Invention:
This invention is a system designed to perform optical quality metrology on freeform or convex optics. This system provides a full aperture surface reconstruction sag map of freeform surfaces. The method relies on the creation of virtual source enclosure that surrounds the unit under testing (UUT) and produces a virtual 2 Pi-steradian measurement range.
Background:
Freeform optics provide many possibilities in the design of cutting-edge optical systems. However, their fabrication and metrology are challenging. To verify the freeform shape, two non-contact optical metrology methods are commonly used for UUT, interferometry and deflectometry. Interferometry offers high accuracy and precision in surface metrology. However, this method relies on prohibitively expensive computer-generated holograms and requires a null setup to obtain accurate results. Deflectometry is an alternative non-null test method that relies on rays leaving a source, being deflected by a UUT. Convex optics both standard and freeform are highly challenging to measure. Interferometric approaches typically require measuring sub-apertures that are then stitched together. The required setup is not always a viable option. Deflectometry is used in 3D construction for surfaces up to weak convex surfaces; however; a full aperture optical precision test of general convex surfaces is yet to be achieved.
Applications:
- Metrology of freeform and convex optics
Advantages:
- Creates a full aperture surface sag map of freeform surfaces including highly convex surfaces
