NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Three-Flat Test Solutions based on Simple Mirror Symmetry
Published
Author(s)
Ulf Griesmann
Abstract
Three-flat tests are the archetypes of measurement procedures used in interferometric surface and wavefront metrology to separate errors in the interferometer reference wavefront from errors due to the tests part surface, so-called absolute tests. A new class of solutions for the three-flat problem for circular flats is described in terms of functions that are symmetric or anti-symmetric with respect to reflections at a single vertical line through the center of the flat surfaces. The new solutions are simpler, and easier to calculate than the known solutions based on two-fold mirror symmetry or rotation symmetry. Strategies for effective determinations of azimuthal wavefront averages are also discussed.
Griesmann, U.
(2006),
Three-Flat Test Solutions based on Simple Mirror Symmetry, Applied Optics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=822358
(Accessed October 10, 2025)