Measuring device based on an optical measurement in an opto-mechanical cavity

Patent metadata

Field	Value
Publication number	US-10845242-B2
Application number	US-201916674080-A
Country	US
Kind code	B2
Filing date	Nov 5, 2019
Priority date	Nov 6, 2018
Publication date	Nov 24, 2020
Grant date	Nov 24, 2020

Abstract

A measuring device includes a first light source for emitting an excitation beam at an excitation wavelength; and an excitation optical cavity, optically resonant at the excitation wavelength, and arranged such that it receives the excitation beam; a second light source for emitting a measurement beam at a measurement wavelength; and a mechanical element mounted such that it can move about an elastic recovery position and/or such that it is elastically deformable, located both on the optical path of the excitation beam in the excitation optical cavity and on the optical path of the measurement beam, and capable of being displaced and/or deformed by the excitation beam. One of either the excitation beam or the measurement beam is capable of causing the movable and/or deformable mechanical element to oscillate. The measuring device can in particular be used as a gas sensor or as a mass spectrometer.

First claim

The invention claimed is:

1. A device for measuring a physical variable comprising:
a first light source, configured to emit an excitation light beam with at least one emission peak centred at an excitation wavelength (λ E ); and
an excitation optical cavity, optically resonant at said excitation wavelength, and configured to receive, at the input, said excitation light beam;

wherein the measuring device further comprises:
a second light source, configured to emit a measurement light beam with an emission peak centred at a measurement wavelength (λ D ); and
a movable and/or deformable mechanical element mounted to move about an elastic recovery position and/or to be elastically deformable, located both on the optical path of the excitation light beam in the excitation optical cavity and on the optical path of the measurement light beam, and configured to be displaced and/or deformed by the excitation light beam;
wherein one of either the excitation light beam or the measurement light beam is configured to cause the movable and/or deformable mechanical element to oscillate, the device being configured such that the oscillation of said mechanical element depends on the physical variable to be measured, the measuring device further comprising detection means for detecting a variation in at least one property of the measurement light beam induced by the oscillation of said mechanical element, and computing means for deducing a measurement of the physical variable from the variation in said at least one property thus detected.

2. The device for measuring a physical variable according to claim 1 , wherein the measurement wavelength (λ D ) is located in the visible and near-infrared spectrum, between 380 nm and 1 μm, and wherein the excitation wavelength (λ E ) is located outside of the visible and near-infrared spectrum.

3. The device for measuring a physical variable according to claim 1 , wherein the excitation light beam is configured to cause the movable and/or deformable mechanical element to oscillate, and wherein the measurement light beam has a light intensity that is at most half that of the excitation light beam.

4. The device for measuring a physical variable according to claim 1 , characterised wherein the excitation wavelength (λ E ) corresponds to the maximum of a resonance peak of the excitation optical cavity in equilibrium, the excitation optical cavity being considered to be in equilibrium when the movable and/or deformable mechanical element is located in a central position between two end positions of the oscillating movement thereof.

5. The device for measuring a physical variable according to claim 1 , characterised further comprises a measurement optical cavity, optically resonant at said measurement wavelength (λ D ) and configured to receive, at the input, the measurement light beam, and wherein the movable and/or deformable mechanical element belongs both to the excitation optical cavity and to the measurement optical cavity.

6. The device for measuring a physical variable according to claim 5 , wherein the measurement wavelength (λ D ) is situated on a resonance peak of the measurement optical cavity in equilibrium, the measurement optical cavity being considered to be in equilibrium when the movable and/or deformable mechanical element is located in a central position between two end positions of the oscillating movement thereof.

7. The device for measuring a physical variable according to claim 6 , wherein the measurement wavelength (λ D ) is located on a slope of said resonance peak.

8. The device for measuring a physical variable according to claim 5 , wherein a first face of the movable and/or deformable mechanical element is optically reflective at the excitation wavelength (λ E ), and wherein a second face of the movable and/or deformable mechanical element, opposite said first face, is optically reflective at the measurement wavelength (λ D ), with the excitation optical cavity extending on the same side as the first face of the movable and/or deformable mechanical element and the measurement optical cavity extending on the second face of the movable and/or deformable mechanical element.

9. The device for measuring a physical variable according to claim 5 , wherein the excitation optical cavity and the measurement optical cavity at least partially cover one another, and wherein the movable and/or deformable mechanical element extends in a region located both within the excitation optical cavity and within the measurement optical cavity.

10. The device for measuring a physical variable according to claim 1 , wherein the movable and/or deformable mechanical element extends along a surface area that lies in the range 100*100 μm 2 to 10*10 mm 2 .

11. The device for measuring a physical variable according to claim 1 , wherein at least one region within the excitation optical cavity is configured to receive a gaseous or liquid medium, and wherein the excitation wavelength (λ E ) corresponds to an absorption wavelength characteristic of a predetermined gas or liquid, such that during operation, the presence of said predetermined gas or liquid in the excitation optical cavity modifies the oscillation of the movable and/or deformable mechanical element.

12. The device for measuring a physical variable according to claim 11 , wherein the movable and/or deformable mechanical element extends inside a vacuum housing.

13. The device for measuring a physical variable according to claim 1 , wherein the movable and/or deformable mechanical element comprises a receiving area for receiving one or more particles, and wherein the movable and/or deformable mechanical element is configured such that, during operation, the oscillation thereof is modified by the presence of said particles on the receiving area.

14. The device for measuring a physical variable according to claim 1 , wherein the detection means comprise an interferometer including arms, and one of the arms of the interferometer includes the measurement optical cavity.

15. The device for measuring a physical variable according to claim 1 , wherein the device is configured such that the oscillation frequency of said mechanical element depends on the physical variable to be measured and such that said at least one property of the measurement light beam is a variation in the optical phase thereof and/or the modulation amplitude thereof.

Assignees

• Commissariat Energie Atomique

Inventors

• Duraffourg Laurent
• Fedeli Jean-Marc
• Gidon Serge
• Labeye Pierre

Classifications

• G01N21/39 Primary

  using tunable lasers · CPC title

• G01J3/42 Primary

  Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry (beam switching arrangements G01J3/08) · CPC title

• G01N21/3504

  for analysing gases, e.g. multi-gas analysis · CPC title

• G01N21/1702

  with opto-acoustic detection, e.g. for gases or analysing solids · CPC title