JPS60111931A - Light applied temperature measuring apparatus - Google Patents

Abstract

PURPOSE:To eliminate the variation in the output of a light source and the transmission loss of a light transmitting member, by constituting the title apparatus so that a diffraction grating is brought into contact with an object to be measured and the temp. around the diffraction grating is measured from the peak wavelength of the spectrum distribution of reflected light. CONSTITUTION:Light emitted from a light emitting element 19 is projected to the diffraction grating 33 in a temp. detector 23 and light reflected from said grating 33 is guided to a light receiving part 25 and the spectrum distribution of the reflected light is detected by a photodiode array 29. Therefore, by calculating the peak wavelength of the spectrum distribution from the detection result, the temp. in the vicinity of the diffraction grating 33 in the temp. detecting part 23 is measured. Because the peak wavelength utilized in this measurement is an amount not relating to the intensity of a light source for projecting light or the light transmission loss of a light transmitting member, the accurate measurement of a temp. subjected to no effect of said phenomena can be performed.

Description

Detailed Description of the Invention [Technical field to which the invention pertains] The present invention relates to a temperature measuring device that utilizes the characteristics of light, in particular, a temperature measuring device that projects light onto a diffraction grating that is brought into contact with an object to be measured.
[Contact temperature measuring device that measures the temperature of the object to be measured from the wavelength of the spectral distribution of light reflected from a grating and is unaffected by variations in the characteristics of the light source and light transmission member i
Regarding K.

[Prior art and its problems]

A contact temperature measuring device that directly measures the temperature of the object by contacting the object t11+1 is a radiation temperature measuring device b.
Compared to non-contact temperature measuring devices such as i, it is not affected by the amount of radiation, allowing for more accurate temperature measurements; In the past, many IP) types have been proposed due to their properties such as safety and explosion-proof properties.

Figure 1 is a 141 diagram of an example of a contact temperature measurement system using such light; in Figure 1, 1a is a pulse generator 2
1b is a light emitting diode that is driven by a pulse generator 2b and a drive circuit 3b to generate light with a wavelength of λ2; 1 a, 1
b Pi pulse generation times N 2 a and 2 b Emit light alternately from K. The light emitted by the light emitting diodes la and lb is combined by an optical multiplexer 4 and guided to a temperature sensor 8 via a backlight 7 eyeper 5, an optical connector 6, and an optical fiber 7, and is transmitted through this center 8. Optical fiber 9 in the rear panel,
The light is connected to a light receiving diode 12 via a connector 10 and a light receiving diode 11 in sequence. 13 is the optical connector 6.10 mentioned above.
, a detection section consisting of an optical fiber 7.9 and a temperature sensor 8. In this case, the temperature sensor 8 is brought into contact with the object to be measured. The wavelength λ1 is set to the wavelength pressure near the absorption edge of this characteristic, and the wavelength λ2 is set to the wavelength of the light transmission region that is separated by light from the absorption 71~ of this characteristic. , the absorption edge changes depending on the femaleness of the material. When the temperature sensor 8 is brought into contact with the 1j fixed nose and the temperature of the temperature sensor 8 changes by yH, the transmission rate of the light of wavelength λl in this sensor changes, so the light receiving diode The intensity of the light of wavelength λ1 reaching 12 is 'a
The intensity of the light with the wavelength λ2 reaching the light receiving diode 12 is not affected by the temperature of the temperature sensor. The light receiving diode 12 outputs a signal corresponding to *tf of the received light, this signal is amplified by the amplifier 14, and the wavelength λ1 . The output signals of both hold circuits 15 and 16 are sampled and held in each section of λ2, and are input to a divider 17, which outputs a signal 17a according to the ratio of both output signals of hold circuit 15 and IG. be done.

