Magnification of three-dimensional optical image without distortion in dynamic holographic projection

Abstract

We propose a simple technique to enlarge the reconstructed three-dimensional (3D) optical image and shorten the reconstructed distance simultaneously in real time holographic projection using a conventional lens or concave reflecting mirror based on the optical reversibility theorem. The main factors causing the longitudinal and transversal distortions of a 3D enlarged optical image are analyzed, and the 3D optical images are enlarged where severe distortions are precompensated by constructing objects with distortions directly instead of computing the precompensated phase iteratively so that it does not increase the computing time. Numerical simulations and optical experiments are performed for magnifying a simple cubic model. The results show that a 3D enlarged optical image is achieved successfully without any distortion and the reconstructed distance is shortened simultaneously. It is believed that this proposed technique is useful for 3D real time holographic projection in the future. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).Subject terms: computer holography; holographic display; magnification of threedimensional image size; distortion of the image; compensation of the distortion. Paper 110845R IntroductionHolographic three-dimensional (3D) display is a promising technology in true 3D display. It can produce virtual 3D images by looking directly into the spatial light modulators (SLMs) or real images by reconstructing on a frosted glass plate or a thick Agarose gel. 1 In recent years, various technologies have been developed for holographic 3D projection. However, there are still two main problems hindering the realtime applications of state-of-art holographic 3D projection: one is the enormous computational time, 2 and the other is the limited size and viewing zone of the reconstructed 3D optical image due to the limitations of the total size and its pixel pitch of the SLM. 3-5 As is well known, higher resolution and smaller pixel pitch of the SLM on which the hologram is loaded will lead to a larger viewing zone and a bigger size of the 3D reconstructed image. Over visible range for human visual perception, a spatial light modulator with the resolution higher than 2000 lines/mm is required for realizing the 3D display with high quality, while the resolution of currently commercial SLMs is normally limited to no more than 150 lines/mm. Therefore, it is difficult to achieve a big enough 3D image in proper reconstructed distance.To obtain a reconstructed image with higher quality, scientists have proposed a lot of techniques to enlarge the viewing zone or 3D image. 3-9 Fukaya et al. 10,11 use several SLMs and a plano convex lens with a very large diameter and long focal length in geometrical combination by a beam splitter for achieving a larger image size and wider viewing zone simultaneously. In this system, the main function of the plano convex lens is the combination of the images reconstructed from different SLMs, not the enlargement of the 3D image. For solving the aberration caus...

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