JP2005069975A - Laser distance measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser distance measuring instrument reduced in a size, and easy to be assembled and regulated, wherein a scanning area for scanning a laser beam two-dimensionally and a field angle therefor are optionally selected. <P>SOLUTION: In this laser distance measuring instrument, a photoreception part 20 is arranged on an optical axis faced optically to a light emitting part 10 for projecting the laser beam, the laser beam projected from the light emitting part 10 is reflected one of the mirror faces by a polygon mirror 1 arranged on the optical axis and rotation-driven to be emitted toward an object, and the laser beam reflected by the object is reflected by the mirror face different from the mirror face hereinbefore to be guided to the photoreception part 20. The instrument is provided with a distance computing part 50 for calculating a distance up to the object, based on a projection permission control signal output by a projection control part 11 for controlling the projection of the laser beam from the light emitting part 10 synchronized with rotation of the polygon mirror 1, and based on propagation lag time with respect to a photoreception signal photoreceived by the photoreception part 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laser distance measuring device, and more particularly to a laser distance measuring device that receives a reflected light from an object in the same direction as a laser light irradiation direction and measures a distance.

  Conventionally, a laser distance measuring apparatus using laser light is known. For example, as shown in FIG. 12, this laser distance measuring apparatus has a main scanning motor 2 that rotationally drives a polyhedral mirror (polygon mirror) 1 at a constant speed, and a rotation axis that is orthogonal to the main scanning motor 2. And an optical system including a sub-scanning motor 3 that tilts the rotation axis of the polygon mirror 1 within a predetermined angle range and swings the rotation surface of the polygon mirror 1 at a predetermined speed. .

  The laser pulse light emitted from the laser light source 4 is projected onto the polygon mirror 1 through the half mirror 5. The laser pulse light is emitted from the laser light source 4 according to the rotation of the polygon mirror 1 and the mirror surface of the polygon mirror 1 is oscillated at a predetermined speed by the sub-scanning motor 3 to irradiate a predetermined measurement range. . Then, the reflected light from the object existing within the laser light irradiation range is guided to the condensing lens 6 by the polygon mirror 1, and the light receiving element 7 receives the reflected light condensed by the condensing lens 6.

The laser distance measuring device is basically formed of, for example, a glass window provided in the housing (not shown) of the laser distance measuring device in which the optical system configured as described above is incorporated. The laser beam is irradiated / reflected between the object and the object through the window, and the distance to the object is measured.
Alternatively, the same surface as shown in FIG. 13 is used for the purpose of reducing the so-called noise and improving the detection accuracy, in which the laser light emitted from the laser light source 4 is reflected at the aforementioned window and reaches the light receiving element 7. There is also a laser distance measuring device in which two polygon mirrors 1 and 1 having a configuration are attached to the same rotation axis. The laser pulse light emitted from the laser light source 4 and projected through the light projection lens 8 is reflected by one of the polygon mirrors 1 to irradiate the object, and the reflected light from the object is reflected. The light is reflected by a polygon mirror 1 different from the polygon mirror 1 and led to a light receiving element 7 through a condenser lens 6. Unlike the laser distance measuring apparatus described above, the laser distance measuring apparatus configured as described above reflects the laser light emitted from the laser light source 4 to the window formed by a glass window or the like and reaches the light receiving element 7. Therefore, distance measurement with higher accuracy can be performed.

Incidentally, various laser distance measuring devices based on the above-described operation principle have been proposed (see, for example, Patent Documents 1 to 4).
JP-A-8-122426 JP 9-33655 A Japanese Patent Laid-Open No. 9-15333 Japanese Patent Laid-Open No. 11-326499

  However, it cannot be denied that a part of the laser light emitted from the laser light source 4 is reflected and reaches the light receiving element 7 by, for example, glass provided in the window as described above. For this reason, there has been a problem that the detection accuracy is lowered by the reflected light. Further, in this type of laser distance measuring device, when the diameter of the laser beam emitted from the laser light source 4 is increased, it is necessary to make the diameter of the light receiving lens larger than the diameter of the laser beam.

