Sensitivity and nonlinearity of optical path difference measurements using triple-exposure heterodyne holographic interferometry

Triple-exposure dual-reference beam holographic recording offers a convenient means by which high-speed transient phenomena may be investigated using heterodyne interferometry. Although convenient, use of the technique imposes certain compromises both in measurement linearity and sensitivity compared with analysis of more conventional double-exposure recordings. Fortunately, linearity can be assumed for events where only small (e.g., one-tenth wavelength) optical path changes are observed. By appropriate control of the intensity ratio of the reconstructed image wave fronts, the region of linearity may be extended. Furthermore, measurement sensitivity can be optimized by proper control of recording and reconstruction parameters.