A photosensor element suitable for incorporation into charge-coupled device (CCD) imaging arrays in which the charge injected into the CCD is proportional to the logarithm of incident light intensity is presented. The photosensor element consists of a photodiode directly coupled to a two-stage MOSFET common source amplifier. This element occupies an area of 25 × 100 μm and is arranged so that it could be incorporated into a linear CCD imaging array having a period of 25 μm. A logarithmic response is measured over a 68.6-dB range of incident light intensity with a sensitivity of 55 mV/decade of light intensity.
© 1983 Optical Society of America
Original Manuscript: June 20, 1983
Published: November 15, 1983
S. H. Chang and J. T. Boyd, "Log-converting processor element for CCD linear imaging arrays," Appl. Opt. 22, 3569-3571 (1983)