  On the other hand, in the laser distance measuring device provided with separate polygon mirrors for light projection and light reception, the laser light emitted from the laser light source 4 is reflected by the window portion of the laser distance measuring device and is reflected on the light receiving element 7. Although there is no concern of returning, the shape of the polygon mirror 1 becomes large. For this reason, the swing mechanism that swings the polygon mirror 1 within a predetermined range with respect to the rotation axis and scans the laser light two-dimensionally becomes a large and complicated mechanism, and it is difficult to downsize the laser distance measuring device. There was also a problem.

  In addition, when the laser light emitted from the laser distance measuring device is scanned two-dimensionally, the scanning area is restricted by the scanning mechanism (swinging mechanism) of the polygon mirror 1, so that there is a problem that the scanning area cannot be made large. . Of course, in order to enlarge the scanning area, the polygon mirror 1 may be enlarged, but there is also a problem that the polygon mirror scanning mechanism (swing mechanism) becomes large. Furthermore, since the dimension of the polygon mirror becomes long, there is a concern that the stability of the rotational speed is sacrificed, and the operation mechanism including the motor that operates the polygon mirror becomes a large scale, and the laser distance measuring device. There was also a problem that it took time to assemble and adjust.

  The present invention has been made in consideration of such circumstances, and the object thereof is to arbitrarily select a scan scanning area and an angle of view for scanning laser light two-dimensionally, and to achieve downsizing. An object of the present invention is to provide a laser distance measuring device that can be easily assembled and adjusted.

  In order to achieve the above-described object, a laser distance measuring device according to the present invention includes a light emitting unit that projects laser light, a light receiving unit that is disposed on an optical axis that is optically opposed to the light emitting unit, and a rotating shaft. A plurality of mirror surfaces positioned at a predetermined angle with respect to each other, arranged on the optical axis and driven to rotate, and reflects the laser light projected from the light emitting unit by one of the mirror surfaces. A polygon mirror that irradiates an object and reflects laser light reflected by the object on a mirror surface different from the mirror surface and guides the laser light to the light receiving unit, and rotation of the polygon mirror in a predetermined direction about the optical axis A swing unit that swings the shaft, a projection control unit that controls projection of laser light from the light emitting unit in synchronization with the rotation of the polygon mirror, and a projection permission signal that the projection control unit gives to the light emitting unit; The light receiving unit And wherein the propagation delay time of the received light signal that includes a distance calculator for calculating a distance to the object.

  Preferably, the polygon mirror is composed of a polyhedron having at least a tetrahedron with different mirror surfaces by 90 degrees. Specifically, it is configured as a polygonal polyhedron such as a tetrahedron, an octahedron, or a dodecahedron.

  In the laser distance measuring apparatus described above, a light receiving unit is disposed on an optical axis that is optically opposed to the light emitting unit, and a single mirror of a polygon mirror having a plurality of mirror surfaces disposed in the optical axis. The laser beam projected from the light emitting unit is reflected and applied to the object, and the laser beam reflected by the object is reflected by a mirror surface different from the mirror surface and guided to the light receiving unit. Then, the rotation axis of the polygon mirror is swung by a swinging portion in a predetermined direction with the optical axis as an axis. For this reason, it is possible to arbitrarily select a scan scanning region and an angle of view in which laser light is scanned two-dimensionally.

  In addition, the polygon mirror is a polyhedron having at least a tetrahedron whose mirror surfaces are different by 90 degrees, so that the laser light projected from the light emitting unit is, for example, a window (glass window) provided in a laser distance measuring device. A so-called noise that does not enter the light receiving portion, and can perform a highly accurate distance measurement, and can provide a laser distance measuring device that can be miniaturized and easily assembled and adjusted. it can.

