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Patent Document Number: 2537214

(54) English Title: OPTICAL FIBER PRESSURE AND ACCELERATION SENSOR FABRICATED ON A FIBER ENDFACE

(54) French Title: CAPTEUR DE PRESSION ET D'ACCELERATION A FIBRE OPTIQUE ELABORE SUR LA FACE D'EXTREMITE D'UNE FIBRE


Claims:

Note: Claims are shown in the official language in which they were submitted.




What is Claimed is:


1. An optical fiber sensor, comprising:

a) an optical fiber with a fiber endface;

b) a hollow tube bonded to the fiber endface;

c) a diaphragm bonded to the hollow tube opposite to the fiber endface,
whereby the fiber
endface and diaphragm define an etalon cavity.


2. The optical fiber sensor of claim 1, wherein the hollow tube has a length
in the range of
1-1000 microns.


3. The optical fiber sensor of claim 1 or 2, wherein the hollow tube has an
outer diameter
approximately equal to an outer diameter of the optical fiber.


4. The optical fiber sensor of any one of claims 1 to 3, wherein the optical
fiber, hollow tube
and diaphragm are made of a material selected from the group consisting of
silica and sapphire.

5. The optical fiber sensor of any one of claims 1 to 4, further comprising a
weight bonded
to the diaphragm.


6. The optical fiber sensor of any one of claims 1 to 5, wherein the diaphragm
has a
thickness in the range of 1-1000 microns.


7. The optical fiber sensor of any one of claims 1 to 6, wherein an exterior
surface of the
diaphragm is a chemically etched surface.


8. The optical fiber sensor of any one of claims 1 to 7, further comprising an
etchant
protection layer on the optical fiber.



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9. The optical fiber sensor of any one of claims 1 to 8, further comprising a
first fusion
splice bonding the hollow tube to the fiber endface and a second fusion splice
bonding the hollow
tube to the diaphragm.


10. The optical fiber sensor of any one of claims 1 to 9, further comprising
an orifice in said
hollow tube which extends from said etalon cavity to an outside wall of said
hollow tube.


11. The optical fiber sensor of any one of claims 1 to 10, further comprising
a coating on at
least one of said fiber endface and said diaphragm.


12. The optical fiber sensor of claim 11, wherein said coating is a metal.


13. The optical fiber sensor of claim 11, wherein said coating is a
dielectric.


14. The optical fiber sensor of any one of claims 1 to 13, further comprising
a means to detect
one of applied pressure and impact.


15. The optical fiber sensor of any one of claims 1 to 13, further comprising
a means to detect
one of vibrations and acoustic waves.


16. The optical fiber sensor of claim 5, further comprising a means to detect
one of
acceleration and mechanical vibrations.


17. An optical fiber sensor, comprising:
a) an optical fiber with a relatively etchable core, and a relatively etch-
resistant cladding,
wherein the etchable core is recessed;

b) a diaphragm bonded to the etch-resistant cladding.


18. The optical fiber sensor of claim 17, wherein the optical fiber and
diaphragm are
primarily made of silica.



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19. The optical fiber sensor of claim 17 or 18, wherein the etchable core is
doped with a
material selected from the group consisting of germanium and fluorine.


20. The optical fiber sensor of any one of claims 17 to 19, wherein the
diaphragm has a
thickness in the range of 1-1000 microns.


21. The optical fiber sensor of any one of claims 17 to 20, wherein an
exterior surface of the
diaphragm is a chemically etched surface.


22. A method for making an optical fiber pressure sensor, comprising the steps
of:
a) fusion splicing a hollow tube to an endface of an optical fiber;

b) cleaving the hollow tube so that a portion of the hollow tube remains
attached to the
fiber endface;

c) fusion splicing a solid rod to a cleaved end of the hollow tube;

d) cleaving the solid rod so that a diaphragm remains attached to the hollow
tube.


23. The method of claim 22, further comprising the step of chemically etching
an exterior
surface of the diaphragm to adjust a diaphragm thickness.



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