JPH0262184B2 - - Google Patents

Description

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

[Conventional technology] Light is emitted onto a measurement target using an optical fiber,
There is a device that collects the reflected light and guides it to a detection section again through an optical fiber to measure moisture and other properties of the object to be measured.

As shown in Fig. 3, this kind of optical fiber 1
For example, a light emitting fiber 1a is provided at the center, a light receiving fiber 1b is provided at the periphery, and so on.

As shown in FIG. 4, when projecting light from the end face 10 of the optical fiber 1 to the measurement object 2, if the light is simply projected, the light will spread and effective measurement cannot be performed. Condensing lens 30 in the light section 3
is installed to increase the efficiency of light projection and collection.

[Problems to be Solved by the Invention] Usually, the central axis of the optical fiber 1 and the condensing lens 30
The condenser lens 3 is aligned parallel to the end surface 10 orthogonal to the longitudinal direction of the optical fiber 1.
0 is set.

Therefore, 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
The light enters the optical fiber 1 without being projected onto the measurement object 2, and is superimposed on the light actually reflected by the measurement object 2, 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 condensing 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 offset from the optical 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
It is arranged in the condensing section 3 so as to be offset from the central axis of the condenser lens 30, and emits light onto the measurement object 2 through the condensing lens 30, and condenses the reflected light. Although not shown, the other end of the optical fiber 1 is provided with a light projecting section for projecting light and a detecting section for receiving reflected light.

That is, the central axis of the condensing lens 30 is shifted from the central axis of the end face 10 of the optical fiber 1, and the optical fiber 1
The condenser lens 30 is installed so as to be parallel to the end surface 10 which is perpendicular to the longitudinal direction of the lens.

Therefore, the light L emitted from the center of the optical fiber 1
The light R travels parallel to the optical axis of the condenser lens 30 and is focused and projected onto the measurement object 2 by the condenser lens 30, but the light R reflected by the surface S of the condenser lens 30
is not a specular reflection, so the end face 1 of the optical fiber 1
0 and does not overlap with the reflected light of the measurement object 2, resulting in no measurement error.

FIG. 2 is a configuration explanatory diagram showing another embodiment. In this example, the central axis of the optical fiber 1 and the central axis of the condensing lens 30 of the condensing section 3 almost coincide, but the condensing lens 30
It is tilted and shifted relative to 0.

Therefore, the light emitted from the center of optical fiber 1 is
Light R is projected onto the measurement target 22 through the condenser lens 30, but is reflected by the surface S of the condenser lens 30.
is not a specular reflection, so the end face 1 of the optical fiber 1
0 and does not cause measurement errors.

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.

Also, by combining Figures 1 and 2, the optical fiber 1
The condenser lens 3 is tilted and not aligned with the optical axis of the lens 3.
0 may be provided.

[Effects of the Invention] As described above, in the present 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 enters the optical fiber. Therefore, measurement errors caused by this reflected light can be prevented, and highly accurate measurement can be performed.

[Brief explanation of the drawing]

1 and 2 are structural explanatory diagrams showing an embodiment of the present invention, FIG. 3 is an explanatory diagram of an optical fiber, and FIG. 4 is a structural explanatory diagram showing a conventional example. DESCRIPTION OF SYMBOLS 1... Optical fiber, 2... Measurement object, 3... Condensing part, 30... Condensing lens, 10... End face of optical fiber, S... Surface of condensing lens.

Claims (1)

[Claims] 1. An optical fiber that transmits light emitted to a measurement object and light reflected by the measurement object, and an optical fiber that projects light from the optical fiber to the measurement object and transmits light from the measurement object to the optical fiber. 1. An optical measuring device comprising a condensing lens for condensing light, the condensing lens being provided at a position shifted from an optical fiber. 2. The optical measuring device according to claim 1, wherein the central axis of the condensing lens is shifted 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.