JP2018126520A - Detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an S/N ratio of a signal outputted from a detector.SOLUTION: A detector (100a) comprises a board (10), a light emitting part (20) arranged on the board to emit light, a light receiving part (31) arranged on the board to receive scattered light from an object out of the emitted light, and a sealing part (40) arranged on the board so as to cover the light emitting part and the light receiving part. The light receiving part also receives internally reflected light reflected by a boundary surface of the sealing part out of the light emitted from the light emitting part. A reflecting film (41) is arranged on at least a portion of a surface of the sealing part.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a technical field of a detector mounted on an optical measuring device that performs measurement using, for example, laser light.

  As this type of measuring apparatus, for example, a sensor unit in which a semiconductor laser and a light receiving element are arranged on the same plane is provided, and blood flow volume, blood volume, blood flow in the living tissue is utilized using scattered light from the living tissue. An apparatus for measuring speed, pulse, etc. has been proposed (see Patent Document 1).

Japanese Patent No. 4718324

  However, the technique described in Patent Document 1 has a technical problem that there is room for improvement with respect to, for example, the S / N ratio (Signal to Noise Ratio).

  The present invention has been made in view of the above problems, for example, and an object of the present invention is to provide a detector capable of improving the S / N ratio.

  In order to solve the above-described problem, the detector according to claim 1 is a substrate, a light emitting unit that is disposed on the substrate and emits light, and a target of the emitted light that is disposed on the substrate. A light receiving portion that receives scattered light from an object, and a sealing portion that is disposed on the substrate so as to cover the light emitting portion and the light receiving portion, and the light receiving portion is configured to receive the emitted light. Internally reflected light reflected at the interface of the sealing portion is further received, and a reflective film is disposed on at least a part of the surface of the sealing portion.

  The effect | action and other gain of this invention are clarified from the form for implementing demonstrated below.

It is a schematic block diagram which shows the structure of the detector which concerns on an Example. It is a perspective view of the photon detection apparatus which concerns on an Example. It is a block diagram which shows the structure of the photon detection apparatus which concerns on an Example. It is a conceptual diagram which shows the light which injects into a light receiving element. It is a schematic block diagram which shows the structure of the detector which concerns on the 1st modification of an Example. It is a schematic block diagram which shows the structure of the detector which concerns on the 2nd modification of an Example. It is a schematic block diagram which shows the structure of the detector which concerns on the 3rd modification of an Example. It is a block diagram which shows the structure of the photon detection apparatus which concerns on the 3rd modification of an Example. It is a schematic block diagram which shows the structure of the detector which concerns on the 4th modification of an Example. It is a block diagram which shows the structure of the photon detection apparatus which concerns on the 4th modification of an Example. It is a schematic block diagram which shows the structure of the detector which concerns on the 5th modification of an Example. It is a block diagram which shows the structure of the photon detection apparatus which concerns on the 5th modification of an Example.

  An embodiment according to the detector of the present invention will be described.

  The detector according to the embodiment includes, for example, a substrate that is a submount, a light emitting unit that is disposed on the substrate and emits light, and a scattered light from a target object that is disposed on the substrate and is emitted. A light receiving portion that receives light, and a sealing portion that is disposed on the substrate so as to cover the light emitting portion and the light receiving portion.

  For example, a light source such as a surface emitting laser can be applied to the light emitting unit. Here, when the measurement object is a living body, a light source that emits light in a wavelength range of 700 nm (nanometers) to 1300 nm, which is relatively low in absorption by the living body, is desirable.

  When a light source that emits light in the wavelength range of 700 nm to 1300 nm is used as a light emitting part, the sealing part has a transmittance of 10% or less for light having a wavelength of 650 nm or less (that is, visible light). In addition, it is desirable to apply a resin having a transmittance of 90% or more for light having a wavelength of 700 nm to 1300 nm. If comprised in this way, incidence | injection to the light-receiving part of the visible light which can become disturbance light can be suppressed, and it is very advantageous practically.

  When the measurement object is a living body, for example, scattered light received by a light receiving unit such as a photodiode includes light scattered by a living tissue (for example, skin) and a moving object (for example, a living body). Light scattered by red blood cells or the like). Then, Doppler shift proportional to the speed of the moving object occurs in the light scattered by the moving object of the living body. Therefore, interference light between light scattered by the stationary tissue of the living body and light scattered by the moving object of the living body enters the light receiving unit.

