1 November 1997 Forming of selected unimodal complex amplitude distributions by means of novel DOEs of MODAN type
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Abstract
We present results of iterative calculation, manufacturing and experimental as well as theoretical investigations of a novel diffractive optical element (DOE) which transforms a Gaussian TEM00 input beam into a unimodal Gauss-Hermite complex distribution. The iterative calculation procedure is based on the application of the method of generalized projections. The projection operator onto a set of modal functions is implemented through partition of the focal plane into a 'useful' and an 'auxiliary' domain. As a result of this calculation there will be a 2D phase distribution which has to be transferred into the optical element. This element has been manufactured as 16 level surface profile by electron-beam direct-writing into a PMMA resist film and a subsequent development procedure of the resist. Each of the generated 15 steps of the resist profile corresponds to a certain electron dose, comparable to a usual 'isobathic process'. The final element consists of a fused silica substrate coated with the structured PMMA film, and has been designed for transmission mode and (lambda) equals 633 nm. Whereas computation results consist in the form of lateral distributions of the complex amplitude in the Fourier-plane, experimental results will be intensity distributions only. To measure additionally the phase distribution, we realized a special interferometric set-up. Both computational and experimental results are presented and demonstrate a good conformity with each other. Energy efficiency has been measured in the Fourier-plane as 37.7 percent, compared with the calculated value of 45 percent. The achieved results show good perspectives of such an approach for the formation and application of unimodal distributions.
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Michael Rudolf Duparre, Michael Rudolf Duparre, Vladimir S. Pavelyev, Vladimir S. Pavelyev, Barbara Luedge, Barbara Luedge, Ernst-Bernhard Kley, Ernst-Bernhard Kley, Richard M. Kowarschik, Richard M. Kowarschik, Victor A. Soifer, Victor A. Soifer, } "Forming of selected unimodal complex amplitude distributions by means of novel DOEs of MODAN type", Proc. SPIE 3134, Optical Manufacturing and Testing II, (1 November 1997); doi: 10.1117/12.295137; https://doi.org/10.1117/12.295137
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