Laser speckle reduction utilized by lens vibration for laser projection applications

In this paper, a compact speckle reduction method utilizing vibrating lenses for laser beam scanning is proposed and demonstrated. The maximum speckle reduction efficiency was found to be 75.6% and 81.25% for a 532 nm diode-pumped solid-state (DPSS) laser and a 520 nm laser diode (LD), respectively. The minimum speckle contrast ratio observed using our method was 0.11 for the DPSS laser and 0.06 for the LD. The proposed method can provide speckle reduction with minimal power requirements, a low implementation cost, and no bending for the optical path of the laser beam. Additionally, this method is promising to withstand high-power lasers for use in high lumen laser projectors by optimizing the lens parameters. The demonstrated technique has a small form factor while simultaneously demonstrating a high degree of speckle reduction, which shows potential for speckle reduction in mini- and pico- laser projector applications.