1 November 1997 Ray-tracing-based phase elements as tools for CO2 laser beam profile homogenization: influence of different parameters and ranges of tolerances
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Modulo-2(pi) phase elements calculated by relatively simple ray-tracing methods turned out to be suitable tools for laser beam profile homogenization under certain preconditions. As an example, we present results of the transformation of a Gaussian TEM00-input beam with (lambda) equals 10.6 micrometers into a box-shaped intensity profile which has to be generate in the so called focal plane at a given distance from the element. The manufacturing of the investigated elements was realized by electron-beam lithography in combination with reactive ion etching. For computer modeling of the behavior of these elements a FFT- algorithm was used, working on the basis of paraxial approximation of the Kirchhoff-integral. The quality of achieved beam shaping depends of several parameters covering effects which are design-dependent, input-beam dependent, set-up dependent, or technology dependent. In an earlier paper we investigated the influence of varying beam waist diameter and beam waist position for a given element as well as of varying distance of the plane under investigation from the designed focal plane. In the present paper the interest is focused onto the influence of varying size of the element's clear aperture and of technologically caused deviations of realized step heights from the design values for the multi-level binary profile. Evaluation criteria were the lateral intensity distribution as well as the quantities diffraction efficiency and mean square amplitude deviation.
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Michael Rudolf Duparre, Michael Rudolf Duparre, Michael A. Golub, Michael A. Golub, Barbara Luedge, Barbara Luedge, Richard M. Kowarschik, Richard M. Kowarschik, Ernst-Bernhard Kley, Ernst-Bernhard Kley, Hans-Joerg Fuchs, Hans-Joerg Fuchs, "Ray-tracing-based phase elements as tools for CO2 laser beam profile homogenization: influence of different parameters and ranges of tolerances", Proc. SPIE 3134, Optical Manufacturing and Testing II, (1 November 1997); doi: 10.1117/12.295138; https://doi.org/10.1117/12.295138

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