Method and apparatus for estimating piston using a grism
US6909512B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 30, 2003 |
| Grant date | Jun 21, 2005 |
| Priority date | — |
| Expiry date | Oct 15, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B27/0012
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method is provided for reducing the piston of neighboring first and second surfaces illuminated by polychromatic light transmitted from an unresolved-light source such that light transmitted or reflected from the first surface is out of phase with light respectively transmitted or reflected from the second surface, and the out-of-phase light is passed through a grism that generates a fringe pattern in the far-field. According to one exemplary embodiment, the method includes Fourier transforming the fringe pattern to generate a two-dimensional (2D) power spectrum; generating the absolute value of the 2D power spectrum to form an absolute value representation; displaying the 2D the absolute value representation on a computer display; and reducing the piston to affect rotation of the absolute value representation on the computer display and approximately align a central axis of the absolute value representation with an axis that indicates approximate alignment of the first and second surfaces.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.