High contrast imaging in the presence of a bright background

Harbans S. Dhadwal; Jahangir Rastegar; Dake Feng

doi:10.1117/12.2177506

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14 May 2015 High contrast imaging in the presence of a bright background

Harbans S. Dhadwal, Jahangir Rastegar, Dake Feng

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Proceedings Volume 9489, Dimensional Optical Metrology and Inspection for Practical Applications IV; 94890N (2015) https://doi.org/10.1117/12.2177506
Event: SPIE Sensing Technology + Applications, 2015, Baltimore, Maryland, United States

Abstract

An adaptive spatial filtering technique is described for enhancing image contrast of objects viewed against the background of an intense light source, both in the transmitting and reflecting imaging modes. The spatial distribution of the source captured in the back focal plane of the imaging lens corresponds to the angular distribution of the source. The measured distribution of energy is used to adaptively control the transmittance of a spatial light modulator positioned in the back focal plane of the imaging lens. The spatial light modulator blocks the transmission of the high energy hot spots through to the image plane. Subsequently the image formed by the objective lens is free of the bright background. Thus, the digital image capture system can use the full dynamic range of the detector and the analog to digital converter, giving rise to a captured image with the highest contrast possible. Contrast enhanced images of MEMS accelerometer are presented.

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Harbans S. Dhadwal, Jahangir Rastegar, and Dake Feng "High contrast imaging in the presence of a bright background", Proc. SPIE 9489, Dimensional Optical Metrology and Inspection for Practical Applications IV, 94890N (14 May 2015); https://doi.org/10.1117/12.2177506

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