Hereinafter, a laser distance measuring apparatus according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a laser distance measuring apparatus according to the present invention. In this figure, reference numeral 10 denotes a light emitting unit that emits pulsed laser light and irradiates the measurement target with the laser light. The laser light source (light emitting element) 4 that emits the laser light and the light emitting element 4 A projection lens 8 is provided for projecting the emitted laser beam into a beam and projecting the laser beam efficiently onto a measurement object (not shown).

  On the other hand, a light receiving unit 20 is provided on the optical axis that is optically opposed to the laser light emitting unit 10. The light receiving unit 20 includes a light receiving element 7 that receives laser light reflected from an object to be measured, reflected by a mirror surface of a polygon mirror 1 described later, and converts the light into an electric signal. The light receiving unit 20 is provided with a condenser lens 6 that efficiently applies light reflected by the mirror surface of the polygon mirror 1 to the light receiving element 7 and an optical filter 9 that reduces the influence of disturbance light.

  The laser distance measuring apparatus according to the present invention is provided with a polygon mirror 1 having a plurality of mirror surfaces positioned at a predetermined angle with respect to the rotation axis. The polygon mirror 1 is disposed on an optical axis where the light emitting unit 10 and the light receiving unit 20 described above are optically opposed to each other, and is rotated by a main scanning motor 2. Then, the laser light projected from the light emitting unit 10 is reflected by one mirror surface of the polygon mirror 1 to irradiate the object, and the laser light reflected by the object is reflected on a mirror surface different from the mirror surface. The light is reflected and guided to the light receiving unit 20.

  As will be described in detail later, this laser distance measuring device swings the rotational axis of the polygon mirror 1 in a predetermined direction with the optical axis of the laser beam formed by the light emitting unit 10 and the light receiving unit 20 as a central axis. A swinging part is provided (not shown in FIG. 1). The swinging unit plays a role of scanning the laser beam projected from the light emitting unit 10 and irradiated on the object by the polygon mirror 1 in the swinging direction of the swinging unit.

  In addition, the laser distance measuring device is provided with a projection control unit 11 that controls the emission timing of the laser light projected from the light emitting unit 10 in synchronization with the rotation of the polygon mirror 1 that is rotationally driven by the driving unit 40. Yes. On the other hand, the light receiving unit 20 is provided with an amplifying unit 21 that amplifies an electrical signal output from the light receiving element 7 in accordance with the level of the laser light reflected from the object. The laser distance measuring device receives the projection permission signal given to the light emitting unit 10 by the projection control unit 11 and the received light signal received by the light receiving unit 20 and amplified by the amplifying unit 21, and the propagation delay time thereof. A distance calculation unit 50 for calculating the distance from the object to the object is provided.

  The laser distance measuring device according to the present invention is characterized in that a plurality of mirror surfaces are formed in the optical axis formed by the light receiving unit 20 disposed on the optical axis that is optically opposed to the light emitting unit 10. The polygon mirror 1 having the polygon mirror 1 is disposed, and the laser beam projected from the light emitting unit 10 is reflected by one mirror surface of the polygon mirror 1 to irradiate the object, and the laser beam reflected by the object is irradiated with the laser beam. The point is that the light is reflected by a mirror surface different from the mirror surface and led to the light receiving unit 20.

  The laser distance measuring apparatus having such a feature will be described in more detail with reference to the drawings. FIG. 2A is a diagram showing the polygon mirror 1 arranged on the optical axis formed by the light emitting unit 10 and the light receiving unit 20. As shown in this figure, the light receiving unit 20 is disposed on the optical axis that is optically opposed to the light emitting unit 10, and the polygon mirror 1 is disposed in the optical axis. Specifically, the polygon mirror 1 is positioned at a predetermined offset d between the rotation axis (center axis) O of the polygon mirror 1 and the optical axis. The polygon mirror 1 is rotationally driven at a predetermined rotational speed by the main scanning motor 2 controlled by the driving unit 40 as described above.

