Passive, temperature compensated techniques for tunable filter calibration in bragg-grating interrogation systems
US6573489B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 9, 2000 |
| Grant date | Jun 3, 2003 |
| Priority date | — |
| Expiry date | Aug 9, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B6/02204
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A passive, temperature compensated tunable filter calibration device for a Bragg grating interrogation system. In a first system, a dual-substrate Bragg grating calibration system, the temperature of an array of gratings is estimated using an array of gratings bonded to a common host substrate and a single grating bonded to a material with a different coefficient of thermal expansion. Changes in a common temperature of the substrates is measured by monitoring the difference between shifts of grating wavelength. As a filter voltage is scanned from its lowest to its highest voltage, the voltages are recorded. The second lowest wavelength corresponds to the grating attached to the differing substrate. The voltages are used to calculate a voltage-to-wavelength function for the scanning range of the filter. To compensate for variations in a calibration curve and temperature variations of the calibration array, the temperature is estimated and function re-calculated at every pass of the scanning filter. In a second system, a hydrogen-cyanide wavelength reference absorption cell that absorbs light at discrete wavelengths corresponding to the molecular vibrational mode frequencies of the g…
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