Devices and methods for quartz enhanced photoacoustic spectroscopy
US10908129B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 13, 2017 |
| Grant date | Feb 2, 2021 |
| Priority date | — |
| Expiry date | Oct 23, 2038 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S5/3401
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In quartz-enhanced photoacoustic spectroscopy (QEPAS), an analyte (typically in gas phase) generates a pressure wave in response to incident laser light. A quartz tuning fork (QTF) resonant at the frequency of the pressure wave transduces the pressure wave into an electrical signal. Pulsing the laser briefly reduces the amount of thermal chirp and increases the fraction of time that the laser emits at the wavelength(s) of interest. This increases the measurement efficiency. Pulsing the incident laser light with bursts of short pulses at the QTF resonant frequency increases signal strength. Exciting the sample with a two pulses at different laser wavelengths, separated by a half QTF period yields signal and background acoustic waves that partially cancel when integrated by the QTF, producing a differential measurement. Pulsing the incident laser light at a frequency faster than the gas response cut off frequency can improve the noise performance of a QEPAS measurement.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.