Optical MEMS scanning micro-mirror comprising: —a movable scanning micro-mirror (101), being pivotally connected to a MEMS body (102) substantially surrounding the lateral sides of the micro-mirror, —a transparent window (202) substantially covering the reflection side of the micro-mirror; —wherein a piezo-actuator assembly (500) and a layer of deformable transparent material (501) are provided on the outer portion of said window (202); —the piezo-actuator assembly (500) being arranged at the periphery of the layer of transparent material (501); —said piezo-actuator assembly (500) and transparent material (501) cooperating so that when actuated, the piezo-actuator assembly (500) causes micro-deformation of the transparent material (501), thereby providing an anti-speckle effect. The invention also provides the corresponding micro-projection system and method for reducing speckle.