JP2000065527A - Optical range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a small-size lightweight, and low-cost light-guide means which form a reference optical path and a distance measurement optical path in the optical range finder. SOLUTION: This device has a light source 1, the light guide means 4 which branches light from the light source 1 into a reference optical path and a distance measuring optical path, and guides the lights from both the optical paths to a photodetection part, a photodetecting means 19 which constitute the photodetection part and receives and converts the light from the distance measurement optical path or reference optical path into an electric signal, and a distance measuring means 20 which finds the distance to an object to be measured by the electric signal from the photodetecting means. Then the light guide means 4 which forms the reference optical path and distance measurement optical path is constituted of a light guide member 4 formed by laminating glass substrates slanting to the incidence direction of the light from the light source 1, and the light guide member 4 has at least a 1st optical function element 14 which is formed on the top surface of a glass substrate and branches into the reference optical path and distance measurement optical path and a 2nd optical function element 15 which guides the lights from both the optical paths to the photodetection part 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light wave distance measuring device, and more particularly to a light wave distance measuring device having a novel configuration in which a part of the optical system is constituted by a light guide member comprising a small and light laminated prism.

[0002]

2. Description of the Related Art A lightwave distance measuring device transmits a laser beam toward an object to be measured, receives return light from the object to be measured, and measures a distance based on the phase and delay time of the received laser beam. I do. FIG. 8 is a block diagram showing a conventional lightwave distance measuring device for measuring a distance based on a delay time of a laser beam. 8, a laser diode 101 as a light source is shown.
Is converted into a parallel beam by the relay lens 102, and is split by the beam splitter 103 into transmitted light and reflected light.

The transmitted light transmitted through the beam splitter 103 passes through the position of an optical path switching shutter 104, is condensed by a relay lens 105, and enters an optical fiber 106. Further, the light passes through the optical fiber, and passes through the relay lens 109.
Then, the light is converted into a parallel beam, attenuated to a predetermined amount by a light amount attenuation filter 110, condensed by a relay lens 112 via a beam splitter 111, and is incident on a light receiving element 113 as reference pulse light. The light receiving element 113 outputs a signal corresponding to the amount of incident reference pulse light to a distance measuring unit 114.
Output to An optical path from the beam splitter 103 to the beam splitter 111 via the optical fiber 106 is a reference optical path. And an optical path switching shutter 1
When the reference light path side is opened by 04 (at this time, the distance measurement light path side described later is closed), the reference pulse light passing through the reference light path enters the light receiving element 113. The transmittance of the light amount attenuation filter 110 is adjusted at the time of assembly so that the amount of light incident on the light receiving element 113 from the reference optical path is attenuated to a predetermined value.

On the other hand, the reflected light reflected by the beam splitter 103 passes through the position of the optical path switching shutter 104, is condensed by a relay lens 115, and is condensed by an optical fiber 116.
, Passes through it, is reflected by the mirror-coated surface 120 near the optical axis of the beam splitter 119, is reflected by the dichroic mirror 121, and travels from the objective lens 123 to a measurement object (not shown). And transmitted as transmission pulse light. Then, the pulse light returned from the measurement target is received by the objective lens 123 and becomes a received pulse light. This received pulse light is reflected by the dichroic mirror 121 and is reflected on the surface 12 of the beam splitter 119.
The optical fiber 124 passes through a portion other than the mirror 0,
The light enters the beam splitter 111 via the relay lens 125 and the light amount adjustment filter 126. Then, the light reflected by the beam splitter 111 is condensed by the lens 112 and enters the light receiving element 113.

The path from the beam splitter 103 to the objective lens 123 is the transmission optical path of the distance measuring optical path, and the path from the objective lens 123 to the light receiving element 113 via the beam splitter 111 is the receiving optical path of the distance measuring optical path. is there.
The light receiving element 113 outputs to the distance measuring means 114 a signal corresponding to the amount of incident pulse light received. The reception pulse light enters the light receiving element 113 when the optical path switching shutter 104 is switched to open the distance measuring optical path side. Then, the distance measuring means 114
Calculates the distance to the measurement object from the time difference between the signal based on the reference pulse light and the signal based on the received pulse light.

