JP4639366B2 - Multi-core optical fiber probe - Google Patents

Description

  The present invention generally relates to an optical fiber probe used for ATR spectrum detection, and more particularly to a multi-core optical fiber probe that can take a wide measurement area of a sample on a detection surface.

  ATR (Attenuated Total Reflectance) spectroscopy is performed when a sample detection surface is irradiated with IR, UV, or other light at a critical angle or higher and totally reflected on the sample surface. By utilizing the phenomenon that the evanescent wave that exudes to the surface layer absorbs a specific wavelength peculiar to the sample and returns to the reflected light, the absorption spectrum of the specific wavelength for the reflected light is measured, so that the surface state of the sample, chemical species, etc. Is detected.

  Conventionally, as one of the probes used for this ATR spectroscopy, a prismatic crystal (prism) having an isosceles triangle cross section is provided in a probe housing, and a surface sandwiched between isosceles surfaces is used as a detection surface. An optical fiber on the light-irradiation side is placed on one surface, sandwiching the detection surface of the crystal symmetrically with respect to the vertical plane passing through the top of the crystal, and received on the other surface. An arrangement in which an optical fiber on the side is arranged is known.

  According to this probe, by irradiating the detection surface of the crystal from one optical fiber, the light totally reflected by the detection surface is received by the other optical fiber, and the reflected light is guided to the detector and detected. The absorption spectrum can be measured. However, since the light is reflected once on the detection surface of the crystal, there is a problem that the measurement area on the detection surface is narrow and the detection accuracy is low.

  Therefore, a prismatic crystal with a rectangular cross section is arranged horizontally, and light is irradiated from the optical fiber from one end surface of the crystal in the longitudinal direction to the detection surface, and the light totally reflected on the detection surface is opposed to this surface (also on this surface). A multiple reflection type probe that receives the reflected light from the other end face with an optical fiber by repeating the reflection over many times over the entire length of the crystal. It has been. However, since light is scattered every time it is repeatedly reflected, the intensity of the finally obtained reflected light becomes weak, the peak of the absorption spectrum becomes small, and there is a problem that the detection accuracy cannot be greatly improved.

  Therefore, an object of the present invention is to take a wide measurement area of the sample on the detection surface without causing the light to undergo total reflection multiple times, and to improve the detection accuracy of the sample by measuring the absorption spectrum. It is to provide a multi-core optical fiber probe that is made possible.

  (1) A multi-core optical fiber probe having a detection surface positioned in an opening formed in a front end surface of a housing and disposed in the housing, wherein the detection surface is in contact with a measurement sample; Light that irradiates light at an angle greater than the critical angle from each optical fiber toward the detection surface, with a plurality of optical fibers optically connected to one side across the detection surface A plurality of optical fibers optically connected to the irradiation side ribbon cable and the other side across the detection surface of the crystal are arranged along the longitudinal direction of the crystal in a manner corresponding to the optical fiber of the light irradiation side ribbon cable. Each optical fiber includes a light receiving side ribbon cable that receives light irradiated from the corresponding optical fiber of the light irradiation side ribbon kale and reflected by the detection surface.

  (2) The multi-core optical fiber probe according to claim 1, wherein the crystal has a triangular shape with a cross section having one surface as a detection surface or a trapezoidal prismatic shape with its head cut, and sandwiches the detection surface of the crystal. The optical fiber of the light-irradiation side ribbon cable is arranged on the other surface, and the optical fiber of the light-receiving side ribbon cable is arranged on the other surface sandwiching the detection surface of the crystal.

  (3) The multi-core optical fiber probe according to claim 2, wherein an isosceles trapezoidal prismatic body shape having an isosceles triangle section or a head section cut by using a surface sandwiched between isosceles surfaces as a detection surface. None, the optical fiber on the light irradiation side and the optical fiber of the ribbon cable on the light receiving side are arranged symmetrically with respect to a plane perpendicular to the detection plane passing through the top of the crystal.

  (4) The multi-core optical fiber probe according to claim 3, characterized in that the crystal has an isosceles trapezoidal prismatic shape with a right-angled isosceles triangle section or a truncated head.

  (5) In the multicore optical fiber probe according to any one of claims 1 to 4, the light irradiation side ribbon cable and the light receiving side ribbon cable each process or connect a cylindrical multicore cable having a plurality of optical fibers. It is formed in the front end side of a cylindrical multi-core cable by connecting through a container.

  According to the multi-core optical fiber probe of the present invention, the total reflection of each light on the detection surface of the crystal is performed at a plurality of locations by a plurality of light, so that the measurement area of the sample on the detection surface is multiplied by a multiple. In addition, the detection accuracy of the sample by measuring the absorption spectrum of reflected light can be remarkably improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a multi-core optical fiber probe according to an embodiment of the present invention with a part cut away, FIG. 2 is a transverse sectional view showing a detection portion of the probe, and FIG. 3 is a horizontal sectional view showing the probe.

  In this embodiment, the multi-core optical fiber probe 1 includes a prism 3 crystal 3 having a right-angled isosceles triangle cross section in a housing 2, and the crystal 3 is sandwiched between isosceles surfaces as a detection surface 4. The detection surface 4 is installed in a rectangular opening 5 opened at the center of the front end surface of the housing 2. A ribbon cable 8A on the light irradiation side and a ribbon cable 9A on the light receiving side are inserted into the housing 2 from the upper surface, and the ribbon cables 8A and 9A are bent upward toward the crystal 3 to detect the detection surface 4 of the crystal 3 Are disposed on one inclined surface 6 and the other inclined surface 7.

