Speckle mitigation techniques for laser point scanned displays in head-up display applications

T. Gus McDonald; Pierre Mermillod

doi:10.1117/12.2650722

14 March 2023 Speckle mitigation techniques for laser point scanned displays in head-up display applications

T. Gus McDonald, Pierre Mermillod

Proceedings Volume 12443, Advances in Display Technologies XIII; 124430C (2023) https://doi.org/10.1117/12.2650722
Event: SPIE OPTO, 2023, San Francisco, California, United States

Abstract

Laser source displays offer wide color gamut and deep color saturation. However, they also suffer from speckle due to their coherent wave-front interaction with surface roughness or imperfections from any component in the optical chain of the display. Speckle can be offensive to the viewer as it gives the displayed image a noticeable "shimmer" or grainy appearance. For an expanded beam, flood illumination display such as those using a Spatial Light modulator (SLM), there exist methods to minimize this speckle to where it is not noticeable to the viewer. However, a laser scanned display is a different situation as the image is generated by a single flying spot and speckle strategy relying on mitigation of flood illumination imaging cannot be efficiently used. Static components such as close packed microlens arrays used in the diffuser optical plane in a typical Head Up Display (HUD) layout are a good compromise and do a reasonable job mitigating speckle. However, the microlens size must be closely matched to the laser beam spot size to minimize other artifacts such as Moiré pattern in the image. Despite being a good countermeasure against speckle, in high magnification HUD systems, the microlens array structure can be viewed in the image and can sometimes be perceived as "pixelization". We propose utilizing discrete step index motion of a close packed microlens array to both double the perceived image resolution and mitigate speckle.

Conference Presentation

Citation Download Citation

T. Gus McDonald and Pierre Mermillod "Speckle mitigation techniques for laser point scanned displays in head-up display applications", Proc. SPIE 12443, Advances in Display Technologies XIII, 124430C (14 March 2023); https://doi.org/10.1117/12.2650722

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