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Performance of a dual Fabry-Perot cavity refractometer
Optics Letters
|September 15, 2015
Summary
A novel refractometer uses two Fabry-Perot cavities to measure nitrogen gas refractivity, enabling high-resolution pressure sensing. This device offers a new method for precise pressure determination across multiple decades.
Area of Science:
- Metrology
- Optical Physics
- Gas Sensing
Background:
- Accurate pressure measurement is crucial in scientific and industrial applications.
- Refractometry offers a non-intrusive method for gas property determination.
- Fabry-Perot interferometry provides high sensitivity for optical measurements.
Purpose of the Study:
- To develop and characterize a novel refractometer for gas refractivity measurement.
- To utilize gas refractivity for high-resolution, multi-decade pressure sensing.
- To establish a reference value for nitrogen refractivity and compare pressure measurements.
Main Methods:
- Constructed a refractometer with two Fabry-Perot cavities on a dimensionally stable spacer.
- Employed two helium-neon lasers locked to respective cavity resonances.
- Measured differential cavity length changes as a function of gas refractivity and pressure.
Main Results:
- The refractometer successfully measured differential optical length changes, correlating to gas refractivity.
- A reference value for nitrogen refractivity was established at specific pressure, temperature, and wavelength.
- Pressure determinations using the refractometer were compared against a mercury manometer.
Conclusions:
- The developed refractometer functions as a high-resolution, multi-decade pressure sensor.
- The device's performance relies on accurate knowledge of gas molar refractivity and virial coefficients.
- This work provides a new tool for precise gas property and pressure metrology.
