JP2018169388A - Optical device - Google Patents

Abstract

To improve the detection sensitivity for light of narrow spectral width.SOLUTION: Fluorescent light generated from a tooth and dental plaque as detection object is guided to be transmitted through a bandpass filter 205 transmitting therethrough light of a prescribed wavelength range, and received by a light receiving element 206. An outer peripheral surface of an optical waveguide member 204 guiding the light is covered by a refractive index adjustment member 301. Refractive index n of the refractive index adjustment member 301 falls within a range indicated by n>n>n*sin(acos(n/n*sin(θ))), where an emission angle of the fluorescent light emitted from the optical waveguide member 204 to the bandpass filter 205 is denoted by θ, a refractive index of a medium outside the refractive index adjustment member 301 is denoted by n, and a refractive index of the optical waveguide member is denoted by n.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an optical device that detects light having a narrow spectral width.

  It is known that when light having a wavelength of about 405 nm is irradiated on plaque, fluorescence having a wavelength of about 630 nm is emitted, and a plaque detection method using this principle has been proposed. Conventionally, for example, there has been a method in which fluorescence generated by irradiating a tooth or plaque with excitation light having a wavelength of 405 nm using a waveguide is guided to a light receiving unit through another waveguide, and the fluorescence intensity is detected. Alternatively, conventionally, for example, there has been a method of detecting fluorescence with a coaxial optical system using a dichroic mirror utilizing the fact that the wavelengths of excitation light and fluorescence are different.

  In these methods, unnecessary light components such as external illumination light, reflected light from teeth or autofluorescence of teeth are detected at the same time. Therefore, a filter such as a long-pass filter or a band-pass filter is provided in front of the receiver. There was a method of cutting unnecessary wavelengths.

  Here, when fluorescence from dental plaque is detected by light intensity, the fluorescence spectrum with respect to light in the vicinity of excitation light 405 nm is in the range of about 640 nm ± 20 nm, and light outside this range becomes noise. Therefore, the filter is preferably a band-pass filter that transmits only the fluorescence range from dental plaque. Among various bandpass filters, the bandpass filter using a dielectric multilayer film is particularly excellent in the ability to block light other than a predetermined wavelength, and removes light having a wavelength other than weak light such as fluorescence from plaque. Suitable for However, it is known that dielectric multilayer filters such as bandpass filters shift the wavelength of the transmission spectrum with respect to the incident angle of light.

  Specifically, the transmission wavelength band shifts to the short wavelength side as the incident angle increases. Since fluorescence is light having no directivity, in the configuration using the above-described waveguide, when it is assumed that the waveguide is linear and in a uniform plane state (incident angle is preserved), the filter The incident angle depends on the NA of the waveguide, and in the above configuration, when light with a large incident angle is incident, light that does not contain fluorescent components from dental plaque is irradiated to the light receiving unit, resulting in increased noise. It becomes. Since the fluorescence of dental plaque is weak, such a noise component is preferably as small as possible, and a method for cutting a component having a large incident angle is required.

  As a related technology, conventionally, the fluorescence generated from the tooth irradiated with light through the optical fiber is guided to the light receiving unit with another optical fiber, and the light intensity is obtained. There has been a technique for determining whether or not there is (see, for example, Patent Document 1 below).

  As a related technique, conventionally, a high refractive index material having a higher refractive index than that of the clad of the waveguide is provided between the waveguide and the filter, and the emission angle of the light emitted from the waveguide after propagating through the waveguide. Will totally reflect light larger than the critical angle between the optical filter and the high refractive index material, refract light with an incident angle smaller than the critical angle by the high refractive index material, and smaller incidence than without the high refractive index material. There has been a technique in which light is incident on an optical filter at a corner (see, for example, Patent Document 2 below).

JP-T-2004-521714 JP 2007-033477 A

  However, since the conventional technique described in Patent Document 1 directly irradiates the filter with the light output from the optical fiber, the irradiated light is irradiated at an angle depending on the NA of the optical fiber. There is a problem that it is difficult to detect only light in a narrow spectral band such as plaque. In addition, since the conventional technique described in Patent Document 1 uses a lens, there is a problem that it is difficult to reduce the size because the optical system becomes large.

  Further, in the conventional technique described in Patent Document 2 described above, by providing a high refractive index material, the distance from the waveguide end face to the light receiving portion is increased by the thickness of the high refractive index material, and according to this opening There has been a problem that the area of the spread light in the light receiving part is larger than the area of the light receiving part, which may cause detection loss. Further, when a high refractive index material is formed on the optical filter, there is a problem that the cost becomes high.

  An object of the present invention is to provide an optical device capable of improving the detection sensitivity of light having a narrow spectral width in order to eliminate the above-described problems caused by the prior art.

  In order to solve the above-described problems and achieve the object, an optical device according to the present invention includes a band-pass filter that transmits light in a predetermined wavelength range, a light-receiving element that receives light transmitted through the band-pass filter, and a detection An optical waveguide that guides fluorescence generated from a target and guides the fluorescence to the bandpass filter; and a refractive index adjusting member that covers an outer peripheral surface of the optical waveguide member that constitutes the optical waveguide. The fluorescence that is totally reflected is incident on the band-pass filter.

Further, in the optical device according to the present invention, in the above invention, the refractive index n of the refractive index adjusting member is θ _{0 as} an emission angle of the fluorescence emitted from the optical waveguide member to the bandpass filter side, and the refractive When the refractive index of the medium outside the rate adjusting member is n ₀ and the refractive index of the optical waveguide member is n ₁ , n ₁ >n> n ₁ * sin (acos (n ₀ / n ₁ * sin (θ ₀ ))).

Further, in the optical device according to the present invention, in the above invention, when the refractive index adjusting member has a diameter of the optical waveguide member as φ, the length d = It is characterized by being provided to be longer than φ / (tan (π / 2-acos (n ₀ / n ₁ * sin (θ ₀ )))).

  In the optical device according to the present invention as set forth in the invention described above, the refractive index adjusting member is further provided between the bandpass filter and the optical waveguide.

  Moreover, in the optical device according to the present invention, the refractive index adjusting member provided between the bandpass filter and the optical waveguide is filled between the bandpass filter and the optical waveguide. It is characterized by being.

  In the optical device according to the present invention, the refractive index adjustment member provided between the refractive index adjustment member covering the outer peripheral surface of the optical waveguide member and the bandpass filter and the optical waveguide in the above invention. The member is integrally formed.

によって示されることを特徴とする。 Further, in the optical device according to the present invention, in the above invention, the refractive index n of the refractive index adjusting member is θ _{0 as} an emission angle of the fluorescence emitted from the optical waveguide member to the bandpass filter side, and the refractive When the refractive index of the medium outside the index adjusting member is n ₀ and the refractive index of the optical waveguide member is n ₁ ,

It is characterized by being indicated by.

Moreover, in the optical device according to the present invention, in the above invention, when the refractive index adjusting member covering the outer peripheral surface of the optical waveguide member has a diameter of the optical waveguide member as φ, the fluorescence of the optical waveguide member is reduced. In the waveguide direction, the length is longer than d = φ / (tan (π / 2−acos (n ₀ / n ₁ * sin (θ ₀ )))).

  In the optical device according to the present invention, in the above invention, the refractive index adjusting member that covers the outer peripheral surface of the optical waveguide member has a shape in which an outer surface scatters light transmitted to the outside of the refractive index adjusting member. It is characterized by that.

