Speckle reduction methods in laser-based picture projectors

Methods and Devices of Speckle-Noise Suppression (Review)

“…When the same CCD is used, and a size of objective and subjective speckles is the same, the speckle contrast measured in the image plane, is in good agreement with that when measured in free space [7] [15].…”

“…Experiments have shown that a despeckler can be recognized as effective, which is capable of providing a speckle pattern contrast of less than 3% for still images [5] and no more than 5% for moving images [6]. In this case the observer does not notice the noise practically [7]. However, we will consider below the methods and devices providing the value of speckle contrast at the level of about 10%, when the quality of the generated image is quite acceptable.…”

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

“…The main advantage of using a laser in display application is the wide color gamut a display can achieve from the sharp emission spectrum of a laser. In addition to color generation, the high brightness and high contrast provided by a laser make laser a promising light source for projection displays [3]. However, the speckles from the coherent nature which reduces the image quality is the main obstacle of laser-based projection display.…”

Speckle contrast reduction of laser light using a chiral nematic liquid crystal diffuser

“…We found that, in this case, C ¼ 0.04 and is in good agreement with previously published results for similar devices. 20 Evidently, our LC device does not quite reach the low value obtained by the RGGD, but it does have the benefit of being more compact and free of mechanically rotating parts. Furthermore, by altering the E-field amplitude, it is possible to control the magnitude of C should an application require a moderate amount of speckle.…”