JPH11316123A - Laser range finder, and its optical axis adjusting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser range finder capable of aligning easily an optical axis, and to provide an optical axis adjusting method using it. SOLUTION: A laser beam S1 from a laser projecting element 11 irradiates a laser range finder 20 when a measuring object 1 is absent, and it is reflected by a half-mirror 22 as a beam t2 to get incident into an optical axis monitoring light receiving element 24. The light receiving element 24 is also a one- dimensional optical sensor, and a light-incident position in its longitudinal direction can be detected. An imaging point of the beam t2 on a light receiving element 23 is in its central part when optical axes of one-dimensional laser range finders 10, 20 arranged to be face each other are consistent. But, when the axes are shifted, an imaging point of the beam t2 on the optical axis monitoring light receiving element 24 is shifted from the central part, and an electric signal output of the light receiving element 24 is also varied. Since shifting amounts and directions of the optical axes are determined by variation of the signal output, correction for the optical axes is easily carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for sandwiching a measurement object between two opposing laser distance meters and measuring the size of the measurement object from the distance between each distance meter and the measurement object. More particularly, the present invention relates to a laser distance meter that facilitates optical axis alignment at that time and an optical axis alignment method using the same.

[0002]

2. Description of the Related Art As a distance meter, a linear laser beam is radiated to an object to be measured, the reflected light is received by a one-dimensional optical sensor, and the distance from the light receiving position of the one-dimensional optical sensor to the object to be measured is measured. Is widely used.
FIG. 4 shows the measurement principle. In FIG. 4, reference numeral 51 denotes a distance meter, 52 denotes a laser diode, and 53 denotes a position detecting element (1).
Reference numeral 54 denotes a laser light emitting circuit, 55 denotes a light emitting lens, 56 denotes a light receiving lens, and 57 denotes an object to be measured.

[0003] The laser diode 52 is
4 to generate a laser beam. The laser light generated here is transmitted through the light projecting lens 55 to the object 5 to be measured.
The laser beam projected on the surface 7 and reflected on the surface of the measuring object 57 is received by the position detecting element 53 via the light receiving lens 56. As the light receiving element 57, a CCD or PSD
Etc. are used. At this time, as shown in the figure, since the laser beam is received at a position corresponding to the distance between the measuring object 57 and the distance meter 51, when the light receiving element is a CCD, the position of the element in which the electric charge is accumulated, When the element is a PSD, if the current value is detected, the distance between the measuring object 57 and the distance meter 51 can be measured.

Further, by applying this principle, the object to be measured is irradiated with a slit-shaped laser beam, and the reflected light is received by a two-dimensional optical sensor. A method of measuring the distance to a vehicle is widely used. This corresponds to an arrangement in which a large number of one-dimensional rangefinders as shown in FIG. 4 are arranged in a direction perpendicular to the paper surface.

[0005] As described above, two rangefinders are opposed to each other as a set, and they are arranged so as to sandwich the object to be measured. When the distance from each rangefinder to the object to be measured is measured, the size of the object (the sensor becomes It is possible to measure the shape (when the sensor is two-dimensional) or at a certain cross section (when the sensor is two-dimensional).

[0006]

However, in the method for measuring the size and shape of the object to be measured, if the optical axes of the two opposing distance meters do not match, the size and the shape of the object to be measured may be reduced.
There is a problem that the shape cannot be measured accurately. This situation will be described with reference to FIG. In FIG. 5, 51, 51 ′
Is a distance meter, 57 is an object to be measured, a1, b1, a2, b2
Indicates a point at which the light beam of the range finder hits the measuring object 57.

In FIG. 5, (a) shows distance meters 51 and 5.
When the optical axes of 1 ′ are aligned, that is, when the optical axes of the respective distance meters coincide with each other and are perpendicular to the measuring object 57, (b) indicates that the optical axis direction of the distance meter 51 is θ1,5
The case where the optical axis direction of 1 ′ is shifted by θ2 is shown.

