JP2006029995A - Optical method and instrument for measuring physical quantity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical physical quantity measuring instrument of high measuring precision by simple constitution. <P>SOLUTION: Light from a light source 11 is received by a slant type grating 13 to make transmission light intensity changed inclinedly within a gradient wavelength range in response to a wavelength getting long, the light from the slant type grating 13 is received by a Bragg grating 15 to transmit the light having one characteristic of a prescribed wavelength width within the gradient wavelength range, the light from the Bragg grating 15 is received by a photoreception part 17 to be converted into photoreception intensity, and fluctuation of physical quantity applied onto the Bragg grating 15 is converted thereby into the photoreception intensity by the photoreception part 17. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical physical quantity measuring device, and provides an optical physical quantity measuring device capable of measuring a physical quantity with a particularly simple structure.

  An optical waveguide is an optical component having a structure for propagating light along a predetermined path, and generally has a structure in which the outer periphery of a core having a high refractive index is covered with a clad having a refractive index lower than that of the core. It has a structure that allows light to propagate through it. Examples of the material of the optical waveguide include silica-based glass and polymer. In particular, an optical waveguide made of silica-based glass has a small propagation loss and is widely used for large-capacity communication and long-distance communication. Typical examples of these optical waveguides include optical fibers and substrate type optical waveguides.

  When periodic perturbation is applied to this optical waveguide, it can be used as an optical filter that emits light out of the waveguide according to the period or reflects only light of a specific wavelength. The component is called a grating type optical component.

  In the case of periodic perturbations in the waveguide due to refractive index changes, a light-sensitive substance is added to the optical waveguide, and light corresponding to the photosensitive substance is irradiated (exposed) to the optical waveguide. The manufacturing method is widely used. However, the photosensitivity referred to here is a property in which the refractive index of a substance is changed by light irradiation.

  Among the grating-type optical filters, the one having the characteristic of reflecting light having a specific wavelength guided in the reverse direction is called a Bragg grating. The reflection wavelength of the Bragg grating is determined by the grating period and the refractive index of the optical waveguide. For this reason, the reflection center wavelength of the Bragg grating also changes due to periodic fluctuations and refractive index changes caused by temperature changes and strain application. Therefore, by measuring the change in the center wavelength, it can be used as an optical physical quantity measuring device for measuring physical quantities such as temperature and strain in the grating section.

  As such an optical physical quantity measuring device, for example, Patent Literature 1, Patent Literature 2, and Patent Literature 3 disclose examples of sensors that measure distortion by a reflection wavelength from a Bragg grating. Patent Document 4 discloses a sensor that measures distortion by measuring the intensity of reflected light from two fiber Bragg gratings.

  In the methods shown in Patent Document 1, Patent Document 2 and Patent Document 3, the wavelength spectrum of reflected light is measured in order to measure the fluctuation of the central wavelength depending on the light intensity wavelength reflected from the grating. Yes.

On the other hand, Patent Document 4 discloses a method of measuring the intensity of reflected light by combining two fiber Bragg gratings. This utilizes the fact that two Bragg gratings are produced and the reflected light intensity changes in accordance with the degree of overlap of the reflection spectra, that is, the amount of wavelength fluctuation. By using this method, wavelength spectrum measurement is not necessary, and an inexpensive configuration can be achieved.
JP 2000-221085 A JP 2001-183248 A JP 2003-65730 A JP 2000-346722 A

  However, in the methods shown in Patent Document 1, Patent Document 2 and Patent Document 3, in order to measure the wavelength spectrum, an optical spectrum analyzer or a device combining a wavelength variable light source and an optical power meter is used. These devices are very expensive, and an operation for obtaining the center wavelength from the measured spectrum shape is required. Therefore, an expensive operation device and a time required for the operation are also required.

  In addition, the grating characteristics change with respect to two changes of temperature and strain. Therefore, when measuring strain, temperature compensation is necessary to separate the change due to temperature and the change due to strain. Usually, the temperature compensation uses a method of measuring the center wavelength of the reflection spectrum from two gratings and calculating the temperature and strain from these two values. As a result, it is difficult to increase the measurement accuracy in addition to the need for arithmetic processing to perform temperature compensation.

  On the other hand, in the method shown in Patent Document 4, there is reflected light from the grating even when the reflection spectra of the two gratings, which are the conditions where the reflected light intensity is the smallest, are completely overlapped. The measurement range becomes smaller. In addition, since there is always reflected light from the Bragg grating, there is a problem that small fluctuations in light intensity cannot be measured with high accuracy.

  It was also difficult to make a linear relationship between wavelength fluctuation and light intensity. Further, in order to increase the distortion measurement range in the grating section, it is necessary to widen the reflection spectrum band of the Bragg grating, but there is also a problem that the measurement cannot be performed with accuracy as the width is increased.

  Furthermore, since reflections by the two gratings are large, multiple reflections occur between the gratings, and it is difficult to accurately measure intensity changes due to minute wavelength fluctuations due to intensity changes due to the multiple reflections.

  The present invention has been made in view of the above, and an object thereof is to provide an optical physical quantity measuring apparatus having a simple configuration and high measurement accuracy.

  In order to solve the above problem, the invention according to claim 1 is a light source that emits light in a predetermined wavelength range, and the transmitted light intensity changes in an inclined manner as the wavelength of the light received from the light source becomes longer. A gradient filter using a slanted grating having a gradient wavelength range, a Bragg grating having one transmission characteristic of a predetermined wavelength width within the gradient wavelength range of the gradient filter, and having sensitivity within the gradient wavelength range, The gist of the present invention is to provide a gradient filter and a light receiving unit that converts light transmitted through the Bragg grating into received light intensity, and to convert a change in physical quantity applied to the Bragg grating into received light intensity by the light receiving unit.

  In order to solve the above problems, the invention according to claim 2 is a light source that emits light in a predetermined wavelength range, and the transmitted light intensity changes in an inclined manner as the wavelength of the light received from the light source becomes longer. An inclined filter using a slanted grating having an inclined wavelength range, and a Bragg grating having one reflection characteristic having a predetermined wavelength width within the inclined wavelength range of the inclined filter, provided between the light source and the inclined filter Branching the light from the light source to the inclined filter and branching the light from the inclined filter to the other, and having sensitivity within the inclined wavelength range; A light receiving unit that converts light received via the light receiving intensity into light receiving intensity, and a change in physical quantity applied to the Bragg grating is converted into light receiving intensity by the light receiving unit. The gist of the door.

