Different plane-parallel optics testing methods for at-wavelength filter surface error and shape characterization (Conference Presentation)

Plane parallel optics are challenging to measure due to signal artifacts affecting standard methods like Fizeau interferometry. The difficulty increases for coated optics which add spectral limitations on the testing wavelength. Alternatives, such as contact-based techniques or temporary coatings, are unsuitable for fragile, coated parts and hinder quality control. This work introduces different optical metrology approaches based on Shack-Hartmann and phase retrieval techniques, offering testing wavelength flexibility, rapid, high-resolution measurements. In particular, we will introduce a patented method to measure both surface and transmitted wavefront errors simultaneously without manipulating the sample and compare it with classic measurements in reflection on each face of the sample. Results on coated samples will be presented to demonstrate the effectiveness of this approach, addressing key limitations in optical metrology of high end precision components.