Abstract
Phase shifting interferometry requires an intentional shifting of the relative phase between the reference arm and the test arm of fan interferometry. Vibration can lead to uncertainty in the relative phase difference with respect to time and result in erroneous surface measurements. We have developed a method for actively compensating for vibration using a closed-loop phase servo system. An essential feature of this is a high frequency phase measurement. The phase is modulated and the intensity variations are measured with a high sped photodiode and digitized. This information is processed by a DSP and a five step algorithm is used to determine the instantaneous phase. These high speed phase measurements are used in a closed loop phase servo to compensate for vibration and also allow for phase shifting interferometry. Test results with and without the vibration compensation will be presented.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 438-446 |
| Number of pages | 9 |
| Journal | Proceedings of SPIE - The International Society for Optical Engineering |
| Volume | 3134 |
| DOIs | |
| State | Published - 1997 |
| Externally published | Yes |
| Event | Optical Manufacturing and Testing II - San Diego, CA, United States Duration: Jul 27 1997 → Jul 27 1997 |
Keywords
- Interferometry
- Large optics
- Metrology
- Phase shifting
- Telescopes
- Testing
- Vibration
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Computer Science Applications
- Applied Mathematics
- Electrical and Electronic Engineering