JP2011047682A - Laser range finder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily miniaturized laser range finder capable of searching a range-finding target efficiently, by rapidly displacing the direction of the irradiation axis of laser beams, when losing the range-finding target. <P>SOLUTION: The laser range finder acquires distance information to a range-finding target, based on the time when receiving the reflected light of pulse laser beams irradiated on the range-finding target. The laser range finder includes a laser resonator for generating pulse laser beams that uses a Q-switch 2; Q-switches 5, 6 for refracting an advance direction of pulse laser beams generated by the laser resonator in a prescribed direction; a Q-switch driver 7 for generating pulsed laser beams, by pulsatingly applying high-frequency power to the Q-switch 2 and controlling on/off of each of the Q-switches 5, 6; and a control section 11 for controlling the advance direction of pulse laser beams emitted from the laser resonator for each pulse, by controlling the Q-switch driver 7 to synchronize the Q-switch 2 to each of the Q-switches 5, 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laser distance measuring apparatus that measures a distance value to a distance measuring object using pulsed laser light.

  Conventionally, a distance measuring object is irradiated from a predetermined position by irradiating the object to be measured with a pulse laser beam for measurement generated from a light source such as a semiconductor laser and detecting the pulse laser light reflected by the object to be measured. A laser range finder that measures the distance to the position is used.

  A conventional laser distance measuring device scans with a pulsed laser beam for measurement over a wide range and efficiently captures a distance measuring object, for example, a reflection mirror for reflecting the pulsed laser light to the distance measuring object side. Etc. In this case, the laser distance measuring device uses a plurality of motors and drive mechanisms that are driven in two orthogonal directions to drive the reflecting mirror and the like, and drives the plurality of motors by a predetermined amount to perform reflection. The object to be measured can be captured by controlling the light reflection direction of the mirror to be gradually shifted.

  In addition, a wedge plate is used as an operation in the irradiation direction of the pulse laser beam. The wedge plate is a thin prism lens having a small apex angle (wedge angle), and the laser beam can be bent at an angle corresponding to the wedge angle by entering the laser beam perpendicularly to the wedge plate. The conventional laser distance measuring device can control the irradiation direction of the pulse laser by operating the rotation angle of the wedge plate by providing a wedge plate that can be rotated by a motor or the like on the optical path of the pulse laser beam for measurement. It is possible to capture the distance measuring object efficiently.

  Patent Document 1 describes a distance measuring device that uses a single light source and a single projection optical system and that can measure a distance by linearly scanning an object to be measured. This distance measuring device includes a light projecting optical system that projects light from a light source onto an object, and a light receiving optical system that reflects the incident light from the object and enters the light into each optical system. It has a deflecting means.

  The projection light deflecting means provided in the light projecting optical system has two optical wedges having the same wedge angle that deflects light from the light source and rotates at the same angular velocity in opposite directions, and emits light to be projected. The angle is repeatedly changed on a straight line. On the other hand, the incident light deflecting means provided in the light receiving optical system has two optical wedges having the same wedge angle that deflect incident light and rotate at the same angular velocity in opposite directions, and the incident light is incident. The incoming angle is repeatedly changed on a straight line.

  According to this distance measuring device, two optical wedges having the same shape provided in the light projecting optical system or the light receiving optical system rotate at the same rotational speed opposite to each other, so that a plurality of laser diodes and optical systems are used. Therefore, continuous scanning is possible over a wide range, and the apparatus can be configured at low cost without using a special light emitting element or the like. Furthermore, since the projection light deflecting means and the incident light deflecting means are synchronized, the reflected light from the object can be measured within a wide range with less disturbance light.