  Each of the ribbon cables 8A and 9A is formed by bundling a plurality of optical fibers 8, 9 in parallel in this example, and the plurality of optical fibers 8, 9 are coated with the ribbon cables 8A, 9A. With or without peeling, the optical fibers 8 and 9 are arranged one by one so as to correspond to the inclined surfaces 6 and 7 symmetrically with respect to the plane ν perpendicular to the detection surface 4 passing through the top of the crystal 3. The crystals 3 are arranged along the longitudinal direction. Then, the optical fibers 8 on the light irradiation side are optically connected with their end faces close to each other in a manner orthogonal to the inclined surface 6, and the optical axis of each optical fiber 8 is equal to or greater than the critical angle and the intersection of the detection surface 4 and the vertical surface ν. At an angle θ. Similarly, the optical fibers 9 on the light receiving side are optically connected with their end faces close to each other in a manner orthogonal to the inclined surface 7, and the optical axis of each optical fiber 9 is the intersection of the detection surface 4 and the vertical surface ν, and the above. They intersect at the same angle θ.

  Ribbon cables 8A and 9A introduced into the housing 2 are connected to cylindrical multi-core cables 10A and 11B having the same number of optical fibers 10 and 11, respectively, via connectors 10a and 11a. The multi-core cable 10A is connected to a light source (not shown), and the multi-core cable 11B on the light receiving side is connected to a photodetector.

  According to the probe 1 of this embodiment, the detection surface 4 of the crystal 3 at the tip of the probe is brought into contact with the sample, and the light generated by the light source is passed through the optical fiber 10 of the cylindrical multicore cable 10A and the optical fiber 8 of the ribbon cable 8A. When sequentially guided to the crystal 3, a total of seven parallel light beams are irradiated from a total of seven optical fibers 8 onto the detection surface 4 of the crystal 3 at an incident angle (θ) greater than the critical angle. The reflected light from the seven strips is received by a total of seven corresponding optical fibers 9 on the light receiving side, and sent from the optical fibers 9 to the detectors through the optical fibers 11 of the multicore cable 11A. The absorption spectrum is measured.

  According to this, by using seven light beams, each light is totally reflected at seven locations on the detection surface 4 and the measurement area of the sample on the detection surface 4 is increased sevenfold. Therefore, the measurement accuracy of the sample can be significantly improved. Further, the seven light beams may be light having different wavelengths.

  In the embodiments described above, the crystal has a prismatic shape with an isosceles right angle triangle, but the prism may be an isosceles triangle having an acute or obtuse cross section, or may be an unequal triangle. Further, the cross section obtained by cutting the top of the triangular prism corresponding to the detection surface may be a prismatic body having an isosceles trapezoidal shape or an unequal leg trapezoidal shape, and may be a rectangular column having a rectangular cross section or a prism having a cross section of a pentagon or more.

  The optical fiber is arranged perpendicular to the crystal surface on both the light-irradiation side and the light-receiving side. However, if the loss due to reflection of light incident on the crystal is acceptable, tilt it with respect to the crystal surface. It can also be arranged.

  The optical fiber of the ribbon cable is connected to the optical fiber of the cylindrical multicore cable via a connector. However, the tip of the cylindrical multicore cable may be processed to form a ribbon cable.

1 is a perspective view showing a multi-core optical fiber probe according to an embodiment of the present invention with a part cut away. FIG. It is a cross-sectional view which shows the detection part of the probe of FIG. It is a horizontal sectional view which shows the probe of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multi-core optical fiber probe 2 Case 3 Crystal 4 Detection surface 5 Aperture 6, 7 Inclined surface 8, 9 Optical fiber 8A, 9A Ribbon cable 10a, 11a Connector 10A, 11A Cylindrical multi-core cable

Claims (5)

A crystal that contacts the measurement sample with the detection surface disposed in the housing with the detection surface positioned at the opening formed in the front end surface of the housing;
A plurality of optical fibers optically connected to one side across the detection surface of the crystal are disposed along the longitudinal direction of the crystal, and light is emitted from each optical fiber toward the detection surface at an angle greater than the critical angle. Light irradiation side ribbon cable,
A plurality of optical fibers optically connected to the other side across the detection surface of the crystal are arranged along the longitudinal direction of the crystal in a manner corresponding to the optical fiber of the light irradiation side ribbon kale. A multi-core optical fiber probe comprising: a light receiving side ribbon cable that receives light irradiated from a corresponding optical fiber of the light irradiation side ribbon kale and reflected by a detection surface.   The crystal has a triangular shape with a cross-section with one surface as a detection surface or a trapezoidal prismatic shape with its head cut, and the optical fiber of the light irradiation side ribbon cable is arranged on one surface sandwiching the detection surface of the crystal 2. The multi-core optical fiber probe according to claim 1, wherein an optical fiber of the light receiving side ribbon cable is arranged on the other surface sandwiching the detection surface of the crystal.   The crystal is in the form of an isosceles triangle with a section sandwiched between two isosceles faces or an isosceles trapezoidal prismatic shape with its head cut off, and the optical fiber on the light irradiation side and the ribbon cable on the light receiving side The multi-core optical fiber probe according to claim 2, wherein the optical fiber is arranged symmetrically with respect to a plane perpendicular to a detection plane passing through the top of the crystal.   4. The multi-core optical fiber probe according to claim 3, wherein the crystal has an isosceles right triangle shape or an isosceles trapezoidal prismatic shape with its head cut. The light irradiation side ribbon cable and the light receiving side ribbon cable are formed on the distal end side of the cylindrical multi-core cable by processing a cylindrical multi-core cable having a plurality of optical fibers or connecting them via a connector. The multi-core optical fiber probe according to any one of claims 1 to 4, wherein the multi-core optical fiber probe is formed.

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