  Here, the electric field intensity of the light scattered by the stationary tissue of the living body is expressed by the following expression (1), and the electric field intensity of the light scattered by the moving object of the living body is expressed by the following expression (2), the interference light The intensity of can be expressed by the following equation (3).

“Ａ_０”及び“Ａ_１”は、光の振幅であり、“ｆ_０”は光の周波数であり、“Δｆ”はドップラーシフトに起因して変動する周波数である。“ｉ”はｉベクトルであり、“ｊ”はｊベクトルである。ｉベクトル及びｊベクトルは、光の進行方向を表わす単位ベクトルである。

“A ₀ ” and “A ₁ ” are the amplitude of light, “f ₀ ” is the frequency of light, and “Δf” is a frequency that varies due to the Doppler shift. “I” is an i vector, and “j” is a j vector. The i vector and the j vector are unit vectors representing the traveling direction of light.

  The first term of the above formula (3) is a stationary light component, and the second term is a beat component. As can be seen from the above equation (3), the beat component becomes stronger as the direction of the i vector approaches the direction of the j vector.

  Incidentally, the light emitted from the light emitting unit is scattered in various directions by the measurement object. In addition, the light scattered by the moving object of the living body is weaker than the light scattered by the stationary tissue of the living body. For this reason, it is difficult to make the beat component of the formula (3) sufficiently strong with only scattered light.

  However, in this embodiment, since the light emitting part is covered by the sealing part, a part of the light emitted from the light emitting part passes through the sealing part and reaches the measurement object, and another part. Is reflected at the interface of the sealing portion. For this reason, scattered light from the measurement object and internally reflected light reflected at the interface of the sealing portion are incident on the light receiving portion.

  The internally reflected light is incident on the light receiving unit at an incident angle close to 90 degrees and can be handled in the same manner as the light scattered by the stationary tissue of the living body. In addition, although the ratio of internally reflected light to the light emitted from the light emitting unit is small, the ratio of being reflected by the interface and entering the light receiving unit is compared with the ratio of scattered light scattered by the measurement object and entering the light receiving unit. High enough.

  That is, in the present embodiment, the beat component of the above expression (3) can be sufficiently strengthened by using the internally reflected light. In addition, of the light scattered by the moving object of the living body due to the internally reflected light, a beat component related to light incident at an incident angle close to 90 degrees with respect to the light receiving unit is strongly measured.

  As a result, according to the detector according to the present embodiment, the S / N ratio can be improved. In addition, the spatial resolution of the detector can be improved. Further, in the detector, since the light emitting part and the light receiving part are integrally molded, for example, the manufacturing process can be shortened, which is very advantageous in practice.

  In one aspect of the detector according to the present embodiment, the light receiving unit includes a first photoelectric conversion element and a second photoelectric conversion element, and the anode of the first photoelectric conversion element and the anode of the second photoelectric conversion element are mutually connected. The cathode of the first photoelectric conversion element and the cathode of the second photoelectric conversion element are electrically connected to each other.

  According to this aspect, it is possible to cancel the DC component of the current output from the first photoelectric conversion element and the DC component of the current output from the second photoelectric conversion element, and S in the signal output from the detector. / N ratio can be improved.

  In another aspect of the detector according to the present embodiment, a reflective film is disposed on at least a part of the surface of the sealing portion.

  According to this aspect, the amount of internally reflected light can be increased, which is very advantageous in practice. In addition, as a reflecting film, thin films, such as aluminum, are applicable, for example.

  In another aspect of the detector according to the present embodiment, the sealing portion has a thickness of the sealing portion from the light receiving portion side toward the light emitting portion side (that is, between the substrate surface and the sealing portion upper surface). The first inclined surface becomes thinner, and the second inclined surface where the thickness of the sealing portion becomes thinner from the light emitting portion side toward the light receiving portion side. The inclined surface is formed so that the angle formed between each other approaches 90 degrees.

  According to this aspect, the magnitude of the emission angle of the light emitted from the light emitting section and the magnitude of the incident angle of the internally reflected light to the light receiving section can be made substantially the same. Here, since the emission angle is approximately 90 degrees, the incident angle is also approximately 90 degrees, and the beat component of the expression (3) can be strengthened relatively easily.