  Patent Document 2 describes an infrared guidance device and a flying object guidance method that are small, light, and highly reliable. The infrared guiding device includes a detection unit including a condensing optical system that collects incident infrared rays and a detector that converts the collected infrared rays into an electrical signal, and is generated based on at least an electrical signal from the detection unit. This is a device for guiding a flying object to a target with reference to an image. The detection unit includes one or more wedge prisms whose one surface is inclined at a predetermined angle with respect to the other surface, and a rotation mechanism that rotates the wedge prism in a plane substantially perpendicular to the optical axis of the detector. The infrared rays radiated from the target are refracted by one or more wedge prisms and made incident on the condensing optical system.

  According to the infrared guiding device described in Patent Document 2, a wedge prism is disposed in front of the condensing optical system, and the wedge prism is rotated in a plane substantially perpendicular to the optical axis of the detector by a rotation mechanism. Therefore, the size of the drive part itself can be reduced. Further, the rotation mechanism that rotates about one axis can simplify the structure and drives the entire housing on which the detector and the condensing optical system are mounted in order to rotate only the wedge prism. Driving means having a smaller torque than that of the gimbal system can be used, which contributes to the weight reduction of the entire apparatus.

JP-A-7-218633 JP 2006-162206 A

  However, if the object to be measured is lost during laser ranging, the method of searching for the object by changing the irradiation direction of the laser beam by adjusting the angle of the reflecting mirror or rotating the wedge plate is used to change the irradiation direction. Since the speed depends on the angle adjustment speed of the reflecting mirror and the rotational speed of the wedge plate, there is a problem that the efficiency is poor. The mechanically rotated wedge plate is about several hundred Hz at the highest speed. On the other hand, since the pulse repetition frequency of the laser light is, for example, several tens of kHz, it is about two orders of magnitude higher than the rotational frequency of the wedge plate. Therefore, since the laser beam is irradiated many times while the wedge plate is hardly moving (in substantially the same direction), the conventional laser distance measuring device is wasted when searching for the object to be lost. Many are considered inefficient.

  In addition, since the conventional laser distance measuring device needs to be provided with a rotating mechanism such as a wedge plate and a motor that rotates the wedge plate, there is also a problem that the size of the device increases.

  The present invention solves the above-mentioned problems of the prior art, and is easy to downsize, and when the object to be measured is lost, the irradiation axis direction of the laser beam is quickly displaced to efficiently measure the distance. It is an object of the present invention to provide a laser distance measuring device capable of searching for an object.

  In order to solve the above-described problem, the laser distance measuring device according to the present invention acquires distance information to the distance measuring object based on the time when the reflected light of the pulse laser beam irradiated on the distance measuring object is received. A laser range finder, wherein a laser resonator generates pulsed laser light using a first Q switch, and one or more first refracting directions of the pulsed laser light generated by the laser resonator in a predetermined direction. A Q switch driver that applies a high frequency power to the first Q switch in a pulsed manner to generate a pulsed laser beam, and controls on / off of each of the one or more second Q switches; A pulse emitted from the laser resonator is controlled by controlling the Q switch driver so that the first Q switch and each of the one or more second Q switches are synchronized. Characterized in that it comprises a control unit for controlling the traveling direction of the laser beam for each pulse.

  According to the present invention, it is easy to reduce the size, and when the object to be measured is lost, the irradiation axis direction of the laser beam can be quickly displaced, and the object to be measured can be searched efficiently.

It is a figure which shows the structure of the laser ranging apparatus of the form of Example 1 of this invention. It is a figure explaining the optical axis adjustment by Q switch of the laser ranging apparatus of the form of Example 1 of this invention. It is a figure which shows the operation | movement which searches the ranging object by the laser ranging apparatus of the form of Example 1 of this invention. It is a figure which shows another structural example of the laser distance measuring device of the form of Example 1 of this invention. It is a figure which shows another structural example of the laser distance measuring device of the form of Example 1 of this invention. It is a figure which shows the operation | movement which searches the ranging object by another structural example of the laser ranging apparatus of the form of Example 1 of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a laser distance measuring apparatus according to a first embodiment of the present invention. The configuration of the laser distance measuring device will be described with reference to FIG. As shown in FIG. 1, the laser distance measuring device of the present embodiment is composed of mirrors 1 and 4, Q switch 2, laser solvent 3, Q switches 5 and 6, Q switch driver 7, and control unit 11. The distance information to the distance measuring object is acquired based on the time when the reflected light of the pulse laser beam irradiated to the distance object is received.

