JPH08313249A - Laser range finder - Google Patents

Abstract

PURPOSE: To provide a laser range finder by which the optical axis is adjusted simply by a method wherein a first laser beam is divided into a second laser beam which is directed to an object to be measured and a third laser beam which is made to fall onto a photodetector and the position to which the third laser beam is directed is detected. CONSTITUTION: A laser beam is incident to a semitransparent mirror 21, and it is divided into a laser beam traveling to an object 3 to be measured and into a laser beam reaching a semitransparent mirror 24 via a condensing lens 23. When the light projection axis and the light receiving axis are directed to the same direction, a laser beam which has been transmitted through the mirror 24 is incident on a photodetector 25, and a reflected laser beam is directed to a reference position. Then, when the light projection axis is deflected by θ, the laser beam is directed to a position which is deviated by d' from the reference position on a detection element. The magnitude of the deviation d' corresponds to the magnitude of a deviation (d) from the focal point of the beam which has been transmitted through the mirror 24. Consequently, the correspondence relationship between the deviation amounts (d), d' is input in advance so as to be computed, a control amount is output to the driving gear of a rocking mirror 28, and the light projection axis can be made to agree with the light receiving axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser distance measuring device for measuring a distance to an object using laser light.

[0002]

2. Description of the Related Art As a method for performing distance measurement and surveying, a laser beam is applied to an object to be measured, the reflected light generated from the laser beam is captured by a light receiver, and the difference between the emitted laser beam and the received reflected light is analyzed. There is a method of measuring the distance to the object to be measured by doing so, and the device used for this is called a laser distance measuring device. The laser range finder has higher resolution and accuracy than the theodolite used in conventional surveying, and is also used when measuring distances to distant objects such as the moon and artificial satellites in addition to trilateration on the ground. Has been.

The configuration of a conventional laser distance measuring device will be described with reference to the drawings. The laser range finder shown in FIG. 3 includes a laser oscillator 1 for emitting a laser beam toward a DUT 3,
It is composed of a light receiver 2 which receives the laser light emitted from the laser oscillator 1 and reflected by the DUT 3. The light receiver is composed of a condenser lens 7 and a photodetector 8. The light emitting axis of the laser oscillator and the light receiving axis of the light receiver are both adjusted to face the same direction.
If this adjustment is not done accurately, it may be impossible to measure. Therefore, the axis adjustment of the distance measuring device is very important. Although it depends on the size of the object to be measured and the specifications of the device, it is necessary to keep the axis deviation within a range of about 10 ⁻⁴ rad.

An optical axis adjusting device for adjusting the parallelism of the light projecting axis and the light receiving axis will be described with reference to the drawings. The optical axis adjusting device shown in FIG. 4 includes a collimator lens 10, a reflecting mirror 11, a half mirror 12, a laser light detector 13, and a light source 14. A method of axis adjustment using this device will be described. First,
The laser light emitted from the laser oscillator 1 is made to enter the optical axis adjusting device. At this time, the direction of the optical axis adjusting device is changed so that the incident laser light is collimator lens 10 and reflecting mirror 11.
It is adjusted so that it is reflected by and is guided to the laser light detector 13. Adjustment of the light receiving axis is performed while maintaining the relative angle between the laser oscillator 1 and the optical axis adjusting device obtained in this way. The position where the light source 14 provided in the optical axis adjusting device is provided, that is, the optical position with respect to the reflecting mirror 11 is provided at a position equivalent to the laser light detector 13. The light emitted from the light source 14 is guided to the collimator lens 10 by the half mirror 12 and the reflecting mirror 11, processed into parallel light by the collimator lens 10, and emitted to the outside of the optical axis adjusting device. This parallel light is made incident on the light receiver 2. At this time, the direction of the photodetector 2 is adjusted so that the photodetector 8 provided in the photodetector 2 can receive the incident parallel light so that the projection axis of the laser oscillator 1 and the photodetection axis of the photodetector 2 are aligned. Can be turned in the same direction.

[0005]

However, the conventional laser range finder having the above-mentioned structure has the following problems. That is, in the conventional laser distance measuring device, it is necessary to match the light receiving axis and the light projecting axis, so that an optical system such as a collimator lens and a reflecting mirror as shown in FIG. 4, a laser light detecting element such as a CCD camera and a photodiode, and An optical axis adjusting device having a light source must be prepared.

