Linearization of defocus for projector optical alignment in structured light illumination systems

Matthew E. L. Jungwirth; Eric P. Rudd

doi:10.1117/12.2567172

20 August 2020 Linearization of defocus for projector optical alignment in structured light illumination systems

Matthew E. L. Jungwirth, Eric P. Rudd

Proceedings Volume 11488, Optical System Alignment, Tolerancing, and Verification XIII; 1148806 (2020) https://doi.org/10.1117/12.2567172
Event: SPIE Optical Engineering + Applications, 2020, Online Only

Abstract

High-quality imaging is typically dependent upon well-focused optical systems. We present a method that linearizes defocus to provide a clear zero-crossing along the optical axis for structured light illumination (SLI) systems. Here, sinusoidal fringes are projected onto a quad target, a diffuse target with different heights along the optical axis in separate quadrants. Shifting the focus alters the fringe contrasts on the quad target. Best focus is achieved when the contrast between the different heights is balanced. The method was tested using a commercial SLI system and compared to a published phase-shifted reconstruction technique. The non-linear defocus behavior was efficiently linearized using the quad target method as evidenced by linear regressions. Finally, focal position estimates agreed well with the phaseshifted technique, thereby demonstrating viability of the method.

Conference Presentation

Citation Download Citation

Matthew E. L. Jungwirth and Eric P. Rudd "Linearization of defocus for projector optical alignment in structured light illumination systems", Proc. SPIE 11488, Optical System Alignment, Tolerancing, and Verification XIII, 1148806 (20 August 2020); https://doi.org/10.1117/12.2567172

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