Suppression of Speckle Patterns Based on Temporal Angular Decorrelation Induced by Multiple Beamlets with Diverse Optical Paths

摘要

We investigate an effective technique to alleviate the speckle contrast based on the temporal angular decorrelation induced by multiple beamlets with diverse optical paths. Multiple beamlets with diverse optical paths are generated by using a microlens array incorporating a galvo-mirror at the foci of two spherical lenses. As the multiple beamlets with different optical paths are interfered after the screen, versatile uncorrelated speckle patterns with random phases in the time domain should be induced. The random phases of the versatile uncorrelated speckle patterns can effectively suppress the speckle contrast after averaging all intensities of versatile uncorrelated speckle patterns by accumulating speckle patterns during the exposure time of the CCD camera. The speckle contrast ratios with or without the homogenizer are reduced by 10.2% and 14.2%, respectively, with a low loss of less than 5%. Evidently, the homogenizer can improve the suppression efficiency of the speckle contrast ratio.