  However, the laser distance measuring device shown in FIG. 1 shows the structure of a light projecting optical system that irradiates a distance measuring object with pulsed laser light, and is a device of a light receiving optical system that receives reflected light. The description is omitted. This is because the devices constituting the light receiving optical system do not necessarily have to be configured integrally with the devices constituting the light projecting optical system, and can be installed at remote locations. Here, as shown in FIG. 1, the part which comprises especially the light projection optical system of the laser distance measuring device of this invention is demonstrated.

  The mirrors 1 and 4, the Q switch 2, and the laser solvent 3 correspond to the laser resonator of the present invention, and generate pulsed laser light using the Q switch 2. The mirror 1 and the mirror 4 are arranged to face each other and resonate the laser beam. The Q switch 2 corresponds to the first Q switch of the present invention, and is for obtaining a pulse laser beam having a narrow pulse width and a large peak power. The laser solvent 3 is provided on the laser optical axis in the laser resonator.

  The Q switches 5 and 6 correspond to the second Q switch of the present invention, and refract the traveling direction of the pulsed laser light generated by the laser resonator in a predetermined direction. In this embodiment, the laser distance measuring apparatus includes two Q switches 5 and 6 as the second Q switch, but the number is not necessarily limited to two. That is, any number of the second Q switches in the present invention may be provided as long as it is one or more.

  The Q switches 5 and 6 can be configured using, for example, an AO (Acoustic Optic) Q switch. The AOQ switch is capable of generating a pulsed elastic wave by inputting a microwave pulse into a material having an acoustooptic effect, and instantaneously changing the direction of laser light.

  The Q switch driver 7 applies high frequency power in a pulsed manner to the first Q switch (Q switch 2) to generate a pulsed laser beam, and each of the one or more second Q switches (Q switches 5 and 6). Control on / off.

  The control unit 11 emits from the laser resonator by controlling the Q switch driver 7 so that the first Q switch (Q switch 2) and each of the one or more second Q switches (Q switches 5 and 6) are synchronized. The traveling direction of the pulsed laser beam is controlled for each pulse.

  Specifically, the control unit 11 sets on / off combinations for each of one or more second Q switches (Q switches 5 and 6) for each pulse in accordance with the emission timing of the pulse laser beam from the laser resonator. The Q switch driver 7 is controlled so as to cover all ON / OFF combinations for each of the one or more second Q switches (Q switches 5 and 6).

  The control unit 11 does not necessarily have to change the combination of on / off for each of the Q switches 5 and 6 for each pulse. For example, the control unit 11 changes the combination for every 5 pulses or every 10 pulses. Also good. However, the control unit 11 can search for the distance measuring object most rapidly by changing the combination of ON / OFF for each of the Q switches 5 and 6 for each pulse.

  Next, the operation of the present embodiment configured as described above will be described. First, the laser distance measuring device needs to search for a distance measuring object. Alternatively, when the laser distance measuring device loses sight of the captured distance measuring object, it is necessary to search for the distance measuring object.

  In such a case, the control unit 11 generates and outputs a control signal for controlling the Q switch driver 7 so that the Q switch 2 and each of the Q switches 5 and 6 are synchronized. The Q switch driver 7 applies high frequency power in a pulsed manner to the Q switch 2 based on the control signal generated by the control unit 11 to generate a pulsed laser beam, and each of the Q switches 5 and 6 Control on / off.

