JP2002090457A - Distance measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distance measuring apparatus which can measure the distance from a short range of several meters to a long range of more than 100 meters by satisfying a safety standard when incident light reaches eyes. SOLUTION: Light is made to irradiate an object to be measured from light emitting elements while the reflected light from the object is received by photo detectors to measure the distance from the object. The light emitting elements are arranged in plurality to emit light with different wavelengths and hence, have different detection regions. The photodetectors 110 and 120 are arranged in plurality corresponding to the respective light emitting elements and have sensitivities adaptive to light with the respective wavelengths. The photodetector 110 transmits the light with the first wavelength and has a sensitivity to the light with the second wavelength less than the first wavelength. The photodetector 120 has the sensitivity to the light with the first wavelength. The photodetectors 110 and 120 are arranged on the same optical path.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device, and can be used, for example, in an inter-vehicle distance measuring device.

[0002]

2. Description of the Related Art In recent years, a system that measures the distance between automobiles using a semiconductor laser or a light emitting diode and issues a warning when the inter-vehicle distance is kept constant or the vehicle approaches the vehicle in front too much. Systems that measure the distance to a car or obstacle and issue an alarm, and security systems that issue an alarm when the light is blocked have been developed.

In an inter-vehicle distance measuring system, it is necessary to detect an object at a distance of 100 m or more, and for that purpose, a light output of 20 to 80 W is required by pulse driving for several tens to several hundreds of nanoseconds. In such a system, the light output is determined in consideration of safety when the emitted light enters the eyes. Further, when the safety standard is not satisfied within a range of several meters from the emission point or when the speed becomes several tens km / h or less, the light emission is stopped to ensure safety.

[0004] However, such a system has a problem that it cannot follow a forward vehicle at a low speed or cope with a stop of the forward vehicle. Also, Japanese Patent Application Laid-Open No. Hei 7-134
According to Japanese Patent Publication No. 178, a method of controlling the emission power of laser light in accordance with the distance between the own vehicle and the vehicle to be measured is proposed. However, since the detection angle (irradiation range) is constant, for example, If the distance between the vehicle running in the adjacent lane is shorter than that of the vehicle traveling ahead in the same lane as your own vehicle, lowering the light emission power to match the vehicle in the adjacent lane will allow the vehicle ahead in the same lane There is a problem of losing sight, and it is dangerous to the eyes of a person in a vehicle in the next lane if the light emission power is not reduced in order to recognize a vehicle traveling ahead in the same lane. There's a problem.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to satisfy safety standards in the case where emitted light enters an eye, and to reduce the distance from a short distance of several meters to one.
An object of the present invention is to provide a distance measuring device capable of measuring a distance up to a distance of 00 m or more without erroneous recognition.

[0006]

According to the first aspect of the present invention, in a reflection type distance measuring device using light, a plurality of light emitting elements which emit light of different wavelengths are provided, and each of the light emitting elements having different wavelengths is used. The distance is measured using light selectively. This satisfies the safety standard when the emitted light enters the eyes, and
It is possible to measure a distance from a short distance to a long distance of 100 m or more without erroneous recognition. Further, when this distance measuring device is attached to a moving body and the light output and the emission wavelength of the light emitting element are changed according to the speed of the moving body, for example, it becomes preferable as an inter-vehicle distance measuring device.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present embodiment is a distance measuring apparatus for measuring a distance by emitting a light emitting element to illuminate an object, sensing reflected light from the light emitting element, and comprising a plurality of light sources ( Light-emitting element). Further, the distance between different regions is measured depending on the light emitting element.

FIG. 1 shows a laser pulse width of 1 to 100 ns.
3 shows the wavelength dependence of the safety standard MPE (maximum allowable exposure amount) in FIG. As can be seen from this figure, the MPE depends on the emission wavelength.
Changes. In particular, the figure shows that the emission wavelength is 1.4 μm.
At m or more, the value of MPE is large, indicating that the eye is safe. Therefore, it is understood that light having a wavelength of 1.4 μm or more may be used in all the measurement regions. However, currently, a semiconductor laser having an emission wavelength of 1.4 μm or more has low luminous efficiency and measures a long distance. Therefore, it is necessary to increase the output. for that reason,
Light of different wavelengths is emitted using a plurality of light emitting elements.