  In order to solve the above problems, the invention according to claim 3 is a light source that emits light in a predetermined wavelength range, and the transmitted light intensity changes in an inclined manner as the wavelength of the light received from the light source becomes longer. An inclined filter using a slanted grating having an inclined wavelength range, a Bragg grating having one transmission / reflection characteristic of a predetermined wavelength width within the inclined wavelength range of the inclined filter, and having sensitivity within the inclined wavelength range A first light receiving unit that converts light transmitted through the gradient filter and the Bragg grating into received light intensity, and is provided between the light source and the gradient filter, and branches light from the light source to the gradient filter. And a branching part for branching the light from the tilted filter to the other, and having sensitivity within the tilted wavelength range, and passing through the branching part from the tilted filter The received light and a second light receiving section for converting the received light intensity Te, and summarized in that converting the variation of the physical quantity applied to the Bragg grating to the light-receiving intensity by the first and second light receiving portions.

  In order to solve the above problem, the invention according to claim 4 is a light source that emits light in a predetermined wavelength range, and the transmitted light intensity changes in an inclined manner as the wavelength of the light received from the light source becomes longer. A gradient filter using a slanted grating having a gradient wavelength range, a Bragg grating having one transmission characteristic of a predetermined wavelength width within the gradient wavelength range of the gradient filter, and having sensitivity within the gradient wavelength range, A first light receiving unit that converts light received from the Bragg grating into received light intensity, provided between the light source and the gradient filter, and branches a part of the light from the light source to the gradient filter, A branching portion for branching light from the light source to the other, and a sensitivity having sensitivity within the tilt wavelength range, and converting light received from the light source via the branching portion into received light intensity. And a light receiving portion, and be required to convert the variation of the physical quantity applied to the Bragg grating to the light-receiving intensity by the first and second light receiving portions.

  In order to solve the above problems, the invention according to claim 5 is a light source that emits light in a predetermined wavelength range, and the transmitted light intensity changes in an inclined manner as the wavelength of the light received from the light source becomes longer. An inclined filter using a slanted grating having an inclined wavelength range; and a Bragg grating having one transmission / reflection characteristic of a predetermined wavelength width within the inclined wavelength range of the inclined filter, wherein the inclined filter and the Bragg grating A first branching section that is provided in between and branches the light from the tilted filter to the Bragg grating and branches the light from the tilted filter to the other; and has sensitivity within the tilted wavelength range; A first light-receiving unit that converts light received from the filter through the first branching unit into received light intensity, and is provided between the light source and the gradient filter. A second branching unit for branching light from the light source to the tilted filter and for branching light from the tilted filter to the other, and having sensitivity within the tilted wavelength range; And a second light receiving unit that converts light received through the two branching units into received light intensity, and changes in physical quantity applied to the Bragg grating into received light intensity by the first and second light receiving units. And

  In order to solve the above problems, the invention according to claim 6 is a light source that emits light in a predetermined wavelength range, and the transmitted light intensity changes in an inclined manner as the wavelength of the light received from the light source becomes longer. An inclined filter using a slanted grating having an inclined wavelength range; and a Bragg grating having one transmission / reflection characteristic of a predetermined wavelength width within the inclined wavelength range of the inclined filter, and between the light source and the inclined filter. A branching section for branching light from the light source to the other side and branching light from the tilting filter to the other side, and having sensitivity within the tilt wavelength range, and the light source A first light receiving unit that converts light received through the branch unit into received light intensity, and has sensitivity within the tilt wavelength range, and receives light from the tilt filter through the branch unit. Provided and the second light receiving unit that converts light into received light intensity, and be required to convert the variation of the physical quantity applied to the Bragg grating to the light-receiving intensity by the first and second light receiving portions.

  In order to solve the above-mentioned problem, the gist of the present invention is that it includes a calculation unit that inputs the received light intensity from the first and second light receiving units and calculates the received light intensity ratio from both.

  In order to solve the above problems, the invention according to claim 8 is a light source that emits light in a predetermined wavelength range, and the transmitted light intensity changes in an inclined manner as the wavelength of the light received from the light source becomes longer. A tilt filter using a slanted grating having a tilt wavelength range, a Bragg grating having one reflection characteristic of a predetermined wavelength width within the tilt wavelength range of the tilt filter, and both longitudinal ends of the tilt filter are fixed. A fixed base material for fixing one end in the longitudinal direction of the Bragg grating on the side close to the inclined filter, and a movable base material for fixing the other end of the Bragg grating movably in the longitudinal direction, the inclined wavelength range And a light receiving unit that converts light received from the inclined filter through the branching unit into received light intensity, and And summarized in that the converting the displacement amount applied to the Bragg grating from the moving substrate to the received light intensity by the light receiving unit.

  In order to solve the above problems, the invention according to claim 9 is a light source that emits light in a predetermined wavelength range, and the transmitted light intensity changes in an inclined manner as the wavelength of the light received from the light source becomes longer. A tilt filter using a slanted grating having a tilt wavelength range, a Bragg grating having one reflection characteristic having a predetermined wavelength width within the tilt wavelength range of the tilt filter, and a first end that fixes both ends in the longitudinal direction of the tilt filter. A fixed substrate; a second fixed substrate that fixes both ends in the longitudinal direction of the Bragg grating; and a light-receiving unit having sensitivity within the tilt wavelength range, and the Bragg from both ends of the second fixed substrate. The gist of the invention is to convert the fluctuation of the temperature applied to the grating into the received light intensity by the light receiving unit.

  In order to solve the above-described problem, the invention according to claim 10 includes a correction filter that corrects the wavelength dependence of the measurement system by the light source and the light receiving unit in the middle of the optical path between the light source and the light receiving unit. Is the gist.

  In order to solve the above problems, the invention according to claim 11 is characterized in that the inclined filter is composed of a slanted grating having a slant angle in a range of 1 to 15 degrees and a reflectance of 5% or less. And

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as an optical physical quantity measuring apparatus with a simple structure and high measurement precision.

  The best mode for carrying out the invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram showing a configuration example of a transmissive optical physical quantity measuring apparatus 10 according to the first embodiment of the present invention.

  As shown in FIG. 1, the transmissive optical physical quantity measuring device 10 includes a light source 11 that emits light within an inclined wavelength range 21 of a slanted grating, which will be described later, and a longer wavelength of light received from the light source 11. One slant type grating 13 constituting an inclined filter having an inclined wavelength range in which transmitted light intensity increases in an inclined manner, and one transmission characteristic having a wavelength width within the inclined wavelength range 21 of light received from the slanted grating 13 The Bragg grating 15, the light receiving portion 17 that has a substantially flat light receiving sensitivity within the inclined wavelength range 21 of the slanted grating 13, and converts the light received from the Bragg grating 15 into received light intensity, and these optical components are optically The optical waveguides 19a, 19b, and 19c are connected to each other.

