JP2019174354A - Light receiving and emitting device and optical concentration measuring device - Google Patents

Abstract

To further improve the accuracy of measuring a gas concentration in an optical concentration measuring device.SOLUTION: A light receiving and emitting device 20 comprises a light emitting unit 21 having a light emission surface 21a and radiating light that includes infrared light, a light condensation unit 23 for condensing the light radiated from the light emission surface 21a, and a photodiode 22 having a light receiving surface 22a, with the light receiving surface 22a arranged at a light condensed point by the light condensation unit 23, the photodiode 22 including a first semiconductor substrate and a first semiconductor multilayer unit formed on one side of the first semiconductor substrate. At least a portion of the other side of the first semiconductor substrate is the light receiving surface 22a, and a short side a [μm] and long side b [μm] of the light receiving surface 22a and a short side c [μm] and long side d [μm] of the light emission surface 21a satisfy the formulas a-c>40 and b-d>40. The concentration of a substance in an optical path from the light emitting unit 21 to the photodiode 22 is measured by a concentration computation unit on the basis of a signal from the photodiode 22 of this light receiving and emitting unit 20.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a light emitting / receiving device and an optical density measuring device.

Conventionally, as a gas concentration measurement device that measures the concentration of the gas to be measured in the atmosphere, the gas concentration is measured by detecting the amount of absorption using the fact that the wavelength of infrared rays that are absorbed depends on the type of gas. Non-dispersive Infrared gas concentration measuring devices are known.
For example, the light receiving and emitting device described in Patent Literature 1 includes a gas cell that includes a light emitting unit, a light collecting unit, and a reflecting unit that reflects the collected light. The light emitting part and the light receiving part are arranged at the condensing points of the light collecting parts provided corresponding to the light emitting part and the light receiving part, respectively, and the light emitted from the light emitting part is received through the light collecting part and the reflecting part. Incident light. At that time, by introducing the measurement target gas into the gas cell, the concentration of the measurement target gas is detected according to the output signal of the light receiving unit.

JP 2017-15567 A

In order to make the light emitted from the light emitting part efficiently enter the light receiving part, it is common to use a light collecting part. In such an optical concentration measuring device, the light collecting part, the light emitting part and the light receiving part are used. Therefore, there is a problem that individual differences and lot differences are likely to occur.
The present invention has been made in view of the above problems, and the object of the present invention is a light receiving and emitting device that is highly robust and advantageous for detecting gas concentration with higher accuracy, and optical concentration measurement using the same. To provide an apparatus.

  In order to achieve the above object, a light receiving and emitting device according to one embodiment of the present invention has a light emitting surface, emits light including infrared light, and collects light emitted from the light emitting surface. And a photodiode having a light collecting portion and a light receiving surface, the light receiving surface being disposed at a light collecting point by the light collecting portion, wherein the photodiode is a first semiconductor substrate and one surface of the first semiconductor substrate. And at least a part of the other surface of the first semiconductor substrate is the light-receiving surface, and the short side a [μm] and the long side b [μm] of the light-receiving surface In addition, the short side c [μm] and the long side d [μm] of the light emitting surface are characterized by satisfying a−c> 40 and b−d> 40.

  Further, an optical concentration measurement device according to one embodiment of the present invention receives a signal from the light emitting / receiving device of the above embodiment and a photodiode of the light emitting / receiving device, and a concentration of a substance in an optical path from the light emitting unit to the photodiode. And a concentration calculation unit that measures the above.

  According to the present invention, the robustness is strong and the gas concentration can be detected with higher accuracy.

It is explanatory drawing for prescribing | regulating the short side and long side of the light emission surface of a light emission part, and the light-receiving surface of a photodiode. It is explanatory drawing for prescribing | regulating the short side and long side of a light emission surface in case a light emission part has a several light emission surface. It is a schematic block diagram for demonstrating an example of a light emitting diode. It is a schematic block diagram for demonstrating an example of a photodiode. It is a schematic block diagram which shows an example of a light emitting / receiving device. It is a schematic block diagram which shows an example of an optical density | concentration measuring apparatus.

