Fiber-optic interferometer employing low-coherence-length light for precisely measuring absolute distance and tilt
US6507405B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 17, 1999 |
| Grant date | Jan 14, 2003 |
| Priority date | — |
| Expiry date | May 17, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/70
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Disclosed are first and second embodiments of a 3-channel probe-plate structure of the fiber-optic interferometer, wherein low-coherent-length light from a superluminescent light-emitting diode is split by a tree splitter into three light branches which are coupled as separate light inputs to the probe-pate structure by single-mode, polarization-preserving optical fibers. For each of the 3 channels, the first embodiment of the probe-plate structure comprises an integrated polarizing lithium-niobate Y splitter-modulator for deriving separate reference-arm light and probe-arm light. The reference-arm light is transmitted as an air-path reference light beam directed parallel to the probe plate surface from a transmitting gradient-index microlens to a receiving gradient-index microlens, while the probe-arm light is transmitted as an air-path probe light beam directed to be incident on a movable surface at a glancing angle from a transmitting gradient-index microlens and then be reflected from the movable surface to a receiving gradient-index microlens. The received reference-arm light and probe-arm light, for each of the 3 channels, are combined in an integrated polarizing lithium-niob…
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