  In the optical device according to the present invention, in the above invention, at least one excitation light source that emits excitation light including a wavelength near 405 nm, and excitation light emitted from the excitation light source. An irradiation optical system for irradiating the detection target, wherein the bandpass filter transmits fluorescence having a peak near 635 nm out of the fluorescence generated from the detection target irradiated with the excitation light by the irradiation optical system. Features.

  Moreover, the optical device according to the present invention is characterized in that, in the above-described invention, the optical device includes a determination unit that determines the presence or absence of a detection target based on the intensity of light received by the light receiving element.

  The optical device according to the present invention has an effect of improving the detection sensitivity of light having a narrow spectral width.

It is explanatory drawing which shows the structure of a dental plaque detection toothbrush. It is explanatory drawing which shows a coaxial optical system in detail by the structure of a dental plaque detection part. FIG. 5 is an explanatory diagram showing the shape and function of a refractive index adjusting member in the first embodiment. It is explanatory drawing which shows the principle of the light guide by a refractive index adjustment member. FIG. 10 is an explanatory diagram showing the shape and function of a refractive index adjusting member in a second embodiment. FIG. 10 is an explanatory diagram showing the shape and function of a refractive index adjusting member in a third embodiment. It is explanatory drawing which shows the structure of the plaque detection part with which the plaque detection toothbrush in Embodiment 4 is provided. It is explanatory drawing which shows the implementation example of the optical waveguide member by an optical fiber. It is explanatory drawing which shows the apparatus used for verification of the effect of a refractive index adjustment member. It is explanatory drawing which shows the verification result of the effect of a refractive index adjustment member. FIG. 10 is an explanatory diagram showing the shape and function of a refractive index adjusting member in a fifth embodiment. It is explanatory drawing which shows the principle of the light guide by a refractive index adjustment member. It is explanatory drawing which shows an example which provided the light absorption material in the outer surface of the refractive index adjustment member. It is explanatory drawing which shows the positional relationship of a 2nd optical waveguide and a band pass filter.

  Exemplary embodiments of an optical device according to the present invention will be explained below in detail with reference to the accompanying drawings. In this embodiment, a plaque detection toothbrush provided with an optical device according to the present invention will be described. Here, the plaque detection toothbrush will be described. However, this is not limited to the toothbrush, and is applicable to all embodiments including the present invention including a plaque detector without a brush.

(Embodiment 1)
First, the configuration of a dental plaque detection toothbrush provided with the optical device according to the first embodiment of the present invention will be described. FIG. 1 is an explanatory diagram showing a configuration of a dental plaque detection toothbrush. In FIG. 1, a plaque detection toothbrush 100 includes a main body part (handle) 110 and a toothbrush part 120. The main body 110 includes an exterior case 111 that is gripped by a user's hand.

  The exterior case 111 is provided with a switch 111 a that receives an operation by the user of the plaque detection toothbrush 100. The exterior case 111 is waterproofed to prevent water from entering the exterior case 111. Inside the exterior case 111, a power source 112, an excitation light source 113, a coaxial optical system 114, a light receiving element 115, a control circuit 116, a notification device 117, and the like are provided. The power source 112 supplies electricity to each part included in the dental plaque detection toothbrush 100. The power source 112 may be a primary battery or a secondary battery.

  The excitation light source 113 emits excitation light in a predetermined wavelength band. Specifically, the excitation light source 113 emits excitation light having a wavelength peak at 395 nm to 415 nm. The excitation light emitted from the excitation light source 113 is incident on the coaxial optical system 114. The coaxial optical system 114 guides excitation light incident from the excitation light source 113 to the toothbrush part 120 side, and guides plaque or tooth fluorescence incident from the toothbrush part 120 side to the light receiving element 115.

  The light receiving element 115 detects the intensity of light near a specific wavelength included in the fluorescence guided from the coaxial optical system 114 and outputs a signal corresponding to the detected fluorescence intensity to the control circuit 116. The control circuit 116 can be realized by a microcomputer including a CPU, various memories, signal input / output terminals, and the like, and drives and controls each unit included in the dental plaque detection toothbrush 100.

  The control circuit 116 drives and controls each unit included in the dental plaque detection toothbrush 100. For example, the control circuit 116 controls ON / OFF of the excitation light source 113 according to a signal output from the operated switch 111a, or calculates the amount of plaque based on the signal output from the light receiving element 115. In addition, a notification signal (a signal for notifying the user of the amount of plaque) corresponding to the amount of plaque is output to the notification device 117.

  The notification device 117 can be realized by, for example, a light emitting element such as an LED. In this case, the amount of plaque is notified by lighting or blinking the LED in a pattern based on the notification signal output from the control circuit 116. Alternatively, the notification device 117 may be realized by an eccentric motor, for example, instead of the LED. In this case, the amount of plaque can be notified by vibration generated by rotating the eccentric motor in a pattern based on the notification signal output from the control circuit 116. Alternatively, the notification device 117 may be realized by a buzzer or the like.

  The toothbrush part 120 includes a neck 121 connected to the main body part 110 and a toothbrush head 122 provided at the tip of the neck 121. The neck 121 and the toothbrush head 122 are provided with an optical waveguide 123 so that one end is connected to the coaxial optical system 114 and the other end is located on one surface side of the toothbrush head 122.

  The toothbrush head 122 supports one end of a plurality of fibers (bristle bundles) 124. The optical waveguide 123 is disposed so that the other end (hereinafter referred to as “sensor head”) 123 a located on the toothbrush head 122 side is located between the plurality of fibers 124 supported by the toothbrush head 122. The tip of the sensor head 123a is positioned at the same height as the tips of the plurality of fibers 124 supported by the toothbrush head 122, or at a position retracted to the base side. The optical waveguide 123 emits the excitation light emitted from the coaxial optical system 114 to the outside of the dental plaque detection toothbrush 100 from the sensor head 123a.

  For example, when a plurality of fibers 124 supported by the toothbrush head 122 are used while being abutted against the user's tooth, the excitation light emitted from the sensor head 123a to the outside of the plaque detection toothbrush 100 is irradiated to the tooth. . When the excitation light is irradiated to the teeth, substances forming the teeth (such as enamel and dentin collagen) are excited, and fluorescence is generated from the teeth.

  When plaque is adhered to the tooth, when excitation light having a wavelength of about 405 nm (purple) is irradiated, fluorescence having a peak in the wavelength band of about 635 nm is generated from the plaque. Fluorescence resulting from plaque originates from protoporphyrin IX (abbreviated PPIX), one of the bacterial metabolites contained in plaque.

  Fluorescence generated from the teeth and dental plaque enters the optical waveguide 123 from the sensor head 123a. The optical waveguide 123 guides fluorescence incident from the sensor head 123a to the coaxial optical system 114. In the optical waveguide 123, the excitation light emitted from the coaxial optical system 114 is incident through the sensor head 123 a from the outside of the plaque detection toothbrush 100 and the optical path of the excitation light that is emitted outside the plaque detection toothbrush 100. The optical paths of fluorescence generated from the teeth and dental plaque guided to the coaxial optical system 114 overlap.