Hereinafter, modes for carrying out the present invention will be described.
The following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

<Optical concentration measuring device>
An optical concentration measuring apparatus according to an embodiment of the present invention is a concentration that receives a signal from a light emitting / receiving device and a photodiode of the light emitting / receiving device and measures the concentration of a substance in an optical path from the light emitting unit to the photodiode. And an arithmetic unit.
The light receiving and emitting device has a light emitting surface, and includes a light emitting unit that emits light including infrared light, a light collecting unit that collects light emitted from the light emitting surface, and a light receiving surface. A photodiode disposed at a light condensing point by the optical unit, the photodiode having a first semiconductor substrate and a first semiconductor stacked unit formed on one surface of the first semiconductor substrate; At least a part of the other surface of the first semiconductor substrate is the light receiving surface, the short side a [μm] and the long side b [μm] of the light receiving surface, and the short side c [μm] and the long side d of the light emitting surface. [Μm] satisfies a−c> 40 and b−d> 40.

Here, the short side and the long side of the light receiving surface and the light emitting surface are, for example, as shown in FIG. 1A, when the light receiving surface of the photodiode is rectangular, or the light emitting surface of the light emitting unit is rectangular. In some cases, the short side of the rectangle is referred to as the short side a of the light receiving surface or the short side c of the light emitting surface, and the long side of the rectangle is referred to as the long side b of the light receiving surface or the long side d of the light emitting surface. For example, a, b, c, and d can be appropriately selected from a range of 200 μm to 2000 μm.
The shape of the light receiving surface and the light emitting surface is not limited to a rectangular shape as shown in FIG.

For example, as shown in FIG. 1B, the light receiving surface may be elliptical or the light emitting surface may be elliptical. In this case, the short side of the rectangle that circumscribes the ellipse and has the smallest area, that is, The short diameter is the short side a of the light receiving surface or the short side c of the light emitting surface, and the long side of the circumscribed rectangle, that is, the long diameter is the long side b of the light receiving surface or the long side d of the light emitting surface.
Further, as shown in FIG. 1C, the light receiving surface may be a hexagon having two parallel sides or a light emitting surface having two parallel sides. In this case, the hexagon is circumscribed. Of the rectangles having two parallel sides of the hexagon as part of the two sides of the rectangle and having the smallest area, the short side a of the light receiving surface or the short side c of the light emitting surface is circumscribed. The long side of the rectangle to be used is the long side b of the light receiving surface or the long side d of the light emitting surface.

In addition, as shown in FIGS. 2A and 2B, when the light emitting unit has a plurality of light emitting surfaces, a rectangular shape that circumscribes the plurality of light emitting surfaces and includes all of the plurality of light emitting surfaces inside. Among them, the short side of the rectangle having the smallest area is defined as the short side c, and the long side of the circumscribed rectangle is defined as the long side d.
Here, in order to make the light emitted from the light emitting part incident on the photodiode without waste and to increase the output signal of the photodiode, it is preferable that the light collecting part condenses the light in as small a range as possible. However, since the light emitting surface of the light emitting unit has a finite area, it is difficult for the light collecting unit to collect light so as to be within the range of the area of the light emitting surface. Therefore, even if the area of the surface (hereinafter referred to as the light condensing surface) where the light emitted from the light emitting unit and collected by the light condensing unit is incident on the same plane as the light receiving surface of the photodiode is small, the light emitting surface The area is equivalent to

However, when the light emitting unit and the photodiode are mounted on a printed circuit board or the like, a positional deviation of about 20 μm occurs at least in manufacturing. For this reason, when the light emitting part or the photodiode is displaced, the light converging surface is shifted 20 μm vertically and horizontally within the same plane with respect to the light receiving surface of the photodiode, and the output signal of the photodiode is reduced. End up.
Here, when a to d representing the short side and the long side of the light receiving surface and the light emitting surface are set so as to satisfy ac> 40 and bd> 40, the mounting positions of the light emitting unit or the photodiode are provided. Even when the deviation occurs, the light condensing surface is included in the light receiving surface. Therefore, individual differences and lot differences in the output signals of the photodiodes due to manufacturing variations can be reduced. Therefore, it is possible to realize an optical concentration measuring device that is robust and can detect the gas concentration with higher accuracy.

