Abstract

Many imaging applications required laser level brightness for high speed and sensitive imaging. However, high spatial coherence of the laser causes the speckle noise which covers up the information present in the images. Therefore, there have been many attempts for reducing speckle noise, e.g. using random lasers, diffractive optical elements, and spatial sampling, but most of those are complicated in design and implementation. Here, we report using electroactive optical diffusers with various diffusion angle (6°, 12°) to tune the spatial coherence hence reducing the speckle noise. continuous-wave (CW) laser beam (638 nm) was coupled with double static and moving diffuser for the purpose. The spatial coherence of the illumination was measured using Young’s double slit experiment and the fringe visibility analysis. We then demonstrated the ability of the method to prevent the speckle formation in imaging of Air Force (AF) test target with scattering film in the illumination path. This proposed method is expected to enable speckle-free far-field laser imaging in various biomedical and material applications.

© 2017 Optical Society of America