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Proceedings Paper

Wide Dynamic Range CCD Camera
Author(s): J. M. Younse; R. J. Gove; P. A. Penz; D. E. Russell
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Paper Abstract

A liquid crystal attenuator (LCA) operated as a variable neutral density filter has been attached to a charge-coupled device (CCD) imager to extend the dynamic range of a solid-state TV camera by an order of magnitude. Many applications are best served by a camera with a dynamic range of several thousand. For example, outside security systems must operate unattended with "dawn-to-dusk" lighting conditions. Although this can be achieved with available auto-iris lens assemblies, more elegant solutions which provide the small size, low power, high reliability advantages of solid state technology are now available. This paper will describe one such unique way of achieving these dynamic ranges using standard optics by making the CCD imager's glass cover a controllable neutral density filter. The liquid crystal attenuator's structure and theoretical properties for this application will be described along with measured transmittance. A small integrated TV camera which utilizes a "virtual-phase" CCD sensor coupled to a LCA will be described and test results for a number of the camera's optical and electrical parameters will be given. These include the following camera parameters: dynamic range, Modulation Transfer Function (MTF), spectral response, and uniformity. Also described will be circuitry which senses the ambient scene illuminance and automatically provides feedback signals to appropriately adjust the transmittance of the LCA. Finally, image photographs using this camera, under various scene illuminations, will be shown.

Paper Details

Date Published: 8 November 1984
PDF: 11 pages
Proc. SPIE 0501, State-of-the-Art Imaging Arrays and Their Applications, (8 November 1984); doi: 10.1117/12.944645
Show Author Affiliations
J. M. Younse, Texas Instruments Incorporated (United States)
R. J. Gove, Texas Instruments Incorporated (United States)
P. A. Penz, Texas Instruments Incorporated (United States)
D. E. Russell, Texas Instruments Incorporated (United States)

Published in SPIE Proceedings Vol. 0501:
State-of-the-Art Imaging Arrays and Their Applications
Keith N. Prettyjohns, Editor(s)

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