Microscope objective production: on the way from the micrometer scale to the nanometer scale
Abstract
Cemented doublets and triplets, which are the principle parts in high quality, high numerical aperture (NA) objectives, can not be used for objectives working at wavelengths of 248 nm and shorter, because the optical cement can not withstand the high photon energies. We will show that high NA deep UV objectives can be designed and built successfully with the help of air spaced doublets. Assuring Strehl ratios above 95% enforces very tight tolerances. For example the distance error of the lens vertex to its mount has to be <1 μm. This calls for a new manufacturing precision never realized before in series production. We show how a white light Mirau interferometer can be used to measure lens vertex positions with an accuracy of +/-200 nm. We also demonstrate how the fine-tuning process can be optimized by using a "simulated star test," where the point-spread function is calculated in real time with a FFT-algorithm from the optical path difference data, acquired by a Twyman-Green interferometer.
- Publication:
-
Ultra-fast MTF Test for High-Volume production of CMOS Imaging Cameras
- Pub Date:
- January 2004
- DOI:
- 10.1117/12.505803
- Bibcode:
- 2004SPIE.5180..283S