  In this aspect, the sealing portion has an upper surface that is a surface along the substrate surface of the substrate, and one side of the upper surface is shared with the first inclined surface and is opposed to the one side. May be shared with the second inclined surface.

  If comprised in this way, the height of the said detector can be suppressed and it is very advantageous practically.

  Embodiments according to the detector of the present invention will be described with reference to the drawings.

  The detector according to the embodiment will be described with reference to FIG. FIG. 1 is a schematic configuration diagram illustrating a configuration of a detector according to the embodiment. 1A is a top view, FIG. 1B is a bottom view, and FIG. 1C is a side view.

  In FIG. 1, a detector 100 includes a substrate 10, a surface emitting laser 20 disposed on the substrate 10, a light receiving element 31 disposed on the substrate 10, the surface emitting laser 20 and the light receiving element 31. And a sealing portion 40 disposed on the substrate 10 so as to cover the substrate.

  The surface emitting laser 20 as an example of the “light emitting unit” according to the present invention emits light having a wavelength of, for example, 850 nm. The wavelength of the light emitted from the surface emitting laser 20 is not limited to 850 nm as long as it is included in the range of 700 nm to 1300 nm.

  The sealing portion 40 is made of a resin such as an epoxy resin, for example. In the resin constituting the sealing portion 40, the transmittance for light having a wavelength of 650 nm or less is 10% or less, and the transmittance for light having a wavelength of 700 nm to 1300 nm is 90% or more. Dye is mixed.

  The anode and cathode of the surface emitting laser 20 are electrically connected to an electrode (not shown) on the upper surface of the substrate 10 using wire bonding or the like. The electrode on the upper surface of the substrate 10 penetrates the lower surface of the substrate 10.

  As shown in FIG. 1B, on the lower surface of the substrate 10, there are terminals 20 a electrically connected to the anode of the surface emitting laser 20 and terminals 20 c electrically connected to the cathode of the surface emitting laser 20. As an example of the “light receiving unit” according to the present invention, a terminal 31a electrically connected to the anode of the light receiving element 31 and a terminal 31c electrically connected to the cathode of the light receiving element 31 are exposed. doing.

  The size of the detector 100 is, for example, 3 mm × 3 mm. The distance from the upper surface of the surface emitting laser 20 to the upper surface of the sealing portion 40 and the distance from the upper surface of the light receiving element 31 to the upper surface of the sealing portion 40 are, for example, 0.5 mm. The distance between the light emitting point of the surface emitting laser 20 (see FIG. 1A) and the center of the light receiving surface of the light receiving element 31 (see FIG. 1A) is, for example, 0.6 mm.

  When the detector 100 is mounted on a light detection device, it is mounted on a circuit board stored in a case 300 made of, for example, aluminum as shown in FIG. The case 300 is provided with a window 301 so as not to block light emitted from the surface emitting laser 20 and light incident on the light receiving element 31.

  The size of the case 300 is, for example, 10 mm × 15 mm × 3 mm. The size of the window 301 is, for example, 3 mm × 3 mm.

  Next, the photodetector will be described with reference to FIG. FIG. 3 is a block diagram illustrating the configuration of the photodetecting device according to the embodiment. In this embodiment, a laser Doppler blood flow meter is taken as an example of the light detection device.

  In FIG. 3, the photodetector is configured to include a detector 100 (that is, a photocurrent conversion unit) and a current-voltage conversion unit 200. Input light (incident light) to the detector 100 is light obtained by reflecting or scattering light emitted from the surface emitting laser 20 by an object (for example, a human finger).

  The light receiving element 31 is a photodiode such as a PIN diode. The detector 100 outputs the current Idt output from the light receiving element 31 from the terminal 31a as the detection current Idt. The detector 100 outputs a current (-Idt) obtained by inverting the polarity of the detection current Idt output from the terminal 31a from the terminal 31c.

  The current-voltage conversion unit 200 includes input terminals In1 and In2, a fully differential amplifier 230, feedback resistors Rf1 and Rf2, an amplifier 240, and an output terminal Out. The current-voltage converter 200 converts the detection current Idt input from the detector 100 to the input terminals In1 and In2 into a voltage signal and outputs the voltage signal from the output terminal Out.