Prior to distance measurement, an object to be measured is measured by an eyepiece lens 127 and a reticle 12 by a measurer.
8. Observation is performed through a collimating optical system including the erecting prism 129, the focusing lens 122, and the objective lens 123, and the focusing lens 122 is adjusted in the X direction to focus on the measurement object. Further, the amount of the received pulse light that enters the light receiving element 113 via the receiving optical path side of the distance measuring optical path is the same as the amount of the reference pulse light that enters the light receiving element 113 via the reference optical path in order to secure the accuracy of distance measurement. The light amount is adjusted by the light amount adjustment filter 126 so as to be at the level. Light intensity adjustment filter 1
Reference numeral 26 denotes a circular filter whose optical density continuously changes in the circumferential direction. The circular filter 26 is rotated by a motor 130 having a rotation axis fixed at the center of the light amount adjustment filter 126 to adjust the transmittance of the received pulse light. .

[0007]

As described above, the conventional distance measuring device includes a laser diode 101 as a light source and a light receiving element 1.
It is necessary to configure a reference optical path, a transmission optical path, and a reception optical path between the optical path 13 and the optical path 13. As shown in FIG. Further, recent distance measuring devices have been improved so that angle measurement can be performed simultaneously in addition to distance measuring, and such devices tend to be larger and heavier. Such an increase in size and weight has a problem that it is difficult to carry the surveying device in surveying performed outdoors and that the workability of surveying is deteriorated. In addition, the use of many parts leads to an increase in cost, which is equivalent to mass production, and the surveying equipment tends to be expensive.

It is an object of the present invention to solve the above-mentioned problems and to provide a light-wave distance measuring device in which light guide means for forming a reference light path, a transmission light path, a reception light path and the like are small and lightweight.

It is another object of the present invention to provide a light guide means for forming a reference light path, a transmission light path, a reception light path, etc., which is small and lightweight, is suitable for mass production, and has stable performance and low cost. Is to provide a lightwave distance measuring device that can simultaneously satisfy the above conditions.

[0010]

In order to achieve the above object, the present invention provides a light source, a light source for splitting light from the light source into a reference optical path and a distance measuring optical path, and guiding light from both optical paths to a light receiving unit. A guide unit, a transmission / reception optical system that transmits light that has passed through a transmission optical path of the distance measuring optical path to a measurement target, receives reflected light from the measurement target, and sends the reflected light to a reception optical path of the distance measurement optical path; A light receiving unit that constitutes a light receiving unit and receives light from the distance measuring optical path or light from the reference optical path and converts the light into an electric signal; and a distance measurement for obtaining a distance to the object to be measured by the electric signal from the light receiving means. Means, the light guide means is constituted by a light guide member in which a plurality of glass substrates inclined with respect to the incident direction of light from the light source are stacked, and the light guide member is Formed on the surface of the glass substrate , And having a first optical functional element that splits the distance measuring optical path and the reference optical path and a second optical functional element for guiding light from the two optical paths to the light receiving portion at least.

According to the above invention, the light guide means for forming the reference optical path and the distance measuring optical path is constituted by a laminate prism which is formed by laminating a plurality of glass substrates and obliquely cutting them. Then, in order to constitute the light guide means, a first optical functional element for branching and a second optical functional element for light reception are formed on the surface of the laminated glass substrates. Such a laminated prism is more compact and lighter than a conventional configuration. Moreover, the light guide member can be formed relatively easily and with high precision by utilizing the existing semiconductor wafer process. Therefore, cost reduction can be realized.

[0012] In the above invention, the light guide member may further include a third optical functional element formed on a surface of the glass substrate and changing a diffusion angle of light from the light source. A specific example of the third optical function element is, for example, a hologram. In this example, the third optical function element can be formed by etching the surface of a glass substrate into a predetermined shape.

