JP2015190779A - Displacement information generation device and displacement information generation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate information about displacement of a structure with a simple configuration by utilizing the characteristic of spatial propagation of light.SOLUTION: A displacement information generation device 1 includes a light source 2, a hologram 3, a reflection layer 4, and a photodetector 5. The hologram 3 and the reflection layer 4 are attached to a structure 10. When the light source 2 and the hologram 3 have a prescribed positional relation, the hologram 3 is irradiated with light emitted from the light source 2, and the hologram 3 generates diffracted light 13, and the photodetector 5 receives the diffracted light 13. As the positional relation between the light source 2 and the hologram 3 is changed in accordance with displacement of the structure 10, diffraction efficiency of the hologram 3 is changed. An output signal of the photodetector 5 obtained when the hologram 3 is irradiated with the light emitted from the light source 2 is information about the displacement of the structure 10.

Description

  The present invention relates to a displacement information generating apparatus and a displacement information generating method for generating information related to displacement of a structure using light.

  In recent years, for example, a technique called structural health monitoring has been drawing attention, in which physical quantities such as sound, vibration, and displacement are observed using sensors installed in the structure and the soundness of the structure is determined based on the observed values. . In the present application, attention is paid to a technique for generating information related to displacement of a structure among various elemental techniques for realizing structural health monitoring. In this technique, it is desirable that the sensor installed in the structure is simple in structure, low in cost, and excellent in environmental resistance.

  Various techniques for generating information related to the displacement of a structure already exist, such as those using electrical sensors, those using ultrasonic waves, and those using light. Among these, the technique using light has an advantage that it is not affected by electromagnetic noise. In addition, with the technology using light, there is a possibility that a system that can acquire information on the displacement of the structure at a location away from the structure without using a lead will be constructed by utilizing the feature of light propagating in space. There is.

  For example, Patent Documents 1 to 4 are documents that describe a technique for generating information on displacement of a structure using light.

  Patent Document 1 describes an optical fiber strain sensor sheet that includes a sheet portion and an optical fiber sensor portion that is folded back on the sheet portion.

  In Patent Document 2, a photoelastic gauge is attached to the surface of a stress measurement object, the transmitted light of the polarizing plate is irradiated onto the photoelastic gauge, and the reflected light is captured by an electronic camera through the polarizing plate. A method is described in which the amount of change in RGB signals of an electronic camera is converted into the strain amount of a photoelastic gauge, and the stress is obtained from the strain amount.

  Patent Document 3 discloses an optical system for measuring the distribution of displacement and strain of an object using digital holography, in which light emitted from one laser light source is irradiated with object light and a plurality of light beams. An optical system is described in which a reference plane having a specific pattern is attached to a stage that can be moved minutely in a plurality of directions at a place where a measurement target is placed, which is separated into reference light irradiated to an image sensor.

  In Patent Document 4, the light emitted from the laser device is divided into two, one light is irradiated onto the inspection object, the other light is used as reference light, and the reference light and the reflected light from the inspection object are used. A method is described in which a plurality of holograms are formed at regular time intervals, and the mechanical behavior of the inspection object is evaluated using the plurality of holograms.

JP 2002-131023 A JP-A-5-79927 JP 2012-220349 A Japanese Patent No. 2554996

  The conventional techniques for generating information on the displacement of a structure using light as described in Patent Documents 1 to 4 have the following various problems when applied to structural health monitoring. .

  For example, in the technique using an optical fiber as described in Patent Document 1, it is necessary to connect a light source and a photodetector to the optical fiber. Therefore, when this technology is applied to structural health monitoring, it is necessary to install a light source and a photodetector together with an optical fiber in the structure. If these optical fibers, light sources, and photodetectors are regarded as one sensor, this sensor is large and cannot be said to be suitable for installation in a structure. Further, in the technology using an optical fiber, the light propagating in the space is not utilized because the light propagating in the space is not used.

  In the technique described in Patent Document 2, there is a problem in that it is impossible to detect the displacement of the structure without strain and stress.

  In the techniques described in Patent Documents 3 and 4, when applying to structural health monitoring, it is necessary to construct a complex, large-scale, and high-precision optical system near the structure. Therefore, the techniques described in Patent Documents 3 and 4 have a problem that it is difficult to apply to structural health monitoring.

  SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and its purpose is to generate displacement information that can generate information on the displacement of a structure by utilizing the feature of light that propagates in space with a simple configuration. An apparatus and a displacement information generation method are provided.

  The displacement information generation apparatus of the present invention is an apparatus that generates information related to the displacement of a structure. The displacement information generating device outputs a hologram that generates diffracted light when irradiated with reproduction reference light, a light source that emits light irradiated on the hologram, and a signal corresponding to the received light, and the hologram is diffracted. And a photodetector capable of receiving diffracted light when light is generated. The displacement information generation device changes the positional relationship between the light source and the hologram or the state of the light path emitted from the light source and applied to the hologram in accordance with the displacement of the structure, and the light source and the hologram have a predetermined positional relationship. Or when the light path is in a predetermined state, the light emitted from the light source is set to be the reproduction reference light. And the output signal of the photodetector when the hologram is irradiated with the light emitted from the light source becomes information relating to the displacement of the structure.

  The displacement information generating method of the present invention outputs a hologram that generates diffracted light when irradiated with reproduction reference light, a light source that emits light irradiated to the hologram, and a signal corresponding to the received light, This is a method of generating information related to displacement of a structure using a displacement information generating device including a photodetector capable of receiving diffracted light when the hologram generates diffracted light. According to the displacement information generation method, the positional relationship between the light source and the hologram or the state of the light path emitted from the light source and applied to the hologram changes according to the displacement of the structure, and the light source and the hologram have a predetermined positional relationship. Or when the light path is in a predetermined state, a procedure for installing the displacement information generating device so that the light emitted from the light source becomes the reference light for reproduction, and a procedure for generating information on the displacement of the structure It has. The information regarding the displacement of the structure is an output signal of the photodetector when the hologram is irradiated with light emitted from the light source.

  In the displacement information generating apparatus and the displacement information generating method of the present invention, the hologram may be attached to the structure, and the positional relationship between the light source and the hologram may be changed according to the displacement of the structure. In this case, the hologram may have flexibility. The hologram may be a transmission hologram, and may have a first surface on which light emitted from the light source is incident and a second surface opposite to the first surface. The displacement information generating device may further include a reflective layer that is in contact with the second surface of the hologram. In this case, when the light source and the hologram are in a predetermined positional relationship, the light emitted from the light source and transmitted through the hologram and reflected by the reflection layer becomes reproduction reference light, and the diffracted light is emitted from the first surface. Is done. Further, when the hologram is a transmission hologram and has a first surface on which light emitted from the light source is incident and a second surface opposite to the first surface, the photodetector May be arranged on the second surface side of the hologram.

  In the displacement information generating apparatus and the displacement information generating method of the present invention, the displacement information generating apparatus may further include a reflecting member that reflects the light emitted from the light source toward the hologram, and the reflecting member has a structure. The state of the light path emitted from the light source and applied to the hologram may be changed according to the displacement of the structure attached to the object. In this case, the reflecting member may have flexibility. The hologram is a transmission hologram, and has a first surface on which light emitted from the light source and reflected by the reflecting member is incident, and a second surface opposite to the first surface. May be. In this case, the photodetector may be arranged on the second surface side of the hologram.

  In the displacement information generating apparatus and displacement information generating method of the present invention, the output signal of the photodetector may be a signal indicating the intensity of light received by the photodetector, or the light received by the photodetector. It may be a signal representing the intensity distribution.

  In the displacement information generation device and the displacement information generation method of the present invention, the positional relationship between the light source and the hologram or the state of the light path emitted from the light source and applied to the hologram changes according to the displacement of the structure. When the hologram is irradiated with light emitted from the light source, the light traveling from the hologram to the photodetector changes. Therefore, the output signal of the photodetector when the light emitted from the light source is irradiated onto the hologram is information regarding the displacement of the structure. Advantageous Effects of Invention According to the present invention, there is an effect that it is possible to generate information related to the displacement of a structure by utilizing the feature of light that propagates in space with a simple configuration.

It is explanatory drawing which shows the structure of the outline of the displacement information generation apparatus which concerns on the 1st Embodiment of this invention. It is explanatory drawing which shows the preparation methods of the hologram shown in FIG. It is explanatory drawing which shows the hologram module shown in FIG. It is explanatory drawing for demonstrating the principle of diffraction light generation of the hologram shown in FIG. It is explanatory drawing which shows the recording optical system used for preparation of the hologram of a 1st Example. It is explanatory drawing which shows the optical system for reproduction | regeneration used in order to measure the characteristic of the hologram of a 1st Example. It is a characteristic view which shows the characteristic of the hologram of a 1st Example. It is explanatory drawing which shows an example of the light source support apparatus shown in FIG. It is explanatory drawing which shows the method to change the direction of the incident light with respect to the hologram of an initial state. It is a characteristic view which shows notionally the relationship between the incident light direction deviation | shift amount and normalized intensity | strength about the hologram of an initial state. It is explanatory drawing which shows the 1st aspect of the displacement of the hologram accompanying the displacement of a structure. It is a characteristic view which shows notionally the relationship between the incident light direction deviation | shift amount and the normalized intensity | strength about the hologram after the displacement of a 1st aspect. It is explanatory drawing which shows the 2nd aspect of the displacement of the hologram accompanying the displacement of a structure. It is explanatory drawing which shows the 3rd aspect of the displacement of the hologram accompanying the displacement of a structure. It is a characteristic view which shows notionally the relationship between the incident light direction deviation | shift amount and the normalized intensity | strength about the hologram after the displacement of the 3rd aspect. It is explanatory drawing which shows the structure of the outline of the displacement information generation apparatus which concerns on the 2nd Embodiment of this invention. It is explanatory drawing which shows the structure of the displacement information generator in FIG. It is explanatory drawing which shows the structure of the outline of the displacement information generation apparatus which concerns on the 3rd Embodiment of this invention. It is explanatory drawing which shows the structure of the displacement information generator in FIG. It is explanatory drawing which shows the structure of the outline of the displacement information generation apparatus which concerns on the 4th Embodiment of this invention. It is explanatory drawing which shows the optical system for recording used for preparation of the hologram of a 2nd Example. It is explanatory drawing which shows a part of two-dimensional pattern of intensity distribution of the signal light used for preparation of the hologram of a 2nd Example. It is explanatory drawing which shows the optical system for reproduction | regeneration used in order to measure the characteristic of the hologram of a 2nd Example. It is a characteristic view which shows the characteristic of the hologram of a 2nd Example. FIG. 25 is an explanatory diagram showing a part of a reproduced image corresponding to a point P25 in FIG. FIG. 25 is an explanatory diagram showing a part of a reproduced image corresponding to a point P26 in FIG. 24. FIG. 25 is an explanatory diagram showing a part of a reproduced image corresponding to a point P27 in FIG. 24. FIG. 25 is an explanatory diagram showing a part of a reproduced image corresponding to a point P28 in FIG. It is explanatory drawing which shows the structure of the outline of the displacement information generation apparatus which concerns on the 5th Embodiment of this invention. It is explanatory drawing which shows the structure of the displacement information generator in FIG.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, a schematic configuration of the displacement information generating apparatus 1 according to the first embodiment of the present invention will be described with reference to FIG. The displacement information generation device 1 is a device that generates information related to the displacement of the structure 10. As shown in FIG. 1, the displacement information generating apparatus 1 includes a light source 2, a hologram 3, a reflective layer 4, and a photodetector 5.

