An array of phase retarders can be used as an optical phased array (OPA) to steer light [McManamon et al., Proc. IEEE 84(2), 268–298 (1996)]. The introduction of resets enables steering to larger angles without requiring an optical path difference (OPD) greater than one wavelength. These resets, however, are correct only at the design wavelength. The beam steerer is therefore very dispersive. It has been shown theoretically that resets of an integer multiple of the wavelength will make the beam steerer less dispersive [McManamon and Watson, Proc. SPIE 4369, 140–148 (2001)]. We offer the first experimental proof that resets of n are less dispersive than resets of a single . We also show experimentally that the dispersion associated with fixed period resets does vary, but only within a fixed limit. Last, we show the equivalent of power shifting from one order to the next as larger resets move from being divisible by one integer times the nondesign wavelength toward being divisible by the next integer times the nondesign wavelength.
Methods of nonmechanically steering broad spectral band light will enable many low cost electro-optical systems that employ broadband sensors (such as flir or TV). Nonmechanical optical phased array approaches have been demonstrated for narrow band electro-optical systems. However these approaches tend to be highly dispersive because of the diffractive effects associated with the modulo 2p phase resets within the apertures. In this paper we describe approaches to compensate or minimize these dispersive effects. A means to compensate for the dispersion using wavelength independent phase modulators and achromatic Fourier transform lenses is discussed. A means to minimize dispersive effects through the use of larger-than-2p phase resets is also presented, including a possible means of implementing such an approach using cascaded microlens arrays that are electronically controllable. The addition of nonmechanical approaches for steering broadband radiation will significantly accelerate the revolution in electro- optical systems from conventional steering to non-mechanical steering.
The Wollaston prism with large deflection angle usually has small cross section size, which constrains its application in beam steering. This paper investigates the possibility of assembling the prisms together to increase the cross section size. Single-layer- and double-layer- assembled Wollaston prisms are investigated. The compression ratio and transmission ratio associated with the diffraction efficiency of assembled prisms are calculated and formulated.
In order to enhance the speed of image processing we apply the optical wavelet transform to vision system by the method of photoelectric hybrid implementation. The state-of-the-art liquid crystal on silicon (LCoS) technology is applied to improve the signal-to-noise ratio of the wavelet transform. A fan out grating implemented by a phase-only LCoS is used to implement multiple channel optical processing. Therefore the parallelism of the vision system is improved further. The research results shows that the optical wavelet transform based vision system is reasonable and feasible. The image feature extraction by optical information processing can enhance the speed of vision processing.
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