Abstract: An optical assembly divides a single image into a plurality of images which are simultaneously projected onto a single sensor array. The optical assembly is arranged so that each of the plurality of images can be made to pass through a filter of a different type. For example a polarizing filter of a different orientation, or a filter which passes a different spectral band. In this way a single digital camera having a single chip sensor array can simultaneously receive multiple substantially identical images which have been acted on by different filters. This allows data capture from a single frame of a single camera to be used to perform stress analysis, or spectral analysis. This is particularly useful when high speed image capture is desired which contains stress or spectral data, because each frame captured from the sensor array contains multiple images which can be processed to obtain stress or spectral data.

Abstract: An optical collector head comprises a beam splitting device (5) capable of producing at least three output beams (9) in different directions; a single objective lens (4) to provide a collimated beam to the beam splitting device (5); and an assembly of: (a) a quarter wave plate (6), or plate producing a similar effect; (b) a polarizer acting as an analyzing element; (c) a lens; and (d) a recording device (3/1, 3/2, 3/4) for the simultaneous capture of phase-stepped images from each output beam. The invention also includes a polarimetric device comprising an optical collector head as defined above and a source (12) of polarized light; and a polarimetric device comprising an optical collector head as defined above and a source (12) of polarized light.

Abstract: A first aspect of the invention relates to an epoxy resin coating used in reflection photoelasticity, which is "black" in the infra-red part of the spectrum; another aspect to the use of an epoxy resin as a coating on at least one surface of a body to be subjected to cyclic loading and examined by thermoelasticity, and another aspect to a method of making thermoelastic measurements of a body when subjected to cyclic loading and hence measurements of stresses or strains, comprising, as an initial step, coating the surface(s) of the body to be measured with an epoxy resin whereby the surface(s) so coated represents a black body.