Performance characteristics of thin film resistor arrays for infrared projector a

摘要

Abstract: The thin film resistor array choice of infrared projector technology is characterized by the comparatively large values of pixel fill factor and emissivity that can be attained but is limited by materials and heat transfer constraints. In this paper, the characteristics and limitations of an infrared projector test device based on a 2 $MUL 25 bilinear thin film nichrome resistor array are described. The steady state and transient performance characteristics have each been assessed by use of both analytical and finite element heat transfer techniques. Test devices based on the design that gave the best predicted performance have been fabricated on a silicon wafer substrate by application of the conventional techniques of photolithography, etching and vacuum deposition, each array being comprised of a patterned polyimide insulation layer sandwiched between the substrate and the nichrome heating elements. Initial characterization experiments have demonstrated a 200$DGR@C operating temperature capability and 10 - 90% rise and fall times of the order of 100 - 200 $mu@s. It is shown that the risetime can be improved significantly by application of a tailored drive voltage waveform, as can the falltime of appropriate thermal connection of the substrate to a low temperature heat sink. Modes of device failure are also discussed.!10