Digital holographic camera with extended stochastic illumination for non-destructive inspection of silicon optics

In present work, we propose a compact digital holographic camera with extended stochastic illumination for full-field non-destructive inspection of silicon optics fabricated in computerized numerical control (CNC) machine. The developed technique overcomes the limitation of digital holography imparted by definite size of active area of the recording sensor to image a specular surface. The original aspect of this research work is to develop a system that enables reconstruction and testing of specular surface. For this a dual diffuser configuration is incorporated in a compact digital holographic camera developed for non-destructive testing applications. The generation of stochastic illumination beam using the diffusers is explained by simulating propagation of a light beam through random phase function of scattering medium. The stochastic optical field produced by the combination of diffusers in the digital holographic camera makes the camera suitable for non-destructive testing of specular surface of silicon optics. The effect of number of diffusers, and their relative positions on imaging area of specular object is studied for development of an optimized configuration of digital holographic camera. Applicability of proposed scheme is demonstrated through detection of defects in silicon optics using digital holographic interferometry.