JPS6280539A - Optical measuring instrument - Google Patents

Abstract

PURPOSE:To attain a high-precision measurement without being affected by reflected light from a condenser lens by providing the condenser lens off an optical fiber. CONSTITUTION:The optical fiber 1 is provided to a converging part 3 so that the center axis is not aligned with the center axis of the converging part 3; and light is projected on the object 2 to be measured through the condenser lens 30 and its reflected light is converged. Namely, the center axis of the condense lens 30 is shifted from the center axis of the end surface 10 of the optical fiber 1 and the condenser lens 30 is installed in parallel to the end sur face 10 intersecting orthogonally with the longitudinal direction of the optical fiber 1. Consequently, light L from the center of the optical fiber 1 travels in parallel to the optical axis of the condenser lens 30 and converged and project ed on the object 2 to be measured through the condenser lens 30, but light R reflected by the surface S of the condenser lens 30 is not reflected regularly, so the light is neither incident directly on the end surface 10 of the optical fiber 1 nor superposed upon the reflected light from the object 2, so that there is no error in measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This optical field relates to an optical measuring device using an optical fiber.

[Prior art] There is a device that uses an optical fiber to project light onto a measurement target, collects the reflected light, and guides the light back to the detection section via an optical fiber to measure the moisture content of the measurement target or the properties of the pond. .

As shown in FIG. 3, this type of optical fiber 1 includes, for example, a light projecting fiber 1a1M! in the center. Light-receiving fibers 1b, . . . are provided on the sides.

Then, as shown in FIG. 4, the first end face 1 of the optical fiber
When projecting light from zero to the measurement target 2, if the light is simply projected, the light will spread and effective measurement will not be possible. It increases the efficiency of light projection and collection.

[Problems to be Solved by the Invention] Normally, the central axis of the optical fiber 1 and the central axis of the condensing lens 30 are aligned,
The condenser lens 30 is installed parallel to the end face 10 perpendicular to the longitudinal direction of the optical fiber 1.

For this reason, the light projected from the center of the end face of the optical fiber 1 is specularly reflected by the surface S of the lens 30, and enters the optical fiber 1 without being projected onto the measurement target 2. This was due to the light reflected by the second lens, causing a large measurement error.

In view of the above points, it is an object of the present invention to provide an optical measuring device that is not affected by reflected light from a condenser lens and is capable of highly accurate measurement.

[Means for Solving the Problems] This invention provides a condenser lens that projects light from an optical fiber onto a measurement target and focuses the light from the measurement target onto the optical fiber, at a position shifted from the redundant fiber. This is an optical measuring device.

[Embodiment] FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention.

In the figure, the central axis of the optical fiber 1 is offset from the central axis of the condensing unit 3, and the condensing unit 3 is provided with a condensing lens 30 that emits light onto the measurement object 2 and collects the reflected light. It has become. Although not shown, the other end of the optical fiber 1 is provided with a light projecting section that projects light and a detecting section that receives reflected light.

That is, the central axis of the condensing lens 3o is shifted from the central axis of the end surface 10 of the optical fiber 1, so that the condensing lens 3o is aligned parallel to the end surface 10 orthogonal to the longitudinal direction of the optical fiber 1.
is installed.

Therefore, the light emitted from the center of the fiber 1 travels to the optical axis and the plane j7 of the condenser lens 30, and is condensed by the condenser lens SO into the measurement pair @2, but the condensed light lens 30
The light R reflected from the surface S (Y, since it is not a specular reflection,
It does not directly enter the end face 1o of the optical fiber 1, and does not overlap with the anti-q' light of the measurement object 2, so that no measurement error occurs.

FIG. 2 is a structural explanatory diagram showing an example of a song.

In this example, the central axis of the optical fiber 1 and the central axis of the condensing lens 30 of the condensing unit 3 almost coincide, but the condensing lens 3o is tilted with respect to the end surface 10 of the optical fiber 1. are staggered.

Therefore, the light emitted from the center of the optical fiber 1 passes through the condensing lens 30 at fF L and is projected onto the measurement object 2, but the light R reflected by the surface S of the condensing lens 30 is reflected in the opposite direction. Since the light is not directly incident on the end face 10 of the optical fiber 1, the measurement error is eliminated by 18%.

Further, by making the inner wall of the condenser 3 a rough surface and diffusing the light reflected by the surface S of the condenser lens 30, the influence of unnecessary reflected light can be further reduced.

y) ζ.If FIG. 1 and FIG. 2 are combined, the condenser lens 30 may be provided not to coincide with the optical axis of the optical fiber 1, but at an angle.

5 Effects of the Invention] As described above, in this invention, the condenser lens is arranged offset from the optical fiber, and the projected light is specularly reflected on the surface of the condenser lens and is transmitted to the optical fiber. Therefore, measurement errors caused by this reflected light can be prevented, and highly accurate measurement can be performed.

[Brief explanation of drawings]

1 and 2 are configuration explanatory diagrams showing an example of this optical fiber, FIG. 3 is an explanatory diagram of an optical fiber, and FIG. 4 is a conventional example (opening explanatory diagram. ...Optical fiber, 2...Measurement object, 3...Condenser, 3o...Condenser lens, 10...Ground of optical fiber, S...Surface of condenser lens 1 2 Immersed feet vs. flames

Claims (1)

[Claims] 1. An optical fiber that transmits the light projected onto the measurement target and the light reflected by the measurement target, and an optical fiber that projects the light from this optical fiber onto the measurement target and transmits the light from the measurement target to the optical fiber. What is claimed is: 1. An optical measurement device comprising: a condensing lens that condenses light into an optical fiber; 2. The optical measuring device according to claim 1, wherein the central axis of the condenser lens is disposed offset from the central axis of the optical fiber. 3. The optical measuring device according to claim 1 or 2, wherein the condenser lens is arranged at an angle with respect to the end face of the optical fiber.