Sensing and metrological applications of holography

An analyte or measurand may change the diffraction efficiency of a hologram or the colour of a reflection hologram. The formation of a holographic grating can itself be a sensing action. Holographic optical elements (HOEs) can provide the reference and object beams in an unbalanced, out-of-plane sensitive, electronic speckle pattern interferometer for metrology, with wavelength modulation enabling the fringe analysis.