Electronic speckle pattern interferometry with violet semiconductor lasers

Abstract

Summary form only given. Semiconductor laser sources were applied for holographic data recording, storage and display. Holographic interferometers based on semiconductor lasers enable rapid display of acquired data in quasi-real (within several seconds) or real time in situ if advanced holographic techniques on silver halide media are applied. In the last case no liquid gates in the recording setup and no repositioning of the interferogram after exposure are required. Semiconductor lasers were also used in electronic speckle pattern interferometry (ESPI). For example a very compact ESPI device with semiconductor laser emitting in the red part of visible spectrum and a special HOE was successfully used for out-of-plane deformation measurements. This HOE when properly illuminated generates a speckled reference wave. A very similar ESPI interferometer can utilize instead of the HOE a microstructured refractive optical element (MROE) also located in front of CCD camera. The MROE shifts object and reference waves horizontally and guides them in-line to the CCD sensor. A novel semiconductor laser emitting in the violet part of visible spectrum was used for the first time in the ESPI setup. An engineering sample (5 mW, 397 nm) of semiconductor violet laser from Nichia Corporation was successfully tested in a compact ESPI device with the MROE.