  FIG. 2 is a diagram for explaining the optical axis adjustment by the Q switches 5 and 6 of the laser distance measuring device of the present embodiment. The laser distance measuring apparatus of the present embodiment can change the irradiation direction of the pulsed laser light with respect to the biaxial direction of the azimuth direction and the elevation direction by using two Q switches.

  In this embodiment, the Q switch 5 is turned on / off according to the control of the Q switch driver 7, and the traveling direction of the pulsed laser light generated by the laser resonator is the left-right direction (azimuth direction) as shown in FIG. To refract.

  On the other hand, the Q switch 6 is turned on / off according to the control of the Q switch driver 7, and the traveling direction of the pulse laser beam generated by the laser resonator is refracted in the vertical direction (elevation direction) as shown in FIG. Let

  In addition, since the strict angle adjustment of the pulse laser beam traveling direction cannot be performed by the Q switches 5 and 6, the Q switch 5 can select two directions (left or right) according to the on / off control. The Q switch 6 can only select two directions (up or down) according to the on / off control.

  That is, the laser distance measuring device of the present embodiment includes the Q switches 5 and 6, so that one of 2 × 2 = 4 directions can be selected for the traveling direction of the pulsed laser light. Since the Q switch driver 7 is controlled so as to cover all combinations of ON / OFF for each of the Q switches 5 and 6, it is possible to search for a ranging object in all four directions.

  FIG. 3 is a diagram showing an operation of searching for the distance measuring object 9 by the laser distance measuring apparatus of the present embodiment. Here, it is assumed that the Q switch 5 bends the traveling direction of the pulsed laser light to the left when turned on, and bends the traveling direction of the pulsed laser light to the right when turned off. Further, it is assumed that the Q switch 6 bends the traveling direction of the pulse laser light upward when turned on and bends the traveling direction of the pulse laser light downward when turned off.

  The control unit 11 controls the Q switch driver 7 so that the Q switch 2 and each of the Q switches 5 and 6 are synchronized, and the traveling direction of the first pulse laser beam emitted from the laser resonator is the upper left direction. The Q switch 5 is controlled to be turned on via the Q switch driver 7 and the Q switch 6 is controlled to be turned on. As a result, as shown in FIG. 3, the pulsed laser light emitted from the Q switch 6 travels in the upper left direction (laser light 8a). In this case, since the distance measuring object 9 does not exist at the destination of the laser beam 8a, the reflected light does not return in the light receiving optical system.

  Next, the control unit 11 controls the Q switch 5 to be turned off via the Q switch driver 7 so that the traveling direction of the second pulse laser beam emitted from the laser resonator is in the upper right direction. Switch 6 is turned on. As a result, as shown in FIG. 3, the pulsed laser light emitted from the Q switch 6 travels in the upper right direction (laser light 8b). In this case, since the distance measuring object 9 does not exist at the travel destination of the laser light 8b, the reflected light does not return in the light receiving optical system.

  Similarly, the control unit 11 controls the Q switch 5 to be turned on via the Q switch driver 7 so that the traveling direction of the third pulse laser beam emitted from the laser resonator is the lower left direction. Switch 6 is turned off. As a result, as shown in FIG. 3, the pulsed laser light emitted from the Q switch 6 travels in the lower left direction (laser light 8c). In this case, since the distance measuring object 9 exists at the destination of the laser beam 8c, the reflected light returns in the light receiving optical system.

  Finally, the control unit 11 controls the Q switch 5 to be turned off via the Q switch driver 7 so that the traveling direction of the fourth pulse laser beam emitted from the laser resonator is the lower right direction. The Q switch 6 is controlled to be turned off. As a result, as shown in FIG. 3, the pulsed laser light emitted from the Q switch 6 travels in the lower right direction (laser light 8d). In this case, since the distance measuring object 9 does not exist in the travel destination of the laser light 8d, the reflected light does not return in the light receiving optical system.