  The light source 2 emits light applied to the hologram 3. The “light” used in the present application is light in a broad sense that is not limited to visible light. The light source 2 emits a laser beam in particular. As the light source 2, for example, a semiconductor laser, a solid-state laser, or a gas laser can be used.

  The hologram 3 generates diffracted light when irradiated with reproduction reference light. The hologram 3 is particularly a transmission hologram. The hologram 3 has a first surface 3a on which light emitted from the light source 2 is incident, and a second surface 3b opposite to the first surface 3a. The reflective layer 4 is in contact with the second surface 3 b of the hologram 3 and is integrated with the hologram 3. Hereinafter, the structure including the hologram 3 and the reflective layer 4 is referred to as a hologram module 6. The hologram 3, the reflection layer 4, and the hologram module 6 may have flexibility.

  The photodetector 5 receives the light from the hologram 3 and outputs a signal corresponding to the received light. The photodetector 5 can receive diffracted light particularly when the hologram 3 generates diffracted light. The output signal of the photodetector 5 in the present embodiment is a signal representing the intensity of light received by the photodetector 5. As the photodetector 5, for example, a photodiode or a photomultiplier tube can be used.

  The displacement information generating apparatus 1 changes the positional relationship between the light source 2 and the hologram 3 or the state of the light path emitted from the light source 2 and applied to the hologram 3 according to the displacement of the structure 10. When 3 is in a predetermined positional relationship, or when the light path is in a predetermined state, the light emitted from the light source 2 is installed so as to become the reproduction reference light. And the output signal of the photodetector 5 when the hologram 3 is irradiated with the light emitted from the light source 2 becomes information regarding the displacement of the structure 10.

  In the present embodiment, in particular, the hologram module 6 including the hologram 3 and the reflection layer 4 is attached to the structure 10, and the positional relationship between the light source 2 and the hologram 3 changes according to the displacement of the structure 10. FIG. 1 shows a case where the light source 2 and the hologram 3 are in a predetermined positional relationship. At this time, the light emitted from the light source 2 and transmitted through the hologram 3 and reflected by the reflective layer 4 becomes reproduction reference light, and the diffracted light is emitted from the first surface 3 a of the hologram 3. In FIG. 1, reference numeral 11 indicates incident light emitted from the light source 2 and incident on the first surface 3 a of the hologram 3. Reference numeral 12 denotes reflected light that is light after the incident light 11 is transmitted through the hologram 3 and reflected by the reflective layer 4. Reference numeral 13 indicates diffracted light generated by the hologram 3.

  The displacement information generation device 1 further includes a light source support device 7 that supports the light source 2 and can change the position and orientation of the light source 2 and a support unit (not shown). The support unit integrally supports the light source support device 7 and the photodetector 5. Hereinafter, an integral structure including the light source 2, the light source support device 7, the photodetector 5, and a support unit (not shown) is referred to as an optical module 8. The light source support device 7 will be described in detail later.

  In the present embodiment, a reflection hologram may be used as the hologram 3 instead of the transmission hologram. In this case, the reflective layer 4 is unnecessary, and the hologram 3 is attached to the structure 10.

  Next, a method for producing the hologram 3 shown in FIG. 1 will be described with reference to FIG. As shown in FIG. 2, the hologram 3 is generated by, for example, causing the recording reference light 21 and the signal light 22 to enter the photosensitive layer 3 </ b> P made of the hologram photosensitive material, and interference between the recording reference light 21 and the signal light 22. The interference fringes are produced by recording on the photosensitive layer 3P as some change in optical constant. The signal light 22 corresponds to object light in holography. FIG. 2 shows a method for producing the hologram 3 when the hologram 3 is a transmission hologram. In this case, the recording reference light 21 and the signal light 22 are incident on the same surface of the photosensitive layer 3P. Here, the surface of the photosensitive layer 3P on which the recording reference light 21 and the signal light 22 are incident is defined as a first surface 3Pa, and the surface of the photosensitive layer 3P opposite to the first surface 3Pa is defined as a second surface 3Pb. To do. Although not shown, when a reflection hologram is manufactured, the recording reference light 21 and the signal light 22 are incident on the opposite surfaces of the photosensitive layer 3P.

  The hologram photosensitive material is a material whose optical constants such as refractive index, transmittance, reflectance, and polarization characteristics can be changed by irradiation with light. Specifically, examples of the photosensitive material for hologram include a photopolymer, a photorefractive crystal, a photorefractive polymer, a chalcogenide compound, a photochromic material, and a thermochromic material.

  The first surface 3Pa on which the recording reference light 21 and the signal light 22 are irradiated may be a flat surface or a surface with irregularities. When the first surface 3Pa is uneven, reflection and scattering of the recording reference light 21 and the signal light 22 due to the refractive index difference between the air and the photosensitive layer 3P can be suppressed, and a good hologram 3 Can be produced. Examples of a method for forming such irregularities include an electron beam processing method, a lithography method, an imprint method, and a light-induced surface relief method.

  Next, with reference to FIG. 3, a manufacturing method of the hologram module 6 shown in FIG. 1 will be described. The photosensitive layer 3P shown in FIG. 2 records the interference fringes generated by the interference between the recording reference light 21 and the signal light 22, and becomes the hologram 3 shown in FIG. The first surface 3Pa and the second surface 3Pb of the photosensitive layer 3P become the first surface 3a and the second surface 3b of the hologram 3, respectively. The hologram module 6 is produced by bonding the reflective layer 4 to the second surface 3 b of the hologram 3.

  Note that the hologram 3 is not limited to the one in which the interference fringes are recorded by the change of the optical constant. For example, the hologram 3 may be a surface relief hologram in which interference fringes are recorded by unevenness on the medium surface.

  The reflective layer 4 may be attached to the second surface 3b of the hologram 3 using an adhesive, or may be formed on the second surface 3b by a vacuum deposition method, a sputtering method, or the like. The reflective layer 4 is formed so as to exhibit a high reflectance, preferably a reflectance of 50% or more, for the light emitted from the light source 2 shown in FIG. Examples of the material of the reflective layer 4 include Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ag, In, Sn, Ta, W, Pd, Pt, Metals such as Au and Pb, and alloys thereof can be used. The reflective layer 4 may be configured using a multilayer reflective film.

  The hologram module 6 may include one or more substrates for supporting the hologram 3 and the reflective layer 4. The substrate is one of a position in contact with the first surface 3 a of the hologram 3, a position between the second surface 3 b of the hologram 3 and the reflection layer 4, and a position in contact with the surface of the reflection layer 4 opposite to the hologram 3. It can be provided in the above positions. The substrate provided at a position in contact with the first surface 3a of the hologram 3 and the substrate provided between the second surface 3b of the hologram 3 and the reflective layer 4 are adapted to the light emitted from the light source 2 shown in FIG. On the other hand, it is necessary to have a high transmittance. The substrate may have flexibility.

  As the material for the substrate, glass, ceramics, resin, and the like are usually used, but resin is preferable from the viewpoint of moldability and cost. Examples of the resin include polycarbonate resin, acrylic resin, polycycloolefin resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer, ABS resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, and urethane resin. It is done. Among these, polycarbonate resin, acrylic resin, polyester resin, and polycycloolefin resin are particularly preferable from the viewpoints of moldability, optical characteristics, and cost. In addition, as the substrate, a substrate whose surface is hard-coated with an ultraviolet curable resin or the like or an antireflection treatment can be used as appropriate. Further, the hologram module 6 may be manufactured using a substrate on which the reflective layer 4 is provided in advance.

  The thickness of the hologram 3 is not particularly limited and can be appropriately selected depending on the purpose. If the thickness of the hologram 3 is in the range of 1 to 3000 μm, the transmittance in the wavelength region of 350 nm to 800 nm becomes high, which is advantageous. When the hologram module 6 is produced without using a substrate, the hologram module 6 may be produced using the hologram 3 whose surface is hard-coated with an ultraviolet curable resin or the like, or the hologram 3 subjected to antireflection treatment.

  Next, the principle of diffracted light generation of the hologram 3 in the present embodiment will be described with reference to FIG. First, the case where the wavelength of the light irradiated on the hologram 3, that is, the wavelength of the incident light 11 is equal to the wavelength of the recording reference light 21 shown in FIG. Incident light 11 incident on the hologram 3 passes through the hologram 3 and is reflected by the reflective layer 4 to become reflected light 12. When the traveling direction of the reflected light 12 is opposite to the traveling direction of the recording reference light 21 shown in FIG. 2, the reflected light 12 is phase conjugate light with respect to the recording reference light 21, and the hologram 3 Thus, the reproduction reference light can be generated from which the diffracted light 13 can be generated. Also, when the traveling direction of the reflected light 12 is opposite to the traveling direction of the recording reference light 21, the Bragg diffraction condition is satisfied, and the diffraction efficiency of the hologram 3 is maximized. The diffracted light 13 generated by the hologram 3 is emitted from the first surface 3 a of the hologram 3. The traveling direction of the diffracted light 13 is opposite to the traveling direction of the signal light 22 shown in FIG. The diffracted light 13 is phase conjugate light with respect to the signal light 22.

  The wavelength of the light irradiating the hologram 3, that is, the incident light 11, may be different from the wavelength of the recording reference light 21 shown in FIG. In this case, when the traveling direction of the reflected light 12 is a predetermined direction not parallel to the traveling direction of the recording reference light 21, the reflected light 12 becomes the reproduction reference light, and the diffraction efficiency of the hologram 3 is increased. Become the maximum. In this case, the traveling direction of the diffracted light 13 generated by the hologram 3 is not parallel to the traveling direction of the signal light 22.

  The wavelength of the light applied to the hologram 3 is not particularly limited and can be appropriately selected according to the purpose. The wavelength of the light applied to the hologram 3 is preferably a wavelength in the visible light region because of easy adjustment of the optical axis.

  The predetermined positional relationship between the light source 2 and the hologram 3 described with reference to FIG. 1 is that the light source 2 and the hologram 3 when the incident light 11 enters the hologram 3 so that the diffraction efficiency of the hologram 3 is maximized. The positional relationship of

  In the present embodiment, when the structure 10 is displaced, the hologram module 6 is also displaced following the displacement, and as a result, the positional relationship between the light source 2 and the hologram 3 changes. If the positional relationship between the light source 2 and the hologram 3 deviates from the predetermined positional relationship due to the displacement of the structure 10, the hologram is compared with the case where the positional relationship between the light source 2 and the hologram 3 is the predetermined positional relationship. 3 is reduced, and the intensity of the diffracted light 13 is reduced. Therefore, the intensity of the light received by the photodetector 5 becomes a maximum value when the positional relationship between the light source 2 and the hologram 3 is the predetermined positional relationship, and the positional relationship between the light source 2 and the hologram 3 is If it deviates from the predetermined positional relationship due to the displacement, it becomes smaller than the maximum value. The photodetector 5 outputs a signal representing the intensity of light received by the photodetector 5. The output signal of the photodetector 5 changes according to the displacement of the structure 10. Therefore, the output signal of the photodetector 5 when the hologram 3 is irradiated with the light emitted from the light source 2 is information regarding the displacement of the structure 10.