Further, the life of a semiconductor laser is inversely proportional to the light emission intensity and the light emission frequency. Therefore, in order to extend the life of the semiconductor laser, it is desirable to lower the light emission intensity and shorten the light emission time. When using a distance measuring device having a plurality of light emitting elements than when using a distance measuring device having one light emitting element, the light emitting time of each element is shortened,
The service life of the system is longer and the reliability is higher. For example, in a distance measuring device used for an automobile, a detection angle is required to be ± 20 ° or more in front to recognize a vehicle in an adjacent lane, and it is desirable to measure substantially 40 ° or more. However, since long distances need only be measured about ± 4 ° in front, the reliability of the system is improved by separating the first light-emitting element for measuring the central part and the second light-emitting element for measuring other parts. Can be done.

In this embodiment, the emission wavelength is 1.4 μm
By using the above light emitting element for the measurement of the range of the short distance area and using the light emitting element of the shorter wavelength for the measurement of the long distance area, it can be used as a distance measuring device that is safe for eyes and long-term reliable Become.

In the distance measuring device, the measured distance is proportional to the light output of the light emitting element. Therefore, it is necessary to increase the light emission output in order to increase the measurement distance. However, when the light emission output is increased, there arises a problem that the measurement at a short distance does not satisfy the MPE standard.

In the present embodiment, light having a wavelength different from that of light for long-distance measurement is used as light for short-distance measurement, and M is safe for eyes in both short-distance and long-distance measurements.
Satisfies PE.

Since the sensitivity of the light receiving element for reflected light has wavelength dependence, when light emitting elements having different wavelengths are used, it is desirable to use another light receiving element for each wavelength to be used. Specifically, when one light-receiving element receives light of a plurality of wavelengths, sufficient sensitivity cannot be obtained due to wavelength dependency, and therefore, it is desirable to use a light-receiving element for each wavelength.

When using light of different wavelengths, it is conceivable to use another optical system for light of each wavelength. However, in this case, the optical system requires twice as much volume as when using light of one wavelength. Further, since the driving system is also different, the volume of the circuit is doubled as compared with the case where one wavelength is used. In the present embodiment, the optical system of each wavelength is the same for miniaturization. For this reason, the light emitting element combines light into the same optical system or mounts light emitting elements of different wavelengths in the same package and uses the same optical system. However, even if the optical system of the light emitting section is the same, the optical system of the light receiving section is not the same because the light receiving element is used for each wavelength.

Therefore, when a plurality of light receiving elements are provided, FIG.
As shown in (1), a method of simply separating light into the light receiving elements 101 and 102 using the half mirror 100 or separating the light using a wavelength filter instead of the half mirror 100 is considered. In the former method, the amount of received light decreases depending on the number of light emitting elements. For example, when light of two wavelengths is used, the amount of light is halved. The latter method is
Since a filter is used for each wavelength, the amount of received light does not decrease and the sensitivity does not decrease.

However, since a plurality of light receiving optical systems are provided, the volume of the entire system becomes large. In the present embodiment, in the light receiving element that converts the light amount into an electric signal, FIG.
As shown in (1), a first light receiving element 110 that transmits light of a first wavelength and has sensitivity to light of a second wavelength shorter than the first wavelength, and a light receiving element of the first wavelength A second light receiving element having sensitivity;
0 and 120 are arranged on the same optical path. By doing so, the light receiving optical system can be made the same.

At this time, as shown in FIG. 4, the first light receiving element 110 is provided with ring-shaped electrodes 111 and 112 for transmitting light of the first wavelength. That is, the base material 113
In contrast, annular electrodes 111 and 112 are used as electrodes arranged on both front and back surfaces. Also, the second light receiving element 1
20 is provided with a ring-shaped electrode 121 and a plate-shaped electrode 122 on a base material 123. In FIG. 4, reference numeral 114 denotes an extraction electrode.

When measuring a long distance, a large output is required. However, since the beam spreads and the beam diameter increases, the eye is safe regardless of the wavelength. At short distances, the beam diameter becomes smaller and the optical power density becomes larger. Therefore, it is desirable to use a light emitting element having a wavelength of 1.4 μm or more to avoid danger to the eyes. From the characteristics of the light receiving element, the short wavelength is desirably 1 μm or less, particularly 800 nm to 9 nm.
A thickness of 00 nm is desirable.

