Simple, low cost, laser absorption sensor system
US6040914A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 10, 1997 |
| Grant date | Mar 21, 2000 |
| Priority date | — |
| Expiry date | Jun 10, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J3/433
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A laser absorption sensor system for performing optical measurements on a sample is described. The sensor system includes a tunable laser, capable of being tuned at rates exceeding 1 KHZ, and with a tuning range approaching 1 GHz. The laser beam is modulated at a modulation frequency between 1 and 100 KHz. Modulation in this frequency range is termed wavelength modulation. The beam is split into two beams, a signal beam and a reference beam. The signal beam traverses the sample where characteristic absorption takes place and is incident on a signal photodetector. The reference beam is incident directly on a reference photodetector. A noise cancellation circuit combines signal and reference photo-currents from signal and reference photodetectors reducing signal noise and increasing system sensitivity. The combination of wavelength modulation and the noise cancellation scheme provide a highly sensitive simple, rugged, low cost laser absorption sensor system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.