  Here, the slant-type grating is a filter in which the grating of the Bragg grating is inclined at a specific slant angle θ from a plane perpendicular to the light transmission direction, as indicated by 13 in FIG.

  In addition, when calculating the moving average of the spectrum of the gradient filter with the full width at half maximum (FWHM) of the Bragg grating used, there is a form that monotonously decreases or monotonically increases in the wavelength range to be used. Yes.

  2A is a graph showing light emission within the tilted wavelength range 21 as the wavelength characteristic of the light source 11, and FIG. 2B is a graph showing the transmitted light within the tilted wavelength range 21 as the wavelength characteristic of the slant grating 13. It is a graph which shows that an intensity | strength inclines, (c) is a graph which shows having a peak centering on a certain wavelength as a wavelength characteristic of the Bragg grating 15, (d) is an inclination wavelength as a wavelength characteristic of the light-receiving part 17. 6 is a graph showing that the area 21 is almost flat.

  In FIG. 3, (a) is a graph showing the wavelength fluctuation that varies according to the change in the physical quantity to be measured, and (b) is a graph showing the received light intensity measured by the light receiving unit 17.

  Next, with reference to FIG. 2 and FIG. 3, the principle of measuring a physical quantity with the transmission optical physical quantity measuring apparatus 10 will be described.

  The light emitted from the light source 11 has a substantially flat wavelength characteristic within the inclined wavelength range 21 as shown in FIG. 2A, and this light passes through the slanted grating 13 to cause the light to pass through FIG. As shown in (b), the transmitted light intensity increases in an inclined manner as the wavelength of light increases.

  Further, the light transmitted through the slant-type grating 13 is transmitted through the Bragg grating 15 serving as a bandpass filter having one transmission characteristic of a certain wavelength width, so that a specific wavelength is obtained as shown in FIG. As shown in FIG. 2D, only the light is transmitted and is incident on the light receiving unit 17 having a substantially flat wavelength characteristic within the tilt wavelength range 21. By detecting this light by the light receiving unit 17, the light intensity within the wavelength band of the Bragg grating 15 can be measured.

  At this time, when the wavelength characteristics of the slanted grating 13 or the Bragg grating 15 are shifted in accordance with the change in the physical quantity to be measured, the amount of transmitted light changes according to the wavelength characteristics of the transmission loss of the slanted grating 13. Thereby, the physical quantity to be measured can be converted into light intensity and can be applied as a sensor.

For example, as shown in FIG. 3A, the slanted grating 13 has a gradient characteristic in which the transmitted light intensity increases as the wavelength characteristic becomes longer, and the Bragg grating 15 changes according to the change in the physical quantity to be measured. Is changed from λ _a to λ _b . At this time, as shown in FIG. 3B, the light intensity measured in the light receiving unit 17 indicates the amount of wavelength variation.

  Of course, if the relative wavelength relationship between the Bragg grating 15 and the slanted grating 13 changes, the wavelength change can be converted into a change in light intensity measured by the light receiving unit 17. Therefore, when the wavelength λ of the Bragg grating 15 is fixed and the wavelength characteristics of the slanted grating 13 change, or when the Bragg grating 15 and the slanted grating 13 exhibit different wavelength fluctuations due to changes in the physical quantity to be measured, the same applies. Result is obtained.

  By adopting the configuration as in the first embodiment, a device for measuring the wavelength spectrum required by the method described in Patent Document 1, Patent Document 2, and Patent Document 3 described above becomes unnecessary. The apparatus can be configured easily.

  Further, by using the slant type grating 13 for the gradient filter, the wavelength variation due to the temperature change of the gradient filter and the Bragg grating 15 shows almost the same characteristics. Therefore, even if the temperature of the slant type grating 13 and the Bragg grating 15 changes, The relative wavelength relationship between the two gratings does not change. For this reason, even if it does not make a special temperature compensation structure, it can be set as the structure where the light intensity in the light-receiving part 17 by a temperature change does not change.

  For this reason, when used as a strain sensor in which the physical quantity to be measured is transmitted as the strain of the grating, a Bragg grating for temperature compensation required by the methods shown in Patent Document 1, Patent Document 2, and Patent Document 3 is separately provided. There is no need to prepare, and a highly accurate sensor can be configured with a simple and inexpensive apparatus configuration.

  According to the present invention, it is possible to reduce the reflection at the inclined filter by using the slanted grating as the inclined filter. As a result, it is possible to widen the range of change in light intensity due to wavelength variation, which was impossible with the method of combining two fiber Bragg gratings disclosed in Patent Document 4, and to improve measurement accuracy. Can be obtained.

  In addition, the fact that the influence of multiple reflections between gratings can be reduced can also contribute to the improvement of measurement accuracy by this configuration.

  In addition, multiple reflection means a phenomenon in which reflection is repeated many times between the gratings. When two ordinary FBGs (optical fiber gratings) are connected in series, there is reflection in each grating. Repeated reflections occur. On the other hand, in the case of a slant type grating, since the reflection is smaller than that of the FBG, such a phenomenon hardly occurs even when combined with the FBG.

  As a physical quantity that can be measured by the optical physical quantity measuring apparatus of the present invention, it is sufficient that the wavelength characteristic of the grating changes due to a change in the physical quantity, and examples thereof include temperature, pressure, strain, distance, and the like.

[Second Embodiment]
FIG. 4 is a diagram illustrating a configuration example of the reflective optical physical quantity measuring device 30 according to the second embodiment of the present invention.

  As shown in FIG. 4, the reflection type optical physical quantity measuring device 30 is characterized in that the traveling direction of light between the light source 11 and the slanted grating 13 in addition to the first embodiment shown in FIG. The beam splitter 31 is provided to branch the beam, and the light reflected by the Bragg grating 15 after passing through the slant grating 13 once passes through the slant grating 13 again, is emitted from the slant grating 13, and is branched by the beam splitter 31. The light intensity is measured by the light receiving unit 33 when the light is received by the light receiving unit 33. These components are optically connected by optical waveguides 35a, 35b, 35c, 35d, and 35e.