From the viewpoint of reducing individual differences and lot differences in the output signals of the photodiode due to manufacturing variations, the short side a [μm] of the light receiving surface of the photodiode, the long side b [μm] of the light receiving surface, and light emission More preferably, the short side c [μm] of the light emitting surface and the long side d [μm] of the light emitting surface satisfy a−c> 80 [μm] and b−d> 80 [μm]. In this case, the light condensing surface can be included in the light receiving surface even when the light emitting portion and the photodiode are simultaneously displaced in the direction in which the light condensing surface is most displaced from the light receiving surface.
From the viewpoint of the cost of the photodiode, the short side a [μm] of the light receiving surface of the photodiode, the long side b [μm] of the light receiving surface, the short side c [μm] of the light emitting surface of the light emitting unit, and the length of the light emitting surface The side d [μm] preferably satisfies a−c <500 [μm] and b−d <500 [μm].

  In addition, when the photodiode is a front-illuminated type and includes a series or parallel connection of a plurality of semiconductor stacked portions, light is incident on a part of the light receiving surface, and light is incident on the plurality of semiconductor stacked portions. The output signal of the photodiode may decrease due to the rate of the photocurrent output from the semiconductor stacked portion with less light. In one embodiment of the present invention, a back-illuminated photodiode is used as the photodiode. Therefore, in a photodiode in which a plurality of semiconductor stacked portions are formed on the same substrate, light incident from the substrate side of the photodiode is diffused in the substrate, and as a result, is uniform to some extent in the plurality of semiconductor stacked portions. The light can be incident on the. However, if there is a significant difference in the size of the light receiving surface of the photodiode and the light emitting surface of the light emitting portion, the output signal of the photodiode is also lowered. Therefore, the short side a [μm] of the light receiving surface of the photodiode, the long side b [μm] of the light receiving surface, the short side c [μm] of the light emitting surface of the light emitting unit, and the long side d [μm] of the light emitting surface are: It is preferable that −c <500 [μm] and bd <500 [μm] are satisfied. It is also preferable to satisfy this from the viewpoint of the cost of the photodiode.

Hereinafter, each component constituting the optical density measuring device will be described with specific examples.
<Condensing part>
In the optical concentration measurement apparatus according to an embodiment of the present invention, the light collecting unit condenses the light emitted from the light emitting unit so that the light condensing point is positioned to overlap the light receiving surface of the photodiode. Specifically, the condensing unit includes a reflecting mirror.
Here, the condensing point is a position uniquely determined from the relative positional relationship between the light emitting unit and the condensing unit and the shape of the reflecting mirror.

Further, the light collecting unit may have a plurality of reflecting mirrors. Thereby, an optical concentration measuring device having a long optical path length is realized, and the accuracy of gas concentration detection can be improved.
The reflecting mirror may be formed of a metal material, and after forming a specific shape with a resin base material, an alloy containing aluminum, gold, silver in a portion that reflects light, or a laminate thereof, etc. May be formed by vapor deposition or plating.
Examples of the reflecting mirror having a condensing point include a spherical mirror, an elliptical mirror, and a parabolic mirror. When light is converted into parallel light using a spherical mirror or a parabolic mirror, a plane mirror may be further included between the two spherical mirrors or the parabolic mirror in order to increase the optical path length.

<Light emitting part>
In the optical density measurement device according to an embodiment of the present invention, the light emitting unit has a light emitting surface. The light emitting unit is installed at a position where the light emitted from the light emitting surface is collected by the light collecting unit, and the light collecting point overlaps the light receiving surface of the photodiode.
A light emission part will not be restrict | limited especially if it outputs the light containing the wavelength absorbed by measurement object gas. Specific examples include a MEMS (microelectromechanical systems) light source and a light emitting diode. Among these, from the viewpoint of reducing noise due to light absorption of components other than the measurement target gas, it is preferable that only light in a wavelength band in which the measurement target gas absorption is large is output.