The temperature shown in Figure 1 of the Imperial Decree (lilJ) is configured like an upper tube, so the optical transmission line consisting of the optical fibers 5, 7, 9.11 and the original connector 6.10 is There are optical transmission losses due to the stirrup of the fiber due to bending and temperature changes, and optical transmission losses due to axis misalignment when connecting and disconnecting the optical connector. is affected by the transmission loss, and the original intensity reaching the light receiving diode 12 is also affected by the output fluctuations of the light emitting diodes 1a and 1b.Therefore, in the measuring device of FIG.
If there is no output fluctuation in the diode and the transmission loss affects both the wavelength λ□ and the wavelength λ2 light equally, then the ratio of the output signals of the divider 17Fi hold circuits 15 and 16 is % 34, compensation for the transmission loss is performed here, and No. 46/17, a becomes a signal corresponding to the temperature of the temperature sensor 8, that is, the temperature of a mere 6111 constant object, but it is generally a self-emitting diode. It is very difficult to reduce each output variation of la and Ib to zero, and the transmission loss of the optical transmission member changes in a very complicated manner over time, and the light that causes this transmission loss The above-mentioned factors affecting fibers and optical connectors act equally on the light of wavelength λ1 and the light of wavelength λ2, and by taking the ratio of the strong IK of these lights, the transmission loss fluctuation of the optical transmission member can be calculated. There is still no empirical data showing that a high degree of compensation is possible. That is, the conventional temperature measuring device as shown in FIG. 1 has a problem in that the measurement results are affected by transmission loss in the optical transmission member and fluctuations in the output of the light emitting diode.

[Purpose of the invention]

The present invention solves the problems of the conventional temperature measuring devices/J, K as described above, and uses light that is not affected by variations in the output direction of the light source or variations in transmission loss in the optical transmission member. The object of the present invention is to provide a contact temperature measuring device.

[Key points of the invention]

In order to achieve the above-mentioned object, the present invention uses an Ichike diffraction grating whose lattice constant changes due to expansion or contraction due to temperature as a temperature sensor, and when light is projected onto this grating, Since the value of the peak wavelength in the spectral distribution of reflected light reflected in a predetermined direction is the value subtracted by the temperature and pressure of the diffraction grating, it has the function of distributing the peak wavelength by bringing the Jr. grating into contact with the object to be measured. The temperature measuring device is configured so that the temperature of the object to be measured is calculated using the light receiving part and the temperature of the object to be measured is determined based on the measurement result.
By doing so, it is possible to perform temperature measurement without being affected by variations in the output direction of light rM and variations in transmission loss in the optical transmission member.

[Embodiments of the invention]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows an embodiment 1 of the optical temperature measuring device according to the present invention.
8, this 611'' fixed device 18 connects light having a relatively wide svector distribution emitted from an LED water element 19 as a light source to an optical fiber, a half mirror 21,
The optical fiber U is sequentially guided to a rod-shaped temperature detection section whose tip is brought into contact with the object to be measured, and the light that is directed to this temperature detection section is reflected by the mechanism described below in the temperature detection section again. After being transmitted in the opposite direction by the light 7 eye/<22, it is guided to the light receiving part 2 via the half mirror ♀l and the light 7 eye bum in order. A diffraction grating that converts the reflected light into a parallel beam using a lens 26;1. bK projection and is configured to focus the light diffracted by the diffraction grating onto the photodiode array through a lens path. That is, the light receiving section 25
This is a spectrometer that measures the spectral division 11 of reflected light with a photodiode array 4.