(Configuration of plaque detection unit)
Next, the configuration of the plaque detection unit will be described. FIG. 2 is an explanatory diagram showing the details of the coaxial optical system 114 in particular in the configuration of the plaque detection unit. In FIG. 2, the plaque detection unit 200 includes an excitation light source 113, a filter 201, a mirror 202, a first optical waveguide 203, a second optical waveguide 204, a bandpass filter 205, and a light receiving element 206. And a control circuit 116.

  In the first embodiment, the optical waveguide according to the present invention is configured by optical members such as the mirror 202, the first optical waveguide 203, and the second optical waveguide 204. In the first embodiment, the optical waveguide member according to the present invention can be realized by the first optical waveguide 203 and the second optical waveguide 204. In the first embodiment, the plaque detecting unit 200 can realize the optical device according to the present invention.

  The excitation light source 113 emits excitation light in a predetermined wavelength band. Specifically, the excitation light source 113 can be realized, for example, by using an LED that emits light having a wavelength of 405 nm. The filter 201 transmits incident light having a wavelength shorter than a predetermined wavelength, and blocks or reflects other light by reflecting or absorbing the light. Specifically, the filter 201 blocks the red component near the wavelength 635 nm of the excitation light source 113. Here, the filter 201 can be realized by a short pass filter (SPF) or the like.

  The mirror 202 reflects the excitation light transmitted through the filter 201 and guides it to the first optical waveguide 203. The first optical waveguide 203 guides the excitation light from the mirror 202 to the vicinity of the teeth. The first optical waveguide 203 can be realized by, for example, a rod-shaped or columnar member formed using a resin material having light guiding properties such as acrylic.

  The light guided to the first optical waveguide 203 is emitted from the tip of the first optical waveguide 203 to the outside of the dental plaque detection toothbrush 100, and the user irradiates the teeth 210 with excitation light. When the plaque 211 is attached to the tooth 210, the emitted excitation light is applied to the tooth 210 and the plaque 211. In the first embodiment, the present invention is achieved by the filter 201, the mirror 202, the first optical waveguide 203, and the like that irradiate the detection target such as the tooth 210 and the plaque 211 with the excitation light emitted from the excitation light source 113. Such an irradiation optical system can be realized.

  Fluorescence generated from the tooth 210 and the plaque 211 enters the first optical waveguide 203 and exits to the mirror 202. The mirror 202 transmits light of a specific wavelength including the fluorescence wavelength range generated from the tooth 210 and the plaque 211 and guides it to the second optical waveguide 204. The mirror 202 can be realized by a dichroic mirror, for example.

  The second optical waveguide 204 guides the fluorescence transmitted through the mirror 202, that is, the fluorescence generated from the tooth 210 and the plaque 211 to the band pass filter 205. The bandpass filter 205 transmits light having a specific range of wavelengths and does not transmit light of other wavelengths. Here, the band-pass filter 205 is formed of a dielectric multilayer film.

  The dielectric multilayer film is formed of a multilayer dielectric film formed of materials having different refractive indexes, and transmits light of a specific range of wavelengths and reflects light of other wavelengths by the light interference effect. Compared to a band-pass filter that uses an absorbing material, for example, it is possible to remove light of unnecessary components, so that even when light of a desired wavelength is weak, light of a desired wavelength is effectively received. The light can be emitted to the element 206 side. Of the fluorescence guided from the second optical waveguide 204, only the wavelength component of the fluorescence from the plaque 211 is transmitted by the band pass filter 205.

  The light transmitted through the band pass filter 205 is irradiated to the light receiving element 206. The light receiving element 206 converts the received light into electric charges and outputs a signal corresponding to the amount of received light to the control circuit 116. For example, a silicon photodiode can be used as the light receiving element 206. The control circuit 116 calculates the amount of plaque based on the signal output from the light receiving element 206.

  The second optical waveguide 204 can be realized by, for example, a rod-shaped or columnar member formed using a resin material having light guiding properties such as acrylic. On the outer peripheral side of the second optical waveguide 204, a refractive index adjusting member that guides only the predetermined fluorescence out of the fluorescence guided to the second optical waveguide 204 to the light receiving element 206 is provided. The refractive index adjusting member will be described later (see FIG. 3).

(Shape and function of refractive index adjusting member)
Next, the shape and function of the refractive index adjusting member in the first embodiment will be described. FIG. 3 is an explanatory diagram showing the shape and function of the refractive index adjusting member in the first embodiment.

  In FIG. 3, the band pass filter 205 is disposed between the second optical waveguide 204 and the light receiving element 206 as described above. The bandpass filter 205 according to the first embodiment transmits light having a wavelength near 635 nm. The wavelength of light transmitted through the bandpass filter 205 is a range including 635 nm to 640 nm, and the lower limit value and the upper limit value can be adjusted as appropriate.

  Specifically, since the spectrum of the fluorescence generated from the plaque 211 irradiated with the excitation light having the wavelength of 405 nm emitted from the excitation light source 113 is in the range of about 640 nm ± 20 nm, the bandpass filter 205 has a wavelength of 620 nm to 660 nm. Preferably, it transmits a wavelength in the range of 630 nm to 650 nm, and does not pass light of other wavelengths.

  Further, a refractive index adjusting member 301 is provided on the outer peripheral side of the second optical waveguide 204. The refractive index adjusting member 301 is provided in close contact with the outer peripheral surface of the second optical waveguide 204, and an air layer or the like is interposed between the outer peripheral surface of the second optical waveguide 204 and the refractive index adjusting member 301. Not done.

  In the plaque detecting unit 200 of the first embodiment, the refractive index adjusting member 301 may be provided on the outer peripheral side of the member that guides the fluorescence generated from the tooth 210 or the plaque 211, and the position thereof is particularly limited. Is not to be done.

(Principle of light guide)
Next, the principle of light guide by the refractive index adjusting member 301 will be described. FIG. 4 is an explanatory view showing the principle of light guide by the refractive index adjusting member 301. In FIG. 4, the refractive index adjusting member 301 is formed using a material whose refractive index is lower than that of the material forming the second optical waveguide 204 and higher than the refractive index on the outer peripheral side of the refractive index adjusting member 301. Yes.

  The refractive index adjustment member 301 reflects fluorescence incident on the interface between the second optical waveguide 204 and the refractive index adjustment member 301 at a predetermined angle or more out of the fluorescence incident on the interface between the second optical waveguide 204 and Fluorescence incident at an angle less than the angle is transmitted and emitted to the outside of the second optical waveguide 204. As a result, only the fluorescence incident at a predetermined angle out of the fluorescence guided to the second optical waveguide 204 can be guided from the second optical waveguide 204 to the bandpass filter 205.

Specifically, in the refractive index adjusting member 301, the maximum emission angle from the second optical waveguide 204 among the fluorescence incident on the interface between the second optical waveguide 204 and the refractive index adjusting member 301 is θ _0. If the incident angle at that time is the critical angle θ _C , the fluorescence incident at an angle smaller than θ _C is emitted to the outside of the second optical waveguide 204. Of the fluorescence guided to the second optical waveguide 204, the fluorescence incident at the angle θ _i smaller than the critical angle θ _{C at} the interface between the second optical waveguide 204 and the refractive index adjusting member 301 is the second Only the fluorescent light that is transmitted from the outer peripheral surface of the optical waveguide 204 to the outside of the second optical waveguide 204 and incident at the interface at an angle θ _i ′ larger than the critical angle θ _C is reflected, and passes through the second optical waveguide 204. Propagated and emitted to the light receiving element.

