Laser Speckle Reduction Using a Motionless Despeckle Element Based on Random Mie Scattering

Abstract

A motionless despeckle element based on Mie scattering and Brownian motion of suspended particles is proposed, which is achieved by filling a light pipe with diluted milk in laser projection systems. The Brownian motion of the milk fat particles leads to the superposition of the intensity of the instantaneous scattered light within the integration time of the human eye, which causes a reduction in laser speckle contrast because of temporal averaging intensity. Experimental results show that the speckle contrast mainly depends on the concentration of the suspended fat particles, and can be reduced down to 3.94% at the fat particle concentration of approximately m .

54‐1: Laser Speckle Reduction using Nanoparticle‐Embedded Liquid Crystals

“…The majority of the proposed solutions are introducing optical components such as diffuser, microlens-array beam shaper, phase matrix and optical fibers with mechanical motion such as rotation or vibration in the system to reduce the coherence of light source [4][5][6][7][8]. Motionless optical components for speckle reductions are demonstrated such as polymer dynamic diffraction gratings, deformable mirrors, scattering from colloidal suspension, spatial light modulator, and ferroelectric liquid crystal cell [9][10][11][12][13]. The mechanical moving parts requires power and space for installation, while most the motionless approaches requires power consumption.…”

Speckle reduction using twin green laser diodes and oscillation of MEMS scanning mirror for pico-projector

“…However, the severe drawback of image quality is also occurred based on laser characteristics which called speckle pattern as a granular pattern [2]. Various efforts have been researched to reduce speckle such as rotating diffuser, diffraction optical elements with mathematical matrix, motionless diffusing elements, and so on [3][4][5]. Previous speckle reduction methods of static and dynamic systems are effective to reduce speckle, however they are unsuitable solution for the tiny pico-projector.…”

P‐222:Late‐News‐Poster:Mechanically‐Static Laser Speckle Reduction Solution

“…Several solutions are proposed based on the temporal decoherence approach, for example, mechanically vibrating or rotating an optical component such as diffuser, microlens array, phase matrix and/or optical fibers [8][9][10][11][12]. Motionless approaches have also been demonstrated by using a polymer dynamic diffraction grating, colloidal suspension, spatial light modulator, ferroelectric liquid crystal (LC), LC with chiral dopant, and nanoparticle (NP)-doped LC devices [13][14][15][16][17][18]. While the solution of using a moving diffuser is mostly selected due to its low cost and effectiveness, motionless approaches are of high interest, since they eliminate the risk of mechanical failure in products.…”