  Now, assuming that the polygon mirror 1 is formed of a tetrahedron, a line segment formed by the central axis O and one side of the mirror surface of the polygon mirror 1 is formed by the light projecting unit 10 and the light receiving unit 20. The polygon mirror 1 is defined to be at a reference angle [0 °] when it is at a position orthogonal to the optical axis. That is, when the line formed by the optical axis formed by the light emitting unit 10 and the light receiving unit 20 and one side of the mirror surface of the polygon mirror 1 forms an angle of [90 °], the reference angle [0 °] is obtained. It shall be.

  Now, it is assumed that the polygon mirror 1 is rotationally driven by the main scanning motor 2 and the angle (rotation angle) of the one side of the mirror surface is at the position [α °] before reaching the reference angle [0 °]. . At this time, if a laser beam is projected from the light emitting unit 10, the laser beam is incident on one mirror surface of the polygon mirror 1 at an incident angle [α °], and the target is incident at the incident angle [α °]. The object is irradiated. Then, the laser light reflected from the object reaches another mirror surface of the polygon mirror 1. At this time, the reflected laser light incident on the mirror surface is incident on the mirror surface at an angle of [90 ° -α °], and is reflected on the mirror surface at an angle of [90 ° -α °] to the light receiving unit 20. Led.

  Alternatively, as shown in FIG. 2B, the polygon mirror 1 is rotationally driven, and the angle of one side of the mirror surface is an angle (rotation angle) [−β °] beyond the reference angle [0 °]. Assume that a laser beam is projected from the light emitting unit 10. The laser light is incident on one mirror surface of the polygon mirror 1 at an incident angle [90 ° −β °] and is irradiated on the object at an incident angle [90 ° −β °].

Then, the laser light reflected by the object reaches another mirror surface of the polygon mirror 1. The reflected laser light incident on the mirror surface is incident on the mirror surface at an angle of [β °] and is reflected by the mirror surface at an angle of [β °] and guided to the light receiving unit 20.
That is, by controlling the pulsed laser light projected from the light emitting unit 10 according to the rotation of the polygon mirror 1, it is possible to irradiate the object at the position equal to the rotation angle of the polygon mirror 1 with the laser light. . Then, the distance to the object is measured by projecting pulsed laser light from the light emitting unit 10 at a predetermined timing according to the rotation angle of the polygon mirror 1 rotated by the driving unit 40 and the main scanning motor 2. can do.

  Incidentally, the dimensions of the polygon mirror 1 may be determined so as to obtain a necessary scanning angle (rotation angle) according to the object to be measured. That is, it is only necessary to determine the dimensions of the mirror so that a part of the laser light (laser beam) projected from the light emitting unit 10 is irradiated to the measurement object without being lost and the reflected laser light from the measurement object can be received. . For example, each laser beam diameter of the light emitting unit 10 and the light receiving unit 20 is set to 35 mm, and the range in which the measurement target is irradiated with the laser beam by the reflection of the polygon mirror 1 is set to the reference rotation angle [0 °] of the polygon mirror 1 described above. When the rotation angle before and after that is within a range of [± 30 °] as a reference, the length of one side of the polygon mirror 1 is [35 / sin30 ° = 70 mm]. Therefore, the mirror dimensions of the polygon mirror 1 may be set to a height [35 mm] and a width [70 mm].

  The polygon mirror 1 described above is a tetrahedron for ease of understanding. For example, as shown in FIG. 3, an octahedron having different mirror surfaces by 45 degrees as shown in FIG. A 4n-hedron (where n ≧ 4) may be used. The point is that the polygon mirror 1 is provided in the optical axis formed by the light emitting unit 10 and the light receiving unit 20, and the laser light projected from the light emitting unit 10 is reflected by one of the mirror surfaces of the polygon mirror 1 to be the object. The laser beam irradiated to the object and reflected by the object is reflected by a mirror surface different from the mirror surface and guided to the light receiving unit 20, and the incident angle of the laser beam incident on the pair of mirror surfaces from the light emitting unit 10 is What is necessary is just to comprise so that the sum with the output angle radiate | emitted to the light-receiving part 20 may be set to 90 degrees.