The refractive index n and the critical angle θ _C of the refractive index adjusting member 301 are set such that the emission angle of the fluorescence emitted from the second optical waveguide 204 to the band pass filter 205 side is θ _0, and the medium outside the refractive index adjusting member 301 When the refractive index is n ₀ and the refractive index of the second optical waveguide 204 is n1, the following expressions (1) and (2) are given.

n = n ₁ * sin (acos (n ₀ / n ₁ * sin (θ ₀ ))) (1)
θ _C = asin (n / n ₁ ) (2)

The refractive index n of the refractive index adjusting member 301 is lower than the refractive index n _{1 of} the second optical waveguide 204 and higher than the refractive index n ₀ of the medium outside the refractive index adjusting member 301. That is, the refractive index n of the refractive index adjusting member 301 is set to a value that satisfies the following mathematical formula (3).

n ₁ >n> n ₁ * sin (acos (n ₀ / n ₁ * sin (θ ₀ )))
... (3)

・・・（３）’ The above mathematical formula (3) can be converted into the following mathematical formula (3) ′.

... (3) '

By setting the refractive index n of the refractive index adjusting member 301 to a value satisfying the mathematical expression (3), the interface between the second optical waveguide 204 and the refractive index adjusting member 301 is brought into the interface at an angle smaller than the critical angle θ _C. Incident light is transmitted to the outside of the second optical waveguide 204, and only a light component having an emission angle θ ₀ or less propagates in the waveguide.

  When the diameter of the second optical waveguide 204 is φ, the refractive index adjusting member 301 has a length d in the length direction of the second optical waveguide 204 (direction from the mirror 202 toward the bandpass filter 205) as follows: It is provided so that it may become more than the length shown by Numerical formula (4).

d = φ / (tan (π / 2-acos (n ₀ / n ₁ * sin (θ ₀ ))))
... (4)

By satisfying Expression (4), light that has directly entered the second optical waveguide 204 and that has directly reached the exit surface of the second optical waveguide 204, excluding the exit light at an angle of θ ₀ or less, All can be incident on the interface between the second optical waveguide 204 and the refractive index adjusting member 301 at least once. As a result, the light incident on the bandpass filter 205 can be made to have an arbitrary incident angle or less, the noise component is reduced in the light receiving element, and the light intensity obtained by filtering only the light in the target wavelength band is detected. be able to.

・・・（４）’ In addition, the said Numerical formula (4) can be converted and shown to following Numerical formula (4) '.

... (4) '

(Embodiment 2)
A plaque detection toothbrush 100 according to a second embodiment of the present invention will be described. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

(Shape and function of refractive index adjusting member)
The shape and function of the refractive index adjusting member 501 in the second embodiment will be described. FIG. 5 is an explanatory diagram showing the shape and function of the refractive index adjusting member 501 in the second embodiment. In FIG. 5, the refractive index adjusting member 501 in Embodiment 2 has a shape (scattering structure) in which the outer surface scatters light.

  Specifically, for example, light can be scattered from the outer surface of the refractive index adjusting member 501 by providing unevenness on the outer surface of the refractive index adjusting member 501 or performing mat processing (matting processing). Alternatively, the outer surface of the refractive index adjusting member 501 is scratched to roughen the surface, or a paint containing a bead material having a predetermined particle diameter is applied to the outer surface of the refractive index adjusting member 501 to scatter light. You may let them.

  Thereby, compared with the case where the outer surface of the refractive index adjusting member 501 is made smooth, the component reflected on the outer surface of the refractive index adjusting member 501 can be surely reduced, so that it returns to the second optical waveguide 204 again. This can be suppressed, and the light incident on the bandpass filter 205 can be made to have an arbitrary incident angle or less.

(Embodiment 3)
A plaque detection toothbrush 100 according to a third embodiment of the present invention will be described. In the third embodiment, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted.

(Shape and function of refractive index adjusting member)
The shape and function of the refractive index adjusting member 601 in the third embodiment will be described. FIG. 6 is an explanatory diagram showing the shape and function of the refractive index adjusting member 601 in the third embodiment. In FIG. 6, the refractive index adjusting member 601 in the third embodiment has a tapered shape in which the outer diameter decreases toward the fluorescence emission side, that is, the band-pass filter side. The tapered surface of the refractive index adjusting member 601 is flat.

  By making the refractive index adjusting member 601 into a tapered shape, the incident angle of light guided into the refractive index adjusting member 601 can be reduced. Specifically, the light reflected by the tapered surface (the outer surface of the refractive index adjusting member 601) has a value twice the taper angle α with respect to the incident angle before the incident angle to the next tapered surface is reflected. Incident at the subtracted angle. That is, as the number of times of incidence on the taper surface increases, the incident angle to the next taper surface decreases, and as the number of times increases, the light enters the taper surface at an angle that is less than the critical angle. As a result, the light incident on the bandpass filter 205 can be made to have an arbitrary incident angle or less.

(Embodiment 4)
A plaque detection toothbrush 100 according to a fourth embodiment of the present invention will be described. In the fourth embodiment, the same parts as those in the first to third embodiments are denoted by the same reference numerals, and the description thereof is omitted. FIG. 7 is an explanatory diagram illustrating a configuration of a plaque detection unit included in the dental plaque detection toothbrush 100 according to the fourth embodiment.

  In FIG. 7, the plaque detection unit 700 included in the plaque detection toothbrush 100 according to the fourth embodiment includes an excitation light source 113, a filter 201, a mirror (dichroic mirror) 202, optical waveguides 701, 702, 703, A band pass filter 205 and a light receiving element 206 are provided.

  On the outer peripheral side of the optical waveguide 703, a refractive index adjusting member 704 specified by the above formulas (1) to (4) is provided. The refractive index adjusting member 704 in the fourth embodiment can be provided with the refractive index adjusting members 301, 501, and 601 having various structures described in the first to third embodiments. By providing the refractive index adjusting member 704 in the optical waveguide 703 that emits fluorescence to the light receiving element 206, that is, the band pass filter 205, light at a desired angle can be reliably incident on the band pass filter 205.

  In each of the above-described embodiments, each optical waveguide is formed by a rod-shaped or cylindrical member formed using a resin material having light guiding properties such as acrylic, but may be realized by an optical fiber. Good.

  FIG. 8 is an explanatory view showing an implementation example of an optical waveguide member using an optical fiber. As shown in FIG. 8, the refractive index adjusting member according to the present invention can be realized by the core 801 and the clad 802 of the optical fiber 800.

That is, in FIG. 8, the emission angle θ ₀ from the optical fiber 800 depends on the refractive index ratio between the core and the clad, that is, NA (Numerical Aperture) indicating the maximum light receiving angle. Here, the refractive index of the core in the optical fiber and ncore, the refractive index of the cladding and nclad, if the refractive index of the medium outside of the optical fiber (such as air) and n _0, nclad is the following formula (5) Indicated.

nclad = ncore * sin (acos (n ₀ / ncore * sin (θ ₀ )))
... (5)

(Verification)
Next, verification of the effect of the refractive index adjusting member according to the present invention will be described. 9 and 10 are explanatory views showing an apparatus used for verifying the effect of the refractive index adjusting member. In FIG. 9, an apparatus 900 used for verification includes a waveguide 901 formed using acrylic, a bandpass filter 205, and a light receiving element 206.