  The fully differential amplifier 230 includes an input terminal In + electrically connected to the input terminal In1, an input terminal In− electrically connected to the input terminal In2, an output terminal Out−, an output terminal Out +, and a reference And a potential terminal Vref. The reference potential is input via the reference potential terminal Vref. The output terminals Out− and Out + are electrically connected to input terminals In− and In + of an amplifier 240 described later, respectively.

  The feedback resistor Rf1 has one end electrically connected to the input terminal In + of the fully differential amplifier 230 and the other end electrically connected to the output terminal Out− of the fully differential amplifier 230. Convert to voltage.

  The feedback resistor Rf2 has one end electrically connected to the input terminal In− of the fully-differential amplifier 230 and the other end electrically connected to the output terminal Out + of the fully-differential amplifier 230. Convert to voltage.

  The fully differential amplifier 230 converts the current Idt input to the input terminal In1 into a voltage signal −Rf1 · Idt and outputs the voltage signal from the output terminal Out−. At the same time, the fully-differential amplifier 230 converts the current −Idt input to the input terminal In2 into the voltage signal Rf2 · Idt, and outputs the voltage signal from the output terminal Out +. That is, the fully-differential amplifier 230 is configured as a transimpedance amplifier that independently converts currents input to the input terminals In1 and In2 into current-voltage and outputs them differentially.

  The amplifier 240 amplifies and outputs a potential difference (2 · Rf · Idt) between the voltage signal −Rf1 · Idt inputted from the input terminal In− and the voltage signal Rf2 · Idt inputted from the input terminal In + (note that Rf1 = Rf2 = Rf).

  The light detection signal output from the current-voltage converter 200 is input to a signal processing device (not shown) via one of the wirings 302 (see FIG. 2). The signal processing device calculates biological information such as a blood flow value, a blood flow velocity, and a pulse by processing the light detection signal. It should be noted that various known aspects can be applied to the method for obtaining the blood flow value and the like from the photodetection signal, and therefore the detailed description thereof is omitted.

  In the current-voltage conversion unit 200 described above, negative feedback is performed by the feedback resistors Rf1 and Rf2, so that the potential difference between the input terminal In + of the fully differential amplifier 230 and the reference potential terminal Vref is almost zero. Similarly, the potential difference between the input terminal In− and the reference potential terminal Vref of the fully differential amplifier 230 is almost zero. As a result, the potential of the input terminal In + and the potential of the input terminal In− are almost the same.

  Accordingly, the current voltage is applied to the terminal 31a electrically connected to the input terminal In + of the fully differential amplifier 230 via the input terminal In1 of the current-voltage converter 200 and to the input terminal In− of the fully differential amplifier 230. The potential difference from the terminal 31c electrically connected via the input terminal In2 of the conversion unit 200 is also almost zero. That is, the light receiving element 31 can be operated in a zero bias state, that is, a so-called power generation mode. For this reason, the dark current generated in the light receiving element 31 can be reduced or eliminated.

  As a result, the noise current resulting from the fluctuation of the dark current can be reduced, and the S / N ratio related to the light detection signal output from the current-voltage conversion unit 200 can be improved.

  Next, light incident on the light receiving element 31 of the detector 100 will be described with reference to FIG. FIG. 4 is a conceptual diagram showing light incident on the light receiving element.

  Most of the laser light emitted from the surface emitting laser 20 (see “emitted light” in FIG. 4) passes through the sealing portion 40 and is irradiated to the living body as the object through the window 301 of the case 300. The laser light applied to the living body is reflected and scattered by the living body, and part of the laser light passes through the sealing portion 40 and enters the light receiving element 31. Further, part of the laser light emitted from the surface emitting laser 20 is reflected at the interface of the sealing portion 40 and enters the light receiving element 31 (see “internally reflected light” in FIG. 4).

  The light reflected / scattered by the living body includes light reflected / scattered by the stationary tissue of the living body (see “return light from stationary tissue” in FIG. 4) and reflected / scattered by the moving object of the living body such as red blood cells. Light (see “Return Light from Red Blood Cells” in FIG. 4). Here, the light reflected and scattered by the moving object of the living body causes a Doppler shift proportional to the speed of the moving object.

  The light received by the light receiving element 31 is caused by a steady light component (that is, a component that does not vary due to reflection / scattering by a living body) and a beat component (that is, a Doppler-shifted modulation component) due to the interference of the light with each other. (See above formula (3)).

