Novel testing technique for coated plane parallel optics

Optics integrators and users are increasingly demanding that parts be tested after coating. For dichroic and filter manufacturers, this can be difficult for two main reasons. Firstly, the spectral properties of these parts once treated may not be compatible with the 632.8 nm HeNe wavelength, on which common metrology tools such as Fizeau interferometers are based. Secondly, the shape of these samples, with their flat, parallel surfaces, makes them prone to generating back reflections that are difficult to eliminate and affect the accuracy of surface shape reconstruction. Imagine Optic has developed and patented a new approach called POP that brings easy access to the optical testing of such samples, based on the combination of incoherent light at any wavelength and Shack Hartmann wavefront sensing. We will present the technique principle and how it works as implemented in a metrology system we called MESO. We will report the validation process of the approach and showcase results on real samples highlighting the advantages of the technique.