When a light emitting element having an emission wavelength of 1.4 μm or more is used, a Ge avalanche photodiode, an InGaAs-PIN photodiode, a Ge photodiode, or the like is used as a light receiving element. When a light emitting element having an emission wavelength of 1 μm or less is used, a Si photodiode or a Si-PIN photodiode is used as a light receiving element. The wavelength dependence of the light receiving sensitivity is shown in FIGS. The Si photodiode of FIG.
At a wavelength of 1 μm (1000 nm) or more, there is no sensitivity, and light having a wavelength longer than 1 μm is transmitted. FIG.
The InGaAs-PIN photodiode has a low sensitivity when its characteristic is 1 μm or less, so that a long wave is 1 μm.
It is desirable to use m to 1.65 μm. In consideration of safety to human eyes, it is not necessary to measure a long distance at low speed and at a stop, so that only light having a wavelength of 1.4 μm or more may be used.

Further, by attaching this distance measuring device to a moving body such as a car, a motorcycle, a train, etc., the distance between the moving bodies can be measured, and collision and contact can be prevented. In particular, unlike a train running on a track, automobiles and motorcycles have a high possibility of collision or contact not only from the front and rear but also from any direction from the left and right. By installing a distance measuring device, safety in traveling is improved. Further, the short distance measurement is also useful for a system that measures the distance to a vehicle or an obstacle when the vehicle is parked or stopped.

Next, a method of manufacturing a semiconductor laser will be described. FIG. 7 shows an example of a cross-sectional structure of a semiconductor laser.
The semiconductor laser performs epitaxial growth on a substrate 200 such as GaAs, InP, sapphire, etc., and forms each operating region (buffer layer 201, cladding layer 202,
Light guide layer 203, active layer 204, light guide layer 205,
A cladding layer 206 and a cap layer 207) are provided. Generally, an n-type substrate is used as the substrate 200. As a material system, GaAs-AlGaAs system, InGaAsP-G
aAs system, InGaAsP-InP system, InGaP-I
nGaAlP system, GaInNAs-InAs system, GaI
There are an nNAs-GaAs system, a GaAs-GaN system, and the like, but there is no particular limitation. Epitaxial growth methods include liquid phase epitaxy and molecular beam epitaxy (MB
E: molecular beam epitaxy, MOCVD: metal organic chemical vapor depo
sition), but any method may be used. Further, the structure of the active layer 204 may be any structure such as a double hetero structure and a quantum well structure.

Thereafter, an ohmic contact electrode (p-type electrode) 208 is formed. The p-type electrode 208 is formed to a predetermined thickness by electron beam evaporation, sputtering, or the like. Then, when patterning is required, it is processed into a predetermined pattern using photoresist processing, chemical etching, ion beam etching, or the like. Further, an annealing process is performed on materials that need to be alloyed. p-type electrode 2
08 is, for example, Au-Zn / Au, Cr / Au,
There are Mo / Au, Ti / Pt / Au, Cr / Pt / Au and the like, but this is not limited as long as an ohmic contact can be obtained.

Thereafter, the back surface of the substrate is polished to make the thickness of the wafer about 100 μm to facilitate chip formation. This thickness may be about 1/3 or less of the cavity length (resonator length), and the cavity length is about 300 μm to 1 mm.
The thinner the better, the better the heat dissipation.
0 μm is desirable. However, this does not apply to the case where the reflection surface is manufactured by dry etching without using the cleavage surface.

Subsequently, an n-type electrode 209 is formed to a predetermined thickness by electron beam evaporation, sputtering, or the like. As the n-type electrode 209, for example, Au—Ge / Ni / Au,
There is Au-Sn / Au or the like, and after film formation, arrowing is performed to form an n-type electrode 209.

Then, a thin film as a solder layer (not shown in FIG. 7) is provided by vapor phase growth. As a film forming method, a solder layer is formed by electron beam evaporation, resistance heating evaporation, sputtering, or the like. Au-Sn, P
b-Sn or the like is used.

