63‐1: Speckle Reduction for Laser Pico‐projector with Dynamic Deformable Mirrors

Tsao, Che-Wei; Chen, Hsuan-An; Pan, Jui-Wen; Yang, Zu‐Po

doi:10.1002/sdtp.12280

Cited by 1 publication

(1 citation statement)

References 9 publications

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“…It is well known that the measurement conditions have a significant impact on measuring the SCR, thus the measurement conditions used correspond to the human eye perception. In order to ensure an accurate SCR value, the parameters used in this work agree with the previously reported work in [15,17,19,22,26] to measure the SCR in a handheld laser projector such as pico-projector. The pixel size of the CCD camera is 5.2 um×5.2 um with a resolution of 1280×1024 pixels.…”

Section: Speckle Reduction Characterizationsupporting

confidence: 58%

Speckle reduction by employing two green lasers and two-dimensional vibration of lenses

Mohamed

Kashak

et al. 2019

Eng. Res. Express

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A method of speckle reduction suitable for use in a laser projector was proposed in the paper. Speckle contrast ratio (SCR) reduction was achieved by combining wavelength diversity and angular diversity methods. First, wavelength diversity was demonstrated by the use of two green laser sources (a 520 nm laser diode (LD) and a 532 nm diode-pumped solid-state (DPSS) laser) at a power ratio of 4:1. Second, angular diversity was achieved via the vibration of two lenses in two orthogonal directions placed directly after the laser source. The vibrating lenses are small and do not require changes to the beam path of the laser source, allowing for more compact projector designs. The frequency of vibration of these lenses was optimized to minimize the SCR in the output image. A SCR of less than 4% was achieved without the use of optical diffusers, which significantly reduces optical losses. Optical transmission could be further increased with the optimization of optical coatings on the lenses. This result shows great promise for applications such as laser pico-projectors within the realm of heads-up displays (HUDs) and mobile devices.

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