  5A is a graph showing the wavelength characteristics of the light source 11, FIG. 5B is a graph showing the wavelength characteristics of the slanted grating 13, and FIG. 5C is a graph showing the wavelength characteristics of the Bragg grating 15. The graph shows the wavelength characteristic of the light receiving unit 33, which has one reflection characteristic having a predetermined wavelength width within the tilt wavelength range of the light received from the slanted grating 13. FIG.

  Next, with reference to FIG. 4 and FIG. 5, the principle of measuring a physical quantity with the optical physical quantity measuring device 30 will be described.

  The light emitted from the light source 11 has a substantially flat wavelength characteristic within the inclined wavelength range 37 as shown in FIG. 5A, and this light is branched in the direction of the slanted grating 13 by the beam splitter 31. Then, when the light branched by the beam splitter 31 is transmitted through the slanted grating 13, as shown in FIG. 5B, a loss that varies depending on the wavelength is generated and the light intensity depends on the wavelength.

  Furthermore, as shown in FIG. 5C, only a specific wavelength is reflected by being reflected inside the Bragg grating 15 that functions as a bandpass filter having one reflection characteristic of a certain wavelength width. On the other hand, the light having a wavelength that is not reflected inside the Bragg grating 15 is transmitted as it is and emitted to the outside from the optical waveguide 35d.

  The light having a specific wavelength reflected inside the Bragg grating 15 is again transmitted through the slanted grating 13 and incident on the beam splitter 31, and is branched in the direction of the light receiving unit 33 by the beam splitter 31. Is incident on. That is, as shown in FIG. 5D, the light is incident on the light receiving unit 33 having a substantially flat wavelength characteristic within the inclined wavelength range 37. By detecting this light with the light receiving unit 33, the light intensity within the wavelength band of the Bragg grating 15 can be measured.

  At this time, when the wavelength characteristics of the slanted grating 13 or the Bragg grating 15 are shifted in accordance with the change in the physical quantity to be measured, the amount of transmitted light changes according to the wavelength characteristics of the transmission loss of the slanted grating 13. Thereby, the physical quantity to be measured can be converted into light intensity and can be applied as a sensor.

For example, as shown in FIG. 3A, the wavelength characteristic of the slanted grating 13 is an inclination characteristic, and the wavelength of the Bragg grating 15 is changed from λ _a to λ _b according to the change of the physical quantity to be measured. And At this time, as shown in FIG. 3B, the light intensity measured in the light receiving unit 33 indicates the amount of wavelength variation.

  Of course, if the relative wavelength relationship between the Bragg grating 15 and the slanted grating 13 changes, the wavelength change can be converted into a change in light intensity measured by the light receiving unit 33. Therefore, when the wavelength λ of the Bragg grating 15 is fixed and the wavelength characteristics of the slanted grating 13 change, or when the Bragg grating 15 and the slanted grating 13 exhibit different wavelength fluctuations due to changes in the physical quantity to be measured, the same applies. Result is obtained.

  By adopting the configuration as in the second embodiment, a device for measuring the wavelength spectrum required by the method described in Patent Document 1, Patent Document 2, and Patent Document 3 described above becomes unnecessary. The apparatus can be configured easily. Further, by using the slant type grating 13 for the gradient filter, the wavelength variation due to the temperature change of the gradient filter and the Bragg grating 15 shows almost the same characteristics. Therefore, even if the temperature of the slant type grating 13 and the Bragg grating 15 changes, The relative wavelength relationship between the two gratings does not change. For this reason, even if it does not use a special temperature compensation structure, it can be set as the structure where the light intensity in the light-receiving part 33 by a temperature change does not change.

  For this reason, when used as a strain sensor in which the physical quantity to be measured is transmitted as the strain of the grating, a Bragg grating for temperature compensation required by the methods shown in Patent Document 1, Patent Document 2, and Patent Document 3 is separately provided. There is no need to prepare the sensor, and the apparatus configuration is simple, and a highly accurate sensor can be obtained.

  According to the present invention, it is possible to reduce the reflection at the inclined filter by using the slanted grating as the inclined filter. As a result, it is possible to widen the range of the amount of change in light intensity due to wavelength fluctuations, which was impossible with the method of combining two fiber Bragg gratings disclosed in Patent Document 4, and the measurement accuracy is improved. it can. Further, the influence of multiple reflections between the gratings can be reduced, which contributes to improvement in measurement accuracy by this method.

  As a physical quantity to be measured using the present invention, various physical quantities can be measured by adopting a structure in which the wavelength characteristic of the grating changes due to the change in the physical quantity. For example, temperature, pressure, strain, distance, etc. Is mentioned.

[About optical waveguide]
In the first and second embodiments described above, some or all of the optical waveguides 19a to 19c and 35a to 35e may be optical fibers.

  By using an optical fiber as the optical waveguide, light can be transmitted over a long distance, and sensing at a remote point becomes possible. In particular, the light source 11 and the light receiving units 17 and 33 require a power source and are also susceptible to electromagnetic noise. On the other hand, the slanted grating 13 and the Bragg grating 15 do not require a power source, and are resistant to electromagnetic noise. Therefore, by installing only the grating part at the point where the physical quantity is actually measured, it is possible regardless of the surrounding conditions. Stable measurement is possible.

  For example, the distance between the sensing portion, that is, the grating portion, the light source 11 and the light receiving component can be separated by 1 meter or more, and the noise generated in the sensing portion affects the light source 11 and the light receiving portions 17 and 33 and the electronic circuit portion that analyzes them. Can be reduced.

  In addition, since optical fibers are widely used for optical communications, there is an advantage that they are inexpensive and easy to procure.

  Examples of this include measuring strain in tunnels and cliffs, measuring building strains, using pressure sensors to measure water levels, and measuring strain on large generators. Cases.

  As the optical fiber to be used, optical fibers made of various materials such as quartz glass and polymer can be used. However, it is desirable that the optical fiber be single mode in the wavelength band to be used. This is because a multi-mode fiber has different wavelength characteristics in different modes, and measurement accuracy is not stable.

[About slant type grating and Bragg grating]
In the first and second embodiments described above, the optical waveguide in which the slanted grating 13 and the Bragg grating 15 are manufactured may be an optical fiber.

  By manufacturing the slanted grating and the Bragg grating using an optical fiber widely used for communication, an inexpensive optical component can be obtained. Further, since the optical fiber is usually thin with a diameter of about 125 μmφ, the amount of deformation due to a change in the tension of the fiber can be increased, so that it is easy to obtain a highly sensitive sensor. In addition, there is an advantage that the loss due to the connection can be reduced by manufacturing the optical waveguide connecting the components with the optical fiber.

