25 April 1997 Near-infrared two-wavelength shift-and-add
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Abstract
With the advent of ground-based 8-meter telescopes and large format detector arrays, the mid-IR (MIR) astronomy is expected to produce images with higher angular resolution and improved sensitivity than currently available. TO obtain diffraction limited images, it is necessary to compensate for atmospheric seeing. We proposed a scheme in which, by detecting the near-IR (NIR) speckle positions of a reference star, for which we have higher sensitivity than in the MIR, we superpose the MIR images taken simultaneously by shifting its position to cancel the effects of seeing. We call this two-wavelength shift-and-add (TWSAA) method. In this paper, we describe an observation carried out in the fall of 1995 to test the concept. A NIR camera was built with 256 by 256 InSb array detector. With a dichroic splitter, a pair of images of a single start at two wavelengths were formed on two halves of the array. We obtained 126 pairs of images each integrated for 0.1 seconds simultaneously at the K- and L-bands. With the TWSAA method using the K-band images as the reference, the peak signal to noise ratio of the L-band integrated image was enhanced by a factor of 5.7 compared to simple addition.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Daigo Tomono, Tetsuo Nishimura, "Near-infrared two-wavelength shift-and-add", Proc. SPIE 3019, Solid State Sensor Arrays: Development and Applications, (25 April 1997); doi: 10.1117/12.275176; https://doi.org/10.1117/12.275176
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