JPS63111443A - Optical sensor - Google Patents

Abstract

PURPOSE:To detect whether or not there is a specific material (ice) to be detected by providing a lacking part to the intermediate part of an optical transmission line and slanting the end surface of the optical transmission line facing the absence part by a specific angle to the optical axis. CONSTITUTION:The lacking part 15 which is sectioned in a right-angled isosceles triangle shape is provided to a glass substrate 14, and an optical waveguide 14 is divided by this lacking part 15 into two optical waveguides 14a and 14b. When ice is formed on the lacking part 15 and increases in thickness to some extent, the refractive index at the lacking part 15 increases and total reflection is not caused. Consequently, transmitted light is incident on the optical waveguide 14b to a considerable extent and a photodetector outputs a signal. For the purpose, the output signal of the photodetector is monitored to detect the icing on a blade 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sensor for detecting the presence or absence of a substance to be detected.

[Summary of the invention]

The present invention provides a sensor as described above, in which a cutout is provided in the middle of the optical transmission path, and the cutout is configured such that the transmitted light is totally reflected when the refractive index of the cutout is less than or equal to a predetermined value. By tilting the facing end of the optical transmission line with respect to the optical axis,
It is small in size and allows direct detection at a desired detection position.

[Conventional technology]

For example, in aircraft, it is necessary to detect ice buildup on the wings during flight, and sensors are used for this purpose. As such a sensor, there has conventionally been a rod-type icing sensor that combines a crystal resonator and an icing rod.

This rod-type icing sensor uses a rod that is mechanically connected to a crystal oscillator placed inside the aircraft to protrude outside the aircraft, and measures the amount of ice that has formed in the loft using the natural vibration of the crystal oscillator. It is detected as a change in number.

[Problem that the invention seeks to solve]

However, loft-type icing sensors have a complicated structure because the loft needs to protrude from the aircraft, and when attached to a wing, the sensor substantially disturbs the shape of the wing.

For this reason, rod-type icing sensors cannot be attached to the wings, and the state of icing on the wings must be estimated from the detection results of the rod-type icing sensors attached to the fuselage. Therefore, the rod-type icing sensor could not accurately detect icing on the wing.

[Means for solving problems]

The optical sensor according to the present invention is provided with a cutout 15 in the middle part, and faces the cutout 15 so as to totally reflect the transmitted light when the refractive index in the cutout 15 is less than or equal to a predetermined value. Optical transmission lines 11a, l whose end faces are inclined with respect to the optical axis
lb, 14, and a light source and a light receiver connected to both ends of the optical transmission lines 11a, llb, 14, respectively.

[Function] In the optical sensor according to the present invention, the end surfaces of the optical transmission paths 11a, 11b, and 14 facing the cutout 15 are exposed to light so that the transmitted light is totally reflected when the refractive index in the cutout 15 is less than or equal to a predetermined value. Since it is tilted with respect to the axis, if a substance having a refractive index higher than the above-mentioned predetermined value exists in the cutout part 15,
The transmitted light is not totally reflected.

Therefore, the presence or absence of a predetermined substance to be detected can be detected by positioning the cutout portion 15 at the detection target position and monitoring the output of the light receiver.

〔Example〕

An embodiment of the present invention applied to an aircraft icing sensor will be described below with reference to the drawings.

In this embodiment, the optical fibers Ila and llb and the optical waveguide body 1 are
It has an optical transmission line consisting of 2. The guide waveguide body 12 has an optical waveguide 14 formed in the glass substrate 13 by ion exchange with the glass substrate 13.

However, the glass substrate 14 is provided with a cutout 15 whose cross section is a right-angled isosceles triangle.
Accordingly, the optical waveguide 14 also has two optical waveguides 14a and 14.
It is divided into b.

One end of each of the optical fibers lla and llb is connected to an optical waveguide 1.
They are optically coupled to the end faces of 4a and 14b opposite to the end face facing the cutout 15 by an optical fiber arraying device 16. In addition, at the other end of the optical fiber lla, a light T1 is provided.
．． (not shown) is connected to the optical fiber llb, and a light receiver (not shown) is connected to the other end of the optical fiber llb.

The optical fiber arraying tool 16 fixes the optical waveguide body 12 and one end of the optical fibers lla and llb. Protected by 17.

The sheath 17 is inserted into the hole 18a of the blade 18, and the protrusion 17a is inserted so that the leading waveguide body 12 and the surface of the sheath 17 on the cutout 15 side are flush with the outer surface of the blade 18. Sheath 17 is positioned.

In this embodiment, when no icing occurs on the outer surface of the blade 18, and therefore on the cutout 15, the light emitted from the light source and transmitted through the optical fiber lla and the optical waveguide 14a is , the light is totally reflected in the direction shown by arrow A in the figure at the end face of the optical waveguide 14a facing the cutout 15.

Therefore, no light is transmitted from the optical waveguide 14a to the optical waveguide 14b, and as a result, no signal is output from the light receiver connected to the optical fiber 11b.

On the other hand, if ice has formed on the cutout 15 and the thickness of the ice is more than a certain level, the refractive index in the cutout 15 will be high and the above-mentioned total reflection will not occur. For this reason, a considerable amount of transmitted light enters the leading waveguide 14b, and a signal is output from the optical receiver. Therefore, by monitoring the output signal from the light receiver, icing on the wing 18 can be detected.

Note that the pattern of the optical waveguide 14 and the shape of the cutout 15 may be other than those shown in the drawings. By appropriately changing the shape, angle, etc. of the cutout portion 15, the minimum sensitivity to icing can be changed.

Moreover, although the above-described embodiments apply the present invention to an icing sensor for aircraft, the present invention can also be applied to a sensor for detecting oil leakage, for example.

〔Effect of the invention〕

In the optical sensor according to the present invention, a cutout is provided in the middle of the optical transmission line, and the end face of the optical transmission line facing the cutout is inclined at a predetermined angle with respect to the optical axis. The presence or absence of a substance to be detected can be detected. Therefore, since it is small and does not require a protrusion in its shape, it can be easily attached to a desired detection position, and detection can be performed directly at the desired detection position.

[Brief explanation of the drawing]

The drawing is a side sectional view of a main part of an embodiment of the present invention. In addition, in the symbols used in the drawings, 11 a, 11 b-----・---・・
Optical fiber 14...
・・・・・・・・・−・−・・Optical waveguide 15-1−−・・
−・−・・−・−・・−・・−・・−・・This is the missing part.

Claims (1)

[Claims] 1. A cutout is provided in the intermediate portion, and the end face facing the cutout is configured such that the transmitted light is totally reflected when the refractive index at the cutout is less than or equal to a predetermined value. An optical sensor that includes an optical transmission line that is inclined with respect to an optical axis, and a light source and a light receiver that are connected to both ends of the optical transmission line. 2. The angle of the inclination is set so that when the cutout is filled with air, the transmitted light is totally reflected, and when the cutout is filled with ice, the transmitted light is not totally reflected. Optical sensor as defined in claim 1.