THERMO-FLUORESCENT OPTICAL FIBER, MANUFACTURING METHOD AND APPLICATIONS

Abstract

A thermo-fluorescent optical fiber including a core able to propagate light and a sheath, the fiber carrying at least at one of its ends or at one site along its length, devoid of sheath, the optical fiber being provided with a probe consisting of a matrix having thermo-fluorescent particles, the matrix being photo-polymerized. Also provided is a method that relates to manufacturing such an optical fiber as well as to its applications.

Claims

1. A thermo-fluorescent optical fiber comprising a core able to propagate light and a sheath, the fiber carrying at least at one of its ends or at one site along its length, devoid of sheath, a probe consisting of a matrix comprising thermo-fluorescent particles, wherein the matrix is polymer and photo-polymerized in the presence of the thermo-fluorescent particles.

2. The fiber according to claim 1, wherein the photo-polymerized matrix is selected from the group of polymers comprising polyacrylates and polymethacrylates and mixtures thereof.

3. The fiber according to claim 1, wherein the matrix is in the form of at least two layers, made of identical or different polymers and identical or different thermo-fluorescent particles.

4. A method for manufacturing a thermo-fluorescent optical fiber, comprising the following steps: An optical fiber is provided, comprising a core able to propagate light and a sheath, the optical fiber having at least one end or one site along its length, devoid of sheath, the end or the site being able to irradiate light radiation, coming from the core of the optical fiber, At least one photo-polymerizable system comprising at least one photo-polymerizable monomer and thermo-fluorescent particles is deposited on the end and/or the site of the optical fiber, and Radiation is sent into the optical fiber activating the photo-polymerization of the photo-polymerizable system to form a photo-polymerized matrix comprising the particles, and thus obtain the thermo-fluorescent optical fiber.

5. The method according to claim 4, wherein the photo-polymerizable system comprises at least one photo-polymerizable monomer selected from acrylates and methacrylates and mixtures thereof.

6. The method according to claim 5, wherein the content of acrylate(s) and/or methacrylate(s) is from 70 to 95% by weight relative to the weight of the photo-polymerizable system.

7. The method according to claim 4, wherein the photo-polymerizable system comprises at least one photo-initiator selected from type 1 photo-initiators and methyl benzoyl formate.

8. The method according to claim 4, wherein, after the formation of the photo-polymerized matrix, the steps of depositing on the end and/or the site of the optical fiber are repeated one or several times, at least one photo-polymerizable system and thermo-fluorescent particles, and activating the photo-polymerization of the photo-polymerizable system by sending radiation into the optical fiber activating the photo-polymerization.

9. The method according to claim 8, wherein the photo-polymerizable system and/or the thermo-fluorescent particles are different from one time to another.

10. A temperature sensor comprising a thermo-fluorescent optical fiber according to claim 1.

11. A method comprising: applying a temperature sensor according to claim 10 to an electrochemical generator, and determining a temperature of the electrochemical generator.

Description

[0054] It is illustrated in the following examples in support of FIG. 1 to FIG. 3 according to which:

[0055] FIG. 1 and FIG. 2 are optical microscope photographs of an optical fiber (diameter 150 μm, reference Thorlabs® M137L02 200 μm in diameter) on one end of which a first film of a matrix containing PTIR545F particles from Phosphor Technology® has been deposited FIG. 1 and a second film from the same matrix FIG. 2; and

[0056] FIG. 3.1 to FIG. 3.7 illustrate implementation variants of the method of the invention.

EXAMPLE 1

Preparation of a Photo-Polymerization System

[0057] 50g of Al(OH).sub.3 are put in an oven at 150° C. (industrial origin: SASOL) for one night. Then allowed to cool under argon in a Schlenk tube. Then a 20 ml plastic syringe is loaded with 2 g of the powder. At the end of the syringe, a 0.1 μm filter tip is putted. The syringe is filled with methyl methacrylate, then the plunger is replaced and the deprotected monomer is pushed into an opaque bottle containing argon. Argon is bubbled through the bottle to degas traces of O.sub.2.

[0058] Next, a second opaque bottle is prepared under argon into which an Irgacure 2959 photoinitiator in powder form (5% by mass relative to the mass of monomer) is introduced, then 0.5 ml of THF ml of acetone. The quantity is deliberately oversized to ensure optimal reactivity of the photo-polymerization system. THF is not necessary but improves wettability.

EXAMPLE 2

Manufacture of an Optical Fiber According to the Invention Carrying a Probe at One of its Ends

[0059] An exemplary embodiment is illustrated in FIG. 1 and FIG. 2. In FIG. 1, the deposition of a first film of a matrix containing thereto-fluorescent particles is observed. The particles are located exactly at the end of the fiber and nowhere else. The polymer deposition is sufficiently fine and conforms to the optical fiber not to be visible on the photograph. In FIG. 2, the deposition of a second film made on the first film of FIG. 1 is observed. It can be seen that the quantity of particles on the surface has increased. But the deposition remains localized at the end of the fiber.

EXAMPLE 3

Manufacture of an Optical Fiber According to the Invention carrying probes, at several sites along its length

[0060] This example, in support of FIG. 3, illustrates one of the multiple variants that a method according to the invention allows.

[0061] According to the illustrated variant, the method of the invention is carried out on an optical fiber having sites, along its length, devoid of sheath. On some of the bare sites, a mask is applied, so that at the end of the method, the photo-polymerization system has only been activated on the remaining unmasked sites. Then, at least some of the masks are removed and the method is repeated with a different photopolymerizable system, and so on to obtain an optical fiber fitted with different probes.

[0062] FIG. 3 illustrates this sequencing:

[0063] According to FIG. 3.1, an optical fiber comprising a core able to propagate light and a sheath is provided.

[0064] According to FIG. 3.2, certain sites are stripped along the length of the optical fiber by removing the sheath.

[0065] According to FIG. 3.3, some of the bare sites are masked.

[0066] According to FIG. 3.4, the optical fiber is exposed to a first photo-polymerizable system and the photo-polymerization is activated on the unmasked sites.

[0067] According to FIG. 3.5, the masking is removed at some of the bare sites.

[0068] According to FIG. 3.6, the optical fiber is exposed to a second photo-polymerizable system and the photo-polymerization is activated on the unmasked sites.

[0069] According to FIG. 3.7, the method is repeated as above to obtain an optical fiber provided along its length with different probes.

[0070] For example, a polymer that is easy to remove can be used to mask the bare sites of the fiber. Typically, it is a polymer which is not soluble in the solvent used for the deposition of the polymerizable polymer by UV which is used for the deposition of particles. For example, water-soluble polymers with a high molecular point such as PVA (polyvinyl alcohol) or PVP (polyvinylpyrrolidone).