I-Fu Shih

Analysis of miniature FLIR test targets

Hughes Aircraft Company has developed a miniature forward-looking infrared test target that uses differential emissivity to simulate differential temperature. This paper provides a theoretical analysis for the emissivity target. The analysis leads to a semiempirical formula that gives a reasonably good prediction of apparent temperature differences. The formula is useful for designing future emissivity targets.

Aplanatic Two-Mirror Compact Collimator

Design, fabrication, and test results are discussed for a compact two-mirror collimator that was diamond turned from a single piece of material.

Contorted mirror reduction of projected image distortion

An analysis is made of the degree to which a simple contorted mirror can reduce distortion in a projected image. Although it is impossible in general to remove the distortion completely by this means, significant reduction may be achieved. Equations are derived for the shape of a mirror which will give the maximum reduction possible. Equations are also developed for how to stress a planar mirror to create the desired optimal shape. Image blurring is estimated. An example is presented in which this technique is used to reduce the distortion which results when a projection lens appropriate for projection onto a flat screen is used instead to project onto a spherical surface from an oblique angle.