[Substrate for slanted and Bragg gratings]
In the first and second embodiments described above, the optical fibers on which the slanted grating 13 and the Bragg grating 15 are manufactured may be fixed to base materials having different linear expansion coefficients.

  By fixing the slant type grating and the Bragg grating to the base materials having different linear expansion coefficients, it becomes possible to change the wavelength fluctuation amount of each grating due to the temperature change. For this reason, application to a temperature sensor is easily possible.

[Reflectance of slanted grating]
In the first and second embodiments described above, the reflectance of the slanted grating in the tilt wavelength range 21 to be used is preferably 5% or less.

  Compared with a normal Bragg grating in which the diffraction grating is perpendicular to the light propagation direction, the slanted grating 13 in which the diffraction grating is inclined can reduce the reflected light intensity. In particular, by appropriately setting the slant angle θ and setting the reflectance to 5% or less, the influence of the reflected light from the slanted grating 13 on the measurement accuracy can be almost eliminated, and accurate measurement is possible. It becomes.

  In addition, the influence of multiple reflection between the Bragg grating 15 and the slanted grating 13 can be reduced. Note that the slant angle θ necessary for setting the reflectance to 5% or less depends on the shape of the optical waveguide to be used, but is in the range of about 1 to 15 degrees. It becomes 5% or more.

[Third Embodiment]
FIG. 6 is a diagram showing a configuration example of a transmission / reflection type optical physical quantity measuring apparatus 40 according to the third embodiment of the present invention.

  As shown in FIG. 6, in addition to the second embodiment shown in FIG. 4, the transmission / reflection type optical physical quantity measuring device 40 receives the light transmitted through the Bragg grating 15 through the optical waveguide 35d. The light receiving unit 17 receives light and inputs the received light intensity from the light receiving units 17 and 33 to the calculation unit 41 to calculate the ratio of received light intensity from both. The arithmetic unit 41 is provided with two A / D converters inside, and voltage signals representing the respective received light intensities inputted from the light receiving units 17 and 33 are converted into voltage data by the A / D converter. The received light intensity ratio is calculated by calculating the ratio of the voltage data of the two.

  In particular, the Bragg grating 15 has one transmission / reflection characteristic having a wavelength width within the tilt wavelength range of the light received from the slant-type grating 13, and the light transmitted through the slant-type grating 13 and the Bragg grating 15. While the light receiving unit 17 receives light, the reflected light that is reflected by the Bragg grating 15 and branched from the slanted grating 13 by the beam splitter 31 is received by the light receiving unit 33, and the calculation unit 41 receives two light beams from the light receiving units 17 and 33. The received light intensity ratio is calculated from the light intensity to correct the light intensity of the light source 11.

  Since the light receiving unit 17 measures the intensity change of the light source 11 by the transmitted light, the light intensity change at the light source 11 out of the intensity change of the reflected light can be corrected, and accurate and stable measurement is possible. .

Here, the transmittance of the beam splitter 31 is b _T (λ), the branching rate is b _R (λ), the loss in the slanted grating 13 is S (λ), and the reflectance in the Bragg grating 15 is f _R (λ ) If the power of the light source 11 is P (λ), the respective light intensities P ₁ and P ₂ at the light receiving portions 17 and 33 are

Can be written. Here, b _T (λ) and b _R (λ) are constants and can be taken out of the integration by measuring in advance.

Further, when the wavelength dependence of the light source 11 can be ignored within the used wavelength band, the power P (λ) can be out of the integration. Therefore, by taking the ratio of the light intensities P ₁ and P ₂ ,

Thus, since the power P (λ) can be eliminated from the equation, it is possible to correct the influence due to the intensity variation of the light source 11.

[Fourth Embodiment]
FIG. 7 is a diagram showing a configuration example of a transmissive optical physical quantity measuring device 50 according to the fourth embodiment of the present invention.

  As shown in FIG. 7, the transmissive optical physical quantity measuring device 50 is different from the third embodiment shown in FIG. 6 in that a beam splitter 51 having a different transmission / reflection surface inside the beam splitter 31 is used. It is in having established. In particular, a beam splitter 51 for branching a part of the guided light is inserted in the middle of the optical waveguides 35a and 35b for entering light from the light source 11 to the slanted grating 13 and the Bragg grating 15, and the intensity of the branched light is received. It is to convert the intensity of the light source 11 by measuring at the unit 33.

Here, the transmittance of the beam splitter 51 is b _T (λ), the branching rate is b _R (λ), the loss in the slanted grating 13 is S (λ), and the reflectance in the Bragg grating 15 is f _R (λ ) And the power of the light source 11 is P (λ), the respective light intensities P ₁ and P ₂ at the light receiving portions 17 and 33 are

Can be written.

Here, the transmittances b _T (λ) and b _R (λ) are constants and can be taken out of the integration by measuring in advance.

Further, when the wavelength dependence of the light source 11 can be ignored within the used wavelength band, the power P (λ) can be out of the integration. Therefore, by taking the ratio of the light intensities P ₁ and P ₂ ,

Thus, since the power P can be eliminated from the equation, it is possible to correct the influence due to the intensity variation of the light source 11.

[Fifth Embodiment]
FIG. 8 is a diagram showing a configuration example of a reflective optical physical quantity measuring device 55 according to the fifth embodiment of the present invention.

  As shown in FIG. 8, the reflective optical physical quantity measuring device 55 is different from the third embodiment shown in FIG. 6 in that a beam splitter 57 is provided in the middle of the optical waveguide 35c. The branched light is to be measured by the light receiving unit 59.

  In particular, a beam splitter 57 for branching a part of the guided light is inserted in the middle of the optical waveguides 35 c and 35 d for allowing light to enter the Bragg grating 15 from the light source 11 through the slanted grating 13 and branched by the beam splitter 57. The light intensity is converted into the intensity of the light source 11 by measuring the intensity of the light with the light receiving unit 59.

Here, the transmittance of the first beam splitter 31 is b _T1 (λ), the branching rate is b _R1 (λ), the transmittance of the second beam splitter 57 is b _T2 (λ), and the branching rate is b _R2 ( λ), the loss at the slanted grating 13 is S (λ), the reflectance at the Bragg grating 15 is f _R (λ), and the power of the light source 11 is P (λ). The respective light intensities P ₁ and P ₂ are

Can be written.