  In addition, since the rotation axis of the polygon mirror 1 is oscillated (sub-scanned) in a predetermined direction around the optical axis of the laser beam by a oscillating unit described later, the laser beam is two-dimensionally It can be scanned to measure the distance to a two-dimensionally arranged object. Basically, the oscillation angle (sub-scanning angle) can be arbitrarily set in the laser distance measuring apparatus of the present invention. That is, it is possible to perform sub-scanning over the entire circumferential direction (360 °).

  In this way, the polygon mirror 1 having a plurality of mirror surfaces is arranged in the optical axis with the light receiving unit 20 arranged on the optical axis that is optically opposed to the light emitting unit 10, and one mirror surface of the polygon mirror 1 is arranged. Since the laser beam projected from the light emitting unit 10 is reflected and irradiated to the object, the laser beam reflected by the object is reflected by a mirror surface different from the mirror surface and guided to the light receiving unit 20. The laser light projected by the light emitting unit 10 is reflected by a window (for example, a glass window) provided in a housing (not shown) of the laser distance measuring device and does not give noise to the light receiving unit 20, so that it has high accuracy. Distance measurement is possible.

  Further, the measurement is performed based on the pulse period (timing) of the laser light projected by the light emitting unit 10, the rotational speed of the main scanning of the polygon mirror 1, and the sub-scanning swing speed (rotational speed) of swinging the polygon mirror. It is possible to arbitrarily set the area and its resolution. That is, the measurement target range includes the pulse period (timing) of the laser light projected by the light emitting unit 10, the rotational speed at which the polygon mirror 1 is main-scanned, and the sub-scanning swing speed (rotational speed) at which the polygon mirror is swung. Can be arbitrarily determined in mesh form. For example, assuming that the pulse period of the laser light projected from the light emitting unit 10 is constant, the rotational speed of the main scanning motor 2 and the swing speed (rotational speed) of the sub-scanning motor 3 are used for coarse mesh measurement. ) May be increased, and conversely, when fine mesh measurement is performed, the rotational speed of the main scanning motor 2 and the swing speed (rotational speed) of the sub-scanning motor 3 may be decreased. As described above, the laser distance measuring device according to the present invention can perform measurement according to the required resolution.

  Now, a specific configuration of the oscillating unit 30 of the laser distance measuring device according to the present invention described above will be described in more detail with reference to FIG. In this figure, the same members as those of the laser distance measuring apparatus shown in FIG. 1 are denoted by the same reference numerals as those in FIG. Incidentally, this figure shows the oscillating part 30, and only the light emitting part 10, the polygon mirror 1 and the oscillating part 30 are depicted, and other components are omitted.

  The polygon mirror 1 is held by a U-shaped holding tool 31 so as to be rotatable. A wall surface 33 is provided on one side surface of the opening 32 of the gripping tool 31, and a through-hole 34 for applying a laser beam projected from the light emitting unit 10 to the polygon mirror 1 held by the gripping tool 31 is provided. Is provided. The through hole 34 is provided in the wall surface portion 33 as a hole substantially larger than the beam diameter of the laser light projected from the light emitting unit 10.

  The gripper 31 is attached to a swing mechanism 35 that swings the polygon mirror 1 at a predetermined angle with the optical axis of the laser light passing through the through hole 34 as the central axis. The swing mechanism 35 includes a sub-scanning motor 3, a reduction gear 36 that decelerates the rotation of the sub-scanning motor 3, and an encoder 37 that detects a rotation angle of the sub-scanning motor 3 and outputs a pulse signal, for example. Configured. In response to the output signal of the encoder 37 that changes with the rotation of the sub-scanning motor 3, the sub-scanning motor 3 is controlled and decelerated by, for example, a gear provided in the swing mechanism 35, so that the gripper 31 is moved to a predetermined position. Is reciprocally swung in the angular range.