Further, chips are formed into a predetermined size. At this time, since laser oscillation does not occur unless the output surface of the laser beam is a mirror surface, a cleavage surface or a light emitting end surface is manufactured by dry etching. The light-emitting end face is provided with a low-reflection film on the output end face and a high-reflection film on the other end face in order to protect the end face and improve the efficiency of light output. The reflectivity of the reflection film is desirably about 2 to 25% for the low reflection film and about 80 to 100% for the high reflection film. The reflection film may be either a single-layer film or a multilayer film.
A single layer film of ₂ O ₃ , SiO ₂ , SiN _x , SiC, C, MgO, etc. is used, and the high reflection film is made of Al ₂ O ₃ , SiO ₂ , S
iN _x , C, MgO, etc. and a-Si, Cr ₂ O ₃ , TiO
_It is desirable to have a multilayer film structure by a combination of films having a difference in refractive index, such as ₂ . In the case of a light emitting diode, no cleavage is required, and there is no need to form a reflective film on the end face. Therefore, chips may be formed by dicing cut.

In order to obtain a semiconductor laser having a wavelength of 1.4 μm or more, an active layer is formed on a GaAs substrate 200 as an active layer.
A semiconductor element having a configuration in which the InNAs layer 204 is formed, and a semiconductor element having a configuration in which an InGaAsP layer (a member corresponding to the same reference numeral 204) is formed as an active layer on an InP substrate (a member corresponding to the reference numeral 200 in FIG. 7) are desirable. .

In particular, a semiconductor element having a structure in which a GaInNAs layer 204 is formed as an active layer on a GaAs substrate 200 has an emission wavelength of 1.4 by changing the composition of N.
Light emission is possible from a wavelength of 800 nm, not limited to μm or more. In addition, by using GaAs, which has been conventionally used as a semiconductor laser, for a substrate, an element manufacturing process can be easily performed. Further, GaInNAs has a merit that by forming a heterojunction with AlGaAs or GaInPAs having a wide band gap, the band discontinuity (band offset) of the conduction band becomes extremely large, and characteristics with very good temperature characteristics can be obtained. Therefore, even when the output is large, the optical output hardly decreases, and stable characteristics can be obtained.

FIGS. 8A and 8B show GaInPAs.
FIG. 2 shows an energy band diagram in a 1.3 μm band in a system and GaInNAs / GaAs. The larger the energy difference ΔEc between the conduction band of the well layer and the barrier layer of the semiconductor laser, the larger the electron confinement energy. If the electron confinement energy ΔEc is small, even if electrons are injected into the light emitting portion, some of the electrons will overflow due to thermal energy and will not contribute to light emission. Electrons that do not contribute to light emission increase rapidly during high-temperature operation. In the GaInNAs / GaAs system shown in FIG. 8B, since ΔEc is sufficiently large, both electrons and holes can be completely confined in the light emitting portion of GaInNAs even at the time of high-temperature operation, and a semiconductor laser having good temperature characteristics can be obtained. realizable.

FIG. 7 shows a GaInNAs / GaAs-based device structure.
05 may be omitted, and AlGa may be used instead of GaAs.
As may be used.

As shown in FIG. 9, different light emitting elements 301 and 3 emit light of different wavelengths by the same optical system.
02 and the mirrors 303 and 304, and one package 40 as shown in FIG.
There is a method of emitting light of a plurality of emission wavelengths at 0. There are two methods for emitting light having a plurality of emission wavelengths in one package 400. One is to mount light emitting elements 401 and 402 having different emission wavelengths in the same package 400 as shown in FIG. The other is a method of forming light emitting elements having different wavelengths on the same substrate.
In the former method, since different elements 401 and 402 may be mounted, different wavelengths can be easily put in the same package 400. In the latter case, it is difficult to control the wavelength because of the lattice matching with the substrate.

For example, when an AlGaAs-based semiconductor laser is manufactured on a GaAs substrate, the thickness of the semiconductor laser is 600 nm to 900 nm.
Although the change is possible in the range of m, it is difficult to produce an element having a wavelength longer than m. As described above, in order to manufacture a semiconductor laser of 1.4 μm and 800 nm to 900 nm on the same substrate, the semiconductor laser can be manufactured by using an AlGaAs semiconductor laser and a GaInNAs semiconductor laser on a GaAs substrate. (First Embodiment) A distance measuring device was manufactured and mounted on an automobile. The light emitting element includes an AlGaAs semiconductor laser on a GaAs substrate having an emission wavelength of 850 nm, and an emission wavelength of 1.4.
An InGaAsP-based semiconductor laser on a μm InP substrate was used. This device was mounted on one package and used as a light emitting device. As shown in FIG. 3, the light receiving element has a Si photodiode (corresponding to the element 110 in FIG. 3) disposed upstream of the InGaAs-PIN photodiode (corresponding to the element 120 in FIG. 3) on the same optical path. Was used.

