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

TL;DR

This paper introduces a simple, low-loss method for rapid laser speckle reduction using colloidal dispersions, suitable for imaging and display technologies, with high transmission and low speckle contrast.

Contribution

The authors demonstrate a novel approach employing colloidal solutions with optical fiber delivery to achieve fast speckle reduction while maintaining high transmission and low cost.

Findings

Speckle contrast below 4% at 129 μs integration time

Transmission greater than 90% through the colloidal solution

Speckle reduction achieved without significant power consumption

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 {\mu}s. 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.