Abstract

A key aspect in the development of endo-atmosperic hypersonic interceptors is a class of problems called aero-optics. These problems involve performance degradation of a hit-to-kill endo-atmospheric hypersonic missile due to a degradation in sensor performance. The sensor performance is degraded because of an optical image quality reduction at the focal plane of the sensor. One reason for this image quality reduction is the environment that exists in the vicinity of the sensor system aperture. Since the hypersonic environment is so severe, a protection system for the aperture must be used. Typical protection systems involve the use of a coolant stream that is distributed over the aperture and produces an optical disturbance while protecting the aperture. The magnitude of these aero-optics effects are being quantified by using computational fluid dynamics (CFD) techniques for predicting the flow field, geometric optics techniques to predict the optical effects, arc jet testing to evaluate the aerothermal effects, and shock tunnel testing to evaluate aero-optics effects. Advancements in aero-optics technology, including both theoretical methods and experimental measurements, are discussed. The image quality is degraded because of several phenomena: (1) intensity loss due to absorption and scattering of the mixing layer set up by the coolant protection system for the aperture, (2) diffraction of target signature optical beam, (3) refraction of target signature optical beam, (4) high background signal levels due to the mixing layer protection system, and (5) radiation from the shock layer.

© 1992 Optical Society of America