  In this way, the control unit 11 changes the on / off combination for each of the Q switches 5 and 6 for each pulse in accordance with the emission timing of the pulsed laser light by the laser resonator, so that the Q switch with four pulses. All combinations of ON / OFF for each of 5 and 6 can be covered, and the laser distance measuring device can search the distance measuring object 9 in all four directions.

  By performing the above operation, the laser distance measuring device of the present embodiment can quickly search for a distance measuring object. However, by further including a light receiving optical system, the search result is displayed by the Q switches 5 and 6. It can also be reflected in the control.

  FIG. 4 is a diagram illustrating another configuration example of the laser distance measuring apparatus according to the present embodiment. A difference from the configuration of the laser distance measuring device shown in FIG. 1 is that a light receiving unit 10 is further provided.

  The light receiving unit 10 receives reflected light from the distance measuring object, determines that there is reflected light when the received light intensity exceeds a threshold value, and outputs the determination result to the control unit 11.

  The control unit 11 detects the distance measurement object based on the light reception timing of the reflected light by the light receiving unit 10 and the on / off combination for each of the one or more second Q switches (Q switches 5 and 6) immediately before the light reception timing. Specify the direction.

  Specifically, as described with reference to FIG. 3, when the reflected light returns from the distance measuring object 9 with respect to the laser light 8 c of the third pulse, the control unit 11 determines the light reception timing by the light receiving unit 10. Since it is immediately after emission of the laser beam 8c in the lower left direction (Q switch 5 is turned on and Q switch 6 is turned off), it can be specified that the distance measuring object 9 is in the lower left direction.

  After that, when it is necessary for the control unit 11 to continuously capture the distance measuring object 9, the Q switch 5 is connected via the Q switch driver 7 so that the pulse laser beam is continuously emitted in the lower left direction. And the Q switch 6 can be controlled to be turned off. If the distance measuring object 9 is lost, the control unit 11 stops fixing the traveling direction of the laser light in the lower left direction and changes the traveling direction for each pulse again to move the distance measuring object 9. Search.

  When there is no need to continuously capture the distance measuring object 9, the control unit 11 does not necessarily have to be configured to fix the traveling direction of the pulsed laser light after capturing the distance measuring object. For example, if the distance to the distance measuring object 9 can be simply calculated even once, the control unit 11 rotates the irradiation axis of the pulse laser beam in four directions (8a, 8b, 8c, and 8d in FIG. 3). However, the configuration may be such that the irradiation of the laser beam is stopped when the reflected light returns and the distance to the distance measuring object 9 is known.

  The distance to the distance measuring object 9 may be configured to be calculated by the control unit 11, or may be calculated by another distance calculation unit (not shown) or the like. In the case of the configuration calculated by the control unit 11, the control unit 11 determines the distance to the object to be measured based on the generation timing of the pulsed laser light by the Q switch 2 and the reception timing of the reflected light by the light receiving unit 10. Calculate the distance. The calculation result may be displayed on a display or the like, or may be stored in a storage device or transmitted on a network.

  As described above, according to the laser range finder according to the first embodiment of the present invention, the direction of the irradiation axis of the laser light can be changed when a new distance measurement object is searched or the distance measurement object is lost. The object can be quickly displaced and searched for a distance measuring object efficiently. Since the on / off of the Q switches 5 and 6 is controlled by a high-frequency electric signal, the laser beam is at an overwhelmingly higher speed than the method of mechanically rotating the wedge plate as in the conventional laser distance measuring device. Can be displaced and can be completely synchronized with the pulse repetition frequency of the laser beam. Therefore, as compared with the conventional laser distance measuring apparatus, the laser distance measuring apparatus of the present invention can search the distance measuring object very efficiently.

  In addition, since the laser distance measuring device of the present invention can adjust the irradiation axis of the laser beam by the small Q switches 5 and 6, a wedge plate and a motor for rotating the same as in the conventional laser distance measuring device. There is also an advantage that it is not necessary to install a rotating mechanism and the apparatus can be easily downsized.

