Combination of motorized and piezoelectric translation for long-range vertical scanning interferometry
US5446547A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 29, 1994 |
| Grant date | Aug 29, 1995 |
| Priority date | — |
| Expiry date | Apr 29, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/2441
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A scanning interferometer that utilizes a DC gear motor instead of a PZT translator in closed-loop configuration with an LVTD position sensor. The DC motor is connected to the scanning mechanism so that a rotational motion of the motor shaft produces a translation along the optical axis of either the sample or the objective of the interferometer. During scanning, the motor is driven by the input of a ramp signal into the system. The closed-loop configuration is such that a constant, or nearly constant voltage is applied to the DC motor to produce a constant-speed scan in response to the ramp input. Any non-linearity in the speed of motion is corrected by an adjustment to the motor voltage. At the completion of the scan, the ramp input is removed and the motor is automatically returned to the starting position to satisfy the closed-loop condition. In order to maintain the image in focus on the sensor over the wide range of scanning, a pair of relay lenses is inserted in the optical path between the interferometer and the light detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.