Propagation Errors Overview

The following page introduces you with the propagation erros and how to analyze and solve them.

Context

During the ray propagation of a Speos simulation, errors may occur and have different origins.

The simulation tracks the number of encountered errors, according to different causes.

  • The error report part of the simulation report indicates the corresponding percentage of errors. However, most of the time, it is difficult to identify the root causes only through the report and it requires a lot of Speos experience to decrease the error rate.
  • A specific *.lpf file can be generated storing the rays in error to help you analyze and decrease the percentage of errors.

Error Report

The propagation error is expressed as a fraction of the rays emitted (Total number of errors in the HTML Simulation Report) or a fraction of the energy emitted (Error power in the HTML Simulation Report).

We usually recommend a Total number of errors rate below 3%, and below 1% in case of a sensitive project.

Note: The fraction of energy emitted is usually more valuable to assess the criticality of error amount: you may have plenty of rays in error in a part insignificant to your project because almost no energy is propagated there.

In the following report example, 100006 rays are emitted. 98 rays are in error representing an energy of 0,00098 Watt.

Warning: The more propagation errors you have, the more visible the difference between the CPU result and the GPU result for a same simulation. For more information, refer to GPU/CPU Differences.
Figure 1. Report Example

Propagation Error File

To help you identify the root causes and decrease the percentage of errors, a *.lpf file dedicated to store only the rays in error can be generated out of the simulation and analyzed. Through this file you can display the rays in error in the 3D view and the type of error so that you can correct your optical system.

Example: decreasing the error rate

The body being the cause of the errors is identified thanks to the rays in error.
Meshing settings and error report before potential modifications. The error rate is high.
Meshing settings modifications and error report after modifications. The error rate has decreased.