Absolute speckle interferometry with an angular-spectrum-tunable source

Based on the fringe formation in the k-vector space, we proposed an angular spectrum scanning technique for absolute interferometry. Instead of sweeping the optical frequency over a wide range of spectrum, we tune the angular spectrum by changing the incident angle of a monochromatic plane wave with a spatial light modulator (SLM). In the experiment, we built an equivalent spatially incoherent "ring source" to realize the angular spectrum scanning, and applied an algorithm to compensate the offset fluctuation of the fringe intensity.