  The waveguide 901 is made of acrylic having a refractive index of 1.4909. The outside of the waveguide 901 is filled with air having a refractive index of 1. In the device 900, fluorescence from dental plaque is uniformly incident on the waveguide 901 with a spread of ± 30 deg.

  In general, the angle of light propagating through the waveguide 901 depends on the NA of the waveguide 901. Here, when the refractive index adjusting member is not used (the outer peripheral surface is air), the NA of the waveguide 901 is 0.67, that is, the critical angle is 42.19 [deg]. Light from 19 [deg] to 42.19 [deg] propagates. Since the incident angle is defined as ± 30 deg, all of the fluorescent light is incident on the waveguide 901 and propagates to the bandpass filter 205.

  In FIG. 10 (a), the fluorescence spectrum from dental plaque is data measured in advance. Specifically, a spectrum in the range of 630 nm to 650 nm is shown. The light receiving element 206 is irradiated with all the light transmitted through the waveguide 901 and the band pass filter 205.

  A bandpass filter having the characteristics shown in FIG. 10B is used as the bandpass filter 205 to which the light transmitted through the waveguide 901 is irradiated. As shown in FIG. 10B, it can be seen that the transmission wavelength of the band pass filter 205 shifts to the shorter wavelength side as the incident angle increases from 0 °.

  As shown in FIG. 10C, the transmitted light of the band pass filter 205 at this time includes the transmission spectrum of the band pass filter 205 shown in FIG. 10B and the spectrum from the plaque shown in FIG. It becomes the value which multiplied. At this time, since the incident angle is set to ± 30 deg, the values from +30 deg to −30 deg in FIG. 10C are integrated, and the fluorescence intensity from the plaque from 630 nm to 650 nm transmitted through the band-pass filter 205, and the tooth The noise light intensity ratio of the fluorescence intensity from 580 nm to 630 nm and the fluorescence intensity from 650 nm to 660 nm excluding the fluorescence from the stain is 3.35.

  On the other hand, when a refractive index adjusting material (showing a refractive index of 1.4607 at a wavelength of 635 nm) is applied to the outer peripheral surface of the waveguide 901, fluorescent light with an incident angle of 30 deg is The maximum angle propagating through the waveguide 901 is 11.3 [deg], and the bandpass filter 205 is irradiated with a spread of approximately ± 16.9 [deg]. Therefore, the value from +15 deg to −15 deg in FIG. 10C is integrated, and the noise light intensity ratio between the fluorescence intensity from the plaque and the fluorescence intensity excluding the fluorescence from the plaque is 9.83.

  Therefore, by providing the refractive index adjusting member, the ratio of the fluorescence from the target plaque in the detection light can be increased 2.93 times, and the fluorescence from the plaque can be measured with higher sensitivity. Can do.

  As described above, the plaque detection unit 200 that realizes the optical devices according to the first to fourth embodiments of the present invention transmits the bandpass filter 205 that transmits light in the predetermined wavelength range and the bandpass filter 205. A light receiving element 206 that receives light and a first optical waveguide 203 or a second optical waveguide 204 that guides fluorescence generated from the tooth 210 or plaque 211 to be detected and guides it to the bandpass filter 205, or And an optical waveguide member such as the optical waveguides 701, 702, and 703, and a refractive index adjusting member 301 (or a refractive index adjusting member 501, 601, 704, or cladding 802) covering the outer peripheral surface of the optical waveguide member. .

The refractive index n of the refractive index adjusting member 301 is set to θ _{0 as} the emission angle of the fluorescence emitted from the optical waveguide member toward the bandpass filter 205, and n _{0 as} the refractive index of the medium outside the refractive index adjusting member 301. When the refractive index of the optical waveguide member is n _1, it is characterized by n ₁ >n> n ₁ * sin (acos (n ₀ / n ₁ * sin (θ ₀ ))).

Further, in the plaque detecting unit 200 that realizes the optical devices according to the first to fourth embodiments of the present invention, the refractive index adjusting member 301 has the second optical waveguide 204, the optical waveguides 701, 702, 703, and the like. When the diameter of the optical waveguide member is φ, the length d = φ / (tan (π / 2-acos (n ₀ / n ₁ * sin (θ ₀ ))) in the direction of fluorescence guiding by the optical waveguide member It is characterized by being provided so as to be longer than.

  Moreover, the refractive index adjusting member 501 provided in the plaque detecting unit 200 according to the first to fourth embodiments of the present invention has a shape in which the outer surface scatters light transmitted to the outside of the refractive index adjusting member 501. It is a feature.

  Further, the refractive index adjusting member 601 provided in the plaque detecting unit 200 according to the first to fourth embodiments of the present invention is characterized in that it has a tapered shape whose outer diameter becomes smaller toward the band pass filter 205 side.

  In addition, the plaque detection unit 200 according to the first to fourth embodiments of the present invention uses the excitation light source 113 that emits excitation light including a wavelength of 405 nm and the excitation light emitted from the excitation light source 113 as a detection target. The bandpass filter 205 is characterized by transmitting fluorescence having a peak near 635 nm out of fluorescence generated from the detection target irradiated with excitation light by the irradiation optical system.

  Further, in the plaque detecting unit 200 according to the first to fourth embodiments of the present invention, the refractive index adjusting member 704 is a light for a bandpass filter among the optical waveguides 701, 702, and 703 that realize the optical waveguide member. It is provided in the optical waveguide 703 that emits light.

  Further, the plaque detecting unit 200 according to the first to fourth embodiments of the present invention determines the presence or absence of the tooth 210 or the plaque 211 as the detection target based on the intensity of the light received by the light receiving element 206. It is characterized by that.

According to the plaque detecting unit 200 according to the first to fourth embodiments of the present invention, the optical waveguide member such as the second optical waveguide 204, the optical waveguide 703, or the core 801, and the refractive index adjusting members 301, 501, 601, At the interface with 704 or the cladding 802, light incident at an incident angle equal to or greater than θ _C represented by the above formula (2) propagates through the optical waveguide member by total reflection, and light having an incident angle less than θ _C is refracted. Then, the light passes through the refractive index adjusting member. Thus, by adjusting the difference in refractive index between n ₁ and n, it can be arbitrarily determined the angle of reflection at the interface.

Here, by setting the refractive index n of the refractive index adjusting members 301, 501, 601, and 704 or the clad 802 within the range of the above formula (3), the spread angle from the optical waveguide member to the bandpass filter 205 is θ _0. It can be contained below. Further, by setting the length of the refractive index adjusting member to be not less than d represented by the above mathematical formula (4), the light incident on the optical waveguide member can be transmitted at least once with the optical waveguide member and the refractive index adjusting member. Can be incident on the interface. Thereby, the angle component of unnecessary light can be reliably transmitted (emitted) to the outside of the optical waveguide member.

  And by configuring in this way, the incident angle to the bandpass filter 205 is suppressed, the unnecessary wavelength component is prevented from being propagated due to the incident angle dependency in the bandpass filter 205, and the target wavelength Can only propagate. Thereby, the detection sensitivity of light having a narrow spectral width can be improved.

  Further, according to the plaque detection unit 200 of the first to fourth embodiments of the present invention, it can be realized by a simple configuration in which a refractive index adjusting member is provided on the outer peripheral surface of the optical waveguide member. The size of the part 200 and the size of the plaque detection toothbrush 100 on which the plaque detection unit 200 is mounted can be reduced.