When carrying a device while carrying out surveys from various points, the parallelism of the axes easily changes due to vibration during transportation, temperature changes at the survey points, etc. Therefore, when performing a new distance measurement, the axis It is necessary to confirm and adjust the parallelism, and the optical axis adjusting device must always be carried together. Alternatively, if the conventional optical axis adjusting device having the configuration as shown in FIG. 4 is incorporated into the laser distance measuring device and integrated, the device becomes bulky and it becomes inconvenient to carry. Further, since the optical device is very sensitive to vibration, there has been a demand to reduce the number of optical components as much as possible. An object of the present invention is to provide a laser distance measuring device capable of easily adjusting the optical axis in order to solve the above technical problems.

[0007]

The present invention has been made to solve the above technical problems, and a laser oscillator for emitting a first laser beam and an emission of the first laser beam. Adjusting means for adjusting the direction, light splitting means for receiving the first laser light and splitting the first laser light into a second laser light and a third laser light, and the third laser light And a photodetector having a first photodetector that detects a position irradiated with, and a second photodetector that detects reflected light generated by irradiating the DUT with the second laser light. And a control unit connected to the first light detection unit to control the adjustment unit. At this time, it is preferable that the first light detecting means is composed of a PSD element, a CCD or a photodiode, and an XY table. The second light detecting means can also serve as the first light detecting means.

The present invention also provides a laser oscillator having a laser emitting surface for emitting laser light, a first reflecting member for reflecting at least a part of the laser light, and generating first reflected light, A second reflecting member having a reflecting surface of one reflecting member and a surface orthogonal to the surface formed by the laser light and the first reflected light, and reflecting at least a part of incident light; It has a light receiving port for introducing the second reflected light emitted from the second reflecting member, a light detecting means for detecting the second reflected light, and an adjusting means for adjusting the position of the light detecting means. A laser range finder comprising: a light receiver provided with the laser emission surface and the light receiving port facing each other. At this time, it is preferable that the first reflecting member and the second reflecting member are detachably or rotatably provided, or consist of half mirrors.

[0009]

The laser range finder of the present invention has the following functions due to the above-mentioned configuration. That is, in the first invention,
The first laser light emitted from the laser oscillator enters the light splitting means and is split into the second laser light with which the DUT is irradiated and the third laser light which is introduced into the light receiver. The second laser light is applied to the object to be measured to generate reflected light, and the third laser light is applied to the light receiver. When the light emitting axis of the laser oscillator and the light receiving axis of the light receiver are parallel to each other, the third laser light is applied to a certain portion (hereinafter referred to as a reference portion) determined by the device. However, when the light projecting axis and the light receiving axis are not parallel, the third laser beam is applied to a part deviated from the reference part. Therefore, by detecting the position irradiated with the third laser beam by the second light detecting means, the deviation from the reference portion is detected, and the adjusting means is driven by the control means based on the amount of this deviation to project the light. The optical axis and the light receiving axis are made parallel.

Further, in the second invention, since the laser light emitting surface of the laser oscillator and the light receiving port of the light receiver are provided so as to face each other, the light is shielded on the line formed by the optical distance between the laser oscillator and the light receiver. When there is no object, the laser light emitted from the laser oscillator can enter the light receiver. The position of the light detecting means is adjusted by using the moving means provided in the light detecting means so that the light detecting means inside the light receiver can capture the laser light.

After this adjustment, the laser beam emitted from the laser oscillator is applied to the DUT existing in the first direction by the first reflecting member, and the laser beam reflected by the DUT is reflected by the first reflecting member. The light enters the second reflecting member and is introduced into the light receiver.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A configuration example of an apparatus for carrying out the first invention will be described with reference to the drawings. The laser range finder of FIG.
The laser oscillator 1 incorporating the two swinging mirrors 28 as the adjusting means, the first half mirror 21 as the light splitting means for receiving the laser light emitted from the laser oscillator 1, and the first half mirror 21 are transmitted. Reflecting means for receiving reflected light generated by irradiating the DUT 3 with the laser light, and a reflecting mirror 22 provided integrally with the first half mirror 21 with its reflecting surface orthogonal to each other. A condenser lens 23 for receiving and condensing the second reflected light emitted from the reflecting mirror 22, a second half mirror 24 for receiving the light flux condensed by the condensing lens, and a second half mirror A light detector 25, which is a second light detecting means provided at a position where the light transmitted through 24 is focused, and a first light detecting hand for receiving the laser light reflected by the second half mirror 24. That is, it is a PSD stack 26 formed by stacking PSD elements in layers, and a control means for receiving a signal output from the PSD stack 26 and generating a control signal corresponding to this signal to drive the oscillating mirror 28. And a mirror control device 27. PS
The D element is a semiconductor optical element, and when a part of the light receiving portion of this element is irradiated with light, it outputs a signal indicating a portion irradiated with this light. A single unit can obtain a one-dimensional detection space. In the apparatus of this embodiment, the PSD element (Phot
o Sensitive Detector: A semiconductor optical position detection element) is stacked in layers to form a PSD stack, so a two-dimensional detection space can be obtained.