  Specifically, the swing mechanism 35 includes, for example, a crank 38a, a connecting rod 38b, and an output shaft 3a of a reduction gear 36 that reduces the rotation speed of the sub-scanning motor 3 as shown in FIG. A link mechanism 38 comprising: As the sub-scanning motor 3 rotates, the crank 38a rotates and the connecting rod 38b attached to the crank 38a reciprocates. Then, the gripping tool 31 attached to the other end of the connecting rod 38b reciprocally swings within a predetermined angle range with the optical axis of the laser light as the central axis.

  Alternatively, the swing mechanism 35 has, for example, a pinion gear 39a attached to the output shaft 3a of the reduction gear 36 that decelerates and outputs the rotation speed of the sub-scanning motor 3 and one end as shown in FIG. You may comprise using the rack gear 39b attached to the holding | grip tool 31 and reciprocatingly driven by this pinion gear. In this case, the rack gear 39b is driven to reciprocate via the pinion gear 39a by rotating the sub-scanning motor 3 back and forth within a predetermined range. Then, the gripper 31 reciprocally swings within a predetermined angle range with the optical axis of the laser light as the central axis.

Although the details will be described later, the above-described rocking mechanism 35 is not limited to a predetermined angle range, and grips with the optical axis of the laser beam formed by the light emitting unit 10 and the light receiving unit 20 as the central axis. The tool 31 may be configured to rotate 360 °.
The laser distance measuring device according to the present invention configured as described above reflects the laser beam projected from the light emitting unit 10 by one mirror surface of the polygon mirror 1 to irradiate the object, and is reflected by the object. Since the reflected laser beam is reflected by a mirror surface different from the mirror surface and guided to the light receiving unit 20, the laser beam projected by the light emitting unit 10 is provided with a window (not shown) provided in a not-shown casing of the laser distance measuring device. It is possible to measure the distance with high accuracy without reflection.

  For example, as shown in FIG. 7, the swinging mechanism 35 includes a sub-scanning motor 3, a reduction gear 36 and an encoder 37 each having a hollow through hole in the direction of the rotation axis. It is good also as a structure attached to the through-hole 34 provided in the wall surface part 33. FIG. In this case, the laser light projected from the light emitting unit 10 through the respective through holes reaches the mirror surface of the polygon mirror 1 attached to the gripping tool 31, and reaches the target from the opening of the gripping tool 31. Irradiation with laser light is possible. With this configuration, the gripper 31 can be rotated 360 ° around the optical axis of the laser light formed by the light emitting unit 10 and the light receiving unit 20.

  That is, the gripper 31 can be rotated 360 ° about the optical axis of the laser beam formed by the light emitting unit 10 and the light receiving unit 20. For this reason, as will be described later, if the optical axis of the laser beam is arranged so as to be perpendicular to the object (for example, the ground), the measurement object is measured over the entire circumference of [360 °] around the circumference where the laser distance measuring device is arranged. It becomes possible to measure the distance. Even in this case, the laser beam projected from the light emitting unit 10 is reflected by one mirror surface of the polygon mirror 1 to irradiate the object, and the laser beam reflected by the object is reflected on the mirror surface. Since the light is reflected by different mirror surfaces and guided to the light receiving unit 20, the laser light projected by the light emitting unit 10 is not reflected by the window provided in the housing of the laser distance measuring device, and the distance measurement is performed with high accuracy. Is possible.

Next, another configuration example of the oscillating unit 30 of the laser distance measuring device according to the present invention will be described in detail with reference to FIG. In this figure, the same members as those in the laser distance measuring apparatus in FIG. 1 are denoted by the same reference numerals as those in FIG.
The laser distance measuring device shown in this figure is configured such that the light emitting unit 10 and the light receiving unit 20 are brought close to each other so that the length in the optical axis direction is shortened. This laser distance measuring device is provided with reflecting mirrors 5 a and 5 b that reflect the laser light projected from the light emitting unit 10 and give it to the polygon mirror 1. Incidentally, the reflecting mirrors 5a and 5b are fixed by a fixing jig (not shown) so as not to swing even when the polygon mirror 1 is swung by a swinging mechanism 35 described later. As described above, the light receiving unit 20 is disposed on the optical axis that is optically opposed to the light emitting unit 10, and the polygon mirror 1 is disposed in the optical axis.

