Dual band antireflection coatings for the infrared

Sensor performance for dual band forward looking infrared (FLIR) imagers can be substantially improved by increased simultaneous throughput of both sensor bands in the optical systems. Currently available antireflection coatings (ARs) have optimized performance for either spectral band, but not both on the same optic. Where AR coatings cover the mid and long wave infrared (LWIR) bands, or the entire broad band spectrum from visible to LWIR, performance is not sufficient for future systems. A method of designing and fabricating high performance ARs has been developed. This paper presents a discussion of the trade-off of film thickness and complexity versus transmission performance. Fabrication results for high, medium and low index lens materials are also presented.