JPS582602A - Optical displacement detector - Google Patents

Abstract

PURPOSE:To detect physical quantity such as pressure without the effect of electromagnetic fields by mounting light wave guide paths on a displacement body, and detecting the change in the quantity of the received light which is introduced to the light wave guide paths through a prism and fibers. CONSTITUTION:On a diaphragm 1 which is displaced by the pressure to be detected, the thin film light wave guide paths (ZnO, SiO2) 2 and 3 are formed. The light outputted from a laser diode 5 is transmitted to the thin film light wave guide path 3 through the light sending fiber 6, a light sending rod lens 7, and a prism coupler 4, and detected by a photodiode 10 through the prism coupler 4, a light receiving rod lens 8, and the light receiving fibers 9. By processing said electric signal, the pressure is detected without the effect of the electromagnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical displacement detector for detecting physical quantities such as pressure and temperature.

In recent years, for example, many purely electronic pressure sensors for detecting pressure have been developed and put into practice because of their compact size and high performance. However, purely electronic pressure sensors have the disadvantage of being influenced by electromagnetic field induction.

Therefore, an object of the present invention is to provide a displacement detector that can detect physical quantities such as pressure without being influenced by electromagnetic fields.

In order to achieve the above object, the optical displacement detector of the present invention has an optical waveguide mounted on a displacement body that displaces according to the physical quantity to be detected, and a prism coupler arranged above the optical waveguide. In addition to inputting light into the coupler through a light transmission fiber.

The light from the prism coupler is received through a light-receiving fiber, and the displacement of the displacement body due to the physical quantity to be detected is detected as a change in the amount of received light due to a change in the degree of coupling between the optical waveguide and the prism coupler, thereby detecting the physical quantity to be detected. .

The present invention will be explained in detail with reference to embodiments shown in the following two drawings.

FIG. 1 is a schematic diagram of an optical pressure sensor showing an embodiment of the present invention.

In FIG. 1, 1 is a diaphragm that is displaced by the detected pressure, and this diaphragm 1 has a thin film optical waveguide (
ZnO, 5i02)2 and filters are formed and mounted. Reference numeral 4 denotes a prism coupler, into which light emitted from a laser diode 5 as a light source is inputted via a light transmitting fiber 6 and a light transmitting rod lens 7. The light exiting the prism coupler 4 is sent to the light receiving side rod lens 8. The light is received by a photodiode 10 as a light receiving element via a light receiving fiber 9.

The prism coupler 4 is optically coupled to the thin film optical waveguide 6, and the degree of coupling changes as the distance between the thin film optical waveguide 3 and the prism coupler 4 changes due to displacement of the diaphragm 1 due to changes in pressure. Note that 11 is the 111th screw for adjusting the height of the prism, which is constructed as described above.
The operation of the optical pressure sensor according to the first embodiment will be explained.

The light emitted from the laser diode 5 passes through a light transmitting fiber 6 and is guided to a light transmitting rod lens 7, where it is collimated and input to the prism coupler 4. If the distance between the prism coupler 4 and the thin film optical waveguide A is as shown in FIG. As shown in , the introduced light is not transmitted to the light receiving side.

However, if the distance between the prism coupler 4 and the thin film optical waveguide 6 is short, the light introduced into the prism coupler 4 propagates to the thin film optical waveguide 6 through optical coupling, as shown in FIG.
The light propagation path 12 is as shown in the figure, from the right half of the prism coupler 4 to the light receiving rod lens 8. Propagating light is led out through a light receiving fiber 9, and this light is converted into an electrical signal by a photodiode 10 and output. This electrical signal is then processed for display as an indication of pressure.

As described above, since the electrical signal output to the photodiode 10 changes depending on the distance between the prism coupler 4 and the thin film optical waveguide 3, that is, the displacement of the diaphragm 1, pressure can be detected.

Note that while the distance between the prism coupler 4 and the thin film optical waveguide 6 is adjusted by the prism height adjustment screw 11, the prism coupler 4 is fixed at the same time.

FIG. 4 shows another embodiment, in which the same numbers as in FIG. 1 indicate the same parts. As a displacement body, instead of the diaphragm shown in Fig. 1, there is a plate-shaped bimetal 1 whose both ends are fixed.
The difference is that 3 is provided.

When the temperature changes, the plate-shaped bimetal 13 is covered with oil, that is, it is displaced, and due to this displacement.

The distance between the prism coupler 4 and the thin film optical waveguide 6 changes,
As in Figure 1, since the output of the photodiode 10 changes,
Temperature changes can be detected.

Note that in the above embodiments, the physical quantity to be detected is pressure.

Although the case of temperature has been described as an example, the present invention is not limited to this, and can be applied to anything in which the position of the displacement body changes in response to a change in the physical quantity to be detected.

As described above, according to the optical displacement detector of the present invention, an optical waveguide is mounted on a displacement body that displaces according to a physical quantity to be detected, a prism coupler is disposed above the optical waveguide, and a signal is sent to the prism coupler. In addition to inputting light through an optical fiber, the light from the prism coupler is received through a light-receiving fiber, and the displacement of the displacement body is detected as a change in the amount of received light due to a change in the degree of coupling between the optical waveguide and the prism coupler. Most of the detection system is composed of optical systems, and physical quantities can be detected without being affected by surrounding electromagnetic induction.

Furthermore, since an optical system is used, a displacement detector can be realized with a relatively simple configuration.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an optical pressure sensor showing an embodiment of the present invention, and FIGS. 2 and 3 are schematic diagrams of essential parts of the optical pressure sensor to explain the operation of the embodiment of FIG. 1. , FIG. 4 is a schematic diagram of an optical temperature sensor showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Diaphragm, 2.3... Thin film optical waveguide 4... Prism coupler, 5... Laser diode 6... Light transmission fiber, 7... Light transmission rod lens, 8...・Light-receiving rod lens, 9...Light-receiving fiber Patent applicant Shimadzu Corporation Representative Patent attorney Shigeru Nakamura Shinsui 1 Orchid-2 drawing board 3m2! l Glue 4 Figure

Claims (3)

[Claims] (1) An optical waveguide is mounted on a displacement body that displaces according to the physical quantity to be ejected, a prism coupler is arranged above the optical waveguide, and light is input to this prism coupler through a light transmission fiber, and the prism coupler The optical system is characterized in that a physical quantity to be detected is detected by detecting the displacement of the displacement body as a change in the amount of received light due to a change in the degree of coupling between the optical waveguide and the prism coupler. displacement detector. (2) The optical displacement detector according to claim 1, wherein the displacement body is a diaphragm that is displaced in response to pressure. (3) The optical displacement detector according to claim 1, wherein the displacement body is a bimetal that is displaced according to temperature.