  The polygon mirror 1 is gripped by a U-shaped gripping tool 31 and irradiates a target with laser light projected from the light emitting unit 10 through an opening 32 of the gripping tool 31. In addition, a wall surface portion 33 is provided on one side surface of the opening 32 of the gripper 31, and a rocking portion 30 that rocks the wall surface portion 33 about the optical axis from the polygon mirror 1 to the light receiving portion 20 is an axis. It is attached. The swinging unit 30 includes a sub-scanning motor 3, a reduction gear 36 that decelerates the rotation of the sub-scanning motor 3, and an encoder 37 that detects the rotation angle of the sub-scanning motor 3. The gripping tool 30 is reciprocally swung within the range.

  Even in the laser distance measuring apparatus configured as described above, the laser beam projected from the light emitting unit 10 is reflected by one mirror surface of the polygon mirror 1 to irradiate the object, and is reflected by the object. Since the laser beam is reflected by the mirror surface different from the mirror surface and guided to the light receiving unit 20, the laser beam projected by the light emitting unit 10 is not reflected by the window unit of the laser distance measuring device, and the distance is high accuracy. Measurement is possible.

  Now, the laser pulse light irradiated onto the object by the laser distance measuring apparatus configured as described above will be described with reference to FIG. In the laser distance measuring device shown in this figure, the optical axis formed by the light emitting unit 10 and the light receiving unit 20 (respectively omitted in FIG. 9) is positioned so as to be parallel to the surface of the measurement target site such as the ground surface. It is a thing. Then, by controlling the irradiation timing of the pulsed laser projected from the light emitting unit 10 in accordance with the rotation of the main scanning motor 2, laser pulses are equally spaced (constant pitch) with respect to the scanning direction (x-axis direction). Light is irradiated. Incidentally, at the point away from the position of the x-axis reference angle [0 °] where the optical axis and the ground surface hang down in the x-axis direction, although strictly speaking, the laser pulse interval becomes narrower, the laser distance measuring device and If the distance from the point of the x-axis reference angle [0 °] is large, it can be ignored.

  The sub-scanning motor 3 irradiates the laser pulse light in the y-axis direction by swinging the polygon mirror 1 within a predetermined angle range with the optical axis formed by the light emitting unit 10 and the light receiving unit 20 as the central axis. (Lateral scan) Incidentally, if the swing speed of the polygon mirror 1 swung by the sub-scanning motor 3 changes, for example, in a sine wave shape, the swing speed is fast near the y-axis reference angle [0 °], so that the y-axis direction However, the pitch in the y-axis direction becomes narrower at the end of the swing because the swing speed becomes slower.

  Alternatively, as shown in FIG. 10, the optical axis formed by the light emitting unit 10 and the light receiving unit 20 (respectively omitted in FIG. 10) is positioned so as to be suspended with respect to the surface of the measurement target site such as the ground surface. May be. In this case, by controlling the projection timing of the pulsed laser light projected from the light emitting unit 10 in accordance with the rotation of the main scanning motor 2, the scanning direction (x-axis direction) is equally spaced (constant pitch). Laser pulse light is irradiated. Then, the sub-scanning motor 3 irradiates the laser pulse light in the y-axis direction (vertical scanning) by swinging the polygon mirror 1 within a predetermined angle range with the optical axis as the central axis. Incidentally, if the swing speed of the polygon mirror 1 swung by the sub-scanning motor 3 changes, for example, in a sine wave shape, the swing speed is fast near the y-axis reference angle [0 °], so that the y-axis direction However, the pitch in the y-axis direction becomes narrower at the end of the swing because the swing speed becomes slower. This is the same as the laser distance measuring device that performs the lateral scan described above.

