MULTIPLE PASS OPTICAL FILTER

Abstract

A method and apparatus are provided for filtering incident radiation to protect imaging sensors from the damaging effects of high intensity radiation. The apparatus comprises a filter and a plurality of mirrors disposed within a cube. The filter is positioned diagonally within the cube so that portions of the incident radiation reflected by the filter are directed to a beam-stop on a surface of the cube. Portions of the radiation passed by the filter are directed by the mirrors to pass through the filter a plurality of times. Passing the radiation through a single filter a plurality of times provides a high density imaging system in a physically compact geometric shape. A focused beam passes through the filter in regions of successively greater optical gain. High intensity radiation thermally activates the filter to reject the radiation and protect the sensors. Activation of the filter proceeds in stakes starting with the region of the filter receiving the highest optical gain so that the filter is also protected from damaging radiation.

Source: Google Patents

35 USC §181 Secrecy Order

Inventor

• 1PATRICK J. HOOD

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