Figure 3 is a vertical cross-sectional view of the m degree detection section shown in Figure 2,
The highlight is an enlarged view of the diffraction grating mount 31 portion in FIG. 3. In both figures, reference numeral 31 denotes a plug-shaped lattice mount 1J'l' with an EZ extending over one end of the cylindrical outer cylinder J2 so as to close it, and the inner surface 31a of this mount is inclined with respect to the axis of the outer cylinder 32. The inner surface 31a is made of copper,
A diffraction grating 33att, 1iJI having a serrated cross section is fixed to the surface of a metal flat plate made of aluminum or the like so that the back surface of the blaze 33att and 1iJI are in contact with each other. In this case, the diffraction grating mount 31'j-J and the outer 1+; It is installed by TLf bonding or high temperature brazing,
The diffraction grating mount 31 and the outer cylinder 32 are fixed by contacting each other with an inorganic adhesive or by high-temperature brazing. 34
At the other end of 32 is a collimator lens made by Ishio of Shinchichi, and 37 is a cylindrical quartz special source lens with a small diameter core 37a along its axis, a stopper, a lens, and a guide. The optical path 3'7 is sequentially guided outward with the stopper 35 facing the diffraction grating mount 31 side. A cylindrical spring 38 is inserted between the light guide path 37 and the lid 34 in a compressed state, and this spring applies PP pressure in the direction of the diffraction grating mount 31. In this case, the stopper A is the collimator. The lens rear turn V [is formed so that a space 39 is formed between the grating backs. The spring is caused by the light guide path 37 due to the thermal expansion of the outer cylinder 32 and the light shield 37# fitted inside the outer cylinder 32.
It has a function of stably holding each member inserted into the outer cylinder 32 by absorbing the distortion caused by the outer cylinder 32 and the like. 22a and 22
b are the strand and jacket of the original fiber n, respectively, and strand 2
2a is a core 3 whose end is a light guide path 37, which is passed through the lid;
It is attached to the end face of 7a with adhesive, and 40 is M'
, in order to reinforce the Jffr portion between the optical fiber shaft and the core 37a, each end of the reinforcing member 40 has a cylindrical reinforcing portion that is stretched low in the vicinity of each 1 m portion between the optical fiber shaft and the outer tube 32, and each end of the reinforcing member 40 is They are bonded to the outer sheath zb and the outer tube 32 of the original fiber, respectively, using an A-Ha adhesive. In other words, in this case, the temperature detection section 23
is composed of each part except the above-mentioned optical fiber section, and the diffraction grating;
4PL] It is inserted into the proboscis.

In addition, in this temperature detection part, if it is necessary to prevent oxidation of the diffraction grating, the part where the base fiber ηa passes through the hole is hermetically sealed with a sealant. Furthermore, a through hole 3 is provided in the portion of the outer cylinder 32 where the spring 38 is provided.
2a is formed, and the inside of the outer cylinder n is vacuum-sealed by this pressure hole, or is replaced with an inert gas and then sealed with a sealant.

Next, the temperature can be determined using the temperature detection section mentioned above. d will be explained with reference to FIGS. 5 and 6. FIG. 5 is a perspective view illustrating the rotating grating 33, the diffraction grating mount 31, and the light path in their vicinity. 37b is the surface of the core 37a of the light guide that comes into contact with the collimator lens 3. That is, In the temperature detection section shown in FIGS. 2 and 3, the light with a relatively wide spectrum distribution emitted from the light emitting element 19 passes through the core 37a of the original fiber n% light guide path in a ridge direction and reaches the ℃ end face 37b. The light projected from this end surface 37b to the collimator lens 36 is formed into a parallel/C beam 41 by this lens 36, and the total beam is
is projected onto the diffraction grating. However, in this case,
The inner surface 31 of the child mount 31 has a lattice shape around the 9th lattice, and the blaze has a so-called Littrow configuration in which the F plane 33b is strictly aligned with the direction of the light beam 41.
a is formed in the direction of the light beam 41, so that the light with a wavelength centered on the blaze wavelength λ0 among the possibilities projected onto the diffraction grating 33 is specularly reflected by this diffraction grating and returns to the incident light beam 41. It becomes a parallel light beam and is focused on the end surface 37b by the collimator lens holder, and this blaze e has a length λo
The angle between the slope 33b of the n-blaze and the plane of the entire diffraction grating, that is, the blaze angle, is θ (expressed by equation 11).

λo = (2d/m)・sin e...
4...... Song...+11 Here, d is the lattice constant of the diffraction grating 33, and the sacrifice is the rotation order.

Curve A in FIG. 6 shows the end face 37bK, ! 1
m = 1 ('
), and as is clear from the figure, this spectral distribution is a sharp mountain-like distribution with the peak wavelength at the center wavelength λ0, and the wavelength λ0 corresponds to the lattice constant d by (1) 2. It is the wavelength. Since the lattice constant d changes depending on the W3 tension or convergence due to the temperature of the diffraction grating,
7) By measuring the wavelength λ0 i, we can determine the temperature of the diffraction grating. You will be able to know the degree of grave.

