Abstract: An optical power limiter is designed for use with high gain optical systems by providing intensity reduction by the use of a non-linear fluid. As the intensity of light increases in the fluid, the index of refraction becomes non-linear very rapidly. This results in a plasma being formed within the fluid. Picosecond reaction time is provided. Recovery time of less than a microsecond is required for the system to return to its starting point.

Abstract: Collimated incident optical radiation which might contain high-intensity or igh-power radiation is focused into the body of a limiter by a first lens formed at one end of the limiter. The body is a cylinder of revolution with an axis along the optical axis between radiation and a sensitive detector. Radiation of normal intensity or power freely passes through the body and is recollimated by a second lens formed at the other end of the limiter from the first lens. The body is made of material which is subject to two-photon absorption such that high-intensity or high-power radiation undergoes absorption and is consequently self-defocused such that it is diverted from the optical path. For visible light, the material may be ZeSe or ZnS; for ultraviolet, copper chloride; for infrared, HgCgTe.

Abstract: An optical testing apparatus for use in non-destructive testing of optical omponents to evaluate their operational requirements. The optical component to be tested is mounted on a fixture that allows its accurate alignment and rotation so the entire surface area of the optical component can be scanned in discrete areas. A laser light source is positioned to illuminate the optical component with coherent light beams or rays. An aperture positioned in the light beam permits adjustment of the diameter of the light beam impinging on the optical component to be evaluated. Whenever an imperfection is present in the optical component a portion of the light rays illuminating the imperfection will be disarranged or scattered. Both the non-scattered and scattered light rays are gathered by means of pyroelectric detectors and their outputs are compared for obtaining an electrical signal that is proportional to the intensity of the scattered light caused by the imperfection.