In (a), the distance between the distance meter 51 and 51 'is L, the distance between the object 57 measured by the distance meter 51 and the distance meter 51 is la1, and the measurement is performed by the distance meter 51'. Assuming that the distance between the object 57 and the distance meter 51 ′ is lb1,
The dimension d of the measurement object 57 can be expressed as d = L− (la1 + lb1).

However, in (b), since the optical axis is deviated, the distance between the measuring object 57 to be measured as la1 and the distance meter 51 is measured as la2 = la1 / cos θ1, and originally as lb1. Object to be measured 57 and distance meter 5
The distance between 1 ′ is measured as lb2 = lb1 / cosθ1. Therefore, the dimension of the measurement object 57 is measured as d ′ = L− (la1 / cos θ1 + lb1 / cos θ1), and a measurement error occurs. Therefore, in the dimension measuring device of such a system, it is essential to make the optical axes of the two distance meters coincide with each other.

Conventionally, in order to make the optical axes of the two rangefinders coincide, a translucent thin film is inserted on each of the optical axes of the two rangefinders, and an image is formed on the thin film by visual confirmation. The position of the light spot of each of the rangefinders coincides on the thin body, and even if the position of the thin film body is changed, the optical axis of the rangefinder is adjusted by keeping the coincidence.

Japanese Patent Application Laid-Open No. Hei 2-231515 discloses a laser range finder having means for confirming alignment of an optical axis. This has a built-in laser diode with a built-in photodiode behind the laser chip. The laser beam emitted by the laser range finder on the other side is received by this photodiode, and at a position where the output becomes the optimum value. This is a method of determining that the optical axes match.

[0012]

However, in the conventional method of checking the optical axis using a thin film, a laser spot formed on the thin film is visually checked while changing the position of the thin film. Since the optical axis is adjusted above, there is a problem that the work is complicated and the workability is not good. or,
If the laser light is not visible light, this method cannot be used.

The method described in Japanese Patent Application Laid-Open No. Hei 2-231515 uses a photodiode having a point-like light-receiving point, and cannot recognize the position of the image-forming point of the received light. There is a problem that the shift amount and the direction of the optical axis cannot be determined. In addition, this method has a problem that it cannot be applied when two opposing distance meters are two-dimensional laser distance meters.

The present invention has been made in view of such circumstances, and a laser range finder used for measuring a dimension of a measurement object by sandwiching the measurement object between the two laser distance meters. It is an object of the present invention to provide an optical axis easy to align and to provide an optical axis adjusting method using the same.

[0015]

A first means for solving the above-mentioned problem is to irradiate a linear laser beam emitted from a laser light source to an object, receive a reflected light thereof with a one-dimensional optical sensor, A laser distance meter that measures a distance from a light receiving position of the reflected light in the one-dimensional optical sensor to an object,
A half mirror that is provided in front of the laser light source and transmits a part of the laser beam and reflects a part of the external light emitted from the outside; and receives the external light emitted from the outside and reflected by the half mirror. A second one-dimensional optical sensor,
Means for measuring an irradiation position of the extraneous light from a light receiving position of the extraneous light in a second one-dimensional optical sensor (claim 1).

In this means, the laser beam from the opposing laser distance meter is reflected by the half mirror and received by the second one-dimensional optical sensor. Therefore, by looking at the output of the one-dimensional optical sensor, it is possible to know at which position of the laser rangefinder the laser beam from the opposing laser rangefinder is incident. Therefore, while observing the output of the one-dimensional optical sensor, the incident position of the laser beam from the other party is adjusted so as to be at the center of the laser distance meter, so that the optical axes of the two laser distance meters match. be able to.

In this means, since the light receiving cell is a one-dimensional optical sensor, it is possible to determine in which direction the laser beam is shifted, unlike the one disclosed in Japanese Patent Application Laid-Open No. 2-231515. . Therefore, the optical axis adjustment operation can be performed with high efficiency.