Note that the song 4B shown in Figure 6 is the original spectral distribution projected onto the diffraction grating, and as mentioned above, this distribution is
It has a wide range of growth in OV, and the song, ;,,i
t A's peak 11 is almost above the song 11.

1. In other words, as explained above, in the temperature measuring device of F↓2121, the light emitted from the light emitting element 19 is projected onto the v1 grating in the warm box exit part δ, and here, The reflected tt is guided to the light receiving section 6, and the spectral distribution of this reflected light pressure is detected by a photodiode array. Therefore, from the configuration i of this photodiode array to n
(By calculating the peak wavelength λ0 mentioned in 1), the temperature 1〈 of the nearby country of the diffraction grating in ``C thermal detection section'' can be determined by 6111, so the measurement result obtained by using such a temperature measuring device is The output fluctuation of the light-emitting cable 19 as the original Jll and the original fiber J as the optical transmission member.

n,'d! A, Half Mirror 2 Eheda no Koden 11sj The shadow of the shell change is not received, and it is like this lL
The temperature detection unit 7A is configured such that each member such as the diffraction grating and the diffraction grating mount 31 located at the point W is 1 at Ih as described above.
1, it has extremely good heat resistance and durability.

In the above-described embodiment, C1, for example, a transmission member for light incident on temperature Yokode group B and a transmission member for light emitted by reflection from this detection portion i1.2 are connected to one optical fiber &λ1-. I19+j
i; In order to be able to
5f.
When a light is incident on the slope 33b of the blaze at an angle of incidence of 6 at v1' grating, j and $, the specular reflection final condition with a diffraction angle of - and 7L is 7+' in the n4 direction. On the other hand, ゛Tourism 1d (2d/m)・8in6@cO
Since Sg has a peak wavelength and 71 spectral distribution, the zero emitted H1j and this reflected light are different from the second optical fiber. It is also possible to measure the temperature LL.

〔Effect of the invention〕

As explained above, an unexploded +31J K is a light that has a wide spectral distribution in a diffraction grating that changes depending on the temperature and the number of +j'J in the grating changes depending on the temperature. is projected through a light transmission member, and the reflected light by the 4ji grid of this projected light is the same as the previous light transmission section or has a spectroscopic function by using a different light transmission group. The temperature measurement device WY is used to determine the temperature of the three sides of the diffraction grating tL from the peak branch of the spectral portion 41i of the reflected light based on the result of the spectral portion 41i of the reflected light. As a result of this, the peak branches (which are used in this type of rectangular lattice) are
When projecting t (, source strength I, light transmission part I, 7
Since the optical transmission loss is an absolute value, the temperature measurement device of the present invention includes a light output change DC+ and an optical transmission part fC3.
This has the advantage of being able to perform temperature measurements without being affected by transmission losses.

Figure 4.1 shows the conventional temperature measuring device (i diagram, 2nd diagram).
The figure is a sub-figure of one embodiment of the optical temperature measurement value according to the present invention, and FIG.
Fig. 4 is an enlarged view of the main part of No. 31, and Figs.

18... Optical temperature measuring device 1. ', 19... Light emitting element as a light source, 22.24... Optical fiber as a light transmission member, 5... Light receiving di1.33
... Diffraction grating, λ0... Heak wavelength.

Ichika Technical Director Kawa 1) Hakube Possible 7 f mouth Stomach 2 diagram Figure 5

Claims (1)

[Claims] 1) A light source with a wide spectral distribution, a diffraction grating whose lattice constant changes due to expansion or contraction due to temperature change, and optical transmission that transmits light from the light source to the diffraction grating and transmits reflected light from the diffraction grating. member, and a light receiving section that spectrally spectrally reflects the reflected light transmitted by the light transmitting member, and calculates the area around the diffraction grating from the value of the peak wavelength of the spectral distribution of the reflected light based on the spectral results in the light receiving section. An optical temperature measuring device characterized by measuring temperature.