Patent US 3,949,225

Infrared radiation over a field of view is scanned in a first direction by an aximuth scan mirror and optically coupled to a spherical reflecting mirror. The scanned infrared radiation is reflected by the spherical mirror to a first surface of a vertical scanning mirror which forms an image on an adjacent detector array. The electrical signal output of the detector array, proportional to the intensity of the detected infrared radiation, is processed and coupled to an array of light emitting elements. The array of light emitting elements produces a visible image, corresponding to the infrared image, which is projected onto the other surface of the vertical scanning mirror, the visible radiation reflected therefrom being optically coupled to the rear surface of the azimuth scan mirror and thereafter to a recording medium or display device to produce a thermal image of the field of view. The light emitting elements in the array are arranged in a manner whereby the final imagery produced is essentially free of raster lines.