  Next, a displacement information generation method according to the present embodiment will be described. The displacement information generation method according to the present embodiment is a method of generating information related to the displacement of the structure 10 using the displacement information generation device 1 according to the present embodiment. In the displacement information generation method, the positional relationship between the light source 2 and the hologram 3 or the state of the light path emitted from the light source 2 and applied to the hologram 3 changes according to the displacement of the structure 10. , A procedure for installing the displacement information generating device 1 so that the light emitted from the light source 2 becomes the reproduction reference light when the light path is in a predetermined state, and the structure And a procedure for generating information on ten displacements. Information regarding the displacement of the structure 10 is an output signal of the photodetector 5 when the light emitted from the light source 2 is irradiated onto the hologram 3.

  In the procedure for installing the displacement information generating apparatus 1 in the present embodiment, the hologram module 6 is attached to the structure 10 and the optical module 8 is installed at a position that does not change with the displacement of the structure 10. The optical module 8 may be always installed, or may be installed only when generating information regarding the displacement of the structure 10.

[First embodiment]
Hereinafter, the hologram 3 of the first example which is an example of the hologram 3 in the first embodiment and its characteristics will be described. In addition, the hologram 3 in this Embodiment is not limited to the hologram 3 of the 1st Example shown below.

  In the first example, the photosensitive layer 3P shown in FIG. 2 was produced by the following method. First, 34.5 parts (mass part) of hexamethylene diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) as a matrix resin forming component, polyether triol (manufactured by ADEKA Corporation, G-400, average molecular weight 430) 46.1 Part and 10.0 parts of tripropylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.), 0.06 part of dibutyltin dilaurate (manufactured by Tokyo Chemical Industry Co., Ltd.), 4-vinyldiphenyl sulfide (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) ) 2.0 parts by mass, 0.6 part of Irgacure-379 (manufactured by BASF) and 6.0 part of tributyl O-acetylcitrate (manufactured by Tokyo Chemical Industry Co., Ltd.) were prepared to prepare a photopolymer composition. .

  Next, the photopolymer composition is introduced into the gap between two glass substrates bonded together via a silicon film spacer, and subjected to heat treatment at 60 ° C. for 2 hours in a nitrogen atmosphere. In the meantime, a photosensitive layer 3P made of a photopolymer was formed. The size of each surface of the two glass substrates is 30 mm × 30 mm. Five silicon film spacers with thicknesses of 0.3 mm, 0.5 mm, 0.7 mm, 1.0 mm, and 1.5 mm are prepared. By changing the silicon film spacer, the thickness is 0.3 mm and 0 mm, respectively. Five types of photosensitive layers 3P of 0.5 mm, 0.7 mm, 1.0 mm, and 1.5 mm were produced.

  In the hologram 3 of the first embodiment, the recording reference light 21 and the signal light 22 are made incident on the first surface 3Pa of the photosensitive layer 3P using the recording optical system shown in FIG. The interference fringes generated by the interference between the light 21 and the signal light 22 were recorded on the photosensitive layer 3P. The recording optical system shown in FIG. 5 includes a continuous wave semiconductor laser 31, a mirror 32, a half-wave plate 33, a polarization beam splitter 34, and a shutter arranged in this order on the optical path of light emitted from the semiconductor laser 31. 35, a beam expander 36, a half-wave plate 37, a stop 38, and a polarization beam splitter 39.

  The semiconductor laser 31 emits laser light having a wavelength of 405 nm. Light emitted from the semiconductor laser 31 is reflected by the mirror 32, passes through the half-wave plate 33, and is reflected by the polarization beam splitter 34. The half-wave plate 33 and the polarization beam splitter 34 are provided to adjust the intensity of light after being reflected by the polarization beam splitter 34. The light after being reflected by the polarization beam splitter 34 passes through the shutter 35 and further passes through the beam expander 36, and the beam diameter is expanded. The beam expander 36 includes a spatial filter and a collimator lens, and is adjusted so that light after passing through the beam expander 36 becomes a plane wave. The light after passing through the beam expander 36 passes through the half-wave plate 37, further passes through the stop 38, and is incident on the polarization beam splitter 39 after the beam diameter is reduced. The aperture diameter of the diaphragm 38 is 6 mm.

  The polarization beam splitter 39 has an inclined surface that separates incident light into S-polarized light and P-polarized light. The S-polarized light is reflected by the inclined surface and emitted from the polarized beam splitter 39, and the P-polarized light is The light passes through the slope and is emitted from the polarization beam splitter 39. The half-wave plate 37 is provided to adjust the ratio of the intensity of S-polarized light and P-polarized light separated by the polarization beam splitter 39. Here, the P-polarized light incident on the polarizing beam splitter 39 from the stop 38 side and emitted from the polarizing beam splitter 39 is referred to as first P-polarized light.

  The recording optical system shown in FIG. 5 further includes a quarter-wave plate 40 and a mirror 41 that are sequentially arranged on the optical path of the S-polarized light emitted from the polarization beam splitter 39. The S-polarized light emitted from the polarization beam splitter 39 passes through the quarter-wave plate 40 and is converted into circularly-polarized light. This circularly polarized light is reflected by the mirror 41, passes through the quarter-wave plate 40, and is converted to P-polarized light. The P-polarized light passes through the slope of the polarization beam splitter 39 and is emitted from the polarization beam splitter 39. This P-polarized light is referred to as second P-polarized light.

  The recording optical system shown in FIG. 5 further includes a mirror 42 disposed on the optical path of the first P-polarized light emitted from the polarization beam splitter 39 and a second light emitted from the polarization beam splitter 39. A shutter 43 disposed on the optical path of P-polarized light and a rotating stage 44 that supports the photosensitive layer 3P are provided. The shutter 43 is closed in a reproducing optical system to be described later, but is always open in the recording optical system.

  The first P-polarized light emitted from the polarization beam splitter 39 is reflected by the mirror 42 and applied to the first surface 3Pa of the photosensitive layer 3P supported by the rotary stage 44 as the recording reference light 21. The Further, the second P-polarized light emitted from the polarization beam splitter 39 passes through the shutter 43 and is irradiated as the signal light 22 onto the first surface 3Pa of the photosensitive layer 3P supported by the rotary stage 44. The The rotation stage 44 can rotate the normal direction of the first surface 3Pa of the photosensitive layer 3P to change the incident angles of the recording reference light 21 and the signal light 22 with respect to the first surface 3Pa.

When producing the hologram 3 by making the recording reference light 21 and the signal light 22 enter the photosensitive layer 3P, the shutter 35 is opened for a predetermined time, and the photosensitive reference layer 3P is received by the recording reference light 21 and the signal light 22. Were exposed. At that time, the total light intensity of the recording reference light 21 and the signal light 22 in the photosensitive layer 3P was set to 24 mW / cm ² , and the exposure energy was set to 60 mJ / cm ² . After the photosensitive layer 3P was exposed in this way, post-curing for consuming the photopolymerization initiator and the monomer remaining in the photosensitive layer 3P was sufficiently performed, and the photosensitive layer 3P was made into the hologram 3. Post-cure was performed by irradiating the light-emitting diode having a central wavelength of 405 nm to the exposed photosensitive layer 3P. The above processing is performed using the five types of photosensitive layers 3P described above, and the thicknesses of the five types of the first embodiment are 0.3 mm, 0.5 mm, 0.7 mm, 1.0 mm, and 1.5 mm, respectively. Hologram 3 was produced.

  Next, the reproducing optical system used for measuring the characteristics of the hologram 3 of the first embodiment will be described with reference to FIG. This reproducing optical system includes two optical power meters 46 and 47 in addition to the components of the recording optical system shown in FIG. In the reproduction optical system, the shutter 43 is closed. Further, the rotary stage 44 supports the hologram 3 of the first embodiment. The optical power meter 46 is for detecting the intensity of the reproduction reference light incident on the hologram 3. The optical power meter 47 is for detecting the intensity of diffracted light generated by the hologram 3 when the reproduction reference light is irradiated onto the hologram 3.

  In the reproducing optical system, the light emitted from the semiconductor laser 31 having a wavelength of 405 nm passes through a mirror 32, a half-wave plate 33, a polarizing beam splitter 34, a shutter 35, a beam expander 36, a half-wave plate 37, and a diaphragm 38. The light passes in order and enters the polarization beam splitter 39. The aperture diameter of the diaphragm 38 is 2.7 mm. In the reproducing optical system, the first P-polarized light that has passed through the slope of the polarization beam splitter 39 is used. The first P-polarized light is reflected by the mirror 42 and applied to the first surface of the hologram 3 supported by the rotary stage 44 as the reproduction reference light 51.

  The characteristics of the hologram 3 were measured as follows. First, the reproduction reference beam 51 was generated in a state where the hologram 3 was not arranged on the rotary stage 44, and the intensity of the reproduction reference beam 51 was detected by the optical power meter 46. At this time, the intensity of the reproduction reference light 51 detected by the optical power meter 46 corresponds to the intensity of the reproduction reference light 51 incident on the hologram 3 when the hologram 3 is disposed on the rotation stage 44 later. Hereinafter, this intensity is referred to as incident light intensity. Next, the hologram 3 is arranged on the rotary stage 44, and the shutter 35 is rotated for a predetermined time while rotating the normal direction of the first surface 3a of the hologram 3 on which the reproduction reference beam 51 is incident. , The reproduction reference beam 51 is irradiated onto the first surface 3a of the hologram 3, and the intensity of the diffracted beam 53 generated by the hologram 3 (hereinafter referred to as diffracted beam intensity) is detected by the optical power meter 47. did. At this time, the transmitted light 52 that has passed through the hologram 3 enters the optical power meter 46.

  Here, the position of the hologram 3 when the incident angle of the reproducing reference beam 51 with respect to the first surface 3a of the hologram 3 is equal to the incident angle of the recording reference beam 21 with respect to the first surface 3Pa of the photosensitive layer 3P is positive. Called position. Further, a value obtained by subtracting the incident angle of the recording reference light 21 with respect to the first surface 3Pa of the photosensitive layer 3P from the incident angle of the reproducing reference light 51 with respect to the first surface 3a of the hologram 3 is an incident angle deviation amount ( The unit is defined as degrees). The amount of incident angle deviation when the hologram 3 is in the normal position is zero. When the reproduction reference beam 51 is irradiated onto the first surface 3a of the hologram 3, the hologram is set so that the amount of incident angle deviation is changed from a negative value to a positive value via 0 by the rotary stage 44. The position of 3 was changed. In the measurement of the characteristics of the hologram 3, the diffraction efficiency represented by the following formula (1) was then determined.

  Diffraction efficiency = (diffracted light intensity / incident light intensity) × 100 (%) (1)

  In the measurement of the characteristics of the hologram 3, the relationship between the incident angle deviation and the diffraction efficiency was determined for each of the five types of holograms 3 having different thicknesses. Here, a value obtained by dividing an arbitrary diffraction efficiency by the maximum value of the diffraction efficiency is defined as a normalized diffraction efficiency. In measuring the characteristics of the hologram 3, the relationship between the incident angle deviation and the normalized diffraction efficiency was determined for each of the five types of holograms 3 having different thicknesses.