In this way, it is possible to measure a two-dimensional region by irradiating the object with a pulsed laser from the light emitting unit 10 in accordance with the rotation of the polygon mirror 1 driven by the main scanning motor 2.
Further, in the laser distance measuring device according to the present invention, as shown in FIG. 11, the optical axis formed by the light emitting section 10 and the light receiving section 20 (respectively omitted in FIG. 11) is on the surface of the measurement target part (for example, the ground surface). When positioned so as to be suspended, the object can be irradiated with a pulsed laser over the entire area of [360 °] around the optical axis formed by the light emitting unit 10 and the light receiving unit 20. In other words, the light emitting unit 10 projects a pulsed laser beam in accordance with the rotation of the main scanning motor 2 so that the laser beam is irradiated in the radial direction around the intersection between the optical axis and the measurement surface, while the sub-scanning is performed. Since the polygon mirror 1 is rotationally driven by the motor 3, it becomes possible to irradiate pulsed laser light concentrically around the intersection of the optical axis and the measurement surface. Accordingly, distance measurement over a wide range is possible, which is extremely effective in practice.

1 is a perspective view showing a schematic configuration of a laser distance measuring device according to an embodiment of the present invention. The figure which shows the relationship between the rotation angle of the polygon mirror of the laser distance measuring device which concerns on one Embodiment of this invention, and the incident angle and the emission angle of a laser beam. The figure which shows the shape of the polygon mirror of the laser distance measuring apparatus which concerns on another embodiment of this invention. The perspective view which shows an example of the rocking | fluctuation mechanism of the laser distance measuring apparatus shown in FIG. The perspective view which shows an example of another rocking | fluctuation mechanism of the laser distance measuring apparatus shown in FIG. The perspective view which shows an example of the rocking | fluctuation mechanism of the laser distance measuring apparatus shown in FIG. The perspective view which shows an example of the rocking | fluctuation mechanism of the laser distance measuring apparatus shown in FIG. The perspective view which shows schematic structure of the laser distance measuring apparatus which concerns on another embodiment of this invention. The figure which shows the laser scanning method of the laser distance measuring apparatus which concerns on one Embodiment of this invention. The figure which shows another laser scanning method of the laser distance measuring apparatus which concerns on one Embodiment of this invention. The figure which shows another laser scanning method of the laser distance measuring apparatus which concerns on one Embodiment of this invention. The perspective view which shows the principle of the conventional laser distance measuring apparatus. The perspective view which shows the principle of the conventional laser distance measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polygon mirror 2 Main scanning motor 3 Sub scanning motor 4 Laser light source (light emitting element)
5a, 5b Reflector 6 Condensing lens 7 Light receiving element 8 Projecting lens 9 Optical filter 10 Light emitting unit 11 Projection control unit 20 Light receiving unit 21 Amplifying unit 30 Oscillating unit 31 Gripping tool 32 Opening 33 Wall surface unit 35 Oscillating mechanism 36 Reduction gear 37 Encoder 40 Drive unit 50 Distance calculation unit

Claims (2)

A light emitting unit for projecting laser light;
A light receiving portion disposed on an optical axis that is optically opposed to the light emitting portion;
A plurality of mirror surfaces positioned at a predetermined angle with respect to the rotation axis, arranged on the optical axis and driven to rotate, and the laser beam projected from the light emitting unit is one of the mirror surfaces. A polygon mirror that reflects and irradiates the object, reflects the laser light reflected by the object on a mirror surface different from the mirror surface, and guides the laser light to the light receiving unit;
A swinging section that swings the rotation axis of the polygon mirror in a predetermined direction about the optical axis;
A projection control unit that controls the projection of the laser light from the light emitting unit in synchronization with the rotation of the polygon mirror;
A laser distance characterized in that the projection control unit comprises a distance calculation unit for calculating a distance to the object from a propagation delay time between a projection permission signal given to the light emitting unit and a light receiving signal received by the light receiving unit. measuring device.   2. The laser distance measuring device according to claim 1, wherein the polygon mirror is formed of a polyhedron having at least a tetrahedron having different mirror surfaces by 90 degrees.

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