Computer Generated Hologram (CGH)
Complex asphere metrology ideally suited for production-level volumes
Advances in diamond turning and small-tool deterministic polishing have dramatically increased optical manufacturing capabilities to produce nearly any surface shape. Designers have leveraged these capabilities by increasingly designing aspheric optics into imaging, sensing and laser systems to improve performance and reduce size and weight of optical systems.
However, it isn’t just the polishing equipment that is required to produce high quality aspheric optics – metrology is required to guide polishing and material removal from the surface to converge to an ideal surface figure that matches the design closely.
A CGH (Computer Generated Hologram) is an optical null element that creates a unique wavefront enabling interferometric testing of complex optical surfaces including freeform, gullwing and off-axis aspheric shapes.
A CGH extends the capability of standard Zygo laser interferometers by modifying the test wavefront to a specific surface prescription. The result is a metrology setup that leverages many of the benefits of Fizeau interferometry:
- Fast measurement tact time
- High resolution measurement
- High precision measurement
- Low implementation cost