JPS6025561Y2 - temperature measuring device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a temperature measuring device that uses an optical fiber and can easily measure temperature in places susceptible to electromagnetic induction.

A conventional thermometer using an optical fiber is shown in FIG.

The light propagating through the optical fiber 1 is once converted into a parallel beam by the lens 2, and is condensed by the lens 2' to efficiently enter the fiber 1'.

A shielding plate 3 supported by a bimetal 4 is inserted between these lenses, and blocks part of the light beam.

The amount of light to be blocked changes as the shielding plate 3 moves as the temperature changes.

This method measures temperature using optical loss, so there is no malfunction due to electromagnetic induction, so it is effective, but it requires a large number of parts.
It is large in size, and the positions of the fibers 1, 1' and lenses 2, 2' change due to temperature changes, so it cannot be used for measurements at high temperatures.

The present invention reduces the number of parts and enables measurement at relatively high temperatures.

The present invention will be described below with reference to drawings and embodiments.

FIG. 2 shows the constituent countries of an embodiment of the present invention.

1 and 1' are optical fibers, □゛5 is a cylindrical sleeve,
The outer diameter of the fiber and the inner diameter of the sleeve are approximately equal.

Both ends 6 of the sleeve are fixed to the fiber by adhesive or crimping.

There is a difference between the sleeve 5 and the fiber 1.1' material 4 in that the former has a smaller thermal expansion coefficient than the latter, and due to this difference, when the temperature rises, the fiber joint 7
A gap is created at the end face of the fibers 1 and 1', and the light propagating through the fibers 1 and 1' leaks out of the fiber at this portion.

Therefore, temperature can be measured by measuring this propagation loss.

``Experimentally conducted,'' using a quartz fiber with NA-0.16 and a sleeve made of stainless steel with a length of about 5 cm.
It was constructed so that the loss would be 0 at ℃.

The measurement results at this time are shown in FIG.

Since a change in loss of about 0.02 dB can be measured, the sensitivity of this thermometer is about 0.4°C.

The sensitivity and measurable temperature range are determined by the expansion coefficient and length of the sleeve, so they can be determined depending on the location of use.

Furthermore, in the experiment, it was possible to measure from O'C, but it is clear that the measurement range can be arbitrarily set by changing the connecting position of the fiber and the sleeve.

FIG. 4 shows the constituent countries of another embodiment.

The outside of the fiber 1 is covered with a sleeve 5, while one end 6 of the sleeve 5 is fixed with adhesive or crimping.

A reflecting mirror 8 is attached to the other end of the sleeve 5 perpendicularly to the axis.

With the above configuration, by measuring the amount of light propagating through the fiber 1 and reflected by the mirror 8,
Obviously, temperature can be measured.

In this case, due to the difference in thermal expansion coefficient between the sleeve 5 and the fiber 1, a gap is created between them, and the amount of light reflected by the reflecting mirror 8 that enters the fiber 1 changes, allowing temperature measurement to be performed.

As explained above, according to the present invention, a small, lightweight temperature measuring device can be constructed with a simple structure.

Furthermore, if the light emitting source and light receiving source are separated from the sensor section, measurements can be made without being affected by induced noise even in the vicinity of high voltage lines or the like.

[Brief explanation of the drawing]

Figure 1 shows the constituent countries of a conventional temperature measuring instrument, Figure 2 shows the constituent countries of an embodiment of the present invention, and Figure 3 shows the temperature measurement according to the same embodiment.
The loss characteristic diagram, FIG. 4, shows the components of another embodiment of the present invention. 1.1'...Optical fiber, 5...Sleeve, 8...Reflector.

Claims (1)

[Scope of utility model registration request] an optical transmission body that transmits light; an optical medium that transmits or reflects light from the optical transmission body; and an expansion coefficient that is different from the optical transmission body or the optical medium, and the optical transmission body and the optical medium. 1. A temperature measuring device comprising: a holder for holding the optical fiber in a movable state; the temperature measuring device is characterized in that the temperature is measured by the loss of light between the optical transmitter and the optical medium.