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Dept. of Electrical and Computer Engineering & Electro-Optics Program |
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Russell C. Hardie |
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Liquid Crystal Optical-Phased-Array |
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The Problem In many imaging applications, it is highly desirable to replace mechanical beam steering components (i.e., mirrors and gimbals) with a non-mechanical device. One such device is a nematic liquid-crystal optical-phased-array (LCOPA). An LCOPA can implement a blazed phase-grating to steer the incident light. However, when a phase grating is used in a broadband imaging system, two adverse effects can occur. First, dispersion will cause different incident wavelengths arriving at the same angle to be steered to different output angles, causing chromatic aberrations in the image plane. Secondly, the device will steer energy not only to the first diffraction order, but to others as well. This multiple-order effect results in multiple copies of the scene appearing in the image plane. We have developed a digital image restoration technique designed to overcome the degradations described above. The proposed postprocessing technique is based on a Wiener deconvolution filter. The technique is applicable to scenes containing objects with approximately constant reflectivities over the spectral region of interest.
Selected References
J. J. Weinschenk, R. C. Hardie, and S. R. Harris, “Restoration of Broadband Imagery Steered with a Liquid Crystal Optical Phased Array,” Optical Engineering, (41) pp 2613-2619, 2002.
R. J. Broessel, V. Dominic, and R. C. Hardie, “Image Restoration of Dispersion Introduced by a Liquid Crystal Beam Steering Device,” Optical Engineering, Vol.34, No. 11, November 1995, pp. 3138-3145. |
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Liquid-crystal optical-phased-array (LCOPA) device. |
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Broadband beam steering experimental laboratory setup at the University of Dayton. |