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Impact of drawing resolution on ray tracing

Most of the time, the default drawing resolution of native objects in a non-sequential system is enough for providing a good “first guess” as to the location of the ray-object intercept points to be used during ray-tracing. However there might be cases where the drawing resolution needs to be increased by the user in order to get consistent results from a ray trace
Alessandra Croce
12/22/2015
Non Sequential Ray Tracing
OpticStudio

Introduction

As specified in the help files section The Setup Tab > Editors Group > Non-Sequential Component Editor > Object Properties > Draw:

help

Typically this only affects rays incident to steeply curved objects.


A simple example

In the file attached you will see an example of the impact of the drawing resolution on ray-tracing.

A system formed of a Source Gaussian, a Torus Surface and a Detector Rectangle has been replicated 4 times. In each system the source is located close to one end of the torus surface, so that all rays generated by the source are entering the pipe defined by the torus surface. Note that the Material of the torus surface is Mirror, hence all rays entering the pipe should bounce on its surface, and hit the detector located at the end of the pipe.

For comparison, all 4 systems are identical except for the drawing resolution of the Torus Surface. This has been defined differently in the Draw properties of each Torus surface, and has been consequently reported in the Comment column of the non-sequential component editor:

prop
3bis_NSCE

You will notice that the 3D layout shows that some rays are escaping the pipe, and that the higher the torus surface resolution the fewer rays are escaping.

layout

In order to show that this is not just related to the drawing rendering, launch a ray-trace. You will notice that in this case there are no ray errors in the Ray Trace Control:

raytrace

However if you compare the results of the ray trace for the 4 systems, you will notice that the higher the torus surface resolution the higher the Total Hits on the detectors: although no rays should be lost, only the detector with the customized drawing resolution will collect all the rays generated from the corresponding source:

t_detector

Comparing the results of the 4 systems clearly shows the impact of the drawing resolution of the torus surface on ray-tracing: if the drawing resolution is not sufficient to provide an adequate first guess, the ray-trace shows results which are inaccurate and inconsistent with our expectations.
 

Conclusion

Depending on the characteristics of you system, the result of a ray-trace might be inaccurate if the drawing resolution of your object is too low for providing a good “first guess” as to the location of the ray-object intercept points to be used during ray tracing. If the ray trace shows results which you suspect inconsistent with your system, try increasing the drawing resolution of relevant objects (in this example the Torus surface) until you find consistent results when ray tracing.
Please note that this behaviour will strongly depend on your system and there is no general advice for when the drawing resolution needs to be increased. Moreover OpticStudio does not have means to detect such a potential issue, therefore no ray trace errors will be generated in this case. It is up to the user to inspect the results (e.g. via the system layout) to ensure accuracy.