Laser speckle reduction via TiO₂‐sapphire composite rotating wheel in laser projection

Abstract

Laser sources have been considered to be better light sources compared to traditional lamps or light‐emitting diodes used in projectors, which enables the projector to create images with higher color saturation, brightness, and energy efficiency. However, the speckle noise caused by the coherent nature of the laser is a major technology obstacle for laser projection, which severely affects the image quality. To suppress laser speckle, a TiO2‐sapphire composite (TSC) with rough and high reflectivity surface and high thermal conductivity substrate is designed, which reduces the laser speckle by creating spatial diversity. Moreover, combined with a micro motor, the design and fabrication of the TSC rotating wheel are realized, which further reduces the laser speckle by creating time diversity. The experimental results show that the laser speckle contrast can be reduced from 9.0% to 2.2% when placing the TSC rotating wheel in the light path, which is below the speckle perception limit of the human eye (<4%). This new type of laser speckle suppression device is simple to use, low in cost, high in energy utilization, high in thermal conductivity, easy to mass production, and has great application potential in high‐power laser projection.