  As described above, according to the plaque detection unit 200 according to the first to fourth embodiments of the present invention, the detection sensitivity of light having a narrow spectral width is improved, and the plaque detection unit 200 and the plaque detection toothbrush 100 are small. Can be achieved.

(Embodiment 5)
The shape and function of the refractive index adjusting member of the dental plaque detecting toothbrush 100 according to the fifth embodiment of the present invention will be described. In the fifth embodiment, the same parts as those in the first to fourth embodiments are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 11 is an explanatory diagram showing the shape and function of the refractive index adjusting member in the fifth embodiment. As shown in FIG. 11, the plaque detection toothbrush 100 according to the fifth embodiment of the present invention includes a refractive index adjusting member 1101. The refractive index adjusting member 1101 is provided on the outer peripheral side of the second optical waveguide 204 that realizes the optical waveguide member, and between the bandpass filter 205 and the second optical waveguide 204. In other words, the refractive index adjustment member 1101 is provided between the refractive index adjustment member 1101a provided on the outer peripheral side of the second optical waveguide 204 and the bandpass filter 205 and the second optical waveguide 204. Member 1101b.

  The refractive index adjusting member 1101 b is filled between the band pass filter 205 and the second optical waveguide 204 between the band pass filter 205 and the second optical waveguide 204. For this reason, an outer peripheral atmosphere such as air is not interposed between the bandpass filter 205 and the second optical waveguide 204.

  In the refractive index adjusting member 1101, it is preferable that the refractive index adjusting member 1101a and the refractive index adjusting member 1101b are integrally formed. Specifically, the refractive index adjusting member 1101 in which the refractive index adjusting member 1101a and the refractive index adjusting member 1101b are integrally formed is, for example, the outer peripheral side of the second optical waveguide 204 and the second optical waveguide 204. It can be formed integrally by applying (or forming a film) refractive index matching oil to the end face on the band pass filter 205 side.

  Thereby, the refractive index adjusting member 1101 can be easily formed on the outer peripheral side of the second optical waveguide 204 and between the bandpass filter 205 and the second optical waveguide 204. In this case, the material forming the refractive index adjusting member 1101 may be provided so as to cover the entire outer surface of the second optical waveguide 204.

  The refractive index adjusting member 1101 in which the refractive index adjusting member 1101a and the refractive index adjusting member 1101b are integrated is formed using a solid material instead of a liquid material such as refractive index matching oil as described above. May be. The material forming the refractive index adjusting member 1101 is in the form of a liquid when provided on the outer peripheral side of the second optical waveguide 204 and between the bandpass filter 205 and the second optical waveguide 204. It may be a material that forms a solid state by drying or curing using a predetermined method.

  When assembling such a plaque detection unit 200, for example, the bandpass filter 205 is assembled so as to contact the second optical waveguide 204 coated with refractive index matching oil. Alternatively, for example, in a state where the second optical waveguide 204 and the bandpass filter 205 are arranged in a predetermined positional relationship, a refractive index matching oil is applied to the outer peripheral surface of the second optical waveguide 204 and the second optical waveguide The plaque detection unit 200 may be assembled by filling refractive index matching oil between the waveguide 204 and the bandpass filter 205.

(Principle of light guide)
Next, the principle of light guide by the refractive index adjusting member 1101 will be described. FIG. 12 is an explanatory view showing the principle of light guide by the refractive index adjusting member 1101. In FIG. 12, the refractive index adjusting member 1101 has a lower refractive index than the material forming the second optical waveguide 204, as in the first to fourth embodiments described above, and is closer to the outer periphery than the refractive index adjusting member 1101. It is formed using a material having a higher refractive index.

・・・（６） When the emission angle of the fluorescence emitted from the second optical waveguide 204 to the bandpass filter 205 side is θ ₀ and the refractive index of the second optical waveguide 204 is n ₁ , the refractive index adjustment member 1101a and the refractive index adjustment member The refractive index n of the refractive index adjusting member 1101 configured by 1101b is set to a value in a range that satisfies the following mathematical formula (6).

... (6)

The emission angle θ ₀ is the maximum of the fluorescence emitted from the second optical waveguide 204 so that the incident angle of the fluorescence incident on the bandpass filter 205 is within the angle range assumed in the design. The emission angle (maximum emission angle) is shown. By setting the refractive index n of the refractive index adjusting member 1101 to a value that satisfies the above formula (6), the second of the fluorescence incident on the interface between the second optical waveguide 204 and the refractive index adjusting member 1101. Fluorescence incident at an angle θ _i larger than the critical angle θ _C, which is the incident angle when the maximum emission angle from the optical waveguide 204 becomes θ ₀ , is transmitted from the outer peripheral surface of the second optical waveguide 204 to the second Only the fluorescence that is transmitted to the outside of the optical waveguide 204 and incident at the interface at an angle θ _r ′ smaller than the critical angle θ _C is reflected, propagates in the second optical waveguide 204, and is output to the bandpass filter 205. Is done.

The refractive index adjusting member 1101 is in contact with the end surface of the second optical waveguide 204 on the bandpass filter 205 side, and is sandwiched between the second optical waveguide 204 and the bandpass filter 205. As described above, since an outer peripheral atmosphere such as air is not interposed between the bandpass filter 205 and the second optical waveguide 204, the refractive index adjustment in the above formula (3), that is, the above formula (3) ′. The refractive index n ₀ of the medium outside the member 1101 is n ₀ = n.

  Therefore, the refractive index n of the refractive index adjusting member 1101 is not affected by the refractive index of the medium outside the refractive index adjusting member 1101 as shown by the above formula (6).

  In this way, by causing the refractive index adjusting member 1101b to function as a refractive index matching material, the medium outside the refractive index adjusting member 1101 is more than the refractive index n of the refractive index adjusting member 1101, such as air. The incident angle to the band pass filter 205 can be made smaller than in the case of a medium having a low refractive index.

  By reducing the incident angle to the band pass filter 205, the light emitted from the second optical waveguide 204 is converted into the refractive index of the refractive index adjusting member 1101 when light in a certain angle range is incident on the band pass filter 205. More light can be incident on the band-pass filter 205 than when the light is incident on the band-pass filter 205 via a medium having a refractive index smaller than n, and the light utilization efficiency can be improved. Further, by reducing the incident angle to the band pass filter 205, an effect of reducing the influence of the wavelength shift can be obtained. Thereby, a noise component can be reduced and the light intensity which filtered only the light of the target wavelength band can be detected.

・・・（７） In the plaque detection unit 200, light that has entered the second optical waveguide 204 directly reaches the exit surface of the second optical waveguide 204, and excludes light that is excluded from the exit angle at an exit angle θ ₀ or less. In order to make the light incident on the interface between the second optical waveguide 204 and the refractive index adjusting member 1101 at least once, the refractive index adjusting member 1101 has the first optical waveguide 204 with a diameter of φ. The length d in the length direction of the second optical waveguide 204 (the direction from the mirror 202 toward the bandpass filter 205) at the position covering the outer peripheral surface of the second optical waveguide 204 is the above formula (4), that is, the above formula ( In 4) ′, the refractive index n ₀ is provided so as to be equal to or longer than the length indicated by the formula n.