As shown in FIG. 11, with respect to the detection angle (detection range), the light emitting element having a light emission wavelength of 850 nm measures a distance within a range of ± 5 ° in front, and outputs a light output of 40 W so that a maximum of 170 m can be measured. And The light emitting element having a light emission wavelength of 1.4 μm measures a distance in a range of ± 40 ° in front of the light emitting element and outputs a light output of 5 W so that a maximum of 40 m can be measured.
And At a speed of 30 km / h or more, a light emitting element having an emission wavelength of 850 nm is driven to measure a distance in a range of ± 5 ° forward, and a light emitting element of 1.4 μm in emission wavelength is driven to measure a distance in a range of ± 40 ° forward. Measure. on the other hand,
When the speed is less than 30 km / h, the light emitting element having the emission wavelength of 1.4 μm is driven to measure the distance in a range of ± 40 ° in front, but the light emitting element having the emission wavelength of 850 nm is not driven (does not emit light).

As a method of scanning light in the measurement range, a known method using a polygon mirror 603 is employed as shown in FIG. 12, for example. That is, the light emitted from the light emitting element 600 is reflected by the mirror 601 so that the polygon mirror 60
Lead to 3. By rotating the polygon mirror 603, the direction of light from the polygon mirror 601 is changed. Note that the scanning method is not limited to this method.

According to this embodiment, as shown in FIG.
A car traveling about 3 m ahead of the next lane can be recognized, and 1
It is possible to measure the inter-vehicle distance with a car traveling 00 m ahead. (Second embodiment) A light emitting device having a light emitting wavelength of 800 nm
A distance measuring device was manufactured using an InGaAsP-based semiconductor laser on an aAs substrate and a GaInNAs-based semiconductor laser on a GaAs substrate with a light emission wavelength of 1.4 μm. The light receiving element is a Ge photodiode (FIG. 3) as shown in FIG.
A device in which a Si-PIN photodiode (corresponding to the device 110 of FIG. 3) is arranged on the same optical path upstream of the device 120 of FIG.

As described above, the present embodiment is directed to a distance measuring apparatus that irradiates light from a light emitting element to a measurement target, receives reflected light from the measurement target by a light receiving element, and measures the distance to the measurement target. A configuration having a plurality of light-emitting elements that emit light of different wavelengths is adopted, and the distance is measured by selectively using light of different wavelengths. This satisfies the safety standards when the emitted light enters the eyes,
It is possible to measure a distance from a short distance of several meters to a long distance of 100 m or more without erroneous recognition.

In this case, as shown in FIG. 11, each light-emitting element has a different detection area. ・ A plurality of light-receiving elements corresponding to each light-emitting element are provided. As shown in the drawing, it has sensitivity adapted to light of each wavelength, and as shown in FIG. 3, it transmits light of the first wavelength and transmits light of the second wavelength shorter than the first wavelength. First with sensitivity
And the second light receiving element 120 having sensitivity to the light of the first wavelength is disposed on the same optical path. As shown in FIGS. 9 and 10, a plurality of light emitting elements 301,3
02 (401, 402) uses one optical system; ・ A distance measuring device is mounted on a moving body such as an automobile, and an appropriate emission wavelength is selected from a plurality of light emitting elements according to the moving speed of the moving body. A light-emitting element having an appropriate light output is selected from a plurality of light-emitting elements according to the moving speed of the moving body, and a light-emitting element is selected as shown in FIG. , A plurality of light emitting elements,
Light is emitted in the range of different detection angles, the detection angle when the distance between the measured object and the moving body is a short distance,
The detection angle can be made larger than the detection angle when the distance between the measured object and the moving body is long, or the emission wavelength of the light-emitting element can be at least 1.4 μm or more.

In addition, each light emitting element may be configured to emit a plurality of lights having different wavelengths. In other words, the wavelength used for each element may be switched at the time of measurement, and the distance between an object existing in a different region for each light emitting element and the light emitting element may be measured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between MPE (maximum allowable exposure amount) and wavelength.