In the above invention, the transmission optical path, the reception optical path, and the reference optical path of the distance measuring optical path pass through the first end face of the light guide member and are connected to the outside, and the light source is the second light guide member of the light guide member. Wherein the light receiving means is provided on a third end face of the light guide member, and a light absorbing layer is formed on a fourth end face of the light guide member. According to this configuration, the number of end faces connecting the light guide member and the outside can be reduced to one, and the light absorption layer is formed on the remaining end faces except for the end face where the light source and the light receiving unit are provided. The amount of stray light that is reflected and enters the light receiving element can be reduced, and the measurement error due to the stray light can be reduced.

In the above invention, another light receiving means for monitoring the amount of light emitted from the light source is provided. By monitoring the light amount from the light source and controlling the light source based on the light amount, the light amount from the light source can be kept constant, and the distance measurement accuracy can be improved.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, such embodiments do not limit the technical scope of the present invention.

[First Embodiment] FIG. 1 is a block diagram showing a lightwave distance measuring apparatus according to a first embodiment of the present invention. In FIG. 1, a laser diode chip 1 as a light source is mounted on a submount 2 mounted on a block 3. Submount 2 and block 3 are light source 1
And has the function of releasing heat generated by the light source. The light guide member 4 is made of a laminate plasma, and has a rectangular parallelepiped shape of about 3 mm square, for example.
To the fourth glass substrates 5, 6, 8, and 10 are laminated by an adhesive (not shown). FIG. 1 shows a cross-sectional view of a light guide member 4 composed of the laminate prism.

Inside the light guide member 4, a first surface 7 and a second surface 7 are provided between a first glass substrate 5 and a second glass substrate 6.
A second surface 9 between the glass substrate 6 and the third glass substrate 8;
And, there are three slopes of the third surface 11 between the third glass substrate 8 and the fourth glass substrate 10. These slopes
It has a tilt of approximately 45 °. On the side of the second surface 9 and the first surface 7 of the second glass substrate 6, there is provided a reflection-type diffuser having a function of converting the diffusion angle of the emitted light with respect to the diffusion angle of the incident light of the light from the light source 1. Reflect the light near the center of the light flux from the angle conversion holograms 12 and 13 and the diffusion angle conversion hologram 13,
The reflection film 14 that transmits light in the peripheral portion is formed. Further, a beam splitter film 15 is formed on the third surface 11 side of the third glass substrate 8.

As shown in the lower part of FIG. 1, the reflection film 14 reflects the light in the vicinity of the center of the light beam of the laser beam from the light source 1 upward as it is and uses it as distance measurement light. Is passed to the right and used as reference light. That is, the reflection film 14 is an optical function element that branches into distance measuring light and reference light. Further, the return light received around the objective lens 23 passes below the periphery of the reflection film 14 as it is. Further, the beam splitter film 15 is an optical functional element that has a low reflectance and a high transmittance and reflects the reference light and transmits the return light at a high ratio.

The diffusion angle conversion holograms 12 and 13 formed on the second glass substrate 6 change the spread angle of the light beam from the light source 1 to match the shape of the objective lens 23. These holograms 12 and 13 can be formed in large quantities and with high precision, for example, by etching the surface of a glass substrate and processing it into a predetermined shape.

The method of manufacturing the light guide member 4 composed of a laminated prism as described above is described in, for example, OPTRONIC
S (1995) No. 10, pp. 153-157, "Development of integrated optical head for ultra-small magneto-optical recording" and OplusE
May, 1996, pp. 96-101, "Development of Integrated Head for Microminiature Magneto-Optical Recording".

The pulse laser light generated by the laser diode chip 1 enters the light guide member 4 from the surface 4a of the light guide member 4 and reaches the reflection type divergence angle conversion hologram 12. The pulsed laser light is transmitted through the divergence angle conversion hologram 12.
The divergence angle is converted by the hologram and the reflected light reaches the reflection type hologram 13. Further, the light whose diffusion angle has been converted by the diffusion angle conversion hologram 13 and which has been reflected reaches the reflection film 14. As described above, the reflection film 14 is formed only in the central portion of the light beam,
Reference numeral 4 branches the pulse laser light into transmitted light (reference pulse light) and reflected light (ranging pulse light).