Specifically, from the viewpoint that the emission wavelength band can be controlled by the band gap of the active layer, the light emitting unit may have a light emitting diode structure in some cases. The light emitting diodes may be formed on a semiconductor substrate, and are preferably connected in series or in parallel by wiring in order to enhance the light emission intensity. Further, a sensor unit for monitoring the light emission amount may be provided at a position where light emitted from the light emitting diode and reflected by the back surface of the semiconductor substrate is incident.
The light emitting unit includes a second semiconductor substrate and a second semiconductor stacked unit formed on one surface of the second semiconductor substrate, and at least a part of the other surface of the second semiconductor substrate is a light emitting surface. It may be a light emitting diode.

  When the light emitting unit includes a light emitting diode, as shown in FIG. 3, the light emitting diode 1 includes a third semiconductor stacked unit 3 that is electrically insulated from the second semiconductor stacked unit 2. Also have. The arrangement position of the third semiconductor stacked unit 3 is on one surface of the second semiconductor substrate 4 on which the second semiconductor stacked unit 2 is formed, and among the light output from the second semiconductor stacked unit 2, (2) It is preferably set at a position where light reflected by the other surface of the semiconductor substrate 4 enters. In this case, the photocurrent output from the third semiconductor stacked unit 3 can be used to compensate for changes with time due to deterioration of the optical output from the light emitting unit and output fluctuation due to temperature during operation. The second semiconductor stacked unit 2 and the third semiconductor stacked unit 3 are sealed together by the sealing unit 5 by sealing at least a part of the other surface of the second semiconductor substrate 4. The portion not covered with the sealing portion 5 on the other surface of the second semiconductor substrate 4 becomes the light emitting surface 1a. 3A is a bottom view of the light-emitting diode 1, and FIG. 3B is a cross-sectional view of the light-emitting diode 1. FIG.

  The light emitting unit may further include an optical filter having desired optical characteristics in combination with the measurement target gas. For example, when the measurement target gas is carbon dioxide, a configuration in which a band pass filter capable of filtering infrared light in a wavelength band (typically around 4.3 μm) in which infrared absorption by carbon dioxide gas is large is exemplified in the light emitting part. The

<Light emitting surface>
In the optical concentration measurement apparatus according to the embodiment of the present invention, the light emitting surface is a light emitting surface of the light emitting unit.
In the case of the back emission type in which the light emitting part is formed of a light emitting diode, the light emitting diode is formed on the substrate and the semiconductor laminated part is formed, and the light is emitted from the substrate side, the light emitting surface is exposed to the substrate from which the light is emitted. Refers to the surface. Here, an antireflection film or an optical filter may be formed on the surface of the substrate exposed surface. In the case of the surface emission type in which the light emitting diode emits light from the side of the semiconductor stacked portion formed on the substrate, the light emitting surface indicates an active layer that emits light.
Moreover, when a light emission part is comprised including a MEMS heater, the light emission surface points out the member which radiates | emits light by being heated.

<Photodiode>
In the optical density measuring device according to the embodiment of the present invention, the light receiving surface of the photodiode is installed at a position where it overlaps with the condensing point of the condensing unit.
The photodiode includes a first semiconductor substrate and one or more first semiconductor stacked portions formed on one surface of the first semiconductor substrate, and at least a part of the other surface of the first semiconductor substrate. Forms a light receiving surface.
The photodiode has sensitivity in a light band including a wavelength absorbed by the measurement target gas. The shape of the photodiode is not particularly limited as long as a sufficient S / N ratio can be obtained.

