Optical Beam Gradient Sensor

Abstract:
Freeform surfaces in optical components and local modifications of refractive index offer new degrees of freedom in the design of optical systems, resulting in smaller and lighter systems and increased performance. The measurement technique of experimental raytracing (ERT), based on deflectometry, has proven to be a suitable optical measurement technique to characterize topography as well as optical properties. In ERT, precise measurement of the gradient of small light beams is crucial for determination of these parameters. This usually includes the measurement of the position of the reflected ray in at least two parallel planes. In this contribution, a new concept of an integrated beam inclination sensor is introduced. It is retrieving gradient data of an incoming beam by measurement in one plane only, thus saving 50% measuring time. Theory, simulation and design of the sensor are presented as well as the strategy for signal evaluation in case of highly overlapping spots. Evaluation of a demonstrator device shows the high potential of the approach.