The transmitted light on the outer peripheral portion of the light beam transmitted through the reflection film 14 reaches the light receiving element 19 via the reference optical path as follows. That is, the transmitted light exits from the end face 4 b of the light guide member 4, passes through the optical path switching shutter 16, passes through the light amount attenuation filter 17, and is reflected by the mirror 18.
The light reflected at 8 passes through the light amount attenuating filter 17 and the optical path switching shutter 16 and is incident on the light guide member 4 again, where the beam splitter film 1 in the fourth glass substrate 10 is formed.
5, the light is reflected by the beam splitter film 15 and enters the light receiving element 19 formed on the silicon substrate 34 as reference pulse light. The light receiving element 19 outputs an electric signal corresponding to the amount of incident reference pulse light to the distance measuring unit 2.
Output to 0. The light receiving element 19 is connected via the reference optical path.
The reference pulse light is incident on the optical path switching shutter 16 when the reference optical path side is switched to the open state and the distance measuring optical path side is switched to the closed state. The transmittance of the light amount attenuation filter 17 is adjusted during assembly so that the amount of light incident on the light receiving element from the reference optical path is attenuated to a predetermined value.

On the other hand, the reflected light at the center of the light beam reflected by the reflection film 14 reaches the light receiving element 19 as a distance measuring pulse light via a transmitting optical path and a receiving optical path as described below. That is,
The reflected light exits from the end face 4 c of the light guide member 4, passes through the optical path switching shutter 16, and passes through the light amount adjustment filter 30.
, Is reflected by the dichroic mirror 21, and is transmitted as a transmission pulse light toward the measurement object (not shown) via the objective lens 23. Therefore, the above path is the transmission optical path of the distance measuring optical path.

The diffusion angle conversion holograms 12 and 13
When the amount of light reflected by the reflection film 14 is
The spread angle of the distance measurement pulse light is adjusted so as to be transmitted from. Therefore, even if it is not possible to secure a sufficient transmission optical path length by downsizing the light guide member 4 composed of a laminate prism, the holograms 12 and 13 adjust the spread angle of the distance measuring pulse light optimally.

The transmitted pulse light transmitted to the object to be measured (not shown) through the objective lens 23 is reflected by the object to be measured, and is received by a peripheral portion of the objective lens 23 to become a received pulse light. This received pulse light is transmitted to the dichroic mirror 2
The light is reflected by 1, passes through the light amount adjustment filter 30, passes through the optical path switching shutter 16, enters the light guide member 4, passes through the portion around the reflection film 14, and enters the beam splitter film 15. Then, the beam splitter film 1
The light transmitted through 5 enters light receiving element 19. The above path is the receiving optical path of the distance measuring optical path. And the light receiving element 19
Outputs an electric signal corresponding to the amount of incident pulse light to the distance measuring means 20. Note that the reception pulse light enters the light receiving element 19 when the optical path switching shutter 16 is switched to the open state on the distance measuring optical path side and the closed state on the reference optical path side. The distance measuring means 20 obtains the distance to the measurement object from the time difference between the electric signal based on the reference pulse light and the electric signal based on the received pulse light.

Prior to the distance measurement, an object to be measured includes an eyepiece 27, a reticle 28,
Observation is performed through a collimating optical system including the erect prism 29, the focusing lens 22, and the objective lens 23, and the focusing lens 22 is adjusted in the X direction so that the optical system is focused on the object to be measured. Further, the light receiving element 1 is connected via the receiving optical path side of the distance measuring optical path.
9, the amount of the received pulse light incident on the
In order to secure the distance measurement accuracy of the electronic circuit, the light amount adjustment filter 30 adjusts the light amount to the same level as the light amount of the reference pulse light incident on the light receiving element 19 via the reference light path. The light amount adjustment filter 30 is a circular filter whose optical density continuously changes in the circumferential direction. The light amount adjustment filter 30 is rotated by a motor 31 having a rotation axis fixed at the center of the light amount adjustment filter 30 and received. Adjust the transmittance of the pulsed light.

As the light receiving element 19, an avalanche photodiode is preferably used. By using an avalanche photodiode, even weak light can be detected, so that accurate distance measurement can be performed even when the reflectance of the measurement object is low.

