Abstract: Real ray tracing is an essential step to obtain numerical quality performances in optical systems and is also involved in its optimization procedure. Real ray tracing does a complete description of the light ray for a selected number of rays; moreover, real ray tracing mixes the intuitive approach of ray propagation with the right light. Real ray tracing provides a powerful tool to reach, at the same time, information about an individual light trajectory and about all the optical system. Real ray tracing is based on the knowledge of Snell law and the geometric description of the surfaces used to specify the boundaries of different media glass. Both calculations are difficult to do; so in case of exact calculation, the reliability of a given algorithm or program is strongly based on how many rays are traced from the input to the output plane: the larger the number of rays, the better the results. Although the foundations of ray tracing are the simple rules of geometrical optics, the scientists and engineers involved in optical design have made successive refinements to include both the energy carried out by the light and also the wave nature of the electromagnetic radiation. In this contribution, we present the rules of real ray tracing step-by-step; these rules are explained in a clear language and same examples are included for the first-time readers. Real ray tracing is presented in a selfexplanation form to make this contribution readable in itself. The Snell law is revisited and adapted for its implementation in a numeric algorithm. The spot diagrams resulting from a real ray-tracing calculation are discussed. The wave nature of light propagation can be also approximated by using real ray tracing. Therefore we show the method to calculate a geometrical wave front and also its intrinsic limitations. Linked with the spot diagrams, it is possible to evaluate a point spread function. Also, an optical transfer function and a modulation transfer function are defined within this geometrical approach. The evaluation of the flow of energy through the system is discussed within the ray-tracing framework. Some hints about the inner mechanisms used by the optimization procedures of optical systems are discussed and related with a basic classification of the software packages currently used.
Publication Year: 2004
Publication Date: 2004-01-01
Language: en
Type: article
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Cited By Count: 8
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