The semiconductor stacked portion is formed on a semiconductor substrate. A plurality of semiconductor stacked portions may be connected in series, or a plurality of semiconductor stacked portions may be connected in parallel. Since the photodiode is a back-illuminated type in which light is incident from the semiconductor substrate side, even when light is incident on a part of the light receiving surface, the light diffuses in the semiconductor substrate and is uniformly distributed to a plurality of semiconductor stacked portions. Is incident.
More preferably, the root mean square roughness of the back surface of the semiconductor substrate included in the photodiode is 30 nm or more (hereinafter referred to as “roughened”). In this case, light is incident more uniformly on the plurality of semiconductor stacked portions than in the case where the surface is not roughened. Note that the root mean square roughness (Rq) is, for example, a line scan in the range of several μm to several mm with respect to the corresponding surface using a contact step meter, an atomic force microscope (AFM), or the like. It is calculated from the height measured by performing a dimension scan.

The photodiode may further include an optical filter having desired optical characteristics in combination with the measurement target gas. For example, when the measurement target gas is carbon dioxide, the photodiode is exemplified by a band-pass filter that can filter infrared light in a wavelength band (typically around 4.3 μm) in which infrared absorption by carbon dioxide occurs a lot. The
The photodiode may further include a sealing portion that seals the semiconductor stacked portion in a state where at least a part of the back surface of the semiconductor substrate serving as the light receiving surface is exposed. As a material for the sealing portion, for example, a resin mold material or the like can be used.

  FIG. 4 is a schematic configuration diagram illustrating an example of a photodiode. The photodiode 10 includes a first semiconductor substrate 11 and one or a plurality of first semiconductor stacked portions 12 formed on one surface of the first semiconductor substrate 11. Except for at least a part of the other surface of the first semiconductor substrate 11, the first semiconductor substrate 11 and the first semiconductor stacked portion 12 are integrally sealed by the sealing portion 13, and the other side of the first semiconductor substrate 11 is sealed. An unsealed region of the surface forms the light receiving surface 10a. FIG. 4 shows a case where one first semiconductor stacked unit 12 is provided. 4A is a bottom view of the photodiode 10, and FIG. 4B is a cross-sectional view of the photodiode 10.

<Light receiving surface>
In the optical concentration measurement apparatus according to an embodiment of the present invention, the light receiving surface is a light incident surface of a photodiode with the semiconductor substrate exposed. The light receiving surface may be roughened as described above. Examples of the roughening method include pattern formation by grinding and etching. Further, an antireflection film or an optical filter may be directly formed on the surface of the light receiving surface. Even in the case where the above-described bandpass filter is mounted on the photodiode, the light receiving surface indicates an exposed portion on the back surface of the semiconductor substrate where light can enter.

<Case>
The optical concentration measurement apparatus according to an embodiment of the present invention may further include a housing that houses a light receiving and emitting device including a substrate on which a light emitting unit and a photodiode are mounted and a light collecting unit. The board | substrate and / or the condensing part are being fixed to the housing | casing with the resin-made adhesives. According to the present invention, even when the resin adhesive expands and contracts due to an external environmental factor and the light collector is displaced, the robustness is strong and the gas concentration can be detected with high accuracy. . This makes it possible to use an inexpensive resin adhesive.

<Specific example>
Next, an example of the light emitting / receiving device 20 according to an embodiment of the present invention will be described with reference to FIG. FIG. 5 is schematic, and the thickness of each layer is different from the actual one, and the ratio of the thickness of each layer may be different from the actual one. Specific thicknesses and dimensions should be determined in consideration of the description of one embodiment of the present invention.
FIG. 5 is a cross-sectional view showing an example of the light emitting / receiving device 20 according to an embodiment of the present invention.
The light emitting / receiving device 20 according to the embodiment of the present invention has a light emitting surface 21a, a light emitting unit 21 that emits light including infrared light, and a light receiving surface 22a, and light emitted from the light emitting unit 21. Are provided with a photodiode 22 that receives at least a part thereof, and a light collecting unit 23.