  The characteristics of the hologram 3 of the first embodiment obtained by the above method are shown in FIG. In FIG. 7, the horizontal axis represents the incident angle deviation (degrees), and the vertical axis represents the normalized diffraction efficiency. In FIG. 7, the five types of dots and lines marked 0.3 mm, 0.5 mm, 0.7 mm, 1.0 mm, and 1.5 mm have thicknesses of 0.3 mm, 0.5 mm, and 0, respectively. The characteristics of the hologram 3 of 0.7 mm, 1.0 mm, and 1.5 mm are shown.

  As shown in FIG. 7, in any of the five types of holograms 3, the normalized diffraction efficiency becomes the maximum when the incident angle deviation is almost zero, and the standard increases as the absolute value of the incident angle deviation increases. The diffraction efficiency is reduced. Further, in the four types of holograms 3 having a thickness other than 0.3 mm, the normalized diffraction efficiency is almost zero until the absolute value of the incident angle deviation amount becomes 0.1 degrees. Even with the hologram 3 having a thickness of 0.3 mm that is the most gradual change in the normalized diffraction efficiency with respect to the change in the incident angle deviation, the normalized diffraction efficiency is almost zero when the absolute value of the incident angle deviation is 0.15 degrees. It has become. From this, it can be seen that the hologram 3 can be a sensor that can detect the incident angle deviation with high sensitivity.

  Further, as shown in FIG. 7, as the thickness of the hologram 3 increases, the gradient of the change in the normalized diffraction efficiency of the hologram 3 with respect to the change in the incident angle deviation amount increases. Therefore, the sensitivity of the hologram 3 with respect to the change in the incident angle deviation amount can be adjusted by the thickness of the hologram 3.

  FIG. 7 shows the characteristics of the hologram 3 alone, but the characteristics of the hologram module 6 including the hologram 3 and the reflective layer 4 shown in FIG. The predetermined positional relationship between the light source 2 and the hologram 3 corresponds to the case where the incident angle deviation in FIG. In the first embodiment, when the positional relationship between the light source 2 and the hologram 3 is the predetermined positional relationship, the diffraction efficiency of the hologram 3 becomes the maximum value, and the intensity of light received by the photodetector 5 is also the maximum value. become. If the positional relationship between the light source 2 and the hologram 3 deviates from the predetermined positional relationship due to the displacement of the structure 10, the hologram is compared with the case where the positional relationship between the light source 2 and the hologram 3 is the predetermined positional relationship. 3 decreases, and the intensity of light received by the photodetector 5 also decreases.

  Next, an example of the light source support device 7 shown in FIG. 1 will be described with reference to FIG. First, three directions orthogonal to each other are defined as an X direction, a Y direction, and a Z direction. The light source support device 7 shown in FIG. 8 includes an XY rotation stage 71 and an inclination stage 72. The XY rotation stage 71 has a base 71A and a table 71B. The XY rotation stage 71 can move the table 71B in the X direction and the Y direction with respect to the base 71A, and can rotate around the Z direction. The tilt stage 72 is attached to the table 71B. The tilt stage 72 supports the light source 2 and can change the attitude of the light source 2 so that the angle α formed by the direction of the emitted light 73 of the light source 2 with respect to the Z direction can be changed. According to the light source support device 7, the emission position of the emitted light 73 in the light source 2 can be changed in the X direction and the Y direction. According to the light source support device 7, the angle β formed by a vector formed by projecting a vector representing the direction of the emitted light 73 on the XY plane and the angle α can be changed.

  According to the light source support device 7, even if the hologram module 6 is displaced, the position and posture of the light source 2 can be adjusted, and the emitted light 73 of the light source 2 can be incident on the first surface 3 a of the hologram 3. Become. Further, according to the light source support device 7, the direction and direction of the emitted light 73, that is, the incident light 11, on the assumption that the emitted light 73 is incident on the first surface 3 a of the hologram 3 by adjusting the position and orientation of the light source 2. The direction of can be changed.

  Hereinafter, a plurality of modes of displacement of the hologram 3 accompanying the displacement of the structure 10 and an example of a method for detecting the displacement of the structure 10 using the displacement information generation device 1 and the displacement information generation method according to the present embodiment will be described. Conceptually explained. In this detection method, while changing the direction of the incident light 11, the intensity of light received by the photodetector 5 (hereinafter referred to as received light intensity) is obtained, and based on the relationship between the direction of the incident light 11 and the received light intensity. Then, the displacement of the structure 10 is detected. The received light intensity is obtained based on the output signal of the photodetector 5.

  Here, after the hologram module 6 is attached to the structure 10, the state of the hologram 3 at a stage where the structure 10 is not displaced is referred to as an initial state of the hologram 3. Further, the direction of the incident light 11 when the diffraction efficiency of the hologram 3 in the initial state becomes the maximum value, that is, when the positional relationship between the light source 2 and the hologram 3 in the initial state is a predetermined positional relationship is defined as a reference direction. The received light intensity at this time is defined as a reference intensity. The direction of the incident light 11 is defined not by coordinates based on the first surface 3a of the hologram 3, but by coordinates in space. Further, an angle formed by the direction of any incident light 11 with respect to the reference direction is defined as an incident light direction deviation amount (unit: degrees). Further, when the direction of the arbitrary incident light 11 is rotated in the clockwise direction with respect to the reference direction, the amount of deviation of the incident light direction is expressed by a positive value, and the direction of the arbitrary incident light 11 is relative to the reference direction. The amount of deviation in the incident light direction when rotating in the counterclockwise direction is represented by a negative value. A value obtained by dividing an arbitrary received light intensity by a reference intensity is defined as a normalized intensity.

  In the method for detecting the displacement of the structure 10, first, for the hologram 3 in the initial state, the relationship between the amount of deviation of the incident light direction, which is the relationship between the direction of the incident light 11 and the received light intensity, and the normalized intensity is obtained.

  FIG. 9 shows a method of changing the direction of the incident light 11 with respect to the hologram 3 in the initial state. In this method, the position and orientation of the light source 2 are adjusted using the light source support device 7, and the direction of the emitted light 73 is assumed on the assumption that the emitted light 73 of the light source 2 is incident on the first surface 3 a of the hologram 3. That is, the direction of the incident light 11 is changed. In FIG. 9, the light source 2 and the incident light 11 when the positional relationship between the light source 2 and the hologram 3 in the initial state is a predetermined positional relationship are represented by solid lines, and the light source 2 and the incident light 11 at other times are represented by broken lines. Yes.

  FIG. 10 is a characteristic diagram conceptually showing the relationship between the incident light direction deviation and the normalized intensity for the hologram 3 in the initial state. In FIG. 10, the horizontal axis represents the incident light direction deviation (degrees), and the vertical axis represents the normalized intensity. As shown in FIG. 10, in the hologram 3 in the initial state, the normalized intensity is 1 which is the maximum value when the incident light direction deviation amount is 0, and the standardized intensity increases as the absolute value of the incident light direction deviation amount increases. The strength is reduced.

  Next, with reference to FIG. 11, the 1st aspect of the displacement of the hologram 3 accompanying the displacement of the structure 10 is demonstrated. The first mode is a mode in which the hologram 3 is displaced so that the normal direction 3N of the first surface 3a of the hologram 3 rotates. In FIG. 11, the hologram 3 in the initial state is represented by a broken line, and the hologram 3 after displacement of the first aspect is represented by a solid line. Here, it is assumed that the displaced hologram 3 is obtained by rotating the normal direction 3N of the first surface 3a of the hologram 3 by dθ with respect to the initial state. In the method for detecting the displacement of the structure 10, the relationship between the amount of deviation of the incident light direction and the normalized intensity is obtained for the hologram 3 after displacement in the same manner as in the case of the hologram 3 in the initial state shown in FIG.

  FIG. 12 is a characteristic diagram conceptually showing the relationship between the incident light direction deviation and the normalized intensity for the hologram 3 after displacement according to the first aspect. The horizontal and vertical axes in FIG. 12 are the same as those in FIG. In FIG. 12, the solid curve indicates the relationship between the amount of deviation of the incident light direction and the normalized intensity for the hologram 3 after displacement according to the first aspect, and the broken curve indicates the incident light direction for the hologram 3 in the initial state. The relationship between the amount of deviation and the normalized strength is shown. As shown in FIG. 12, in the hologram 3 after displacement of the first aspect, the normalized intensity is 1 which is the maximum value when the incident light direction deviation is dθ, and the incident light direction deviation from dθ. As the distance increases, the normalized strength decreases. Therefore, the rotation angle dθ of the hologram 3 before and after the displacement of the first aspect can be obtained from the characteristic diagram shown in FIG.

  In FIG. 11, for convenience, dθ is drawn large, but the actual size of dθ is a small value of about several degrees at most. When the hologram 3 is displaced in the first mode, the direction of the diffracted light 13 generated by the hologram 3 changes with respect to the initial state. However, the magnitude of the change in the direction of the diffracted light 13 is as small as dθ. Therefore, even if the direction of the diffracted light 13 changes, the photodetector 5 can receive the diffracted light 13.

  Next, a second aspect of the displacement of the hologram 3 accompanying the displacement of the structure 10 will be described with reference to FIG. In the second mode, the hologram 3 is displaced in a direction parallel to the first surface 3a. In FIG. 13, the hologram 3 in the initial state is represented by a broken line, and the hologram 3 after displacement in the second mode is represented by a solid line. In the method for detecting the displacement of the structure 10, the relationship between the amount of deviation of the incident light direction and the normalized intensity is obtained for the hologram 3 after displacement in the same manner as in the case of the hologram 3 in the initial state shown in FIG. In this case, if the position of the light source 2 is shifted from the position of the light source 2 shown by the solid line in FIG. 9 by a predetermined distance d1 in the direction perpendicular to the direction of the incident light 11 shown by the solid line in FIG. The relationship between the incident light direction deviation amount and the normalized intensity shown in FIG. Here, the incident angle when the incident light 11 shown by the solid line in FIG. 9 is incident on the first surface 3a of the hologram 3 in the initial state is θi, and the position of the hologram 3 before and after the displacement of the second mode is shown. Let the amount of change be d2. d2 is calculated | required by following formula (2).

  d2 = d1 / cos θi (2)

  The incident angle θi is known. Therefore, by obtaining d1, it is possible to obtain the amount of change d2 of the position of the hologram 3 before and after the displacement of the second mode, using Equation (2).

  Next, with reference to FIG. 14, the 3rd aspect of the displacement of the hologram 3 accompanying the displacement of the structure 10 is demonstrated. The third mode is a mode in which the hologram 3 is displaced so that the first surface 3a of the hologram 3 is distorted. In the method for detecting the displacement of the structure 10, the relationship between the amount of deviation of the incident light direction and the normalized intensity is obtained for the hologram 3 after displacement in the same manner as in the case of the hologram 3 in the initial state shown in FIG.

  FIG. 15 is a characteristic diagram conceptually showing the relationship between the incident light direction deviation amount and the normalized intensity for the hologram 3 after displacement according to the third aspect. The horizontal and vertical axes in FIG. 15 are the same as those in FIG. As shown in FIG. 15, the maximum value of the normalized intensity is smaller than 1 in the relationship between the incident light direction deviation amount and the normalized intensity for the hologram 3 after displacement of the third aspect. Also, the shape of the curve representing the relationship between the amount of deviation of the incident light direction and the normalized intensity for the hologram 3 after displacement of the third aspect is the amount of deviation of the incident light direction for the hologram 3 in the initial state shown in FIG. Compared to the curve representing the normalized strength relationship, it becomes gentler. These phenomena occur because the interference fringes are not uniform in the hologram 3 after displacement according to the third aspect. From the feature of the shape of the curve representing the relationship between the amount of deviation of the incident light direction and the normalized intensity, it can be known that the hologram 3 is displaced in the third mode.

