Speckle reduction and maintaining contrast in a LASER pico-projector using a vibrating symmetric diffuser

Abstract

We proposed a design for a LASER pico-projector with a low speckle contrast value and high contrast ratio that maintains system efficiency. The method for speckle contrast reduction utilizes two diffusers and a Voice Coil Motor (VCM) oscillator. The two different diffusers for a high contrast ratio and high system efficiency can be divided into two categories. In Category 1, the speckle contrast value can be decreased to 2.80% by using a circular symmetric diffuser. At the same time, the fullon/full-off (FO: FO) contrast ratio can be maintained within 1200: 1-1300: 1, but the system efficiency decreases 1.50%. In Category 2, the speckle contrast value can be reduced to 6.50% by using an elliptically scattering diffuser. At the same time, the FO: FO contrast ratio can be maintained within 1300: 1-1400: 1, and the system efficiency decreases by only 1.00%. (C) 2014 Optical Society of America