Advanced metrology plays an important role in the research, production and quality control of optical components. With surface finish, form error and other parameter specifications becoming more stringent, precision measurements are increasingly demanded by optics manufacturers and users. The modern metrologist now has both contact and noncontact measurement solutions available and a combination of these techniques now provides a more detailed understanding of optical components. Phase Grating Interferometry (PGI) with sub-nanometre vertical resolution and sub-micron lateral resolution can provide detailed characterization of a wide range of components including shallow and steep-sided optics. PGI is ideal for precision form measurement of a comprehensive range of lenses, moulds and other spherical or aspheric products. Because of the complex nature of these components, especially precision aspheric and asphero-diffractive optics, control of the form is vital to ensure they perform correctly. Recent hardware and software developments now make it possible to gain a better understanding and control of the form and function of this optics. Another change is the use of high speed 3D non-contact measurement of optics which is becoming more popular. Often scanning interferometric techniques such as coherence correlation interferometry (CCI) can be used to study components not suited to 2D contact analysis, including fragile surfaces and structured surfaces. Scanning interferometry can also be used to measure film thickness and uniformity of any coating present. In this paper the use of both PGI and CCI to measure optical lenses and coatings is discussed.

Date Published: 15 October 2012
PDF: 10 pages
Proc. SPIE 8417, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, 84170H (15 October 2012); doi: 10.1117/12.2002563

Published in SPIE Proceedings Vol. 8417:
6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment
Yudong Zhang; Libin Xiang; Sandy To, Editor(s)