Dual-wavelength image-plane digital holography for dynamic measurement

✍ Scribed by Yu Fu; Giancarlo Pedrini; Bryan M. Hennelly; Roger M. Groves; Wolfgang Osten

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 810 KB
• Volume: 47
• Category: Article
• ISSN: 0143-8166
• DOI: 10.1016/j.optlaseng.2008.10.002

✦ Synopsis

A dual-wavelength image-plane digital holography, combined with a windowed Fourier analysis, is presented for dynamic measurement of a vibrating object. In order to expand the range of the velocity measurement, the object is simultaneously illuminated by two lasers with different wavelengths. A sequence of digital holograms of a vibrating object is captured by a CCD camera and two wrapped phase maps are retrieved from each digital hologram. At each instant, a new phase distribution with a synthetic wavelength is obtained by subtracting these two wrapped phase maps. A windowed Fourier analysis is then applied spatially and temporally to retrieve the high-precision displacement and velocity of the tested object. Experimental results show the requirement on the camera capture frequency is reduced by the proposed method.