In the apparatus of this embodiment, the first half mirror 21
Is integrally formed with the reflecting mirror 22, so that the squareness of both is firmly maintained. Integrating the optical components in this way improves the reliability of the measurement results because the wobble of the components can be suppressed in order to constrain the degree of freedom of each component. Particularly in the device of the first embodiment, since the perpendicularity of the first half mirror 21 and the reflecting mirror 22 is important, the effect of integrating the two is great.

The optical axis adjusting method of the device of the first invention will be described with reference to FIG. The first laser light emitted from the laser oscillator (not shown) passes through a swing mirror (not shown) and is incident on the first half mirror 21, and the second laser light toward the object to be measured (not shown) and a condenser lens. 23 and a third laser light which is vertically incident on the light source 23. Of these, the third laser light is refracted by the condenser lens 23, has its optical path bent, and reaches the second half mirror 24. When the light projecting axis and the light receiving axis are oriented in the same direction, that is, when the optical axis adjustment is unnecessary, the laser light emitted from the laser oscillator is represented by the solid line in FIG. 1B. Draw a locus like that. The photodetector 25 is the condenser lens 2
Since it is located at the focal length of 3, the third laser light transmitted through the half mirror 24 enters the photodetector 25. Further, the third laser light reflected by the second half mirror 24 is at a certain position (reference position) determined by the device.
Is irradiated. A PSD stack (not shown) is provided at this reference position, and the position irradiated with the laser light is constantly monitored. Here, the locus of the laser beam when the projection axis of the laser oscillator is deviated by θ is shown by a dotted line in FIG. The laser light incident with a deviation of θ is irradiated on the PSD element at a position deviated from the reference position by d ′. The magnitude of this deviation d'corresponds to the magnitude of the deviation d from the focus of the light transmitted through the second half mirror 24. Further, the relationship between the shift angle θ and the shift amount d is expressed by θ = d / f using the focal length f of the condenser lens 23. Therefore, by inputting the correspondence relationship between the shift amounts d and d ′ obtained from these relationships into the control device in advance, the calculation can be performed based on the signal from the PSD element, and the optical axes can be matched. Therefore, the required control amount can be uniquely output. By outputting the control amount thus determined to the driving device of the oscillating mirror 28 to drive it, the light projecting axis can be aligned with the light receiving axis.

In the device of the first invention, the PSD element stacked is used as the first photo-detecting means, but any element capable of obtaining a detection space having a two-dimensional spread can be used. It is also possible to use a configuration in which a photodiode attached to an XY table is scanned two-dimensionally. Similarly, a CCD may be used. When the device using the present invention is used in an environment that does not require high light receiving sensitivity, the above-mentioned PSD element or CCD
By using a member such as a photodiode or a photodiode as the second light detecting means, it is possible to combine the functions of the first light detecting means and the second light detecting means.

A configuration example of an apparatus for carrying out the second invention will be described with reference to the drawings. The laser range finder of FIG. 2 includes a laser oscillator 1 that emits YAG laser light as laser light,
4 with respect to the optical axis of the laser light emitted from the laser oscillator 1.
A first mirror 5 which is a first reflecting member having an inclination of 5 degrees
And a second reflecting member which is provided at a right angle to the first mirror 5 and receives the reflected light emitted from the workpiece 3 irradiated with the laser light reflected by the first mirror 5 The mirror 6, the light receiver 2 on which the reflected light emitted from the second mirror 6 is incident, the first mirror 5 and the second mirror 6, and the angle formed by the anti-slopes is kept at 90 degrees. It is composed of a fixed mirror mount 4. Light receiver 2
Is a lens 7 which is a light collecting means for collecting incident light,
The optical detector 8 is a light detecting means for detecting the light condensed by the lens 7, and an XYZ stage 9 which is attached to the light detector 8 and is a moving means for moving the light detector 8 in the directions orthogonal to the three axes. ing.

