16 November 1982 New Two-Dimensional Photon Camera
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A new photon sensitive camera has been developed that determines the position of each photon as it arrives. It is made from easily available parts, is reasonably compact, and modest in cost. The present version will supply 8-bit by 8-bit photon positions (256 x 256 pixels) at rates as high as 106/sec. It has a flexible two-dimensional format, allowing it to be used as a 256 x 256 pixel camera, a 64 x 1024 pixel camera, or any other format that keeps the total number of pixels constant, provided a linear resolution of about 10 microns is not exceeded. The present system records the sequence of photon positions digitally onto video tape using a portable VHS format video tape recorder. Two hours of data can be recorded on a single cassette tape. Although this recording scheme limits the camera to rates of only 105 detected photons/sec, it is still faster than direct digital recording onto portable computer tape drives. If there is no need to store the positions of the individual photons, and the photons are directly summed to form a picture, as in a computer memory, the camera can operate at its maximum rate. A microcomputer is used to monitor the performance of the camera by sampling the data at rates it can handle. The quantum efficiency of photon detection is that obtained with the usual photocathodes, namely about 10 to 20% at visible wavelengths. Since the camera counts photons it has a large dynamic range, and when the photocathode dark count is reduced by cooling, the noise in each pixel is that due to counting statistics alone even when the total count is small. The present application is directed towards speckle imaging of astronomical sources, high-resolution spectroscopy of faint galaxies in a crossed-dispersion spectrograph, and narrow-band direct imaging of galaxies, but other uses are clearly possible.
© (1982) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
C. Papaliolios, L. Mertz, "New Two-Dimensional Photon Camera", Proc. SPIE 0331, Instrumentation in Astronomy IV, (16 November 1982); doi: 10.1117/12.933476; https://doi.org/10.1117/12.933476

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