Then, a measurement target gas is introduced between the light emitting unit 21 and the photodiode 22 and the light collecting unit 23, and based on the output signal of the photodiode 22 at this time, a concentration calculation unit (not shown) composed of a calculation device is used to measure the measurement target. The gas concentration is calculated.
The light emitting unit 21, the photodiode 22, and the light collecting unit 23 are arranged at a position where the light collecting unit 23 collects the light emitted from the light emitting surface 21 a of the light emitting unit 21 on the light receiving surface 22 a of the photodiode 22. .
The light emitting unit 21 and the photodiode 22 are disposed on the same substrate 24. The board 24 is a circuit board that also functions as a base board, and for example, a printed board can be used. The light emitting unit 21 and the photodiode 22 are not limited to being mounted on the same substrate 24, and may be mounted on different substrates.

Here, the light emitting unit 21 and the photodiode 22 are composed of a short side a [μm] of the light receiving surface 22a, a long side b [μm] of the light receiving surface 22a, a short side c [μm] of the light emitting surface 21a, and the light emitting surface 21a. The long side d [μm] satisfies a−c> 40 and b−d> 40.
For this reason, even when a positional deviation occurs between the light emitting unit 21 and the photodiode 22, most of the light collected by the light collecting unit 23 can be received by the light receiving surface of the photodiode 22. In particular, by arranging so as to satisfy a−c> 80 and b−d> 80, the light condensing unit 23 collects light even when the positional deviation between the mounting of the light emitting unit 21 and the photodiode 22 becomes the largest. The received light can be received by the light receiving surface of the photodiode 22. From the viewpoint of the cost of the photodiode 22, it is effective to arrange so that a−c <500 and b−d <500.

  Further, as the photodiode 22, a back-illuminated photodiode is used. Therefore, since the light incident on the photodiode 22 is diffused in the substrate included in the photodiode 22, even if the photodiode 22 includes a plurality of semiconductor stacked portions, the light is incident on the plurality of semiconductor stacked portions to some extent. Light enters uniformly. As a result, the light receiving surface can be made larger than the light emitting surface without reducing the output signal of the photodiode 22. Further, since the light receiving surface 22a is roughened, the light can be diffused more in the substrate than when the light receiving surface 22a is not roughened.

FIG. 6 is a schematic configuration diagram showing an example of the optical density measuring device 40 according to an embodiment of the present invention.
The optical concentration measuring device 40 includes a light emitting / receiving device 20a and a housing 30 that houses the light emitting / receiving device 20a.
As shown in FIG. 6, the light receiving and emitting device 20 a includes a substrate 24 on which the light emitting unit 21 and the photodiode 22 are mounted, a light collecting unit 23, and a light collecting unit 25 for the light emitting unit 21 and the photodiode 22. Prepare. The light collecting unit 25 includes a light collecting unit 25 a that collects the light incident from the light emitting unit 21 and a light collecting unit 25 b that collects the light reflected by the light collecting unit 23. By providing the light collecting unit 25, the optical concentration measuring device 40 makes more light emitted from the light emitting unit 21 incident on the light collecting unit 23, and more light reflected by the light collecting unit 23 is received by the photodiode. 22 is incident.

Then, a measurement target gas is introduced into the housing 30 from a gas inlet (not shown) provided in the housing 30 and is passed between the light emitting unit 21, the photodiode 22, and the light collecting unit 23 to exhaust a gas (not shown). The measurement target gas is discharged out of the housing 30 from the outlet, and the concentration of the measurement target gas is calculated by a concentration calculation unit (not shown) based on the output signal of the photodiode 22 at this time.
In the light emitting / receiving device 20a, for example, the substrate 24 is fixed to the bottom surface of the housing 30 with a resin adhesive, and the light collecting portions 23 and 25 are fixed to the top surface and side surfaces of the housing 30 with a resin adhesive. As a result, it is fixed to the housing 30.

Here, when the light emitting / receiving device 20a is fixed to the housing 30 using the resin adhesive, the light condensing unit 23 is caused to emit the light 21 when the adhesive expands and contracts due to external environmental factors. In addition, there is a possibility that the position of the photodiode 22 is displaced. When the positional deviation occurs in this way, the output signal of the photodiode 22 may change even though the gas concentration of the measurement target gas has not changed, and the gas concentration may not be detected with sufficient accuracy. .
In one embodiment of the present invention, most of the light collected by the light condensing unit 23 can be received by the light receiving surface 22a of the photodiode 22, so that a change in the output signal of the photodiode 22 due to the influence of the adhesive is suppressed. can do.

