Flexible and lightweight speckle noise suppression module based on generation of dynamic speckles with multimode fiber and macro fiber composite

Abstract

We propose a flexible and lightweight laser speckle noise suppression module based on the combination of a multimode fiber (MMF) and a macro fiber composite (MFC). The mechanism underlying speckle suppression involves the time-averaging of dynamic speckles during the exposure time of a charge-coupled device, wherein the MFC causes MMF vibration via its fast and periodic stretching due to the piezoelectric effect. The most efficient speckle reduction condition is realized when the MMF is vibrating in a resonant mode under the application of the highest MFC driving voltage and a large MMF effective numerical aperture. We obtain a speckle contrast of 0.08 when this “most efficient” speckle reduction condition is used to illuminate a diffuser. Further, the image quality is improved when our module is applied in a projector, which makes the device a flexible and lightweight module for speckle reduction in laser displays.