9 May 2012 Optical comparison of detector arrays from modulation transfer function measurements with laser speckle patterns
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Abstract
Charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) matrices offer excellent features in imaging systems. A suitability evaluation of either technology according to a specific application requires a complete characterization of the different detector types. A system is optically characterized by the modulation transfer function (MTF), which represents its response in spatial frequency of this system. One of the methods to measure the MTF uses a laser speckle pattern as the object. Here, we comparatively examine the results provided by the speckle method to determine the MTF for detectors of two types: CCD and CMOS. We generate the speckle pattern using a laser and an integrating sphere with an aperture at its exit port. The aperture determined the spatial-frequency content of the pattern registered in the detector. The precision in determining the MTF of the CCD was studied using two different apertures: a single-slit and a double-slit. For the single-slit, we propose a new procedure of fitting the experimental data which resolves the drawbacks of the conventional procedure. To study the CMOS detector, we used the single-slit because it offered lower uncertainty and better reproducibility. The differences between the MTF values of the CCD and the CMOS detectors proved significant for the spatial frequencies higher than 50 cycles/mm, which is half of the interval studied with both arrays. For these spatial frequencies, our results demonstrate that the CCD detector presented MTF values higher than those of the CMOS array.
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Alicia Fernández-Oliveras, Alicia Fernández-Oliveras, Antonio M. Pozo, Antonio M. Pozo, Manuel Rubiño, Manuel Rubiño, } "Optical comparison of detector arrays from modulation transfer function measurements with laser speckle patterns", Proc. SPIE 8439, Optical Sensing and Detection II, 84391V (9 May 2012); doi: 10.1117/12.921224; https://doi.org/10.1117/12.921224
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