This paper presents the development of a versatile, accurate and efficient speckle simulation tool for the design of laser-based displacement sensors, capable of handling objective as well as subjective speckles. The simulation tool integrates the statistical nature of speckles with the deterministic properties of ray-tracing simulations, providing a reliable estimation of the performance of laser and/or speckle-based sensors in the design phase, even for more complex optical assemblies. It enables the calculation of several simulation outputs in order to determine the best performing system configuration for a given requirement and measurement principle. To validate the simulation results, they are compared against the experimental data of four designed laser-speckle based sensor setups for measuring in- and out-of-plane displacement of a target as well as against analytical relations for describing speckle pattern translation for simple geometries. With resulting simulation errors of less than 2 µm rms for in-plane (output: correlation peak shift) and 2.6 µm for out-of-plane displacements (output: center of gravity shift) for an integrated laser sensor geometry, the good accuracy of the speckle simulation tool is demonstrated.
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