  FIG. 5 is a diagram illustrating another configuration example of the laser distance measuring apparatus according to the present embodiment. A difference from the configuration of the laser distance measuring apparatus shown in FIG. 1 is that Q switches 12 a, 12 b, 13 a, and 13 b are provided instead of the Q switches 5 and 6.

  The Q switches 12a, 12b, 13a, and 13b all correspond to the second Q switch of the present invention, and refract the traveling direction of the pulsed laser light generated by the laser resonator in a predetermined direction. As shown in FIG. 5, by providing a large number of Q switches for adjusting the irradiation axis of pulsed laser light, the laser distance measuring device can bend the laser light in multiple directions, and can measure the distance more extensively and with high accuracy. The object can be searched and irradiated with laser light.

  FIG. 6 is a diagram showing an operation of searching for the distance measuring object 9 by the laser distance measuring device when a large number of Q switches corresponding to the second Q switch of the present invention are provided. The distance measurement object 9 is searched in multiple directions by rotating the irradiation axis of the laser light, and the distance measurement is performed in a wider range and with higher accuracy than when the laser light is irradiated only in the four directions described in FIG. It turns out that the object can be searched.

  For example, the Q switches 12a and 12b shown in FIG. 5 may adjust the traveling direction of the pulse laser light in the azimuth direction, and the Q switches 13a and 13b may adjust the traveling direction of the pulse laser light in the elevation direction. . The laser distance measuring device shown in FIG. 5 includes Q switches 12a, 12b, 13a, and 13b, so that one of 2 × 2 × 2 × 2 = 16 directions can be selected for the traveling direction of the pulse laser beam. The control unit 11 controls the Q switch driver 7 so as to cover all combinations of ON / OFF for each of the Q switches 12a, 12b, 13a, and 13b. It can be carried out.

  The laser distance measuring device according to the present invention can be used for a laser distance measuring device that measures a distance value to a distance measuring object using pulsed laser light.

DESCRIPTION OF SYMBOLS 1 Mirror 2 Q switch 3 Laser solvent 4 Mirror 5 Q switch 6 Q switch 7 Q switch driver 8a, 8b, 8c, 8d Laser light 9 Distance measuring object 10 Light receiving part 11 Control part 12a, 12b Q switch 13a, 13b Q switch

Claims (4)

A laser distance measuring device for acquiring distance information to the distance measuring object based on the time when the reflected light of the pulse laser light irradiated to the distance measuring object is received,
A laser resonator that generates pulsed laser light using a first Q switch;
One or more second Q switches that refract the traveling direction of the pulsed laser light generated by the laser resonator in a predetermined direction;
A Q switch driver that applies high-frequency power to the first Q switch in a pulsed manner to generate a pulsed laser beam, and controls on / off of each of the one or more second Q switches;
By controlling the Q switch driver so that the first Q switch and each of the one or more second Q switches are synchronized, the traveling direction of the pulsed laser light emitted from the laser resonator is controlled for each pulse. A control unit,
A laser distance measuring device comprising:   The control unit changes on / off combinations for each of the one or more second Q switches for each pulse, and covers all combinations of on / off for each of the one or more second Q switches. 2. The laser distance measuring device according to claim 1, wherein the Q switch driver is controlled. A light receiving unit that receives reflected light from the distance measuring object and determines that there is reflected light when the received light intensity exceeds a threshold value,
The control unit specifies the direction of the distance measuring object based on a light reception timing of the reflected light by the light receiving unit and an ON / OFF combination for each of the one or more second Q switches immediately before the light reception timing. The laser distance measuring device according to claim 1 or 2, wherein   The control unit calculates a distance to the object to be measured based on a generation timing of pulsed laser light by the first Q switch and a reception timing of reflected light by the light receiving unit. The laser distance measuring device according to any one of claims 3 to 4.

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