Microbarometer with a bellows and with an interferometric transducer

Patent metadata

Field	Value
Publication number	US-9952109-B2
Application number	US-201314655162-A
Country	US
Kind code	B2
Filing date	Dec 18, 2013
Priority date	Dec 27, 2012
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A microbarometer includes a reference base, a bellows having a first edge fixed to a reference surface of the base and having an elongation direction perpendicular to the reference surface. A cover closes a second edge of the bellows and sealingly insulates an interior volume thereof. The bellows configured such that variations in elongation are directly proportional to pressure variations induced by infrasonic waves. A reflective element is integral the cover and an interferometric component receives a beam from a source is integral with the reference surface of the base. An input/output optical path faces the reflective element and is parallel to the elongation direction of the bellows, so as to emit a beam fraction towards the reflective element and to sense the reflected beam after reflection from reflective element. The interferometric component including integrated optical guide lines and optical separation and combination zones within a substrate.

First claim

The invention claimed is:

1. A microbarometer including a bellows, the microbarometer comprising:
a reference base having a reference surface;
a bellows having a first edge fastened to the reference surface of the base, and having an elongation direction perpendicular to the reference surface;
a cover closing a second edge of the bellows so as to isolate the bellows in fluid-tight manner in relation to an exterior environment, the bellows configured such that variations of elongation are directly proportional to pressure variations induced by infrasonic waves,
a reflective member carried by the cover in close proximity thereto; and
an interferometric component joined to the reference surface of the base and configured to receive a beam from a source and having an input/output optical path facing the reflective member parallel to the direction of elongation of the bellows,
the interferometric component further configured to emit a beam fraction to the reflective member and collect the beam after reflection by the reflective member,
the interferometric component further comprising optical guide lines and optical splitting and combining zones integrated within a substrate,
wherein the interferometric component is joined to the reference surface by a pillar and a coefficient of thermal expansion of the pillar perpendicular to the reference surface is substantially equal to that of the bellows.

2. The microbarometer according to claim 1 , wherein the bellows is between the reference surface and the interferometric component, and the reflective member is mounted on an outside face of the cover.

3. The microbarometer according to claim 2 , wherein the interferometric component is joined to the reference surface via a plurality of pillars disposed around the bellows.

4. The microbarometer according to claim 3 , wherein the pillars comprise a mixture of metal and invar.

5. The microbarometer according to claim 1 , wherein the interferometric component includes an input for an input signal and four outputs, the four outputs including two outputs for interferometric signals in quadrature, one output for an input signal fraction and one output for a signal of the beam reflected by the reflective member.

6. The microbarometer according to claim 1 , wherein the reflective member comprises a planar mirror perpendicular to the elongation direction.

7. The microbarometer according to claim 1 , wherein an interior volume of the bellows is at a rough vacuum.

8. The microbarometer according to claim 1 , wherein the reflective member comprises a planar mirror extending parallel to the cover.

9. A microbarometer including a bellows, the microbarometer comprising:
a reference base having a reference surface;
a bellows having a first edge fastened to the reference surface of the base, and having an elongation direction perpendicular to the reference surface;
a cover closing a second edge of the bellows so as to isolate the bellows in fluid-tight manner in relation to an exterior environment, the bellows configured such that variations of elongation are directly proportional to pressure variations induced by infrasonic waves,
a reflective member joined to the cover; and
an interferometric component joined to the reference surface of the base and configured to receive a beam from a source and having an input/output optical path facing the reflective member parallel to the direction of elongation of the bellows,
the interferometric component further configured to emit a beam fraction to the reflective member and collect the beam after reflection by the reflective member,
the interferometric component further comprising optical guide lines and optical splitting and combining zones integrated within a substrate,
wherein the reflective member and the optical guide lines and optical splitting and combining zones of interferometric component are inside the bellows, and the reflective member is mounted on an inside face of the cover and the interferometric component is on the reference surface of the base.

10. A microbarometer comprising:
a reference base having a reference surface;
a bellows having a first edge fastened to the reference surface of the base, and having an elongation direction perpendicular to the reference surface;
a cover closing a second edge of the bellows so as to isolate the bellows in fluid-tight manner in relation to an exterior environment, the bellows configured such that variations of elongation are directly proportional to pressure variations induced by infrasonic waves,
a reflective member carried by the cover in close proximity thereto; and
an interferometric component joined to the reference surface of the base and configured to receive a beam from a source and having an input/output optical path facing the reflective member parallel to the direction of elongation of the bellows,
the interferometric component further configured to emit a beam fraction to the reflective member and collect the beam after reflection by the reflective member,
the interferometric component further comprising optical guide lines and optical splitting and combining zones integrated within a substrate and a silica substrate,
wherein the optical lines and the optical splitting and combining zones comprise one of index gradients or discontinuities in the silica.

11. A microbarometer comprising:
a reference base having a reference surface;
a bellows having a first edge fastened to the reference surface of the base, and having an elongation direction perpendicular to the reference surface;
a cover closing a second edge of the bellows so as to isolate the bellows in fluid-tight manner in relation to an exterior environment, the bellows configured such that variations of elongation are directly proportional to pressure variations induced by infrasonic waves,
a reflective member joined to the cover;
an interferometric component joined to the reference surface of the base and configured to receive a beam from a source and having an input/output optical path facing the reflective member parallel to the direction of elongation of the bellows,
the interferometric component further configured to emit a beam fraction to the reflective member and collect the beam after reflection by the reflective member,
the interferometric component further comprising optical guide lines and optical splitting and combining zones integrated within a substrate; and
a lid surrounding the bellows and the interferometric component and fastened to the base, the lid including inlet apertures that allow air into an enclosed space around the bellows, the lid further including connection conduits configured to make an optical connection to a coherent monochromatic source of radiation and to a device for processing interferometric signals.

Assignees

• Commissariat Energie Atomique

Inventors

• Olivier Serge
• Ponceau Damien

Classifications

• G01L11/02 Primary

  by optical means · CPC title

• G01L7/06 Primary

  of the bellows type · CPC title

• G01L9/0039

  using photoelectric means · CPC title