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14 May 2007 Low-cost far infrared bolometer camera for automotive use
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A new low-cost long-wavelength infrared bolometer camera system is under development. It is designed for use with an automatic vision algorithm system as a sensor to detect vulnerable road users in traffic. Looking 15 m in front of the vehicle it can in case of an unavoidable impact activate a brake assist system or other deployable protection system. To achieve our cost target below €100 for the sensor system we evaluate the required performance and can reduce the sensitivity to 150 mK and pixel resolution to 80 x 30. We address all the main cost drivers as sensor size and production yield along with vacuum packaging, optical components and large volume manufacturing technologies. The detector array is based on a new type of high performance thermistor material. Very thin Si/SiGe single crystal multi-layers are grown epitaxially. Due to the resulting valence barriers a high temperature coefficient of resistance is achieved (3.3%/K). Simultaneously, the high quality crystalline material provides very low 1/f-noise characteristics and uniform material properties. The thermistor material is transferred from the original substrate wafer to the read-out circuit using adhesive wafer bonding and subsequent thinning. Bolometer arrays can then be fabricated using industry standard MEMS process and materials. The inherently good detector performance allows us to reduce the vacuum requirement and we can implement wafer level vacuum packaging technology used in established automotive sensor fabrication. The optical design is reduced to a single lens camera. We develop a low cost molding process using a novel chalcogenide glass (GASIR®3) and integrate anti-reflective and anti-erosion properties using diamond like carbon coating.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Christian Vieider, Stanley Wissmar, Per Ericsson, Urban Halldin, Frank Niklaus, Göran Stemme, Jan-Erik Källhammer, Håkan Pettersson, Dick Eriksson, Henrik Jakobsen, Terje Kvisterøy, John Franks, Jan VanNylen, Hans Vercammen, and Annick VanHulsel "Low-cost far infrared bolometer camera for automotive use", Proc. SPIE 6542, Infrared Technology and Applications XXXIII, 65421L (14 May 2007);

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