Here, b _T1 (λ), b _R1 (λ), b _T2 (λ), and b _R2 (λ) are constants and can be taken out of the integration by measuring in advance. Further, when the wavelength dependence of the light source 11 can be ignored within the used wavelength band, the power P (λ) can be out of the integration. Therefore, by taking the ratio of the light intensities P ₁ and P ₂ ,

Thus, since the power P can be eliminated from the equation, it is possible to correct the influence due to the intensity variation of the light source.

  As the beam splitter 57 used for optical branching, a directional coupler type optical coupler obtained by melting and stretching an optical fiber can be used.

[Sixth Embodiment]
FIG. 9 is a diagram showing a configuration example of a transmission / reflection type optical physical quantity measuring apparatus 60 according to the sixth embodiment of the present invention.

  As shown in FIG. 9, the transmission / reflection type optical physical quantity measuring device 60 is different from the second embodiment shown in FIG. 4 in that an optical coupler 61 is provided in the middle of the optical waveguides 35a and 35b. The light branched by the coupler 61 is to be measured by the light receiving parts 63 and 65. In particular, the optical coupler 61 that branches the light from the light source 11 is used, the reflected light from the Bragg grating 15 is also branched, and the reflected light intensity is measured by the light receiving unit 63.

Here, the transmittance of the optical coupler 61 is T (λ), the loss at the slanted grating 13 is S (λ), the reflectance at the Bragg grating 15 is f _R (λ), and the power of the light source 11 is P ( λ), the respective light intensities P ₁ and P ₂ at the light receiving parts 63 and 65 are

Can be written.

Here, T (λ) is a constant and can be taken out of the integration by measuring in advance. Further, when the wavelength dependence of the light source 11 can be ignored within the used wavelength band, the power P (λ) can be out of the integration. Therefore, by taking the ratio of the light intensities P ₁ and P ₂ ,

Thus, since the power P can be eliminated from the equation, it is possible to correct the influence due to the intensity variation of the light source 11.

  As such an optical coupler 61, a directional coupler type optical coupler obtained by melting and stretching an optical fiber can be used.

  By using the optical coupler 61 that branches the transmitted light and the reflected light at the same time, it is possible to branch the light intensity change of the light source 11 and the light intensity change due to the change of the physical quantity simultaneously with one component. Therefore, it is possible to obtain a low-cost and highly accurate configuration.

[Seventh Embodiment]
FIG. 10 is a diagram showing a configuration example of a transmissive optical physical quantity measuring device 70 according to the seventh embodiment of the present invention.

  As shown in FIG. 10, the transmissive optical physical quantity measuring device 70 is used in the middle of the optical waveguides 19a and 19b immediately after the light source 11, as compared with the first embodiment shown in FIG. The purpose is to insert a correction filter 71 for correcting the wavelength dependency of the optical component.

  Here, with reference to the wavelength characteristic of the correction filter shown in FIG. 11, the effect of inserting the correction filter 71 will be described.

  FIG. 11A shows that the intensity of the light source 11 has wavelength dependency, and FIG. 11B shows that the sensitivity of the light receiving unit 17 has wavelength dependency. Here, when the wavelength dependency of the intensity of the light source 11 is multiplied by the wavelength dependency of the sensitivity of the light receiving unit 17, the wavelength dependency of the measurement system is obtained as shown in FIG.

  In order to correct the wavelength dependence of the measurement system to a substantially flat wavelength characteristic, a correction filter 71 having a loss characteristic capable of canceling the wavelength dependence of the measurement system as shown in FIG. What is necessary is just to insert in the middle of the optical waveguides 19a and 19b.

  That is, the correction filter 71 only needs to have the wavelength dependency of transmittance as shown in FIG. 11D. If such a correction filter 71 is inserted in the middle of the optical waveguides 19a and 19b, FIG. As shown in (e), the wavelength dependence within the use range can be made small and almost flat.

  As a result, even when a disturbance in which the wavelengths of the slanted grating 13 and the Bragg grating 15 change simultaneously occurs, the measurement intensity at the light receiving unit 17 can be kept constant, so that accurate measurement is possible. It is desirable that the wavelength dependency within the use band is as small as possible. In particular, it is desirable in terms of measurement accuracy that the wavelength dependency after correction is suppressed to 10% (0.5 dB) or less.

  Since an optical physical quantity measuring device is assembled by inserting such a correction filter 71 in the middle of the optical waveguide, an optical physical quantity measuring device such as a spectrum analyzer is unnecessary. Therefore, it is possible to provide an optical physical quantity measuring apparatus that is inexpensive and accurate.

[Eighth Embodiment]
FIG. 12 is a diagram showing a configuration example of a reflective optical physical quantity measuring device 80 according to the eighth embodiment of the present invention.

  As shown in FIG. 12, the characteristic of the reflective optical physical quantity measuring device 80 is used in the middle of the optical waveguides 35a and 35b immediately after the light source 11 with respect to the second embodiment shown in FIG. The purpose is to insert a correction filter 81 for correcting the wavelength dependency of the optical component.

  The wavelength characteristics of the correction filter 81 are the same as those in FIG. 11, and the effect of inserting the correction filter 81 can also be described with reference to the wavelength characteristics of the correction filter shown in FIG. Is omitted.

  It goes without saying that the same effect can be obtained if such a correction filter 81 is inserted into the optical waveguide with respect to the third to sixth embodiments.

[Example 1]
FIG. 13 is a diagram illustrating a configuration example of the reflective displacement measurement sensor 90 according to the first embodiment of the present invention.

  As the light source 11, an ASE light source using an erbium-doped fiber that emits light in a so-called 1550 nm band with an emission wavelength range of 1550 nm to 1555 nm is used, and a photodiode is used as the light receiving unit 33.

  The slanted grating 13 is fabricated in the optical fiber 35 so that the transmission loss continuously changes in the wavelength band between 1550 nm and 1555 nm. The slant angle θ at this time was 5 degrees, and the maximum reflection intensity was 3%. The Bragg grating 15 is formed in the same optical fiber with a reflection center wavelength of 1551 nm and a full width at half maximum of 0.5 nm.

  Both ends of the slanted fiber grating 13 and one end of the Bragg grating 15 are fixed on the same fixing base material 91 with an adhesive 93, and the other end of the Bragg grating 15 is another base that is independently movable in the longitudinal direction. The material 95 was fixed using an adhesive 93.

  By using quartz glass for the fixing base 91, since it has substantially the same thermal expansion coefficient as the optical fiber 35 used, it is possible to prevent tension from being applied to the optical fiber due to temperature changes.

  In this state, when the position of the base material 95 to which the other end of the Bragg grating 15 is bonded is changed in the longitudinal direction A, a tension f is applied to the Bragg grating 15, and as a result, the reflection wavelength of the fiber grating 15 is long. Shift to the wavelength side.

