28 July 2014 Image slicing with a twist: spatial and spectral Nyquist sampling without anamorphic optics
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Abstract
Integral field spectrographs have become mainstream instruments at modern telescopes because of their efficient way of collecting data-cubes. Image slicer based integral field spectrographs achieve the highest fill-factor on the detector, but due to the need to Nyquist-sample the spectra, their spatial sampling on the sky is rectangular. Using anamorphic pre-optics before the image slicer overcomes this effect further maximising the fill-factor, but introduces optical aberrations, throughput losses, and additional alignment and calibration requirements, compromising overall instrument performance. In this paper I present a concept for an image-slicer that achieves both spatial and spectral Nyquist-sampling without anamorphic pre-optics. Rotating each slitlet by 45° with respect to the dispersion direction, and arranging them into a saw-tooth pseudo-slit, leads to a lozenge shaped sampling element on the sky, however, the centres of the lozenges lie on a regular and square grid, satisfying the Nyquist sampling criterion in both spatial directions.
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Matthias Tecza, Matthias Tecza, } "Image slicing with a twist: spatial and spectral Nyquist sampling without anamorphic optics", Proc. SPIE 9151, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation, 915118 (28 July 2014); doi: 10.1117/12.2055977; https://doi.org/10.1117/12.2055977
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