A one-dimensional optical sensor includes a CCD or a PSD.
However, a small photodiode may be provided at the center, and an elongated photodiode may be provided on both sides of the small photodiode. One such element consisting of three or more diodes
Even with a two-dimensional optical sensor, it is possible to determine which side of the optical axis is deviated by knowing which sensor on either side is receiving light, and by adjusting the central photodiode to receive light. The optical axis can be easily adjusted.

A second means for solving the above-mentioned problem is:
An object is irradiated with a slit-shaped laser beam emitted from a laser light source through an irradiation window, the reflected light is received by a two-dimensional optical sensor, and the distance from the light receiving position of the reflected light in the two-dimensional optical sensor to the object is one. A one-dimensional optical sensor provided on each side of the laser irradiation window for receiving external light, and a position of the external light received by the one-dimensional optical sensor, And a means for measuring the irradiation position of the laser range finder (claim 2).

In this means, the slit-shaped laser beam emitted from the opposed laser range finder is received by the laser irradiation window and the one-dimensional light receiving sensors respectively provided on both sides thereof. The length direction of the one-dimensional light receiving sensor is set to a direction intersecting the slit-shaped laser beam, preferably a right angle direction,
If the extension line of the slit-shaped laser beam projected from the laser range finder passes through the center of the one-dimensional light receiving sensor, the slit-shaped laser beam from the opposite laser range finder can receive each one-dimensional light. By adjusting the optical axis so that light is received at the center of the sensor, the optical axes of the two opposing laser distance meters can be matched.

In this means, since a one-dimensional optical sensor is used as a sensor for receiving a laser beam from the facing laser range finder, when the optical axis is shifted, it is determined to which side the optical axis is shifted. Therefore, the adjustment can be easily performed. As the one-dimensional optical sensor, the one described in the first means can be used.

A third means for solving the above-mentioned problem is:
The two laser rangefinders as the first means are opposed to each other, the object to be measured is sandwiched between the two laser rangefinders, and the distance from each laser rangefinder to the object to be measured is measured. A method for adjusting the optical axis of a laser range finder in a device for measuring the size of an object to be measured from a distance, wherein light emitted from one laser range finder is received by the other laser range finder opposite thereto, and the received light is received. The optical axis adjustment method of a laser range finder, wherein the optical axes of the two opposed laser range finder are matched while measuring the irradiation position of the laser range finder (claim 3).

The laser range finder in this apparatus is provided with means for measuring the light receiving position of the laser beam radiated from the opposing laser range finder. Therefore, by adjusting the optical axis while observing the output, The optical axes of the two laser distance meters can be easily matched.

A fourth means for solving the above-mentioned problem is:
The two laser rangefinders as the second means are opposed to each other, the object to be measured is sandwiched between the two laser rangefinders, and the distance from one of the laser rangefinders to the object to be measured is measured. A method for adjusting the optical axis of a laser range finder in an apparatus for measuring the size of an object to be measured from a distance, wherein light emitted from each of the laser range finder is received by the other laser range finder opposite thereto, and each one of the laser range finder is received. An optical axis adjusting method for a laser range finder, wherein the optical axes of the two opposed laser range finder are matched while measuring the irradiation position of the light received by the two-dimensional light receiving sensor. .

The laser range finder in this apparatus is provided with two means for measuring the light receiving position of the laser beam emitted from the opposing laser range finder, so that the optical axis is adjusted while observing the output of the two devices. Thereby, the optical axes of the two laser distance meters can be easily matched.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 shows two opposing 1
1 shows an outline of an apparatus for measuring the thickness of a measurement object having a rectangular cross section using a two-dimensional laser distance meter. In FIG. 1, reference numeral 1 denotes an object to be measured, 10 and 20 denote laser distance meters, 1
Reference numerals 1 and 21 denote laser light emitting elements, 12 and 22 denote half mirrors, 13 and 23 denote distance measuring light receiving elements (first light receiving elements), and 14 and 24 denote optical axis monitoring light receiving elements (second light receiving elements). , S1, and S2 are laser projection elements 11, 2 respectively.
1, laser beams u1 and u2 are reflected from the object to be measured, and t1 and t2 are laser beams S2 and S1 reflected by the half mirrors 12 and 22, respectively.

