Micro-deflectometry in transmission

We present a novel microscopic method that intrinsically measures local phase gradients of transparent objects. The method is based on "phase measuring deflectometry" [1] in transmission. Images similar to those achieved with differential interference contrast or with phase contrast are generated. However, the novel method displays some additional new features: the images display quantitative data about the lateral variation of the optical path length; the sensitivity reaches the physical limit: very small variations of the refractive index can be measured . Moreover, the method is simple (no interference !). Micro-deflectometry in transmission has the potential to compete with established methods to acquire phase object information.