  The ratio at which the light reflected at the interface of the sealing portion 40 (hereinafter referred to as “internally reflected light” as appropriate) is incident on the light receiving element 31 is the light scattered by the measurement object (here, a living body). It is sufficiently stronger than the ratio of incident light on 31. The internally reflected light is incident on the light receiving element 31 at an incident angle close to 90 degrees. For this reason, among the light reflected and scattered by the moving object of the living body, the light incident on the light receiving element 31 at an incident angle close to 90 degrees is selectively emphasized (the above-described formula (3)). reference).

  Specifically, for example, in the detector 100, the incident light is close to 90 degrees with respect to the light receiving element 31 as compared with the case where the surface emitting laser is not covered with the sealing portion (that is, when there is no internal reflection light). The signal intensity of the beat component of the light incident at the angle increases by 15 dB.

<First Modification>
A first modification of the detector according to the embodiment will be described with reference to FIG. FIG. 5 is a schematic configuration diagram illustrating a configuration of a detector according to a first modification of the embodiment.

  In FIG. 5, the detector 100 a is provided on the upper surface of the sealing portion 40 and includes a reflective film 41 made of, for example, aluminum. The reflection film 41 may be disposed so as to cover the entire upper surface of the sealing portion 40, or may be disposed only above the surface emitting laser 20 and the light receiving element 31, for example.

  When the reflective film 41 is disposed so as to cover the entire upper surface of the sealing portion 40, the reflectance of the laser light related to the reflective film 41 is, for example, 20%, and the transmittance of the laser light is, for example, 80%. The reflectance and transmittance of the reflective film 41 may be set so that the light emitted from the surface emitting laser 20 is reliably irradiated onto the object.

  As can be seen from the above equation (3), if either the light reflected / scattered by the moving object of the living body, the light reflected / scattered by the stationary object of the living body, or the internally reflected light is strong, the beat component Becomes stronger. Therefore, by arranging the reflective film 41 on the upper surface of the sealing portion 40, the internal reflected light can be strengthened, so that the S / N ratio of the signal output from the light receiving element 31 can be further improved.

<Second Modification>
A second modification of the detector according to the embodiment will be described with reference to FIG. FIG. 6 is a schematic configuration diagram illustrating a configuration of a detector according to a second modification of the embodiment.

  6A, the sealing portion 40a of the detector 100b includes a first inclined surface that decreases from the light receiving element 31 side toward the surface emitting laser 20 side, and the light receiving element from the surface emitting laser 20 side. And a second inclined surface descending toward the side of 31. Here, in particular, the first inclined surface and the second inclined surface are formed so that the angle formed therebetween approaches 90 degrees.

  Since the angle formed by the first inclined surface and the second inclined surface is near 90 degrees, the emission angle of the light emitted from the surface emitting laser 20 and the incident angle of the internally reflected light to the light receiving element 31 are almost equal. Be the same. Since the emission angle of the light emitted from the surface emitting laser 20 is close to 90 degrees, the incident angle of the internally reflected light to the light receiving element 31 is also close to 90 degrees. As a result, it is possible to increase the amount of internally reflected light incident substantially perpendicularly to the light receiving element 31, so that the S / N ratio of the signal output from the light receiving element 31 can be further improved.

  In FIG. 6B, the sealing portion 40b of the detector 100c shares one side with the first inclined surface, and shares the other side facing the one side with the second inclined surface. Having an upper surface. If comprised in this way, the height of the detector 100c can be suppressed, increasing the light quantity of the internally reflected light which injected substantially perpendicularly with respect to the light receiving element 31, and it is very advantageous practically.

<Third Modification>
A third modification of the detector according to the embodiment will be described with reference to FIGS. FIG. 7 is a schematic configuration diagram illustrating a configuration of a detector according to a third modification of the embodiment. FIG. 8 is a block diagram illustrating a configuration of a photodetecting device according to a third modification of the embodiment.

  In FIG. 7, the detector 100 d further includes a light receiving element 32 disposed on the substrate 10. As shown in FIG. 7A, in the light receiving element 32, the distance between the light emitting point of the light receiving element 32 and the surface emitting laser 20 is substantially equal to the distance between the light emitting point of the light receiving element 31 and the surface emitting laser 20. It is arranged to be. As shown in FIG. 7B, the lower surface of the substrate 10 has a terminal 32 a electrically connected to the anode of the light receiving element 32 and a terminal 32 c electrically connected to the cathode of the light receiving element 32. Exposed.

