfaces cut into a single piece of aluminum. We review the optical and opto-mechanical design and fabrication of FISICA, as well as laboratory test results for FISICA integrated with the FLAMINGOS instrument. Finally, we present performance results from observations with FISICA at the KPNO 4-m telescope and comparisons of FISICA performance to other available IFUs on 4-m to 8-m-class telescopes.
We report on the design and status of the Florida Image Slicer for Infrared Cosmology and Astrophysics (FISICA) - a fully-cryogenic all-reflective image-slicing integral field unit for the FLAMINGOS near-infrared spectrograph. Designed to accept input beams near f/15, FISICA with FLAMINGOS provides R~1300 spectra over a 16x33-arcsec field-of-view on the Cassegrain f/15 focus of the KPNO 4-meter telescope, or a 6x12-arcsec field-of-view on the Nasmyth or Bent Cassegrain foci of the Gran Telescopio Canarias 10.4-meter telescope. FISICA accomplishes this using three sets of “monolithic” powered mirror arrays, each with 22 mirrored surfaces cut into a single piece of aluminum. We review the optical and opto-mechanical design and fabrication of FISICA, as well as laboratory test results for FISICA integrated with the FLAMINGOS instrument. We also discuss plans for first-light observations on the KPNO 4-meter telescope in July 2004.
We discuss the design, fabrication, assembly, and testing of the prototype Florida Image Slicer for Infrared Cosmology and Astrophysics (FISICA) Integral Field Unit (IFU). FISICA is intended for large telescopes with f/numbers close to f/15, such as the KPNO 4-m and GTC 10.4-m telescopes. It implements an image slicing approach, wherein the initial image plane is optically sliced into thin strips and the strips are optically rearranged end-to-end, whereupon the composite slit image is fed into a conventional spectrograph. We divide the field of view into 22 slices, while accommodating the entire f/15 viewing solid angle. The all-reflective instrument resides in a cryogenic dewar at the initial focal plane, and places the composite slit image output precisely at the initial focus, allowing it to interface to the existing FLAMINGOS spectrograph. The mirrors were diamond turned using various tool geometries and state-of-the-art, multi-axis tool control. The mirrors are made from a single billet of aluminum, and the optical bench and mounts are made of the same alloy as the mirrors for optimum performance during cryogenic cooling. We discuss the key design efforts, emphasizing tradeoffs among performance, volume, fabrication difficulty, and alignment requirements. We describe the fabrication, and present preliminary laboratory test results.
We describe a new noncontacting approach for obtaining the full aperture, absolute aspheric profile of large optical surfaces. The metrology instrument is placed in close proximity to the test piece instead of at the center of curvature, and is thus equally useful for measuring concave, flat, and convex optics - even fast (low f-number) optics. It combines the data from multiple probes in a manner that makes the measurement completely self-referencing, and completely insensitive to any small relative rigid body motions between the instrument and the test piece. The relative compactness of the instrument combined with its inherent rigid body insensitivity make it suitable ultimately for in situ measurements. Furthermore, replacement of the noncontacting optical probes with contacting mechanical probes would make the instrument suitable for profiling ground surfaces to a very small fraction of a micron. We have built a prototype instrument to prove the concept, and have demonstrated sub-nanometer capabilities for the optical probes, with full surface figure accuracy capabilities of a few nanometers in an uncontrolled thermal environment. The full surface figure accuracy is improving as we implement modest environmental controls. In this paper, we first describe the underlying theory of the measurement approach, and then describe the prototype instrument. Finally, we summarize the measurements made to date, and discuss likely future applications and projected accuracies.
The Space Interferometer Mission (SIM) will achieve important science objectives of NASA's Origins program by performing astrometric measurements of targets within and beyond our galaxy with a precision of the order of a few microarcseconds. This accuracy can only be attained by carefully balancing sources of astrometric error arising from the systematic accuracy of the interferometer, thermal distortions, vibration caused by spacecraft systems, and errors in knowledge of the spacecraft's altitude and velocity. A rigorous systems engineering approach must be applied to the conduct of trades between these different sources of error and the TRW SIM Study Team has developed a mathematical model of the performance of SIM to support these trades. This paper shows how the model is constructed using simple analytical relationships and then employed to determine the dependence of system performance on a wide range of configuration parameters, such as baseline length, aperture size, and attitude knowledge. These studies indicate where subsystem performance requirements are critical and where requirements may be relaxed with little degradation of overall astrometric accuracy.
Rapid, three-dimensional profilometry with resolution similar to that of mechanical coordinate measuring machines has long been a goal of vision system developers. Some success has been had using structured light projectors, flying spot scanners and the like. However, these techniques are limited by restrictions on the height variation and stability of the target object. This paper describes a phase measuring projected fringe interferometer that overcomes many of these problems. Using data from a high speed mega pixel class camera viewing high precision spatial modulation of a periodic illumination pattern on the target, new software unwraps the surface phase information and rapidly computes a true three dimensional surface. An important capability of the software is to avoid errors due to islands of missing data or high slope regions on the target. Interchangeable camera lenses permit measurements of a wide range of object sizes with a height resolution ratio on the order of 20 microns per meter of test piece size. The current application of the instrument is measurement of structural deflections of hypersonic aircraft structural components. In previous work, the technique has successfully measured the profile of coins and jet engine turbine blades and the curvature of a human spine. We summarize the special qualities of this instrument that make it well suited to such a wide range of measurements. Finally, we discuss some preliminary experimental results and compare them with typical accuracy requirements.
The Solar-A Soft X-Ray telescope will be launched aboard the Japanese Solar-A Satellite in 1991, to
study the sun during the next period of sunspot activity. The mechanical and optical design of this
monolithic, near 2 arc-sec image quality Nariai Telescope was developed previously as explained in reference
1 and depicted in Figure 2.0. Successful achievement of the aggressive performance goals for this design
required precision manufacturing and assembly, and accurate metrology to verify results. In fact, more
than three-fourths of the error budget was allocated to manufacturing and meirology errors because of the
recognized difficulty in producing and measuring the precision grazing-incident optical surfaces. To
obtain the anufacturing precision and metrology accuracy desired, specialized tooling had to be designed to
support and mount the optical substrate during the fabrication, surface metrology, alignment and assembly
processes. The design considerations, the substantiating structural analyses performed and the resulting
successful application of this specialized tooling are reported here in to show the difficulties often
encountered in developing "support" equipment to achieve desired results in the final product.
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