As described above, the reference optical path and the distance measuring optical path for guiding the pulse light from the laser diode 1 of the light source are an optical guide member formed by laminating a plurality of glass substrates having optical functional elements such as reflection and transmission formed on the surface. 4. When it is not necessary to adjust the spread angle of the pulse light, the light guide member 4 includes at least a reflection film 14 formed on the second glass substrate 6 and a beam splitter film 15 formed on the third glass substrate 10. , Branching and combining into a reference optical path and a distance measuring optical path are enabled. The reflection film 14 and the beam splitter film 15 can be formed by forming a dielectric film on the surface of the glass substrate. Further, the diffusion angle changing holograms 12 and 13 can be formed by etching the surface of the glass substrate. These processing techniques are similar to semiconductor wafer processing techniques. The plurality of glass substrates on which the optical function elements are formed are superposed by an adhesive, and the superposed glass substrates are cut out so that the bonding surface is at 45 degrees. It is also described in the above-mentioned literature that the production of the laminated prism is performed by using a wafer process technology.

In the lightwave distance measuring apparatus according to the first embodiment shown in FIG. 1, by using the light guide member 4 made of a laminated glass substrate, the light guide components for forming the distance measuring light path and the reference light path can be reduced in size. Since the weight is reduced and the entire distance measuring device is reduced in size and weight, labor for transporting the device is reduced and operability is improved. Further, the production of the light guide member 4 is possible by the wafer process technology, and the productivity is higher than that of the conventional optical element, and the production cost of the distance measuring device is reduced. Also,
Optical functional elements 12, 13, 14, 1 in light guide member 4
5 is fixed on the surface of each glass substrate,
Excellent in environmental resistance and long-term reliability compared to the conventional example.

[Second Embodiment] FIG. 2 is a block diagram showing a lightwave distance measuring apparatus according to a second embodiment of the present invention. This lightwave distance measuring device is a modification of the lightwave distance measuring device of the first embodiment, and the same components as those of the first embodiment in FIG. 1 are denoted by the same reference numerals.

In the lightwave distance measuring apparatus according to the second embodiment, a liquid crystal shutter 32 instead of the optical path switching shutter 16 is used.
A liquid crystal shutter 33 is used instead of the light amount adjustment filter 30. That is, when the reference optical path is selected, the transmittance of the liquid crystal shutter 33 on the distance measuring optical path side becomes almost 0%, and the transmittance of the liquid crystal shutter 32 on the reference optical path side becomes almost 100%. On the other hand, when the distance measuring optical path is selected, the transmittance of the liquid crystal shutter 32 is almost 0%.
Then, the transmittance of the liquid crystal shutter 33 is adjusted so that the light amount of the received pulse light at the light receiving element 19 becomes a set value in accordance with the reflectance of the measurement object. Other components are the same as in the first embodiment, and the distance measuring operation is also the same.

In the lightwave distance measuring apparatus according to the second embodiment, the motor is driven in the first embodiment to switch the optical path switching shutter and to rotate the light amount adjustment filter. Since they are replaced by 32 and 33, malfunctions of the optical path switching shutter due to failure of the motor and erroneous adjustment of the light amount are eliminated, and reliability and distance measurement accuracy are improved.

[Third Embodiment] FIG. 3 is a block diagram of a lightwave distance measuring apparatus according to a third embodiment of the present invention. The third embodiment is a modification of the lightwave distance measuring apparatus of the first embodiment, and the same components as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals.

In the optical distance measuring apparatus according to the third embodiment shown in FIG. 3, the light guide member 4 according to the first and second embodiments is used.
The diffusion angle conversion is performed by an optical element 35 provided outside instead of the diffusion angle conversion holograms 12 and 13. Optical element 35
For example, an anamorphic prism or a predetermined lens is used. As a result, the diffusion angle conversion holograms 12 and 13 of the first embodiment are not provided, and the second glass substrate 6 can be omitted. Other components are first
And the distance measuring operation is the same.

In the third embodiment, since the diffusion angle conversion hologram is not used, the influence of the wavelength variation of the light source peculiar to the hologram is small, and the generation of unnecessary diffracted light due to an error in the production of the diffusion angle conversion hologram. Can be eliminated.

