Multi-stage data processing for frequency-scanning interferometer
US6741361B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jun 23, 2003 |
| Grant date | May 25, 2004 |
| Priority date | — |
| Expiry date | Jun 23, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/2441
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system of frequency-scanning interferometry uses a computer system operating in accordance with a program for measuring distances or range, including measuring topographical information about test object surfaces. Interferometric data is detected using a single point detector or an array of such detectors and recorded (stored) in the computer system, and a series of measurements are taken over a range of illumination frequencies. The interferometric data varies in a sinusoidal manner with a change in illumination frequency at interference frequencies corresponding to particular measures of distance or range. A Fourier transform for locating peak interference frequencies is first limited in frequency space and second divided into stages to save processing time. A coarse spacing between Fourier frequency samples is used for a first approximation, and finer spacing between Fourier frequency samples are used in the vicinity of the first approximation to make a second more accurate approximation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.