The laser rangefinders 10 and 20 differ from the conventional laser rangefinders described in FIG. 4 in that half mirrors 12 and 22 and light receiving elements 14 and 24 for monitoring the optical axis are provided.

In the laser range finder 10, at the time of measurement, the linear laser beam S1 projected from the laser light projecting element 11 passes through the half mirror 12, is reflected by the surface of the measuring object 1, and is reflected. The light u1 is received by the light receiving element 14 for distance measurement. The light receiving element 14 for distance measurement is a one-dimensional optical sensor such as a CCD or a PSD, and can detect a position where the reflected light is received.
The method of measuring the distance between the laser range finder 10 and the measuring object 1 by the laser range finder 10 is the same as the conventional laser range finder shown in FIG. The laser range finder 20 also has the same structure as the laser range finder 10. Similarly, the distance between the laser range finder 20 and the measurement target 1 is measured.

A method of aligning the optical axes of the laser rangefinders 10 and 20 will be described below. When there is no measurement object 1, the laser beam S1 from the laser light projecting element 11 is applied to the laser range finder 20, reflected by the half mirror 22, becomes a light beam t2, and enters the optical axis monitoring light receiving element 24. The optical axis monitoring light receiving element 24 is also a one-dimensional optical sensor, and can detect at which position in the length direction light has entered.

The light receiving element 24 for monitoring the optical axis is a CCD
Or a PSD, but a small photodiode may be used as a center, and one or a plurality of elongated photodiodes may be arranged on both sides of the small photodiode. One-dimensional laser rangefinders 10, 2 arranged opposite to each other
If the optical axes of 0 coincide, the light receiving element 23 of the light t2
Is the center, but if the optical axis is off,
The image forming point of the light t2 on the optical axis monitoring light receiving element 24 is shifted from the center, and the electric signal output of the light receiving element 24 also changes. Since the shift amount and the direction of the optical axis can be known from the change amount, the optical axis can be easily corrected.

The same can be said for the laser beam S2 projected from the laser light projecting element 21 and incident on the laser range finder 10. By monitoring the output of the light receiving element 14 for monitoring the optical axis, the optical axis can be easily adjusted. be able to.

In many cases, the laser distance meter 1
The objective is achieved even if only one of the 0 and 20 has a light receiving element for monitoring the optical axis, and the other is a conventional laser range finder, and the optical axis is adjusted using only one laser range finder. can do.

FIG. 2 is a diagram showing an outline of an apparatus for measuring the diameter of a cylindrical object using two opposing two-dimensional laser distance meters. 2, (a) is a side view, (b) is a front view, 2 is a cylindrical object to be measured, 30 and 40 are two-dimensional laser rangefinders, 31 and 41 are light projecting units, 32, 33, and 42. ,
43 is a light receiving element for monitoring the optical axis, S3 is a slit-shaped laser beam projected from the light projecting unit 31, S4 is a slit-shaped laser beam projected from the light projecting unit 41, and u3 and u4 are from the object 2 to be measured. It is a reflected laser beam.

