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A method for recording true holograms (not holographic interferometry) directly to a digital video medium in a single image has been invented. This technology makes the amplitude and phase for every pixel of the target object wave available. Since phase is proportional to wavelength, this makes high-resolution metrology an implicit part of the holographic recording. Measurements of phase can be made to one hundredth or even one thousandth of a wavelength, so the technology is attractive for finding defects on semiconductor wafers, where feature sizes are now smaller than the wavelength of even deep ultra-violet light.

A digital holographic reconstruction in the frequency and spatial domain is presented in this paper. This technique applies Fourier transform on heterodyne hologram with interference fringes then the complex amplitude and phase information are extracted from its sidebands. Reconstruction of the phase and amplitude image is completed through inverse Fourier transform back to spatial domain. For best holographic reconstruction qualities, a blind deconvolution filtering and an image based autofocus spatial processing are also adopted and discussed. Experiments show satisfying reconstruction results.

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