Abstract: A system for determining the index of refraction of a sample fluid in which light from a collimated light source is directed through a light pervious cell in which sample and reference fluids are held. The light from the collimated light source which is transmitted through the cell is deflected and is then directed through a pair of gratings to establish patterns. When the cell contains a reference fluid therein, first patterns are established, and second patterns are then established by replacing the reference fluid with the sample fluid. A measurement of the change between the first patterns and the second patterns is used for determining the index of refraction of the sample fluid.

Abstract: A frequency marker system for indicating the wavelength of light rays, said system comprising: means for collimating said light rays, first and second grating means aligned with at least a portion of said collimated light waves and separated by a distance .DELTA. for providing Moire patterns, means for determining the changes in wavelengths responsive to changes in frequency by determining deflections of the Moire patterns.

Abstract: Equipment and method for mapping an object using moire deflectometry wherein collimated radiation deflected from the object is used to generate a moire pattern and wherein by measuring linear deflections in the pattern, variations in characteristics of the object is determined.