  FIG. 14 shows the actual displacement amount d and the voltage V at the light receiving unit 33 measured at that time. As shown in FIG. 14, it was confirmed that the measurement voltage V increased as the displacement amount d increased, and it was confirmed that the displacement amount d could be converted into the voltage amount V and measured.

  FIG. 14 shows the results of the same measurement performed at three temperatures of 10 ° C., 25 ° C., and 40 ° C., but the same characteristics can be obtained under any temperature condition, It was confirmed that the influence of the surrounding temperature change could be compensated by fixing both ends of the slanted fiber grating 13 on the same fixing substrate 91 using the adhesive 93.

[Example 2]
FIG. 15 is a diagram illustrating a configuration example of the reflective temperature measurement sensor 100 according to the second embodiment of the present invention.

  An ASE light source using an erbium-doped fiber that emits light in the 1550 nm band was used as the light source 11, and a photodiode was used as the light receiving unit 33.

  The slanted grating 13 was fabricated in the optical fiber 35 so that the transmission loss continuously changed between 1550 nm and 1555 nm. The slant angle θ at this time was 5 degrees, and the maximum reflection intensity was 3%.

  Further, a Bragg grating 15 having a reflection center wavelength of 1551 nm and a full width at half maximum of 0.8 nm was fabricated on the same optical fiber 35. Both ends of the slanted fiber grating 13 are fixed to the fixed base material 91 using an adhesive 93, and both ends of the Bragg grating 15 are fixed to the fixed base material 101 using an adhesive 93.

Here, quartz glass was used as the fixed substrate 91, and aluminum was used as the fixed substrate 101. Quartz glass has a linear expansion coefficient of 0.5 × 10 ⁻⁶ [1 / ° C.] and has almost the same thermal expansion coefficient as the optical fiber 35 used, but aluminum has a linear expansion coefficient of 23.1 × 10 ^−6. It is [1 / ° C.] and has a linear expansion coefficient nearly 50 times that of quartz glass.

  For this reason, when the fixed base material 101 made of aluminum expands as the temperature rises, a tension is applied to the optical fiber 35 on which the Bragg grating 15 fixed to the upper part of the fixed base material 101 is made, and the fixed base material made of quartz. The wavelength characteristics are shifted to the longer wavelength side than the slanted grating 13 fixed to the substrate 91. That is, for example, the wavelength λa shown in FIG. 3A is shifted in the direction of the wavelength λb.

  For this reason, the relative wavelength positions of the slanted grating 13 and the Bragg grating 15 change due to the temperature change, and the temperature change is observed as the intensity change of the reflected wavelength.

  FIG. 16 shows the actual temperature and the voltage at the light receiving unit 33 measured at that time. It is confirmed that the measurement voltage changes according to the change in temperature, and the change in temperature is converted into a change in voltage. It was confirmed that measurement was possible.

It is a figure which shows the structural example of the transmissive | pervious optical physical quantity measuring device 10 which concerns on the 1st Embodiment of this invention. (A) is a figure which shows the wavelength characteristic of the light source 11, (b) is a figure which shows the wavelength characteristic of the slant type | mold grating 13, (c) is a figure which shows the wavelength characteristic of the Bragg grating 15, (d ) Is a diagram illustrating the wavelength characteristics of the light receiving unit 17. (A) is a graph which shows the wavelength fluctuation | variation which fluctuates according to the change of the physical quantity to measure, (b) is a graph which shows the light reception intensity | strength measured by the light-receiving part 17. FIG. It is a figure which shows the structural example of the reflection type optical physical quantity measuring device 30 which concerns on the 2nd Embodiment of this invention. (A) is a figure which shows the wavelength characteristic of the light source 11, (b) is a figure which shows the wavelength characteristic of the slant type | mold grating 13, (c) is a figure which shows the wavelength characteristic of the Bragg grating 15, (d ) Is a diagram illustrating the wavelength characteristics of the light receiving unit 33. It is a figure which shows the structural example of the transmission / reflection type optical physical-quantity measuring apparatus 40 which concerns on the 3rd Embodiment of this invention. It is a figure which shows the structural example of the transmissive | pervious optical physical quantity measuring apparatus 50 which concerns on the 4th Embodiment of this invention. It is a figure which shows the structural example of the reflection type optical physical quantity measuring device 55 which concerns on the 5th Embodiment of this invention. It is a figure which shows the structural example of the transmission-and-reflection type optical physical quantity measuring device 60 which concerns on the 6th Embodiment of this invention. It is a figure which shows the structural example of the transmissive | pervious optical physical quantity measuring device 70 which concerns on the 7th Embodiment of this invention. (A) is a figure which shows the wavelength dependence of the light source 11, (b) is a figure which shows the wavelength dependence of the light-receiving part 17, (c) is a figure which shows the wavelength dependence of a measurement system, d) is a diagram showing the wavelength dependency of the correction filter 71, and (e) is a diagram showing the wavelength dependency of the light receiving unit 17 that appears as a result of inserting the correction filter 71. FIG. It is a figure which shows the structural example of the reflection type optical physical quantity measuring device 80 which concerns on the 8th Embodiment of this invention. It is a figure which shows the structural example of the reflection type displacement measuring sensor 90 which concerns on Example 1 of this invention. It is a figure which shows the actual displacement amount d and the voltage V in the light-receiving part 33 measured at that time. It is a figure which shows the structural example of the reflection-type temperature measurement sensor 100 which concerns on Example 2 of this invention. It is a figure which shows actual temperature and the voltage in the light-receiving part 33 measured at that time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Light source 13 Slant type grating 15 Bragg grating 17,33,59,63,65 Light-receiving part 19,35 Optical waveguide 31,51,57 Beam splitter 61 Optical coupler 71,81 Correction filter 91,101 Fixing base material 93 Adhesive 95 Moving substrate

Claims (11)