A method for measuring the diameter of the measuring object 2 in this apparatus will be described. The laser beam S3 from the light projecting element 31 of the two-dimensional laser range finder 30 is applied to the measurement target 2 and becomes reflected light u3 from the upper hemisphere.
The reflected light u3 is taken in through a light receiving window of the two-dimensional laser range finder 30, and a two-dimensional light receiving element for distance measurement (not shown).
Image. The two-dimensional light receiving element is composed of a two-dimensional CCD, a two-dimensional PSD, etc., and can two-dimensionally recognize a position of a light imaging point and output the position as an electric signal.
When the distance between the laser distance meter 30 and the object 2 changes, the position of the image point on the two-dimensional light receiving element also changes according to the principle of triangulation (the principle shown in FIG. 4).
The distance between 0 and the upper hemisphere of the object 2 can be measured by the output of the two-dimensional light receiving element.

That is, the two-dimensional laser range finder 30 uses the one-dimensional laser range finder shown in FIG. 4 as a two-dimensional laser range finder shown in FIG. Has the same effect as that of a plurality of units arranged in the direction perpendicular to the plane of the drawing, and can one-dimensionally measure the distance to the surface of the object to be irradiated with the slit-shaped laser beam.

Similarly, the distance between the two-dimensional laser range finder 40 and the measuring object 2 can be measured one-dimensionally. Therefore, if the distance between the two-dimensional laser distance meters 30 and 40 facing each other is measured in advance, each of the two-dimensional laser distance meters 3 can be measured.
By measuring the distance between 0 and 40 and the measuring object 2 one-dimensionally, the dimension of the measuring object 2 can be measured one-dimensionally, and the diameter can be measured from the maximum value.

Also in this apparatus, a measurement error occurs when the optical axes of the two laser distance meters do not match, as in the case of a dimension measuring apparatus using a one-dimensional laser distance meter. In the present embodiment, the two-dimensional laser distance meters 30, 40
In order to align the optical axes of
3, 42, and 43 are provided.

FIG. 3 is a front view of the two-dimensional laser rangefinders 30 and 40. Reference numerals 34 and 44 denote light receiving windows and 35 and 45, respectively.
Is a floodlight window. Optical axis monitoring light receiving elements 32, 33, 4
Reference numerals 2 and 43 denote one-dimensional optical sensors, such as CCDs and PSDs, similar to the optical axis monitoring light receiving element 14 described above. 35, 4
5 is provided so as to be perpendicular to the length direction (length direction of the slit laser beam).

The crossing angle does not necessarily have to be a right angle, and it is only necessary that the longitudinal directions intersect with each other. It is most preferable that the crossing angle be a right angle. The center positions of the optical axis monitoring light receiving elements 32 and 33 are set so as to be on an extension of the slit laser beam from the two-dimensional laser range finder 30, and the optical axis monitoring light receiving elements 42 and 43 are provided.
Is located on an extension of the slit-shaped laser beam from the two-dimensional laser range finder 40.

In the state where there is no measuring object 2 in FIG. 2, the slit slit light S3 emitted from the light projecting element 31 of the two-dimensional laser range finder 30 is projected by the other laser range finder 40 as shown in FIG. The light is irradiated onto the optical axis monitoring light receiving elements 42 and 43 attached to both ends of the window 45. Two two
When the optical axes of the two-dimensional laser rangefinders 30 and 40 coincide, the image forming point of the light S3 on the light receiving elements 42 and 43 is at the center, but when the optical axes are shifted, the light S3 is received. Element 4
The image forming points on the light receiving elements 42 and 43 are shifted from the center.
3 also changes. Since the shift amount and the direction of the optical axis can be known from the change amount, the imaging point of the light S3 on the light receiving elements 42 and 43 is adjusted to the center of the light receiving elements 42 and 43 while monitoring the outputs of the light receiving elements 42 and 43. Thus, the optical axis can be easily corrected.

In FIGS. 2 and 3, the two two-dimensional laser rangefinders 30 and 40 each have a light-receiving element for monitoring the optical axis. The object can be achieved even if a conventional one is used as the other two-dimensional laser distance meter.