  The above embodiment exemplifies an apparatus and a method for embodying the technical idea of the present invention, and the technical idea of the present invention includes the material, shape, structure, arrangement, etc. of the component parts. Not specific. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

DESCRIPTION OF SYMBOLS 1 Light emitting diode 1a Light emitting surface 2, 3 Semiconductor laminated part 4 Semiconductor substrate 5 Sealing part 10 Photodiode 10a Light receiving surface 11 Semiconductor substrate 12 Semiconductor laminated part 13 Sealing part 20, 20a Light receiving / emitting device 21 Light emitting part 21a Light emitting surface 22 Photo Diode 22a Light-receiving surface 23 Condensing part 24 Substrate 40 Optical density measuring device

Claims (12)

A light emitting unit having a light emitting surface and emitting light including infrared light;
A light collecting section for collecting light emitted from the light emitting surface;
A photodiode having a light receiving surface, the light receiving surface being disposed at a light collecting point by the light collecting unit;
With
The photodiode includes a first semiconductor substrate and a first semiconductor stacked portion formed on one surface of the first semiconductor substrate, and at least a part of the other surface of the first semiconductor substrate is the first semiconductor substrate. A light receiving surface,
The short side a [μm] and the long side b [μm] of the light receiving surface, and the short side c [μm] and the long side d [μm] of the light emitting surface are ac> 40 and bd Light emitting / receiving device satisfying> 40.   The short side a [μm] and the long side b [μm] of the light receiving surface, and the short side c [μm] and the long side d [μm] of the light emitting surface are a c> 80 and b d The light emitting / receiving device according to claim 1, satisfying> 80.   The short side a [μm] and the long side b [μm] of the light receiving surface, and the short side c [μm] and the long side d [μm] of the light emitting surface are ac <500 and bd The light emitting and receiving device according to claim 1 or 2, wherein <500 is satisfied.   The said condensing part has a some reflective mirror, The light containing the infrared light radiated | emitted from the said light emission part is reflected in the said some reflective mirror. The light emitting / receiving device described.   5. The light receiving and emitting device according to claim 1, wherein the root mean square roughness of the other surface of the first semiconductor substrate is 30 nm or more.   6. The light emitting / receiving device according to claim 1, wherein the photodiode includes a plurality of first semiconductor stacked portions connected in series with each other. 7.   6. The light receiving and emitting device according to claim 1, wherein the photodiode includes a plurality of first semiconductor stacked portions connected in parallel to each other.   The said photodiode further has the sealing part which seals the said 1st semiconductor substrate and the said 1st semiconductor laminated part in the state which exposed at least one part of the other surface of the 1st semiconductor substrate. Item 8. The light emitting and receiving device according to any one of Items 7. The light emitting unit includes a light emitting diode having a second semiconductor substrate and a second semiconductor stacked unit formed on one surface of the second semiconductor substrate,
The light emitting / receiving device according to any one of claims 1 to 8, wherein at least a part of the other surface of the second semiconductor substrate forms the light emitting surface. The light emitting diode has a third semiconductor stacked portion that is electrically insulated from the second semiconductor stacked portion,
The third semiconductor stacked unit is the one surface of the second semiconductor substrate, and light reflected from the other surface of the second semiconductor substrate is incident on the light output from the second semiconductor stacked unit. The light emitting / receiving device according to claim 9, wherein the light emitting and receiving device is disposed at a position where A housing for holding the light collecting unit;
The light receiving and emitting device according to any one of claims 1 to 10, wherein the light collecting unit is fixed to the housing with a resin adhesive. The light emitting and receiving device according to any one of claims 1 to 11,
An optical concentration measuring apparatus comprising: a light receiving / emitting device; and a concentration calculating unit that receives a signal from the photodiode and measures a concentration of a substance in an optical path from the light emitting unit to the photodiode.

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