FIG. 4 is a block diagram of a lightwave distance measuring apparatus according to a fourth embodiment of the present invention. The lightwave distance measuring apparatus according to the fourth embodiment is a combination of the second embodiment and the third embodiment, and the same reference numerals are given to the same components as the second and third embodiments. Wearing.

In the lightwave distance measuring apparatus according to the fourth embodiment, the liquid crystal shutters 32, 3
3 is used, and instead of the diffusion angle conversion holograms 12 and 13 in the light guide member 4, an optical element 35 for diffusion angle conversion provided outside is provided. As the optical element 35, an anamorphic prism or the like is used similarly to the above.
Other components are the same as those of the second and third embodiments, and the distance measuring operation is also the same.

In the lightwave distance measuring apparatus according to the fourth embodiment, the switching of the optical path and the adjustment of the amount of received light are not performed by the motor, the number of failures is small, and the influence of the fluctuation of the wavelength of the light source is not used because the hologram is not used. And the generation of unnecessary diffracted light due to the production error of the diffusion angle conversion hologram can be eliminated.

[Fifth Embodiment] FIG. 5 is a block diagram of a lightwave distance measuring apparatus according to a fifth embodiment of the present invention. The fifth embodiment is a modification of the lightwave distance measuring device of the first embodiment, and the same components as those of the lightwave distance measuring device of the first embodiment in FIG. .

In the fifth embodiment, the light receiving element 36 for monitoring the power of the laser light emitted from the end face 1 a of the laser diode chip 1 is provided on the submount 2. By controlling a power supply (not shown) for driving the laser diode 1 so that the amount of light received by the light receiving element 36 is constant, the amount of light emission from the laser diode chip 1 that fluctuates due to temperature change and aging can be kept constant. Can be In the embodiment of the present invention, the laser diode chip 1 is directly attached to the end face 4a of the glass member 14 in which a plurality of glass substrates are stacked. Therefore, the laser diode 101 sealed in the conventional chip
No monitor element is built in. Therefore, in the fifth embodiment, the light receiving element 36 for monitoring is mounted on the submount 2 to enable control to make the light emission amount of the laser diode constant.

The other components are the same as those in the first embodiment shown in FIG. 1, and the distance measuring operation is the same.

In the lightwave distance measuring apparatus according to the fifth embodiment, the amount of light emitted from the laser diode is detected by the light receiving element 36, and the amount of light emitted from the laser diode chip 1 is controlled to be constant. Compared with the embodiment, the peak value of the pulse light can be made constant, and the distance measurement accuracy can be improved.

[Sixth Embodiment] FIG. 6 is a block diagram of a lightwave distance measuring apparatus according to a sixth embodiment of the present invention. The sixth embodiment is a modification of the lightwave distance measuring device of the first embodiment, and the same components as those of the lightwave distance measuring device of the first embodiment shown in FIG. .

In the lightwave distance measuring apparatus according to the sixth embodiment, the light quantity attenuation filter 17 and the mirror 18 of the reference light path are arranged on the end face 4c of the light guide member 4, as shown in the figure. As a result, both the distance measuring optical path and the reference optical path are connected to the outside via the end face 4c. Therefore, a beam splitter film 37 is provided on the surface of the third glass substrate 8 of the light guide member 4, the light guide member 4 is composed of five glass substrates, and the fourth glass substrate 10 is provided with a reflection film 40. Provided. Further, since the reference light path is not formed on the end face 4b, the end face 4b is coated with the light absorbing film 44.

The reference optical path is emitted from the upper end face 4c of the light guide member 4, reflected by the mirror 18, and
And a path that passes through the inside and enters the light receiving element 19. That is, the transmitted light on the outer peripheral portion of the light beam transmitted through the outer peripheral surface of the reflective film 14 is reflected by the beam splitter film 37, exits from the surface 4 c of the light guide member 4, and passes through the optical path switching shutter 16.
Then, the light passes through the light amount attenuation filter 17 and is reflected by the mirror 18. The light reflected by the mirror 18 again enters the light guide member 4 via the light amount attenuation filter 17 and the optical path switching shutter 16, passes through the beam splitter film 37, is reflected by the reflection film 40, and is reflected by the beam splitter 40. The light passes through the optical path in the fourth glass substrate 10 that reaches the film 15, is reflected by the beam splitter film 15, and enters the light receiving element 19 in the silicon substrate 34 as reference pulse light. Other components are the same as in the first embodiment, and the distance measuring operation is also the same.

