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Design and Optimization of a Lens for Beam Shaping in a Terahertz Standoff Imaging System
, M.Sc. Thesis Sharif University of Technology ; Ahmadi Boroujeni, Mehdi (Supervisor)
Abstract
Terahertz waves have three important features that make them suitable for security imaging. 1. THz waves can penetrate or can be absorbed from many of non-metallic and non-polar materials and are perfectly reflected from most of the metals, 2. Drugs and explosives have terahertz spectra that can be detected by THz imaging, 3. THz waves do not have an ionizing effect and are harmless to the human body. Lenses can be considered as a major component of the terahertz imaging systems. Because of the relatively large terahertz wavelengths compared with wavelengths, compression, and decreasing the dimensions of the lenses in these systems matters a lot. In addition, reducing the wave reflection...
Optimization of the lens-array structure for performance improvement of integral imaging
, Article Optics Letters ; Volume 36, Issue 20 , Oct , 2011 , Pages 3993-3995 ; 01469592 (ISSN) ; Mehrany, K ; Bagheri, S ; Sharif University of Technology
2011
Abstract
The seemingly inherent deficiencies of integral imaging systems-in particular, the depth of field limitation-are, in this Letter, partly resolved by using an irregular lens array, where each lens is either rotated or displaced from its original position in the conventional flat lens array. It is shown that having an array of lenses in the integral imaging system has some sort of redundancy that could be exploited to improve the quality of the image formation. The needed rotation or displacement of constituent lenses in the array is found by using a meticulous optimization algorithm, which tries to evenly distribute the optical rays emanating from each of the lenses to form the final image