Low-loss high-speed speckle reduction using a colloidal dispersion

Abstract

We present a simple and robust approach to reduce laser speckle, which has limited the adoption of lasers in imaging and display applications. We use colloidal solutions that can quickly reduce speckle contrast due to the Brownian motion of the scattering particles. The high insertion loss associated with propagation through a colloidal solution was overcome by using white paint to cover the sides of the cuvette and an optical fiber to deliver the laser light deep into the colloidal solution, enabling transmission greater than 90%. The diffused laser output followed a Lambertian distribution and produced speckle contrast below 4% at an integration time of 129 μs. The ability for colloidal solutions to achieve fast speckle reduction without power consumption while maintaining high transmission, low cost, a compact size, and a long lifetime makes our approach useful for a wide range of laser imaging and projection applications.

Light source system for high-precision flat-field correction and the calibration of an array detector

“…When the value of R is less than 0.98, the dramatic decrease in the cavity absorption indicates that the absorption of the back wall dominates the energy loss for a short t − L. A long cavity (e.g., t − L > 8 mm), where the medium absorption tends to be a constant value, is preferable for low reflectivity. A similar result was obtained in the experiment by Redding et al [19] . However, as opposed to the conclusion reached by Redding et al, we find that it is difficult to increase the transmittance to as high as the value predicted in that paper, due to the absorption of the water and the cavity.…”

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

“…The CCD camera pixel size is 5.2um × 5.2um with a resolution of 1280 × 1024 pixels. The F/# for the camera lens is 1.3 [10]. The integration time of CCD camera chooses 20ms that is close to integration time of human eyes [11].…”

Electrically pumped semiconductor laser with low spatial coherence and directional emission

“…Various approaches to mitigate speckle artifacts have been developed. A traditional method is to average over many independent speckle patterns generated by a moving diffuser [7,8], colloidal solution [9], or fast scanning micromirrors [10]. However, the generation of a series of uncorrelated speckle patterns is time-consuming and limited by the mechanical speed.…”