... (7)

  That is, the refractive index adjusting member 1101 does not include the dimension of the refractive index adjusting member 1101b in the length direction of the second optical waveguide 204, and the length of the refractive index adjusting member 1101a that covers the outer peripheral surface of the second optical waveguide 204. d is provided so as to be equal to or longer than the length indicated by the mathematical formula (7). For this reason, the overall dimension of the refractive index adjusting member 1101 in the length direction of the second optical waveguide 204 is longer than the length indicated by d.

  The refractive index adjusting member 1101 may have a shape (scattering structure) for scattering light on the outer surface of the refractive index adjusting member 1101a. Thereby, similarly to the refractive index adjusting member 501 in the second embodiment described above, the leakage light from the outer peripheral surface of the second optical waveguide 204 to the refractive index adjusting member 1101 is scattered, and the outer surface of the refractive index adjusting member 1101. The component reflected in can be reduced.

  Alternatively, the refractive index adjusting member 1101 may have a tapered shape in which the outer diameter of the refractive index adjusting member 1101a becomes smaller toward the fluorescence emission side, that is, the band pass filter 205 side. Thus, similarly to the refractive index adjusting member 601 in the third embodiment, the light incident on the refractive index adjusting member 1101 from the outer peripheral surface of the second optical waveguide 204 is converted into an outer surface of the refractive index adjusting member 1101 having a tapered shape. It can discharge | emit out of the refractive index adjustment member 1101 from the taper surface which is.

  Alternatively, a light absorbing material covering the outer surface is provided on the outer surface of the refractive index adjusting member 1101a in the refractive index adjusting member 1101, and light leaked from the outer peripheral surface of the second optical waveguide 204 to the refractive index adjusting member 1101 is emitted. You may make it absorb with an absorbent material. FIG. 13 is an explanatory view showing an example in which a light absorbing material is provided on the outer surface of the refractive index adjusting member 1101a.

  As shown in FIG. 13, by providing the light absorbing material 1300 on the outer surface of the refractive index adjusting member 1101a, the second refractive index adjusting member 1101a is in contact with the outer peripheral atmosphere such as air on the outer surface. It is possible to prevent light incident on the optical waveguide 204 from being reflected at the interface between the refractive index adjusting member 1101 and the outer peripheral atmosphere and returning to the second optical waveguide 204.

Further, when the refractive index adjusting member 1101 is provided so as to cover the entire outer surface of the second optical waveguide 204, the refractive index adjusting member 1101 is provided between the mirror 202 side end face of the refractive index adjusting member 1101 and the mirror 202. You may provide so that it may fill. As a result, since there is no outer peripheral atmosphere such as air between the mirror 202 and the second optical waveguide 204, the mirror 202 is transferred to the second optical waveguide 204 without being affected by the refractive index n ₀ of the outer peripheral atmosphere. It can be guided.

  As described above, the plaque detecting unit 200 that realizes the optical device according to the fifth embodiment of the present invention has the refractive index adjusting member 1101a (covering the outer peripheral surface of the second optical waveguide 204 that realizes the optical waveguide member). Alternatively, the refractive index adjustment member 301, 501, 601, 704, or the cladding 802) and the refractive index adjustment member 1101b provided between the bandpass filter 205 and the second optical waveguide 204 are provided. A member 1101 is provided.

  Further, the plaque detecting unit 200 that realizes the optical device according to the fifth embodiment of the present invention has a refractive index adjusting member 1101b provided between the bandpass filter 205 and the second optical waveguide 204. The filter 205 and the second optical waveguide 204 are filled.

  Further, the plaque detecting unit 200 realizing the optical device according to the fifth embodiment of the present invention is characterized in that the refractive index adjusting member 1101a and the refractive index adjusting member 1101b are integrally formed.

によって示されることを特徴としている。 Further, in the plaque detecting unit 200 that realizes the optical device according to the fifth embodiment of the present invention, the refractive index n of the refractive index adjusting member 1101 is fluorescence emitted from the second optical waveguide 204 to the bandpass filter 205 side. Is _{0 0} , the refractive index of the medium outside the refractive index adjusting member 1101 is n _0, and the refractive index of the second optical waveguide 204 is n ₁ ,

It is characterized by being indicated by.

  Here, when light that does not have directivity and spreads at any angle, such as fluorescence, enters the second optical waveguide 204 that does not include the refractive index adjusting member 1101b, light having a large angle is also reflected in the bandpass filter 205. Will be emitted. When light having a large angle is incident on the bandpass filter 205, the transmission wavelength band is shifted to a short wavelength due to the wavelength shift.

  In the plaque detection unit 200, when light having a large angle is incident on the bandpass filter 205, light that does not contain fluorescent components from the plaque guides the second optical waveguide 204 to the bandpass filter 205. Emitted. For this reason, the bandpass filter 205 detects the intensity of light including light that does not contain fluorescent components from dental plaque. Since the light that does not contain the fluorescent component from the plaque is noise and is an unnecessary component, the incidence of light having a large angle on the bandpass filter 205 results in an increase in noise. Although the spread of light can be limited by a lens or the like, it is not preferable because the number of parts is increased and the apparatus size is increased.

  Since the fluorescence of dental plaque is weak, if the noise is large, the fluorescence signal is buried in the noise, and the target fluorescence intensity may not be measured. For this reason, in the light that is guided through the second optical waveguide 204 and emitted to the band pass filter 205, the light component having a large angle as a noise component is made as small as possible, that is, the noise component is cut. Is preferred.

  According to the plaque detection unit 200 of the fifth embodiment of the present invention, the outer peripheral side of the second optical waveguide 204 that realizes the optical waveguide member, and between the bandpass filter 205 and the second optical waveguide 204. By providing the refractive index adjusting member 1101b in the bandpass, the bandpass of the light emitted from the second optical waveguide 204 to the bandpass filter 205 side in addition to the effect exhibited by the plaque detecting unit 200 of the first to fourth embodiments. The incident angle to the filter 205 can be further reduced.

  Thereby, it is possible to suppress propagation of an unnecessary wavelength component due to the incident angle dependency in the band pass filter 205 and to propagate only a target wavelength. As a result, the detection sensitivity of light having a narrow spectral width can be further improved.

  Further, according to the plaque detection unit 200 of the fifth embodiment of the present invention, the refractive index is adjusted between the outer peripheral side of the second optical waveguide 204 and between the bandpass filter 205 and the second optical waveguide 204. Since it can be realized by a simple configuration in which the member 1101 is provided, the plaque detection unit 200 can be downsized, and the plaque detection toothbrush 100 on which the plaque detection unit 200 is mounted can be downsized.

Further, according to the plaque detection unit 200 of the fifth embodiment of the present invention, the second optical waveguide is filled with the refractive index adjusting member 1101 between the second optical waveguide 204 and the band pass filter 205, thereby providing the second optical waveguide. Since there is no outer peripheral atmosphere such as air between the waveguide 204 and the bandpass filter 205, the light emitted from the second optical waveguide 204 to the bandpass filter 205 side is reflected on the medium outside the refractive index adjusting member 1101. The light can enter the bandpass filter 205 without being affected by the refractive index n ₀ .

  Thereby, for example, even when the surface of the second optical waveguide 204 on the side of the bandpass filter 205 and the light incident surface of the bandpass filter 205 are inclined, the second optical waveguide 204 and the bandpass filter Compared with the case where an outer peripheral atmosphere such as air exists between 205 and 205, the incident angle to the band-pass filter 205 can be kept small.

