The state-of-the-art technique for measuring discontinuous surface profiles, e.g. diffractive optical elements (DOE) is white-light interferometry. Compared to single wavelength phase-shifting interferometry conventional white-light-interferometry is rather slow, because the number of frames to be evaluated is about ten times greater than in phase-shifting-interferometry. Therefore white-light-interferometry needs more memory capacity and computer time. Single wavelength phase-shifting interferometry cannot be used for the mentioned task since the order of the interference fringes cannot be determined. But if three wavelengths, e.g. a red, a green, and a blue one are used which preferably have no common factor it is possible to determine the interference order of the fringes or the absolute optical path difference (OPD) of the interferometer. The interference patterns are simultaneously recorded by a color CCD-camera having 3 separate chips. The OPD is calculated for each pixel from the three phase values mod 2π . The algorithms used and experimental results will be presented.
An interferometer for VUV wavelengths was realized in order to improve the resolution and the sensitivity of optical metrology. To be able to work at wavelengths 157 nm up to 900 nm an apochromatic design was chosen using reflective optics. For the examination of the influence of the wavelength binary gratings with different periods, aspect ratios and depths, have been selected as test structures. The benefits and also the technological problems which come along with the use of VUV wavelengths are discussed. The design of this interferometer and measuring results with different wavelengths are presented.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.