Application of a Logarithmic Complementary Metal-Oxide-Semiconductor Camera in White-Light Interferometry

This paper describes the characterization, modeling, and application of a direct-readout complementary metal-oxide-semiconductor (CMOS) camera in white-light interferometry (WLI). The camera that was used consisted of a direct-readout 1024 X 1024 pixel logarithmic CMOS sensor. A continuous analog voltage from each pixel was converted and processed to an 8-bit value by and internal analog-to-digital converter and processed with a digital signal processor. A mathematical model relating the input light intensity to the 8-bit digitized output is developed, which is critical in applications where knowledge of the scene intensity is essential estimating the maximum allowable frame rates. The camera was utilized in WLI, and its application is analyzed in terms of maximum output signal amplitude, imaging speed, and light intensity. The mathematical modeling is implemented with SPICE simulations and verified with experimental data. Index Terms - Calibration, cameras, complementary metal-oxide-semiconductor field effect transistors (CMOSFETs), machine vision, modeling, optical interferometry.JRC.I.4-Nanotechnology and Molecular Imagin