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Optical beam shaping research includes design of optical systems where the elliptical beam of semiconductor laser is circularized, collimated, and expanded to a desired beam diameter or shape for possible application in LIDAR (Light Detection And Ranging) systems. LIDARs have many diverse applications such as remote sensing, military applications, optical data storage, display technology, and material processing. They have higher accuracy and resolution due to much shorter wavelengths and narrower beam-width relative to the other remote sensing tools. Use of a semiconductor laser as the source in a LIDAR systems has several advantages such as low cost, compactness, broad range of wavelengths, and high PRFs (Pulse Repetition Frequency). However, the semiconductor lasers have different divergence angles in two different transverse directions, resulting in inherent astigmatism and elliptical beam shape. Elliptical beam shape is not desirable for several laser-based applications including LIDAR operating in the far-field region (where target is relatively far away) [1, 2]. For applications that require uniform illumination of an extended target area, optical systems where the undesirable Gaussian irradiance distribution of semiconductor laser beam is transformed to uniform, collimated, and expanded to desired size are needed [3]. Design equations specific to these beam shaping optical systems are determined using geometrical optics principles. These equations are derived analytically and MATLAB codes are developed to solve for the unknown quantities of the optical systems, and ZEMAX is used to verify the analysis results.
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