In the lightwave distance measuring apparatus according to the sixth embodiment, the pulse light of the distance measuring optical path and the pulse light of the reference optical path are emitted and incident from the same end face 4c of the light guide member 4, so that the structure is structurally low. The formation of a window (not shown) for the pulse light can be simplified. In addition, by emitting the pulse light of the reference optical path from the upper end face 4c of the light guide member 4, the end face 4b of the light guide member 4 can be coated with a light absorbing film. Therefore, reflected light at the end face 4b of the light guide member 4 is reduced, stray light reflected by the end face 4b and entering the light receiving element 19 can be eliminated, and measurement errors due to stray light can be reduced.

[Seventh Embodiment] FIG. 7 is a block diagram of a lightwave distance measuring apparatus according to a seventh embodiment of the present invention. The seventh embodiment is a modification of the lightwave distance measuring apparatus of the sixth embodiment, and the same components as those of the sixth embodiment in FIG. 6 are denoted by the same reference numerals.

In the lightwave distance measuring apparatus according to the seventh embodiment, the pulse light on the reference optical path is received by the light receiving element 43 for monitoring and used for controlling the drive voltage of the laser diode 1. For this purpose, the beam splitter film 41 is formed on the fourth glass substrate 8.
However, a reflection film 42 is provided on the end face 4 b of the light guide member 4, and a light receiving element 43 for monitoring is provided on the silicon substrate 34.

The light transmitted through the outer periphery of the reflection film 14 at the outer periphery of the light beam enters the beam splitter film 37. The pulse light reflected by the beam splitter film 37 is used as reference pulse light, but the pulse light transmitted through the beam splitter film 37 is used as a newly provided beam splitter film 41.
Reflected by the reflection film 42 and reflected by the beam splitter film 4
1 and enter the monitor light receiving element 43. Then, the power supply for driving the laser diode 1 is controlled so that the amount of light received by the light receiving element 43 is constant, and the amount of light emitted from the laser diode chip 1 is controlled to be constant.

The other components are the same as those in the sixth embodiment shown in FIG. 6, and the distance measuring operation is the same.

In the lightwave distance measuring apparatus according to the seventh embodiment, similarly to the sixth embodiment, the pulse light of the distance measuring optical path and the pulse light of the reference optical path are transmitted from the same end face 4c of the light guide member 4. Since the light is emitted, the end surface 4c of the light guide member 4 can be coated with a light absorbing film, and stray light reflected on the surface 4b of the light guide member 4 and incident on the light receiving element 19 can be reduced. Further, the light of the reference optical path having originally high energy is branched, and the light amount of the branched light is monitored by another light receiving element 43 to detect the light amount emitted from the laser diode, and the light emission amount of the laser diode chip 1 is kept constant. It can be controlled, and the ranging accuracy is improved. Moreover,
Since the light receiving elements 19 and 43 are only formed on the same silicon substrate 34, the positioning accuracy of both light receiving elements can be increased.

In the first to seventh embodiments, the description has been given of the lightwave distance measuring device for measuring the distance by the time delay of the pulse light. However, the lightwave distance measuring device using the light guide member of the present invention is a reference. The present invention can also be applied to a lightwave distance measuring device that performs distance measurement based on a phase difference between light and distance measurement light.

In the first to seventh embodiments, a laser diode chip is used as the light source 1, but a light emitting diode may be used. In the first to seventh embodiments,
Although the avalanche photodiode is used for the light receiving element 19, another type of photodiode may be used. Also, the first
Although the light receiving elements 19 and 43 are formed on the silicon substrate 34 in the seventh embodiment, they may be formed on a compound semiconductor substrate such as GaAs.

