Abstract: A dual-mode target seeking apparatus having a seeker dome defining an aperture and transmissive to microwave frequency energy of a first frequency and to light wave energy at a second frequency and at a third frequency. An optics system within the seeker dome is transmissive to the microwave frequency energy reflective to the light wave energy received via the aperture. A first detector receives the microwave frequency energy via the aperture, and a second detector images a target by the light wave energy of the second and third frequencies via the optics system.

Abstract: An angle filter for restricting the range of light received by a detector functions as a "cold shield" in an infrared optical system. The angle filter either utilizes fiber optics or a thin film technology and reduces the size of an optical system operating in the infrared region while maintaining high system performance. The cold shield/exit pupil configuration of a traditional optical system is replaced by the angle filter.