  When a displacement in which two or three of the first to third aspects are combined occurs in the hologram 3, the characteristics peculiar to the above-described first to third aspects appear in combination. For example, when a displacement in which the first mode and the second mode are combined occurs in the hologram 3, the direction of the incident light 11 indicated by the solid line in FIG. 9 from the position of the light source 2 indicated by the solid line in FIG. When the position of the light source 2 is shifted by a predetermined distance d1 in the direction perpendicular to the angle, the relationship between the incident light direction deviation and the normalized intensity as shown in FIG. 12 is obtained. Therefore, in this case, by obtaining d1, the change amount d2 of the position of the hologram 3 before and after the displacement of the second aspect can be obtained, and the displacement of the first aspect from the characteristic diagram shown in FIG. The rotation angle dθ of the hologram 3 before and after can be obtained. In the case where a displacement in which the third aspect is combined with the first aspect and the second aspect occurs in the hologram 3, the characteristic of the shape of the curve representing the relationship between the amount of deviation of the incident light direction and the normalized intensity described above From this, it can be seen that the displacement of the third mode is generated in the hologram 3.

  According to the method for detecting the displacement of the structure 10 described above, the displacement of the hologram 3 according to the first to third aspects can be detected. Since the displacement of the hologram 3 follows the displacement of the structure 10, the fact that the displacement of the hologram 3 of a plurality of aspects can be detected means that the displacement of the structure 10 of a plurality of similar aspects can be detected.

  As described above, according to the displacement information generation device 1 and the displacement information generation method according to the present embodiment, information on the displacement of the structure 10 by utilizing the feature of light that propagates in space with a simple configuration. Can be generated.

  In the present embodiment, the hologram 3 is used in particular, but the structure 10 is not used when the hologram 3 is manufactured. Therefore, according to the present embodiment, the hologram 3 can be manufactured not in the vicinity of the structure 10 but in an environment suitable for manufacturing the hologram 3 in terms of vibration countermeasures, stray light countermeasures, temperature / humidity management, and the like. . Therefore, according to the present embodiment, it is possible to produce a highly accurate hologram 3.

  Further, according to the present embodiment, the hologram module 6 that does not require power supply or signal output using a conducting wire is attached to the structure 10, and the optical module 8 that is not connected to the hologram module 6 by the conducting wire is attached. Information regarding the displacement of the structure 10 can be obtained from the photodetector 5 of the optical module 8 by being installed at a location away from the structure 10. Therefore, according to the present embodiment, it is possible to construct a system suitable for structural health monitoring that can acquire information related to the displacement of the structure 10 at a place away from the structure 10 without using a lead wire. .

  In the present embodiment, the hologram module 6 is attached to the structure 10 so that the positional relationship between the light source 2 and the hologram 3 changes according to the displacement of the structure 10, and the optical module 8 is moved along with the displacement of the structure 10. It is preferable to install at a position that does not change. However, in the present embodiment, the optical module 8 is attached to the structure 10 so that the positional relationship between the light source 2 and the hologram 3 changes according to the displacement of the structure 10, and the hologram module 6 is displaced by the displacement of the structure 10. You may install in the position which does not change with. Alternatively, the hologram module 6 and the optical module 8 may be attached to different locations in the structure 10 so that the positional relationship between the light source 2 and the hologram 3 changes according to the displacement of the structure 10.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. First, a schematic configuration of the displacement information generating apparatus 81 according to the present embodiment will be described with reference to FIG. As shown in FIG. 16, the displacement information generation device 81 includes the light source 2, the hologram 83, and the photodetector 85. The displacement information generating device 81 further includes a light source support device 7 and a support unit (not shown) that supports the light source support device 7.

  The displacement information generation device 81 further includes a holding unit 86 that holds the hologram 83 and the photodetector 85 integrally. Hereinafter, the structure including the hologram 83, the photodetector 85, and the holding unit 86 is referred to as a displacement information generator 87. The hologram 83, the photodetector 85, the holding unit 86, and the displacement information generator 87 may have flexibility.

  The displacement information generating device 81 changes the positional relationship between the light source 2 and the hologram 83 in accordance with the displacement of the structure 10, and when the light source 2 and the hologram 83 are in a predetermined positional relationship, the light emitted from the light source 2 is It is installed so as to be a reproduction reference beam for the hologram 83. In the present embodiment, in particular, a displacement information generator 87 including a hologram 83 and a photodetector 85 is attached to the structure 10. Then, the output signal of the photodetector 85 when the hologram 83 is irradiated with the light emitted from the light source 2 becomes information regarding the displacement of the structure 10.

  Next, the configuration of the displacement information generator 87 will be described in detail with reference to FIG. The hologram 83 is a transmission hologram. The hologram 83 has a first surface 83a on which light emitted from the light source 2 is incident, and a second surface 83b opposite to the first surface 83a. In FIG. 17, reference numeral 11 indicates incident light emitted from the light source 2 and incident on the first surface 83 a of the hologram 83. The hologram 83 generates diffracted light 91 when the incident light 11 becomes reproduction reference light. The diffracted light 91 is emitted from the second surface 83 b of the hologram 83. When the diffraction efficiency of the hologram 83 is not 100%, a part of the incident light 11 is transmitted through the hologram 83 and becomes transmitted light 92 emitted from the second surface 83 b of the hologram 83. The traveling directions of the diffracted light 91 and the transmitted light 92 are different from each other.

  The photodetector 85 is disposed on the second surface 83b side of the hologram 83 with a predetermined interval from the second surface 83b. The photodetector 85 outputs a signal corresponding to the light received in the light receiving area. The photodetector 85 can receive the diffracted light 91 when the hologram 83 generates the diffracted light 91. The photodetector 85 in the present embodiment has, in particular, a first light receiving region 85A capable of receiving the diffracted light 91 and a second light receiving region 85B capable of receiving the transmitted light 92. Yes. In addition, the photodetector 85 generates a first signal SA indicating the intensity of light received in the first light receiving area 85A and a second signal SB indicating the intensity of light received in the second light receiving area 85B. Output. As the photodetector 85, for example, a two-divided photodiode can be used.

  The displacement information generation method according to the present embodiment is a method of generating information related to the displacement of the structure 10 using the displacement information generation device 81 according to the present embodiment. In the displacement information generation method, the positional relationship between the light source 2 and the hologram 83 changes according to the displacement of the structure 10, and when the light source 2 and the hologram 83 are in a predetermined positional relationship, the light emitted from the light source 2 is for reproduction. A procedure for installing the displacement information generating device 81 and a procedure for generating information on the displacement of the structure 10 are provided so as to be reference light. Information on the displacement of the structure 10 is an output signal of the photodetector 85 when the hologram 83 is irradiated with light emitted from the light source 2. In the procedure for installing the displacement information generation device 81 in the present embodiment, the displacement information generator 87 is attached to the structure 10 and the light source 2 is installed at a position that does not change with the displacement of the structure 10. The light source 2 may be always installed, or may be installed only when generating information regarding the displacement of the structure 10.

  In the present embodiment, when the light source 2 and the hologram 83 are in a predetermined positional relationship, the diffraction efficiency of the hologram 83 is maximized, and the intensity of light received by the first light receiving region 85A of the photodetector 85 is maximized. Thus, the intensity of the light received in the second light receiving region 85B of the photodetector 85 is minimized. When the structure 10 is displaced, the displacement information generator 87 including the hologram 83 is displaced following the displacement, and as a result, the positional relationship between the light source 2 and the hologram 83 is changed. When the positional relationship between the light source 2 and the hologram 83 deviates from the predetermined positional relationship due to the displacement of the structure 10, the hologram is compared with the case where the positional relationship between the light source 2 and the hologram 83 is the predetermined positional relationship. The diffraction efficiency of 83 decreases, the intensity of light received in the first light receiving area 85A of the photodetector 85 decreases, and the intensity of light received in the second light receiving area 85B of the photodetector 85 increases. . Therefore, the output signals SA and SB of the photodetector 85 when the hologram 83 is irradiated with the light emitted from the light source 2 is information regarding the displacement of the structure 10.

  Here, it is assumed that the light intensities represented by the output signals SA and SB are IA and IB, respectively. Further information regarding the displacement of the structure 10 may be generated by calculation using SA, SB or IA, IB. Examples of information generated by this calculation include IA-IB and IA / (IA + IB).

  According to the displacement information generation device 81 and the displacement information generation method according to the present embodiment, the displacement of the structure 10 is detected in the same manner as the displacement detection method of the structure 10 described in the first embodiment. It becomes possible.

  In the present embodiment, the light source 2 is attached to the structure 10 so that the positional relationship between the light source 2 and the hologram 83 changes according to the displacement of the structure 10, and the displacement information generator 87 is connected to the structure 10. You may install in the position which does not change with a displacement. Alternatively, the light source 2 and the displacement information generator 87 may be attached to different locations in the structure 10 so that the positional relationship between the light source 2 and the hologram 83 changes according to the displacement of the structure 10.

  Other configurations, operations, and effects in the present embodiment are the same as those in the first embodiment.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 18 is an explanatory diagram showing a schematic configuration of the displacement information generating apparatus 101 according to the present embodiment. FIG. 19 is an explanatory diagram showing the configuration of the displacement information generator in FIG.

  As illustrated in FIG. 18, the displacement information generation device 101 includes the light source 2, the light source support device 7, the displacement information generator 87, and the reflection member 102. The displacement information generation device 101 further includes a support unit (not shown) that integrally supports the light source support device 7 and the displacement information generator 87. Hereinafter, an integrated structure including the light source 2, the light source support device 7, the displacement information generator 87, and a support unit (not shown) is referred to as an optical module 103.

  As shown in FIG. 19, the displacement information generator 87 includes a hologram 83, a photodetector 85, and a holding unit 86, as in the second embodiment.

  The displacement information generation device 101 changes the state of the light path emitted from the light source 2 and applied to the hologram 83 according to the displacement of the structure 10. When the light path is in a predetermined state, the light source 2 It is installed so that the emitted light becomes the reference light for reproduction. In the present embodiment, in particular, the reflecting member 102 is attached to the structure 10. The reflecting member 102 has a reflecting surface 102 a, and the light emitted from the light source 2 is reflected toward the hologram 83 by the reflecting surface 102 a. The reflective surface 102a has a high reflectance with respect to the light emitted from the light source 2, and preferably has a reflectance of 50% or more. The reflecting member 102 may have flexibility. For example, the reflecting member 102 may be configured by providing a reflecting layer on a substrate made of resin or the like.

  Here, after the reflection member 102 is attached to the structure 10, the state of the reflection member 102 at a stage where the structure 10 is not displaced is referred to as an initial state of the reflection member 102. In the displacement information generator 87 and the reflection member 102 in the initial state, the emitted light 73 that is the light emitted from the light source 2 is reflected by the reflection member 102 in the initial state to become reflected light 111, and the reflected light 111 is the hologram 83. It arrange | positions so that it may be irradiated. In the present embodiment, the output signal of the photodetector 85 when the hologram 83 is irradiated with the reflected light 111 that is emitted from the light source 2, reflected by the reflecting member 102, and directed toward the hologram 83 is the structure 10 Information on displacement.