In the fifth to seventh embodiments, the optical path switching shutter and the light amount adjusting filter are used, but a liquid crystal shutter may be used instead. In addition, the fifth
In the seventh to seventh embodiments, the diffusion angle conversion hologram is used, but an optical element for converting the diffusion angle may be arranged outside the light guide member instead.

[0055]

According to the present invention, the light guide means for forming the reference light path and the distance measuring light path is constituted by a laminate prism formed by laminating a plurality of glass substrates and cutting the glass substrate obliquely.
Then, in order to constitute the light guide means, a first optical functional element for branching and a second optical functional element for light reception are formed on the surface of the laminated glass substrates. Such a laminated prism is more compact and lighter than a conventional configuration. Therefore, the lightwave distance measuring device can be reduced in size and weight. Moreover, the light guide member can be formed relatively easily and with high precision by utilizing an existing semiconductor wafer process. Therefore,
Cost reduction can also be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a lightwave distance measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a lightwave distance measuring apparatus according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a lightwave distance measuring apparatus according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a lightwave distance measuring apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a lightwave distance measuring apparatus according to a fifth embodiment of the present invention.

FIG. 6 is a block diagram showing a lightwave distance measuring apparatus according to a sixth embodiment of the present invention.

FIG. 7 is a block diagram showing a lightwave distance measuring apparatus according to a seventh embodiment of the present invention.

FIG. 8 is a block diagram showing a conventional lightwave distance measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light source, laser diode chip 4 ... Light guide member 5, 6, 8, 10, 38 ... Glass substrate 7, 9, 11, 39 ... Surface 12, 13 ... Diffusion angle conversion Holograms 14, 40, 42: Reflective film 15, 37, 41: Beam splitter film 16: Optical path switching shutter 17: Light amount attenuation filter 18: Mirror 19, 36, 43: Light reception Element 20 Distance measuring means 23 Objective lens 30 Light amount adjustment filter 31 Motor 32, 33 Liquid crystal shutter 34 Silicon substrate 35 Optical element 44 Light absorbing film

Continued on the front page F term (reference) 2F065 AA06 DD02 FF12 FF13 FF32 GG04 GG06 GG08 JJ01 JJ18 LL01 LL04 LL12 LL20 LL24 LL30 LL46 LL47 LL51 NN16 2H042 CA06 CA14 CA17 5J084 AA11 BB31 BB01 BB01

Claims (4)

[Claims] 1. A light source, light guide means for splitting light from the light source into a reference optical path and a distance measuring optical path, and guiding light from both optical paths to a light receiving section, and light passing through a transmission optical path of the distance measuring optical path. A transmission / reception optical system that transmits to the measurement target, receives reflected light from the measurement target, and sends the reflected light to the reception optical path of the distance measurement optical path, and light from the distance measurement optical path or the reference optical path which constitutes the light receiving unit. A light receiving device that receives light from the light receiving device and converts it into an electric signal, and a light wave distance measuring device having a distance measuring device that obtains a distance to the object to be measured by the electric signal from the light receiving device. The light guide member is formed by stacking a plurality of glass substrates whose surfaces are inclined with respect to the incident direction of light from the light source. The light guide member is formed on the surface of the glass substrate, and the reference optical path and the distance measurement are formed. First optic that branches to the optical path A lightwave distance measuring device comprising at least a functional element and a second optical functional element for guiding light from both optical paths to the light receiving section. 2. The light guide member according to claim 1, further comprising a third optical function element formed on a surface of the glass substrate and changing a diffusion angle of light from the light source. Lightwave distance measuring device. 3. The light guide according to claim 1, wherein a transmission light path, a reception light path, and a reference light path of the distance measuring light path are connected to the outside through a first end face of the light guide member, and the light source is connected to the light guide member. A light receiving means provided on a second end face, wherein the light receiving means is provided on a third end face of the light guide member, and a light absorbing layer is formed on a fourth end face of the light guide member. Distance device. 4. A lightwave distance measuring apparatus according to claim 1, further comprising another light receiving means for monitoring the amount of light emitted from said light source.