Non-contacting torque sensor and displacement measuring apparatus and method
US5754295A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 20, 1996 |
| Grant date | May 19, 1998 |
| Priority date | — |
| Expiry date | Dec 20, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/165
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A displacement measuring apparatus is disclosed, one embodiment of which employs two diffractive code disks, attached to a shaft, and a sensing head which need not contact the shaft. The head includes a light source with beam shaping optics, which creates two individual beamlets and pre-cranks the beamlets so that they reach the first grating at proscribed angles. Two diffracted orders from the first grating are allowed, preferably through free space propagation, to strike the second grating and to be rediffracted by the second grating. A phased-array detector, or equivalent array of detecting elements, are positioned beyond the second grating and in a region of natural interference between rediffracted orders of the incident diffracted orders, to detect the interference fringes which are generated there. The change in phase of the fringes is proportional to the relative displacement between the first and second gratings.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.