Hot spot measurement on CMOS-based image sensor using liquid crystal thermograph

CMOS-based (Complementary metal-oxide semiconductor) imager technology offers the opportunity for large scale (1 megapixel and greater) image capture using substantially lower power consumption than conventional imaging sensors such as CCD´s (Charge Coupled Device). In addition, CMOS-based image sensors provide the advantages of greater on-chip integration of features and reduced system cost. Such devices are excellent candidates for many consumer imaging applications including digital still cameras, video cameras, and cellular phones with imagers. Typically, any final product using a CMOS-based image sensor will possess myriad additional components each of which may produce heating of the entire system. Increased system temperature arising from dense circuitry can lead to degradation of image quality as the sensor itself heats up. An investigation of the thermal profile of a CMOS image sensor will provide useful information for device design and optimization. In this paper, we present thermographs of CMOS imager sensors produced by a technique using a nematic liquid crystal.