A light source that emits light in a predetermined wavelength range;
An inclined filter using a slanted grating having an inclined wavelength range in which transmitted light intensity changes in an inclined manner as the wavelength of light received from the light source becomes longer;
A Bragg grating having one transmission characteristic of a predetermined wavelength width within the tilt wavelength range of the tilt filter;
A light-receiving unit having sensitivity within the tilt wavelength range, and converting light that has passed through the tilt filter and the Bragg grating into light-receiving intensity,
An optical physical quantity measuring apparatus, wherein a change in physical quantity applied to the Bragg grating is converted into received light intensity by the light receiving section. A light source that emits light in a predetermined wavelength range;
An inclined filter using a slanted grating having an inclined wavelength range in which transmitted light intensity changes in an inclined manner as the wavelength of light received from the light source becomes longer;
A Bragg grating having one reflection characteristic of a predetermined wavelength width within the tilt wavelength range of the tilt filter,
A branching section provided between the light source and the gradient filter, for branching light from the light source to the gradient filter, and for branching light from the gradient filter to the other;
A light receiving unit that has sensitivity within the tilt wavelength range and converts light received from the tilt filter via the branching unit into received light intensity;
An optical physical quantity measuring apparatus, wherein a change in physical quantity applied to the Bragg grating is converted into received light intensity by the light receiving section. A light source that emits light in a predetermined wavelength range;
An inclined filter using a slanted grating having an inclined wavelength range in which transmitted light intensity changes in an inclined manner as the wavelength of light received from the light source becomes longer;
A Bragg grating having one transmission / reflection characteristic of a predetermined wavelength width within the tilt wavelength range of the tilt filter;
A first light receiving unit that has sensitivity within the tilt wavelength range and converts light transmitted through the tilt filter and the Bragg grating into received light intensity;
A branching section provided between the light source and the gradient filter, for branching light from the light source to the gradient filter, and for branching light from the gradient filter to the other;
A second light receiving portion that has sensitivity within the tilt wavelength range and converts light received from the tilt filter via the branch portion into received light intensity;
An optical physical quantity measuring apparatus characterized in that a change in physical quantity applied to the Bragg grating is converted into received light intensity by the first and second light receiving sections. A light source that emits light in a predetermined wavelength range;
An inclined filter using a slanted grating having an inclined wavelength range in which transmitted light intensity changes in an inclined manner as the wavelength of light received from the light source becomes longer;
A Bragg grating having one transmission characteristic of a predetermined wavelength width within the tilt wavelength range of the tilt filter;
A first light receiving unit having sensitivity within the tilt wavelength range and converting light received from the Bragg grating into received light intensity;
A branching section provided between the light source and the inclined filter, for branching a part of the light from the light source to the inclined filter, and for branching the light from the light source to the other;
A second light receiving unit that has sensitivity within the tilt wavelength range and converts light received from the light source via the branch unit into received light intensity;
An optical physical quantity measuring apparatus characterized in that a change in physical quantity applied to the Bragg grating is converted into received light intensity by the first and second light receiving sections. A light source that emits light in a predetermined wavelength range;
An inclined filter using a slanted grating having an inclined wavelength range in which transmitted light intensity changes in an inclined manner as the wavelength of light received from the light source becomes longer;
A Bragg grating having one transmission / reflection characteristic of a predetermined wavelength width within the tilt wavelength range of the tilt filter;
A first branching unit provided between the gradient filter and the Bragg grating, for branching light from the gradient filter to the Bragg grating, and for branching light from the gradient filter to the other;
A first light receiving portion that has sensitivity within the tilt wavelength range and converts light received from the tilt filter via the first branch portion into received light intensity;
A second branching unit that is provided between the light source and the gradient filter, branches the light from the light source to the gradient filter, and branches the light from the gradient filter to the other;
A second light receiving unit that has sensitivity within the tilt wavelength range and converts light received from the tilt filter via the second branching unit into received light intensity;
An optical physical quantity measuring apparatus characterized in that a change in physical quantity applied to the Bragg grating is converted into received light intensity by the first and second light receiving sections. A light source that emits light in a predetermined wavelength range;
An inclined filter using a slanted grating having an inclined wavelength range in which transmitted light intensity changes in an inclined manner as the wavelength of light received from the light source becomes longer;
A Bragg grating having one transmission / reflection characteristic of a predetermined wavelength width within the tilt wavelength range of the tilt filter;
A branching unit that is provided between the light source and the gradient filter, branches the light from the light source to the gradient filter and the other, and branches the light from the gradient filter to the other;
A first light receiving unit having sensitivity within the tilt wavelength range and converting light received from the light source via the branch unit into received light intensity;
A second light receiving portion that has sensitivity within the tilt wavelength range and converts light received from the tilt filter via the branch portion into received light intensity;
An optical physical quantity measuring apparatus characterized in that a change in physical quantity applied to the Bragg grating is converted into received light intensity by the first and second light receiving sections.   7. The apparatus according to claim 3, further comprising a calculation unit that inputs the received light intensity from the first and second light receiving units and calculates a received light intensity ratio from both. The optical physical quantity measuring device described. A light source that emits light in a predetermined wavelength range;
An inclined filter using a slanted grating having an inclined wavelength range in which transmitted light intensity changes in an inclined manner as the wavelength of light received from the light source becomes longer;
A Bragg grating having one reflection characteristic of a predetermined wavelength width within the tilt wavelength range of the tilt filter;
A fixing substrate for fixing both ends in the longitudinal direction of the inclined filter and fixing one end in the longitudinal direction of the Bragg grating on the side close to the inclined filter;
A moving base that movably fixes the other end of the Bragg grating in the longitudinal direction;
A light receiving unit that has sensitivity within the tilt wavelength range and converts light received from the tilt filter via the branching unit into received light intensity;
The optical physical quantity measurement according to any one of claims 1 to 7, wherein a displacement applied to the Bragg grating from the fixed base and the moving base is converted into a received light intensity by the light receiving unit. apparatus. A light source that emits light in a predetermined wavelength range;
An inclined filter using a slanted grating having an inclined wavelength range in which transmitted light intensity changes in an inclined manner as the wavelength of light received from the light source becomes longer;
A Bragg grating having one reflection characteristic of a predetermined wavelength width within the tilt wavelength range of the tilt filter;
A first fixing substrate for fixing both ends in the longitudinal direction of the inclined filter;
A second fixing substrate for fixing both ends in the longitudinal direction of the Bragg grating;
A light receiving portion having sensitivity within the tilt wavelength range,
The optical physical quantity measurement according to any one of claims 1 to 7, wherein a change in temperature applied to the Bragg grating from both ends of the second fixed base material is converted into received light intensity by the light receiving unit. apparatus.   The correction filter which correct | amends the wavelength dependence of the measurement system by the said light source and the said light-receiving part was provided in the middle of the optical path between the said light source and the said light-receiving part. The optical physical quantity measuring apparatus according to 1.   11. The slant filter according to claim 1, wherein the slant filter is a slant grating having a slant angle in a range of 1 to 15 degrees and a reflectance of 5% or less. Optical physical quantity measuring device.

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