  When the reflecting member 102 is in the initial state, the reflected light 111 becomes reproduction reference light for the hologram 83. As shown in FIG. 19, the hologram 83 generates diffracted light 91 when the reflected light 111 is reproduction reference light. The diffracted light 91 is emitted from the second surface 83 b of the hologram 83. When the diffraction efficiency of the hologram 83 is not 100%, a part of the incident light 11 is transmitted through the hologram 83 and becomes transmitted light 92 emitted from the second surface 83 b of the hologram 83. The traveling directions of the diffracted light 91 and the transmitted light 92 are different from each other.

  The photodetector 85 has a first light receiving region 85A capable of receiving the diffracted light 91 and a second light receiving region 85B capable of receiving the transmitted light 92. In addition, the photodetector 85 generates a first signal SA indicating the intensity of light received in the first light receiving area 85A and a second signal SB indicating the intensity of light received in the second light receiving area 85B. Output.

  The displacement information generation method according to the present embodiment is a method of generating information related to the displacement of the structure 10 using the displacement information generation device 101 according to the present embodiment. In the displacement information generation method, a light path emitted from the light source 2 according to the displacement of the structure 10 and applied to the hologram 83 via the reflecting member 102 (hereinafter referred to as an irradiation light path). Information regarding the procedure for installing the displacement information generation device 101 so that the light emitted from the light source 2 becomes the reproduction reference light when the state changes and the path of the irradiation light is in a predetermined state, and information on the displacement of the structure 10 And a procedure for generating. Information regarding the displacement of the structure 10 is an output signal of the photodetector 85 when the light emitted from the light source 2 is irradiated onto the hologram 83 via the reflecting member 102. In the procedure for installing the displacement information generating apparatus 101 in this embodiment, the reflecting member 102 is attached to the structure 10 and the optical module 103 is installed at a position that does not change with the displacement of the structure 10. The optical module 103 may be always installed, or may be installed only when generating information related to the displacement of the structure 10.

  In the present embodiment, when the reflecting member 102 is in the initial state and the reflected light 111 becomes the reproduction reference light for the hologram 83, the diffraction efficiency of the hologram 83 is maximized, and the first detector 85 of the photodetector 85 The intensity of light received in the light receiving area 85A is maximized, and the intensity of light received in the second light receiving area 85B of the photodetector 85 is minimized. The state of the irradiation light path at this time is referred to as an initial state of the irradiation light path. When the structure 10 is displaced, the reflecting member 102 is also displaced following the displacement, and as a result, the state of the irradiation light path changes. When the state of the irradiation light path changes from the initial state of the irradiation light path, the diffraction efficiency of the hologram 83 decreases compared to the initial state, and is received by the first light receiving region 85A of the photodetector 85. The intensity of the received light decreases, and the intensity of the light received by the second light receiving region 85B of the photodetector 85 increases. Therefore, the output signals SA and SB of the photodetector 85 when the light emitted from the light source 2 is applied to the hologram 83 via the reflecting member 102 is information regarding the displacement of the structure 10.

  As in the second embodiment, when the light intensities represented by the output signals SA and SB are IA and IB, respectively, the displacement of the structure 10 is further calculated by the calculation using SA and SB or IA and IB. May be generated.

  Hereinafter, a plurality of aspects of the displacement of the reflecting member 102 and the change in the state of the irradiation light path accompanying the displacement of the structure 10 will be described.

  The first mode is a mode in which the reflecting member 102 is displaced so that the normal direction of the reflecting surface 102a of the reflecting member 102 rotates. In this first aspect, the state of the path of the irradiated light changes so that the path of the reflected light 111 rotates around the incident position of the emitted light 73 of the light source 2 with respect to the reflecting surface 102a, as compared with the initial state. . Thereby, the incident angle of the reflected light 111 with respect to the hologram 83 changes.

  The second mode is a mode in which the reflecting member 102 is displaced in a direction parallel to the reflecting surface 102a. When the reflecting member 102 is displaced in this second mode, the position and posture of the light source 2 are changed in order to reflect the emitted light 73 of the light source 2 by the reflecting surface 102a of the reflecting member 102 and enter the hologram 83. In other words, it is necessary to change both the path of the outgoing light 73 and the path of the reflected light 111 compared to the initial state of the path of the irradiation light. Therefore, in the second aspect, the state of the irradiation light path changes so that both the path of the emitted light 73 and the path of the reflected light 111 change compared to the initial state. Similar to the first aspect described above, also in the second aspect, the incident angle of the reflected light 111 with respect to the hologram 83 changes.

  The third mode is a mode in which the reflecting member 102 is displaced so that the reflecting surface 102a is distorted. In the third aspect, the state of the irradiation light path changes so that the state of the reflecting surface 102a constituting a part of the irradiation light path changes compared to the initial state. When the reflecting member 102 is displaced in this third mode, the wavefront of the reflected light 111 changes compared to when the irradiation light path is in the initial state. As a result, the diffraction efficiency of the hologram 83 is lowered.

  In the present embodiment, the position and orientation of the light source 2 are adjusted using the light source support device 7, and the direction of the emitted light 73 is changed on the assumption that the reflected light 111 is incident on the first surface 83 a of the hologram 83. The displacement of the reflecting member 102 of the first to third aspects can be detected by changing and obtaining the relationship between the direction of the emitted light 73 and the intensity of the diffracted light 91. Since the displacement of the reflecting member 102 follows the displacement of the structure 10, the displacement of the reflecting member 102 in a plurality of modes can be detected, and the displacement of the structure 10 in a plurality of similar modes can be detected. .

  According to the present embodiment, the light source 2, the hologram 83, and the photodetector 85, which are the main components of the displacement information generating apparatus 101, can be integrated. Further, according to the present embodiment, what is attached to the structure 10 may be the reflecting member 102 instead of the hologram 83. Therefore, according to the present embodiment, it is possible to prevent the deterioration of the hologram 83 due to the environment. Further, the reflecting member 102 has a simple configuration, low cost, and excellent environmental resistance as compared with the hologram. Therefore, when the reflecting member 102 is regarded as a sensor for generating information related to the displacement of the structure 10, it can be said that the reflecting member 102 is a sensor suitable for installation on the structure in structural health monitoring.

  Other configurations, operations, and effects in the present embodiment are the same as those in the first embodiment.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. First, a schematic configuration of the displacement information generation apparatus 201 according to the present embodiment will be described with reference to FIG. The displacement information generating apparatus 201 includes a hologram 203 instead of the hologram 3 in the first embodiment, and includes a photodetector 205 instead of the photodetector 5 in the first embodiment. Further, the displacement information generating apparatus 201 includes an imaging optical system 207.

  The hologram 203 is recorded with interference fringes generated by interference between the recording reference light and the signal light having a predetermined two-dimensional pattern intensity distribution. The hologram 203 generates diffracted light when irradiated with reproduction reference light. This diffracted light has the same two-dimensional pattern intensity distribution as the signal light. The principle of diffracted light generation of the hologram 203 in the present embodiment is the same as that of the hologram 3 in the first embodiment.

  The hologram 203 is a transmission hologram. The hologram 203 has a first surface 203a on which light emitted from the light source 2 is incident, and a second surface 203b opposite to the first surface 203a. The reflective layer 4 is in contact with the second surface 203 b of the hologram 203 and is integrated with the hologram 203. Hereinafter, the structure including the hologram 203 and the reflective layer 4 is referred to as a hologram module 206. The hologram 203, the reflection layer 4, and the hologram module 206 may have flexibility.

  The photodetector 205 receives the light from the hologram 203 and outputs a signal representing the intensity distribution of the received light. The photodetector 205 can receive diffracted light, particularly when the hologram 203 generates diffracted light. As the photodetector 205, for example, an image sensor using a complementary metal oxide semiconductor (CMOS) or a charge coupled device (CCD) can be used. The imaging optical system 207 includes, for example, a plurality of lenses, and images a two-dimensional pattern of the intensity distribution of the diffracted light on the photodetector 205. The displacement information generation device 201 includes a support unit (not shown) that integrally supports the light source support device 7, the photodetector 5, and the imaging optical system 207. Hereinafter, an integral structure including the light source 2, the light source support device 7, the photodetector 205, the imaging optical system 207, and a support unit (not shown) is referred to as an optical module 208.

  Other configurations of the displacement information generating apparatus 201 are the same as those of the displacement information generating apparatus 1 according to the first embodiment.

  The displacement information generation apparatus 201 changes the positional relationship between the light source 2 and the hologram 203 or the state of the light path emitted from the light source 2 and applied to the hologram 203 according to the displacement of the structure 10. When 203 is in a predetermined positional relationship, or when the light path is in a predetermined state, the light emitted from the light source 2 is installed so as to serve as reproduction reference light. The output signal of the photodetector 205 when the hologram 203 is irradiated with the light emitted from the light source 2 becomes information regarding the displacement of the structure 10. In the present embodiment, the wavelength of the light emitted from the light source 2 is equal to the wavelength of the recording reference light when the hologram 203 is manufactured.

  In the present embodiment, in particular, the hologram module 206 including the hologram 203 and the reflective layer 4 is attached to the structure 10, and the positional relationship between the light source 2 and the hologram 203 changes according to the displacement of the structure 10. FIG. 20 illustrates a case where the light source 2 and the hologram 203 are in a predetermined positional relationship. At this time, the light emitted from the light source 2 and transmitted through the hologram 203 and reflected by the reflective layer 4 becomes reproduction reference light, and the diffracted light is emitted from the first surface 203 a of the hologram 203. In FIG. 20, reference numeral 11 indicates incident light emitted from the light source 2 and incident on the first surface 203 a of the hologram 203. Reference numeral 12 denotes reflected light that is light after the incident light 11 is transmitted through the hologram 203 and reflected by the reflective layer 4. Reference numeral 213 indicates diffracted light generated by the hologram 203.

  In the present embodiment, a reflection hologram may be used as the hologram 203 instead of the transmission hologram. In this case, the reflective layer 4 is not necessary, and the hologram 203 is attached to the structure 10.

  In the present embodiment, the predetermined positional relationship between the light source 2 and the hologram 203 is the positional relationship between the light source 2 and the hologram 203 when the incident light 11 enters the hologram 203 so that the diffraction efficiency of the hologram 203 is maximized. It is.

  In the present embodiment, when the structure 10 is displaced, the hologram module 206 is also displaced following the displacement, and as a result, the positional relationship between the light source 2 and the hologram 203 changes. If the positional relationship between the light source 2 and the hologram 203 deviates from the predetermined positional relationship due to the displacement of the structure 10, the hologram is compared with the case where the positional relationship between the light source 2 and the hologram 203 is the predetermined positional relationship. The diffraction efficiency of 203 is lowered.

  In the present embodiment, when the diffraction efficiency of the hologram 203 is maximum, the photodetector 205 receives light having the same intensity distribution as the signal light. When the diffraction efficiency of the hologram 203 decreases due to the displacement of the structure 10, the sharpness of the intensity distribution of light received by the photodetector 205 decreases. This sharpness can be evaluated based on the output signal of the photodetector 205. Therefore, the output signal of the photodetector 205 when the hologram 203 is irradiated with the light emitted from the light source 2 is information regarding the displacement of the structure 10.

