Asphere & Freeform Metrology
Applications for aspheric and freeform optics are growing and are commonly used where improved imaging performance and fewer optical elements are desirable. Design of these complex optics and their precision manufacturing methods have become enablers in the commercialization of advanced optical systems used in diverse applications, such as LED illumination, laser beam shaping, consumer electronic devices, imaging sensors, telescopes, head-mounted displays, cameras, and lithography stepper lenses.
Unlike traditional curved optics where the surface shape is nominally spherical, aspherical and freeform surfaces exhibit an asymmetrical optical surface with typically complex, high-aspect ratio, sloped surfaces. A freeform optic designed to include spherical, aspherical and toroidal surfaces into a single part, thus making them challenging to design, measure and manufacture.
For these types of complex surfaces, precise metrology plays a key role in providing essential quality control and feedback during the fabrication process. ZYGO laser interferometers and 3D optical profilers ensure quality and process monitoring during manufacturing by characterizing and quantifying critical surface parameters such as form errors, waviness, defects, and surface roughness.
Compared to tactile methods for measurement of optical surfaces, ZYGO interferometers offer several key advantages for more efficient quality control and yield optimization:
- Non-contact methodology – prevents possible damage to the finished, high-quality surfaces
- Full-area, 3D measurement – provides better process insight and characterization of the surfaces compared to individual (2D) profiles.