According to this apparatus, the laser light emitted from the laser oscillator 1 is reflected by the first mirror 5 provided on the mirror mount 4 in the direction of 90 degrees from the projection axis of the laser oscillator 1. The laser light reflected by the first mirror 5 is reflected by the DUT 3. This reflected light is incident on the second mirror 6 provided on the mirror mount 4.
The light is refracted by 0 degree and introduced into the light receiver 2.

In the laser range finder of the second embodiment of the present invention, the light reflectance of the first mirror 5 is set to 99.5%.
The remaining 0.5% of the laser light is configured to pass through the first mirror 5, pass through the mirror mount 4 and the second mirror 6, and enter the light receiver 2. The XYZ stage 9 is provided so that the laser light passing through the lens 7 in the light receiver 2 can be detected.
The position of the photodetector 8 was adjusted using. This completes the adjustment of the light emitting axis and the light receiving axis.

As a method of securing the optical path when performing such optical axis adjustment, in addition to the method of using the half mirror, a method of rotating the mirror together with the mirror mount to move the mirror out of the optical path, or a mirror There is a method of moving the mirror out of the optical path by providing a mount that can be moved up and down, retracted, or detached. However, in these methods, in which no substance is interposed between the laser oscillator and the photodetector, the laser light emitted from the laser oscillator may directly enter the photodetector, resulting in an excessive input state. . Therefore, when these methods are used, it is preferable to provide a means for attenuating the optical energy of the laser light such as installing colored glass on the optical path or switching to a power supply device that suppresses the laser light output and to use them together.

[0020]

According to the laser range finder of the present invention, the axis can be easily adjusted.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of an apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a conventional laser distance measuring device.

FIG. 4 is a schematic view showing an optical axis adjusting device used in a conventional laser distance measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laser oscillator 2 ... Optical receiver 3 ... Object to be measured 4 ... Mirror mount 5 ... First mirror 6 ... Second mirror 7 ... Condenser lens 8 ... Photodetector 9 ... XYZ stage 10 ... Collimator lens 11 ... Reflector 12 ... Half mirror 13 ... Laser light detector 14 ... Light source 21 ... First half mirror 22 ... Reflecting mirror 23 ... Condensing lens 24 ... Second half mirror 25 ... Photodetector 26 ... PSD element 27 ... Mirror control device 28 ... Shake Moving mirror

Claims (10)

[Claims] 1. A laser oscillator that emits a first laser beam, an adjusting unit that adjusts an emission direction of the first laser beam, the first laser beam is received, and the first laser beam is emitted. Light splitting means for splitting into a second laser light and a third laser light, a first light detecting means for detecting a position irradiated with the third laser light, and the second laser light to be measured A light receiver having a second light detection unit that detects reflected light generated by irradiation of an object, and a position where the third laser light detected by the first light detection unit is irradiated. The adjustment amount that causes the third laser beam to be detected by the first photodetector when the second laser beam and the reflected beam have a parallel positional relationship. A laser distance measuring device characterized by comprising: apparatus. 2. A laser distance measuring apparatus according to claim 1, further comprising an introducing means for introducing the reflected light into the light receiver, and the introducing means and the light splitting means are fixed to each other. 3. The laser distance measuring apparatus according to claim 1, wherein the first light detecting means comprises a PSD element. 4. The laser distance measuring apparatus according to claim 1, wherein the first light detecting means is a CCD. 5. The laser distance measuring apparatus according to claim 1, wherein the first light detecting means comprises a photodiode and an XY table. 6. The laser distance measuring apparatus according to claim 1, wherein the second light detecting means also serves as the first light detecting means. 7. A laser oscillator for emitting a laser beam, a first reflecting member for reflecting at least a part of the laser beam to generate a first reflected light, and a reflecting surface of the first reflecting member. A second reflecting member having a reflecting surface orthogonal to the surface formed by the laser light and the first reflected light, and reflecting at least a part of the incident light, and emitted from the second reflecting member. A light receiver having a light receiving port for introducing the second reflected light and the laser light, a light detecting means for detecting the second reflected light, and an adjusting means for adjusting the position of the light detecting means, A laser distance measuring device comprising: 8. The laser distance measuring apparatus according to claim 7, wherein the first reflecting member and the second reflecting member are detachably provided. 9. The laser distance measuring apparatus according to claim 7, wherein the first reflecting member and the second reflecting member are rotatably provided. 10. The laser distance measuring device according to claim 7, wherein the first reflecting member and the second reflecting member are half mirrors.