  With this configuration, the second optical waveguide 204 and the bandpass filter 205 are assembled more than the configuration in which an outer peripheral atmosphere such as air exists between the second optical waveguide 204 and the bandpass filter 205. The degree of freedom in the positional relationship between the second optical waveguide 204 and the bandpass filter 205 can be improved.

  FIG. 14 is an explanatory diagram showing the positional relationship between the second optical waveguide 204 and the bandpass filter 205. As shown in FIG. 14A, when there is no refractive index adjusting member 1101b between the second optical waveguide 204 and the bandpass filter 205, the incident angle to the bandpass filter 205 is influenced by the ambient atmosphere such as air. Therefore, depending on the positional relationship between the second optical waveguide 204 and the band-pass filter 205, it is assumed that the incident angle of the fluorescence incident on the band-pass filter 205 deviates from the designed angular range. .

  On the other hand, as shown in FIG. 14B, the refractive index adjusting member 1101b is filled between the second optical waveguide 204 and the bandpass filter 205, so that the second optical waveguide 204 and the bandpass filter are filled. Regardless of the positional relationship with 205, the incident angle of the fluorescence incident on the band-pass filter 205 can be within the angular range assumed in design without being affected by the ambient atmosphere such as air.

  Thus, by filling the refractive index adjusting member 1101b between the second optical waveguide 204 and the band pass filter 205, compared to the plaque detecting unit 200 that does not include the refractive index adjusting member 1101b, Even when the relative positional relationship between the second optical waveguide 204 and the band-pass filter 205 is wobbled, the detection sensitivity of light having a narrow spectral width can be maintained. Thereby, the yield in the manufacture of the plaque detection unit 200 can be improved.

  Further, the refractive index adjusting member 1101b is filled between the second optical waveguide 204 and the bandpass filter 205, so that the light emitted from the second optical waveguide 204 can be changed from the refractive index n of the refractive index adjusting member 1101. In addition, more light can be incident on the bandpass filter 205 than when the light is incident on the bandpass filter 205 via a medium having a small refractive index. As a result, the detection sensitivity of light having a narrow spectral width can be improved.

  Further, according to the plaque detection unit 200 of the fifth embodiment of the present invention, since the refractive index adjusting member 1101a and the refractive index adjusting member 1101b are integrally formed, the second optical waveguide 204 has a refractive index. High workability when providing the adjustment member 1101 can be ensured. Specifically, for example, high workability can be ensured by suppressing an increase in work load and the number of parts during assembly.

Further, according to the plaque detection unit 200 of the fifth embodiment of the present invention, the emission angle of the fluorescence emitted from the second optical waveguide 204 to the bandpass filter 205 side is θ ₀ , and the refractive index adjustment member 1101 When the refractive index of the outer medium is n ₀ and the refractive index of the optical waveguide member is n ₁ , the refractive index adjusting member 1101 having the refractive index n expressed by the above equation (6) is used. At the interface between the second optical waveguide 204 and the refractive index adjusting member 1101, only the fluorescent light incident at an angle θ _i ′ larger than the critical angle θ _C is reflected and propagated in the second optical waveguide 204, and air Thus, the light can be incident on the bandpass filter 205 without being affected by the ambient atmosphere. Thereby, the incident angle to the band pass filter 205 can be reduced, and the light utilization efficiency can be improved.

  As described above, according to the plaque detection unit 200 of the embodiment of the present invention, it is possible to reduce the incident angle to the bandpass filter 205 and improve the light utilization efficiency. In addition, the detection sensitivity of light having a narrow spectral width can be improved, and the plaque detection unit 200 and the plaque detection toothbrush 100 can be downsized.

  As described above, the optical device according to the present invention is useful for an optical device that detects light having a narrow spectral width, and is particularly suitable for an optical device that is incorporated in a toothbrush.

100 Dental plaque detection toothbrush 110 Main body (handle)
DESCRIPTION OF SYMBOLS 112 Power supply 113 Excitation light source 114 Coaxial optical system 115,206 Light receiving element 116 Control circuit 117 Notification apparatus 201 Filter 202 Mirror 203 1st optical waveguide 204 2nd optical waveguide 205 Band pass filter 301,501,601,704,1101 1101a, 1101b Refractive index adjusting member 701, 702, 703 Optical waveguide 800 Optical fiber 801 Core 802 Clad

Claims (11)

A bandpass filter that transmits light in a predetermined wavelength range;
A light receiving element that receives light transmitted through the bandpass filter;
An optical waveguide that guides the fluorescence generated from the detection target and guides it to the bandpass filter;
A refractive index adjusting member covering an outer peripheral surface of the optical waveguide member constituting the optical waveguide;
With
The optical apparatus, wherein the fluorescence totally reflected by the refractive index adjusting member is incident on the bandpass filter. The refractive index n of the refractive index adjusting member is defined such that the emission angle of fluorescence emitted from the optical waveguide member to the bandpass filter side is θ _0, and the refractive index of the medium outside the refractive index adjusting member is n ₀ , If the refractive index of the optical waveguide member and a n _1,
n ₁ >n> n ₁ * sin (acos (n ₀ / n ₁ * sin (θ ₀ )))
The optical device according to claim 1, characterized by:   The optical apparatus according to claim 1, wherein the refractive index adjusting member is further provided between the bandpass filter and the optical waveguide.   The optical system according to claim 3, wherein the refractive index adjusting member provided between the bandpass filter and the optical waveguide is filled between the bandpass filter and the optical waveguide. apparatus.   The refractive index adjusting member that covers the outer peripheral surface of the optical waveguide member and the refractive index adjusting member provided between the bandpass filter and the optical waveguide are integrally formed. The optical device according to claim 3 or 4. The refractive index n of the refractive index adjusting member is defined such that the emission angle of fluorescence emitted from the optical waveguide member to the bandpass filter side is θ _0, and the refractive index of the medium outside the refractive index adjusting member is n ₀ , If the refractive index of the optical waveguide member and a n _1,

The optical device according to claim 3, which is indicated by: The refractive index adjusting member that covers the outer peripheral surface of the optical waveguide member, when the diameter of the optical waveguide member is φ, in the direction of fluorescence guided by the optical waveguide member,
Length d = φ / (tan (π / 2-acos (n ₀ / n ₁ * sin (θ ₀ ))))
The optical device according to claim 2, wherein the optical device is provided so as to be longer.   The refractive index adjusting member that covers the outer peripheral surface of the optical waveguide member has an outer surface configured to scatter light that is transmitted to the outside of the refractive index adjusting member. The optical device according to one.   9. The optical according to claim 1, wherein the refractive index adjusting member that covers the outer peripheral surface of the optical waveguide member has a tapered shape in which an outer diameter decreases toward the band-pass filter side. apparatus. At least one excitation light source that emits excitation light including a wavelength near 405 nm;
An irradiation optical system for irradiating a detection target with excitation light emitted from the excitation light source;
With
The said band pass filter permeate | transmits the fluorescence which has a peak in the vicinity of 635 nm among the fluorescence produced from the detection target irradiated with the excitation light by the said irradiation optical system. An optical device according to 1.   The optical apparatus according to claim 1, further comprising: a determination unit that determines presence / absence of a detection target based on an intensity of light received by the light receiving element.

Images