Multi-degree-of-freedom geometric error measurement system
US5418611A · kind A · utility
Inventors
Key dates
| Filing date | Jun 14, 1993 |
| Grant date | May 23, 1995 |
| Priority date | — |
| Expiry date | Jun 14, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/26
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A high resolution, compact size and low cost multi-degree-of-freedom geometric error measurement system for simultaneously measuring four geometric errors, horizontal straightness, vertical straightness, pitch and yaw. The pitch and yaw error measurements are based on a new method of angle measurement in turn based on the internal reflection effect at an air/glass boundary. The method uses a differential detection scheme to largely reduce the inherent non-linearity of the reflectance versus the angle of incidence in internal reflection. With non-linearity reduced, the displacement of the angle of incidence can be determined accurately by measuring the reflectance. The resolution and measurement range are determined by the initial angle of incidence, the polarization state of light, and the number of reflections. Compared with interferometers and autocollimators, this method has the advantage of a simple sensor design for applications ranging from very wide measurement range to extremely high resolution. Apparatus for accomplishing the method comprises a beamsplitter, a pair of critical angle prisms and a pair of photodiodes. Each photodiode measures change in reflectance and with t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.