FIG. 2 is a diagram showing a light receiving element.

FIG. 3 illustrates a light receiving element.

FIG. 4 is a diagram showing a light receiving element.

FIG. 5 is a sensitivity characteristic diagram of a Si photodiode.

FIG. 6 is a sensitivity characteristic diagram of an InGaAs photodiode.

FIG. 7 is a longitudinal sectional view of a semiconductor laser.

FIG. 8 is an energy band diagram.

FIG. 9 illustrates a light-emitting element.

FIG. 10 illustrates a light-emitting element.

FIG. 11 is a plan view when applied to an inter-vehicle distance measuring device.

FIG. 12 is a view for explaining a method of scanning a measurement range with light.

FIG. 13 is a plan view when applied to an inter-vehicle distance measuring device.

[Explanation of symbols]

110: light receiving element, 120: light receiving element, 121: ring electrode, 122: ring electrode, 200: n-GaAs
Substrate, 201 ... n-GaAs buffer layer, 202 ... n
-AlGaAs cladding layer, 203 ... GaAs light guide layer, 204 ... GaInNAs active layer (quantum well layer), 2
05 ... GaAs light guide layer, 206 ... p-AlGaAs
Clad layer, 207... P-GaAs cap layer, 301
.., Light emitting element, 302, light emitting element, 303, mirror, 30
4 mirror, 400 package, 401 light emitting element,
402 ... Light-emitting element.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G08G 1/16 H01L 31/12 E 5J084 H01L 31/10 33/00 L 31/12 G01S 17/88 A 33/00 H01L 31/10 A (72) Inventor Aimi Suzuki 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso, Inc. (Ref.) BA36 BA49 BB20 BB24 BB26 CA03 CA11 CA19 CA31 DA01 DA07 EA22 EA29 EA32

Claims (14)

[Claims] 1. A light-emitting element irradiates light to a measurement target and receives light reflected from the measurement target by a light-receiving element.
A distance measuring device for measuring a distance to a measurement object, comprising a plurality of light emitting elements that emit light of different wavelengths. 2. The distance measuring apparatus according to claim 1, wherein each light emitting element has a different detection area. 3. The distance measuring apparatus according to claim 2, wherein each light emitting element emits a plurality of lights having different wavelengths. 4. The light-receiving device according to claim 1, further comprising a plurality of light-receiving elements corresponding to the respective light-emitting elements, wherein each of the light-receiving elements has a sensitivity adapted to light of each wavelength.
The distance measuring device according to the paragraph. 5. A first light receiving element that transmits light of a first wavelength and has sensitivity to light of a second wavelength shorter than the first wavelength, and sensitivity to light of the first wavelength. The distance measuring apparatus according to claim 4, wherein the second light receiving elements having the following are arranged on the same optical path. 6. The distance measuring apparatus according to claim 1, wherein the plurality of light emitting elements use one optical system. 7. The distance measuring device according to claim 1, wherein the distance measuring device is mounted on a moving body. 8. The distance measuring apparatus according to claim 7, wherein a light emitting element having an appropriate emission wavelength is selected from the plurality of light emitting elements according to a moving speed of the moving body to emit light. . 9. The distance measuring apparatus according to claim 7, wherein a light emitting element having an appropriate light output is selected from the plurality of light emitting elements according to a moving speed of the moving body to emit light. . 10. The light-emitting elements each emit light in a range of different detection angles, and the detection angle when the distance between the measured object and the moving body is short is: 8. The apparatus according to claim 7, wherein a distance between the measured object and the moving body is larger than a detection angle in a case where the distance is long.
The distance measuring device according to any one of claims 9 to 9. 11. The light emitting device according to claim 1, wherein a light emitting wavelength of the light emitting element is at least 1.4 μm or more.
0. The distance measuring device according to any one of 0. 12. The plurality of light receiving elements, wherein the first light receiving element is a Si photodiode and the second light receiving element is a G photodiode.
The distance measuring device according to claim 4, wherein the distance measuring device is an e-photodiode or an InGaAs photodiode. 13. The distance measuring apparatus according to claim 1, wherein said light emitting element is a semiconductor laser. 14. The distance measuring apparatus according to claim 1, wherein the plurality of elements are mounted on a same package.