  The “light receiving element 31” and the “light receiving element 32” according to this modification are examples of the “first photoelectric conversion element” and the “second photoelectric conversion element” according to the present invention, respectively.

  In this modification, in particular, as shown in FIG. 8, a terminal 31 a electrically connected to the anode of the light receiving element 31 and a terminal 32 a electrically connected to the anode of the light receiving element 32 are formed on the circuit board 200. They are electrically connected to each other. The cathode of the light receiving element 31 is electrically connected to the terminal 31c. The cathode of the light receiving element 32 is electrically connected to the terminal 32c.

  Since the light receiving elements 31 and 32 are connected in series, the detector 100d uses the difference current (Idt2−Idt1) between the current Idt1 output from the light receiving element 31 and the current Idt2 output from the light receiving element 32 as the detected current Idt. Output from terminal 31c. The detector 100d outputs a current (-Idt) obtained by inverting the polarity of the detection current Idt output from the terminal 31c from the terminal 32c.

  With this configuration, the DC component of the current Idt1 output from the light receiving element 31 and the DC component of the current Idt2 output from the light receiving element 32 can be canceled out, which corresponds to the signal light component included in the input light. A detection current Idt mainly including an AC component can be output. As a result, the S / N ratio in the photodetection signal output from the current-voltage conversion unit 200 can be improved.

<Fourth Modification>
A fourth modification of the detector according to the embodiment will be described with reference to FIGS. 9 and 10. FIG. 9 is a schematic configuration diagram illustrating a configuration of a detector according to a fourth modification example of the embodiment. FIG. 10 is a block diagram illustrating a configuration of the photodetecting device according to the fourth modification example of the embodiment.

  In this modification, in particular, as shown in FIG. 10, the anode of the light receiving element 31 and the anode of the light receiving element 32 are electrically connected to each other inside the detector 100e. With this configuration, it is not necessary to provide wiring for electrically connecting the anode of the light receiving element 31 and the anode of the light receiving element 32 on the circuit board 200, which is very advantageous in practice.

  As shown in FIG. 9, a terminal 31c electrically connected to the cathode of the light receiving element 31 and a terminal 32c electrically connected to the cathode of the light receiving element 32 are provided on the lower surface of the detector 100e. Exposed.

<Fifth Modification>
A fifth modification of the detector according to the embodiment will be described with reference to FIGS. 11 and 12. FIG. 11 is a schematic configuration diagram illustrating a configuration of a detector according to a fifth modification example of the embodiment. FIG. 12 is a block diagram illustrating a configuration of the photodetecting device according to the fifth modification example of the embodiment.

  Particularly in this modification, as shown in FIG. 12, the cathode of the light receiving element 31 and the cathode of the light receiving element 32 are electrically connected to each other inside the detector 100f. With this configuration, it is not necessary to provide wiring for electrically connecting the cathode of the light receiving element 31 and the cathode of the light receiving element 32 on the circuit board 200, which is very advantageous in practice. In addition, in this modified example, similarly to the above-described third modified example, it is possible to suppress the DC component of the detection current caused by the steady component of the light incident on the light receiving element. As a result, the S / N ratio in the photodetection signal output from the current-voltage conversion unit 200 can be improved.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification. Moreover, it is included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 20 ... Surface emitting laser, 31, 32 ... Light receiving element, 40, 40a, 40b ... Sealing part, 41 ... Reflective film, 100, 100a, 100b, 100c, 100d, 100e, 100f ... Detector, 200 ... Current-voltage converter 230 ... Fully differential amplifier 240 ... Amplifier 300 ... Case 301 ... Window

Claims (1)

A substrate,
A light emitting unit disposed on the substrate and emitting light;
A light receiving portion that is disposed on the substrate and receives scattered light from an object of the emitted light; and
A sealing portion disposed on the substrate so as to cover the light emitting portion and the light receiving portion;
With
The light receiving part further receives the internally reflected light reflected at the interface of the sealing part of the emitted light,
A detector, wherein a reflective film is disposed on at least a part of the surface of the sealing portion.

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