Flatness measuring and analyzing method
US6018990A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 26, 1998 |
| Grant date | Feb 1, 2000 |
| Priority date | — |
| Expiry date | Feb 26, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/306
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
While the three-flat method is used as background art, a technique for analyzing the difference between two planes by approximating it with symmetry power series polynomials are employed, and measurement is effected at two positions where the reference surface and the sample surface are in a predetermined reference rotation state and where they are rotated from each other by 90 degrees from the former state; whereby the approximate surface form of the whole plane can be determined by a very simple arithmetic operation with a high accuracy. Of three glass sheets, different pairs of two glass sheets 53 and 54 are successively selected three times. The difference between two surfaces to be measured in each pair of the two glass sheets 53 and 54 is measured at a first position where, with respect to one glass sheet 53, the other is set at a predetermined rotational position; and a second position where the two sheets are rotated from each other by 90 degrees from the first position. Then prepared are relational expressions to which sixth-order Zernike polynomials approximating the difference between the surfaces to be measured is applied. These relational expressions are operated so as…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.