  Next, a displacement information generation method according to the present embodiment will be described. The displacement information generation method according to the present embodiment is a method of generating information related to the displacement of the structure 10 using the displacement information generation device 201 according to the present embodiment. In the displacement information generation method, the positional relationship between the light source 2 and the hologram 203 changes according to the displacement of the structure 10, and when the light source 2 and the hologram 203 are in a predetermined positional relationship, the light emitted from the light source 2 is for reproduction. A procedure for installing the displacement information generation device 201 and a procedure for generating information on the displacement of the structure 10 are provided so as to be reference light. Information on the displacement of the structure 10 is an output signal of the photodetector 205 when the hologram 203 is irradiated with light emitted from the light source 2.

  In the procedure for installing the displacement information generating apparatus 201 in the present embodiment, the hologram module 206 is attached to the structure 10 and the optical module 208 is installed at a position that does not change with the displacement of the structure 10. The optical module 208 may be always installed, or may be installed only when generating information regarding the displacement of the structure 10.

[Second Embodiment]
Hereinafter, the hologram 203 of the second example which is an example of the hologram 203 in the fourth embodiment and its characteristics will be described. In addition, the hologram 203 in this Embodiment is not limited to the hologram 203 of the 2nd Example shown below.

  In the second example, the photosensitive layer 3P shown in FIG. 2 was produced by the following method. First, among the plurality of materials of the photopolymer composition prepared in the first example, Irgacure-379 (manufactured by BASF) 0.6 part was changed to Irgacure-784 (manufactured by BASF) 0.6 part. Was blended to prepare a photopolymer composition.

  Next, the photopolymer composition is introduced into a gap between two glass substrates bonded through a silicon film spacer having a thickness of 0.3 mm, and subjected to heat treatment at 60 ° C. for 2 hours in a nitrogen atmosphere. A photosensitive layer 3P made of a photopolymer was formed between two glass substrates. The size of each surface of the two glass substrates is 30 mm × 30 mm.

  In the hologram 203 of the second embodiment, the recording reference light 21 and the signal light 222 are made incident on the first surface 3Pa of the photosensitive layer 3P using the recording optical system shown in FIG. The interference fringes generated by the interference between the light 21 and the signal light 222 were recorded on the photosensitive layer 3P.

  The recording optical system shown in FIG. 21 is different from the recording optical system in the first embodiment shown in FIG. 5 in the following points. The recording optical system shown in FIG. 21 includes a laser 231 instead of the semiconductor laser 31 in the recording optical system shown in FIG. As the laser 231, a YAG laser was used. The laser 231 emits laser light having a wavelength of 532 nm.

  Further, the recording optical system shown in FIG. 21 is an S-polarized light beam emitted from the polarization beam splitter 39 instead of the quarter-wave plate 40 and the mirror 41 in the recording optical system shown in FIG. A reflective spatial light modulator 240 is provided on the road. Here, a phase modulation type liquid crystal is used as the spatial light modulator 240. The spatial light modulator 240 has a high speed axis and a low speed axis orthogonal to each other, and the high speed axis and the low speed axis are ± 45 ° with respect to the polarization direction of the S-polarized light emitted from the polarization beam splitter 39. Are arranged as follows. In the spatial light modulator 240, the S-polarized light incident on the on-state pixel is phase-modulated so that the phase is shifted by a half wavelength between the polarization component in the fast axis direction and the polarization component in the slow axis direction. Thus, it is emitted as P-polarized light. In the spatial light modulator 240, the S-polarized light incident on the off-state pixel is emitted as the S-polarized light. The spatial light modulator 240 may be an amplitude modulation type using a digital micromirror device (DMD) or the like. In this case, a quarter wavelength plate (not shown) is inserted between the spatial light modulator 240 and the polarization beam splitter 39. In this case, the S-polarized light emitted from the polarization beam splitter 39 passes through the quarter-wave plate, is converted into circularly-polarized light, and then is modulated by the spatial light modulator 240 to be a quarter wavelength. It passes through the plate and is converted to P-polarized light. The P-polarized light modulated by the spatial light modulator 240 and incident on the polarization beam splitter 39 passes through the inclined surface of the polarization beam splitter 39 and is emitted from the polarization beam splitter 39 as second P-polarized light. .

  The recording optical system shown in FIG. 21 includes a condensing lens 241 disposed between the polarization beam splitter 39 and the shutter 43 in the recording optical system shown in FIG. As in the first embodiment, the shutter 43 is closed in a reproducing optical system described later, but is always open in the recording optical system.

  In the recording optical system shown in FIG. 21, the light emitted from the laser 231 is reflected by a mirror 32, a half-wave plate 33, a polarizing beam splitter 34, a shutter 35, a beam expander 36, a half-wave plate 37, and a diaphragm 38. And sequentially enter the polarization beam splitter 39. The first P-polarized light emitted from the polarization beam splitter 39 is reflected by the mirror 42 and applied to the first surface 3Pa of the photosensitive layer 3P supported by the rotary stage 44 as the recording reference light 21. The The second P-polarized light emitted from the polarization beam splitter 39 is condensed by the condenser lens 241, passes through the shutter 43, and is supported as the signal light 222 by the rotating stage 44. The first surface 3Pa is irradiated.

When the recording reference beam 21 and the signal beam 222 are made incident on the photosensitive layer 3P to produce the hologram 203, the shutter 35 is opened for a predetermined time, and the photosensitive layer 3P is used by the recording reference beam 21 and the signal beam 222. Were exposed. At that time, the total light intensity of the recording reference light 21 and the signal light 222 in the photosensitive layer 3P was set to 40 mW / cm ² , and the exposure energy was set to 16 mJ / cm ² . After the photosensitive layer 3P was exposed in this way, post-curing for consuming the photopolymerization initiator and the monomer remaining in the photosensitive layer 3P was sufficiently performed, and the photosensitive layer 3P was made into a hologram 203. Post-cure was performed by irradiating the light-emitting diode having a central wavelength of 530 nm to the exposed photosensitive layer 3P.

  FIG. 22 shows a part of a two-dimensional pattern of the intensity distribution of the signal light 222. In the second embodiment, a two-dimensional pattern of the intensity distribution of the signal light 222 is used, and a bright and dark dot pattern is used. Specifically, the two-dimensional pattern of the intensity distribution of the signal light 222 has 7 × 7 regions arranged, and each region has 50 × 50 dots. This two-dimensional pattern constitutes 122.5 k bits. FIG. 22 shows a part of each of the central region and the surrounding eight regions in this two-dimensional pattern. There are two types of dots: black dots with relatively low brightness and white dots with relatively high brightness.

  Next, the reproducing optical system used for measuring the characteristics of the hologram 203 of the second embodiment will be described with reference to FIG. This reproducing optical system includes an imaging optical system 250 and an image sensor 251 in addition to the components of the recording optical system shown in FIG. In the reproduction optical system, the shutter 43 is closed. The rotating stage 44 supports the hologram 203 of the second embodiment.

  In the reproducing optical system, the light emitted from the laser 231 passes through the mirror 32, the half-wave plate 33, the polarizing beam splitter 34, the shutter 35, the beam expander 36, the half-wave plate 37, and the stop 38 in order. , Enters the polarization beam splitter 39. In the reproducing optical system, the first P-polarized light that has passed through the slope of the polarization beam splitter 39 is used. The first P-polarized light is reflected by the mirror 42 and applied to the first surface 203 a of the hologram 203 supported by the rotary stage 44 as reproduction reference light 51. When the reproduction reference beam 51 is irradiated on the hologram 203, the hologram 203 generates diffracted light 253 having the same two-dimensional pattern intensity distribution as the signal beam 222. The two-dimensional pattern of the intensity distribution of the diffracted light 253 is imaged on the image sensor 251 by the imaging optical system 250 and is imaged by the image sensor 251.

  The characteristics of the hologram 203 were measured as follows. First, the incident angle of the reproduction reference beam 51 with respect to the first surface 203a of the hologram 203 is changed by the rotating stage 44, and the two-dimensional pattern of the diffracted beam 253 is generated by the image sensor 251 at each of a plurality of incident angles. I took an image. Hereinafter, an image captured by the image sensor 251 is referred to as a reproduced image. In this way, a plurality of reproduced images corresponding to a plurality of incident angles were obtained. Next, for each of the plurality of reproduced images, a parameter value corresponding to the sharpness of the reproduced image was obtained. In the second embodiment, the signal-to-noise ratio SNR obtained as follows is used as this parameter.

First, the reproduced image is divided into a plurality of black dots and a plurality of white dots. The positions of the plurality of black dots and the plurality of white dots are known in advance from the information of the two-dimensional pattern of the intensity distribution of the signal light 222. Next, regarding the reproduced image, the average value μ ₀ of the brightness of the plurality of black dots, the average value μ ₁ of the brightness of the plurality of white dots, the standard deviation σ ₀ of the brightness of the plurality of black dots, and the plurality of white dots The luminance standard deviation σ ₁ is calculated. Next, the SNR represented by the following formula (3) is calculated.

SNR = (μ ₁ −μ ₀ ) / √ (σ ₁ ² + σ ₀ ² ) (3)

  Further, the difference between the incident angle of the reproduction reference beam 51 when the diffraction efficiency of the hologram 203 is maximized and the incident angle of the arbitrary reproduction reference beam 51 is defined as an incident angle deviation amount (unit: degree). .

  In the measurement of the characteristics of the hologram 203, the relationship between the incident angle deviation and the SNR was obtained as the characteristics of the hologram 203. FIG. 24 shows the relationship between the incident angle deviation amount and the SNR in the hologram 203 thus obtained. In FIG. 24, the horizontal axis represents the incident angle deviation (degrees), and the vertical axis represents the SNR. In FIG. 24, the SNR value for each incident angle deviation obtained by measurement is indicated by a plurality of triangular points, and these approximate curves are indicated by solid lines.

  25, FIG. 26, FIG. 27, and FIG. 28 respectively show part of the reproduced image corresponding to the points P25, P26, P27, and P28 in FIG. From FIG. 24 to FIG. 27, it can be seen that the greater the SNR value, the higher the sharpness of the reproduced image.

  As shown in FIG. 24, when the incident angle deviation amount is almost zero, the SNR value becomes the maximum value. As the absolute value of the incident angle deviation amount increases, the SNR value decreases, and the incident angle deviation amount becomes smaller. By the time the absolute value becomes 0.3 degrees, the SNR value is almost zero. From this, it is understood that the hologram 203 can be a sensor that can detect the incident angle deviation with high sensitivity.

  FIG. 24 shows the characteristics of the hologram 203 alone, but the characteristics of the hologram module 206 including the hologram 203 and the reflective layer 4 shown in FIG.

  According to the present embodiment, similarly to the first embodiment, it is possible to generate information related to the displacement of the structure 10 with a simple configuration and utilizing the feature of light propagating in space. .

  In this embodiment, the structure 10 described with reference to FIGS. 9 to 15 in the first embodiment is used by using the above SNR instead of the normalized strength in the first embodiment. It is possible to detect the displacement of the hologram 203 and the structure 10 of a plurality of modes in the same manner as the above-described displacement detection method.