[0042]

As described above, according to the present invention,
As one set of two opposing one-dimensional laser rangefinders, the light emitted from the laser rangefinder is received by the other opposite laser rangefinder, and the received light is split by a half mirror to form an image on a light receiving element. , Which are opposed by the output of the light receiving element
Since the displacement and direction of the optical axis of the two laser rangefinders can be checked, the optical axis can be easily adjusted with good workability. Further, when a two-dimensional laser distance meter is used as the distance meter, the slit light emitted from each of the two-dimensional laser distance meters is converted into a slit light by the light receiving elements provided at both ends of the projection window of the other laser distance meter. , And the displacement and direction of the optical axes of the two laser rangefinders facing each other can be confirmed by the output of the light receiving element, so that the optical axis can be easily adjusted with good workability.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of an apparatus for measuring the thickness of a measurement object having a rectangular cross section using two opposed one-dimensional laser distance meters.

FIG. 2 is a diagram showing an outline of an apparatus for measuring the diameter of a cylindrical object using two opposing two-dimensional laser distance meters.

FIG. 3 is a front view of two-dimensional laser rangefinders 30, 40 as an example of an embodiment of the present invention.

FIG. 4 is a diagram illustrating a measurement principle of a conventional laser distance meter.

FIG. 5 is a diagram illustrating the occurrence of an error when the optical axes of two laser rangefinders do not match.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Measurement object 10, 20 ... Laser distance meter 11,21 ... Laser projection element 12,22 ... Half mirror 13,23 ... Distance measuring light receiving element (first light receiving element) 14,24 ... Optical axis monitoring Light receiving element (second light receiving element) 30, 40: two-dimensional laser distance meter 31, 41: light projecting part 32, 33, 42, 43 ... light axis monitoring light receiving element S3, S4: projected slit laser Beams S1, S2: Projected laser beams t1, t2: Laser beams reflected by a half mirror u1, u2: Laser beams reflected from a measurement target u3, u4: Laser beams reflected from a measurement target

Claims (4)

[Claims] An object is irradiated with a linear laser beam emitted from a laser light source, the reflected light is received by a one-dimensional optical sensor, and the distance from the light receiving position of the reflected light in the one-dimensional optical sensor to the object is measured. A laser rangefinder that is provided in front of a laser light source, and a half mirror that transmits part of the laser beam and reflects part of external light emitted from outside, A second one-dimensional optical sensor that receives the extraneous light reflected by the half mirror; and a unit that measures an irradiation position of the extraneous light from a light receiving position of the extraneous light in the second one-dimensional optical sensor. Laser rangefinder characterized by the above-mentioned. 2. An object is irradiated with a slit-like laser beam emitted from a laser light source through an irradiation window, and the reflected light is received by a two-dimensional optical sensor. A laser range finder for measuring the distance to one-dimensionally, a one-dimensional optical sensor provided on each side of the laser irradiation window to receive extraneous light,
Means for measuring an irradiation position of the extraneous light from a light receiving position of the extraneous light in the one-dimensional optical sensor. 3. The two laser rangefinders according to claim 1 are opposed to each other, the object to be measured is sandwiched between the two laser rangefinders, and the distance from each of the laser rangefinders to the object to be measured is measured. A method of adjusting the optical axis of a laser range finder in a device for measuring the dimension of a measurement object from a measured distance, wherein light irradiated from one laser range finder is received by the other laser range finder opposite thereto. And adjusting the optical axes of the two opposed laser distance meters while measuring the irradiation position of the received light. 4. The two laser rangefinders according to claim 2 are opposed to each other, the object to be measured is sandwiched between the two laser rangefinders, and the distance from each of the laser rangefinders to the object to be measured is measured. A method of adjusting the optical axis of a laser range finder in a device for measuring the dimension of a measurement object from a measured distance, wherein light irradiated from one laser range finder is received by the other laser range finder opposite thereto. And adjusting the optical axes of the two opposing laser distance meters while measuring the irradiation position of the light received by each one-dimensional light receiving sensor.