Digital Color Holography for Analyzing Unsteady Wake Flows
Résumé
The fast development of technology, such as high-resolution sensors, various diode-pumped solid-state (DPSS) lasers with long coherence, data postprocessing and computation power, provides opportunities to develop new optical methods capable of simultaneous full-field measurements with high spatial and temporal resolutions and to retrieve absolute data. In the literature, some papers were concerned with works in digital color holographic interferometry and they demonstrated phase shifting digital color holography using a multiwavelength HeCd continuous wave laser and a color charge coupled device (CCD) equipped with a Bayer mosaic. The non-invasive optical methods are based on digital color holography. The holographic numerical processing of all the methods presented in this chapter is based on off-axis holography and filtering in the Fourier spectrum to extract the complex amplitude of the object wave. The optical phase is directly extracted from the complex field and phase differences are computed from a sequence of digitally recorded holograms.