  In the present embodiment, the optical module 208 is attached to the structure 10 so that the positional relationship between the light source 2 and the hologram 203 changes according to the displacement of the structure 10, and the hologram module 206 is displaced by the displacement of the structure 10. You may install in the position which does not change with. Alternatively, the hologram module 206 and the optical module 208 may be attached to different locations in the structure 10 so that the positional relationship between the light source 2 and the hologram 203 changes according to the displacement of the structure 10.

  Other configurations, operations, and effects in the present embodiment are the same as those in the first embodiment.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIG. 29 and FIG. FIG. 29 is an explanatory diagram showing a schematic configuration of the displacement information generating apparatus 301 according to the present embodiment. FIG. 30 is an explanatory diagram showing a configuration of the displacement information generator in FIG.

  As illustrated in FIG. 29, the displacement information generation device 301 includes the light source 2, the light source support device 7, the displacement information generator 287, and the reflection member 102. The displacement information generation device 301 further includes a support unit (not shown) that integrally supports the light source support device 7 and the displacement information generator 287. Hereinafter, an integrated structure including the light source 2, the light source support device 7, the displacement information generator 287 and a support unit (not shown) is referred to as an optical module 303.

  As shown in FIG. 30, the displacement information generator 287 includes a hologram 283, an imaging optical system 284, a photodetector 285, and a holding unit 286 that holds these. Similar to the hologram 203 in the fourth embodiment, the hologram 283 is recorded with interference fringes generated by interference between the recording reference light and signal light having an intensity distribution of a predetermined two-dimensional pattern. The hologram 283 generates diffracted light when irradiated with reproduction reference light. This diffracted light has the same two-dimensional pattern intensity distribution as the signal light. The hologram 283 is a transmission hologram. The hologram 283 has a first surface 283a on which light is incident and a second surface 283b opposite to the first surface 283a. The diffracted light is emitted from the second surface 283b.

  The photodetector 285 receives the light from the hologram 283 and outputs a signal representing the intensity distribution of the received light, similarly to the photodetector 205 in the fourth embodiment. Photodetector 285 can receive diffracted light, particularly when hologram 283 generates diffracted light. The imaging optical system 284 images the two-dimensional pattern of the intensity distribution of the diffracted light generated by the hologram 283 on the photodetector 285.

  Other configurations of the displacement information generating apparatus 301 are the same as those of the displacement information generating apparatus 101 according to the third embodiment.

  The displacement information generation device 301 changes the state of the light path emitted from the light source 2 and applied to the hologram 283 in accordance with the displacement of the structure 10, and from the light source 2 when the light path is in a predetermined state. It is installed so that the emitted light becomes the reference light for reproduction. In the present embodiment, the reflecting member 102 is attached to the structure 10 as in the third embodiment. The reflection member 102 has a reflection surface 102 a, and the light emitted from the light source 2 is reflected toward the hologram 283 by the reflection surface 102 a. When the structure 10 is displaced, the reflecting member 102 is also displaced following the displacement. As a result, a light path emitted from the light source 2 and irradiated onto the hologram 283 through the reflecting member 102 (hereinafter referred to as irradiation light). The state of the route is changed. In this embodiment, the output signal of the photodetector 285 when the hologram 283 is irradiated with the reflected light 111 that is emitted from the light source 2, reflected by the reflecting member 102, and directed toward the hologram 83, is output from the structure 10. Information on displacement. In the present embodiment, the wavelength of the light emitted from the light source 2 is equal to the wavelength of the recording reference light when the hologram 283 is manufactured.

  The displacement information generation method according to the present embodiment is a method of generating information related to the displacement of the structure 10 using the displacement information generation device 301 according to the present embodiment. In the displacement information generation method, the state of the irradiation light path changes in accordance with the displacement of the structure 10, and the light emitted from the light source 2 becomes the reproduction reference light when the irradiation light path is in a predetermined state. In addition, a procedure for installing the displacement information generating device 301 and a procedure for generating information relating to the displacement of the structure 10 are provided. The information regarding the displacement of the structure 10 is an output signal of the photodetector 285 when the light emitted from the light source 2 is irradiated onto the hologram 283 via the reflecting member 102. In the procedure for installing the displacement information generating apparatus 301 in this embodiment, the reflecting member 102 is attached to the structure 10 and the optical module 303 is installed at a position that does not change with the displacement of the structure 10. The optical module 303 may be always installed, or may be installed only when generating information regarding the displacement of the structure 10.

  In the present embodiment, when the reflecting member 102 is in the initial state described in the third embodiment, and the reflected light 111 becomes the reproduction reference light for the hologram 283, the diffraction efficiency of the hologram 283 is maximized. Become. When the structure 10 is displaced, the state of the irradiation light path changes as described above, and the diffraction efficiency of the hologram 283 decreases.

  In the present embodiment, similarly to the fourth embodiment, when the diffraction efficiency of the hologram 283 is maximum, the photodetector 285 receives light having the same intensity distribution as that of the signal light. When the diffraction efficiency of the hologram 283 decreases due to the displacement of the structure 10, the sharpness of the intensity distribution of light received by the photodetector 285 decreases. This sharpness can be evaluated based on the output signal of the photodetector 285 as described in the fourth embodiment. Therefore, the output signal of the photodetector 285 when the light emitted from the light source 2 is applied to the hologram 283 via the reflecting member 102 is information regarding the displacement of the structure 10.

  In the present embodiment, the position and orientation of the light source 2 are adjusted using the light source support device 7, and the direction of the outgoing light 73 is changed on the assumption that the reflected light 111 is incident on the first surface 283 a of the hologram 283. The displacement of the reflecting member 102 and the structure 10 of the plurality of aspects described in the third embodiment is changed to obtain the relationship between the direction of the emitted light 73 and the SNR described in the fourth embodiment. Can be detected.

  Other configurations, operations, and effects in the present embodiment are the same as those in the third or fourth embodiment.

  In addition, this invention is not limited to said each embodiment, A various change is possible. For example, in the present invention, a transmission type hologram is attached to a structure so as to protrude from the structure, and the photodetector can receive diffracted light generated by the hologram and as the structure 10 is displaced. You may install in the position which does not change.

  DESCRIPTION OF SYMBOLS 1 ... Displacement information generation apparatus, 2 ... Light source, 3 ... Hologram, 4 ... Reflection layer, 5 ... Photo detector, 7 ... Light source support apparatus, 10 ... Structure.

Claims (20)

A displacement information generation device that generates information about displacement of a structure,
A hologram that generates diffracted light when irradiated with reproduction reference light;
A light source that emits light applied to the hologram;
A light detector that outputs a signal corresponding to the received light, and capable of receiving the diffracted light when the hologram generates the diffracted light;
Depending on the displacement of the structure, the positional relationship between the light source and the hologram or the state of the light path emitted from the light source and applied to the hologram changes, and the light source and the hologram are in a predetermined positional relationship. At some time or when the light path is in a predetermined state, the light emitted from the light source is set to be the reproduction reference light,
The displacement information generation device, wherein an output signal of the photodetector when the hologram is irradiated with light emitted from the light source becomes information regarding displacement of the structure.   The displacement information generating apparatus according to claim 1, wherein the hologram is attached to the structure, and the positional relationship between the light source and the hologram changes according to the displacement of the structure.   The displacement information generating apparatus according to claim 2, wherein the hologram has flexibility. The hologram is a transmission hologram, and has a first surface on which light emitted from the light source is incident and a second surface opposite to the first surface;
The displacement information generating device further includes a reflective layer in contact with the second surface of the hologram,
When the light source and the hologram are in the predetermined positional relationship, the light emitted from the light source, transmitted through the hologram and reflected by the reflective layer becomes the reproduction reference light,
4. The displacement information generating apparatus according to claim 2, wherein the diffracted light is emitted from the first surface. The hologram is a transmission hologram, and has a first surface on which light emitted from the light source is incident and a second surface opposite to the first surface;
4. The displacement information generating apparatus according to claim 2, wherein the photodetector is arranged on a second surface side of the hologram. Furthermore, a reflection member that reflects the light emitted from the light source toward the hologram,
2. The state of a light path emitted from the light source and applied to the hologram changes according to the displacement of the structure when the reflecting member is attached to the structure. Displacement information generator.   The displacement information generating apparatus according to claim 6, wherein the reflecting member has flexibility. The hologram is a transmission hologram, and has a first surface on which light emitted from the light source and reflected by the reflecting member is incident, and a second surface opposite to the first surface. ,
The displacement information generating device according to claim 6 or 7, wherein the photodetector is arranged on a second surface side of the hologram.   9. The displacement information generating apparatus according to claim 1, wherein the output signal of the photodetector is a signal representing the intensity of light received by the photodetector.   9. The displacement information generating apparatus according to claim 1, wherein the output signal of the photodetector is a signal representing an intensity distribution of light received by the photodetector. A hologram that generates diffracted light when irradiated with reproduction reference light, a light source that emits light irradiated to the hologram, and a signal corresponding to the received light are output, and the hologram generates the diffracted light A displacement information generating method for generating information on the displacement of the structure using a displacement information generating device provided with a photodetector capable of receiving the diffracted light,
Depending on the displacement of the structure, the positional relationship between the light source and the hologram or the state of the light path emitted from the light source and applied to the hologram changes, and the light source and the hologram are in a predetermined positional relationship. A procedure for installing the displacement information generating device so that the light emitted from the light source becomes the reproduction reference light at a certain time or when the light path is in a predetermined state;
Generating information relating to displacement of the structure,
The displacement information generating method, wherein the information related to the displacement of the structure is an output signal of the photodetector when the hologram is irradiated with light emitted from the light source.   The displacement information generating method according to claim 11, wherein the hologram is attached to the structure, and the positional relationship between the light source and the hologram changes according to the displacement of the structure.   The displacement information generating method according to claim 12, wherein the hologram has flexibility. The hologram is a transmission hologram, and has a first surface on which light emitted from the light source is incident and a second surface opposite to the first surface;
The displacement information generating device further includes a reflective layer in contact with the second surface of the hologram,
When the light source and the hologram are in the predetermined positional relationship, the light emitted from the light source, transmitted through the hologram and reflected by the reflective layer becomes the reproduction reference light,
The displacement information generating method according to claim 12 or 13, wherein the diffracted light is emitted from the first surface. The hologram is a transmission hologram, and has a first surface on which light emitted from the light source is incident and a second surface opposite to the first surface;
14. The displacement information generation method according to claim 12, wherein the photodetector is arranged on a second surface side of the hologram. The displacement information generating device further includes a reflecting member that reflects the light emitted from the light source toward the hologram,
12. The state of a light path emitted from the light source and applied to the hologram changes according to the displacement of the structure when the reflecting member is attached to the structure. Displacement information generation method.   The displacement information generating method according to claim 16, wherein the reflecting member has flexibility. The hologram is a transmission hologram, and has a first surface on which light emitted from the light source and reflected by the reflecting member is incident, and a second surface opposite to the first surface. ,
The displacement information generation method according to claim 16 or 17, wherein the photodetector is disposed on a second surface side of the hologram.   The displacement information generation method according to claim 11, wherein the output signal of the photodetector is a signal representing the intensity of light received by the photodetector.   The displacement information generation method according to claim 11, wherein the output signal of the photodetector is a signal representing an intensity distribution of light received by the photodetector.