Dynamic holography for speckle noise reduction in hybrid measurement system

Andreas Faulhaber; Stefan Haberl; Tobias Haist; Marc Gronle; Yousef Baroud; Wolfgang Osten; Sven Simon

doi:10.1117/12.2320486

14 September 2018 Dynamic holography for speckle noise reduction in hybrid measurement system

Andreas Faulhaber, Stefan Haberl, Tobias Haist, Marc Gronle, Yousef Baroud, Wolfgang Osten, Sven Simon

Proceedings Volume 10744, Laser Beam Shaping XVIII; 107440J (2018) https://doi.org/10.1117/12.2320486
Event: SPIE Optical Engineering + Applications, 2018, San Diego, California, United States

Abstract

Measurement systems for metrology incorporating laser-triangulation methods have the problem of speckle noise. This noise is an effect of the coherence of the laser light in combination with the projection onto rough object surfaces. In this contribution, we show results for using spatial light modulators within a simple and effective method in order to reduce the speckle noise in laser-based triangulation.

In the last decades, spatial light modulators have been intensively used for different applications in optical measurement systems. Today, the elements have high enough resolutions to be used even for simple holographic applications. We generate dynamic holograms with a pixelated spatial light modulator by inscribing multiple holograms. The laser-illuminated holograms microscopically translate the measuring point in the object plane. Due to the minimal different spot positions, the speckle patterns are also subject of change.

By averaging of the intensity field in the camera plane the speckle noise can be reduced and the accuracy of the spot's position measurement is increased. Furthermore, experimental measurements show features of correcting spot deformations due to optical system aberrations like defocus, astigmatism and coma.

Citation Download Citation

Andreas Faulhaber, Stefan Haberl, Tobias Haist, Marc Gronle, Yousef Baroud, Wolfgang Osten, and Sven Simon "Dynamic holography for speckle noise reduction in hybrid measurement system", Proc. SPIE 10744, Laser Beam Shaping XVIII, 107440J (14 September 2018); https://doi.org/10.1117/12.2320486

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