Tunable Image Rotator of Light With Optical Geometric Transformation

The traditional method to rotate an image of light is by using a Dove prism, even though it is unreliable, owing to the mechanical adjustment when a tunable image rotation is required. Here, we propose a flexible and nonmechanical scheme to rotate an optical image by an arbitrary angle with optical geometric transformation. The device consists of a Cartesian to log-polar coordinate converter and an inverse converter. The rotated angle can be freely tuned by adjusting the first coordinate converter. In particular, the image rotator is dynamically programmable and continuously tunable if spatial light modulators or digital micromirror devices are employed. Our work promotes its ability of manipulating beams, which has applications in the fields of interferometry, astronomy, beam steering, mode detection, and pattern recognition.