JPH11287860A - Laser measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser measuring apparatus, by which the position and the speed of an object to be measured can be measured simultaneously at low costs with a simple configuration. SOLUTION: In a laser measuring apparatus, a light emitting part 2 which emits laser light is provided, a laser-light driving part 8 in which the laser light radiated from the light emitting part 2 is divided into two beams of light and in which the two beams of light are crossed at a prescribed crossing angle is provided, a light receiving part 10 in which beams of reflected light obtained at a time when the respective beams of laser light divided in the laser-light dividing part 8 are reflected by an object 20 to be measured are received via the laser-light dividing part 8 and the light emitting part 2 is provided, and a frequency analyzing part 12 which analyzes the frequency of a beat waveform to be outputted from the light receiving part 10 and which discriminates the Doppler frequency of the beat waveform is provided. In addition, the laser measuring apparatus is provided with an object-stage judging part 14 which comprises an existence confirming means 16 which judges that the surface of the object to be measured exists in the crossing position of the beams of laser light at a time when a third Doppler frequency other than Doppler frequencies corresponding to the beams of reflected light by the two divided beams of laser light discriminated by the frequency analyzing part 12 appears.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser measuring device, and more particularly, to a laser measuring device for measuring a position of an object to be measured. The laser measurement device of the present invention preferably relates to a laser measurement device that measures the speed of a measurement target together with spatial resolution. Further, it is suitably applied to a flow rate measuring device, a frequency measuring device, and the like.

[0002]

2. Description of the Related Art Conventionally, a laser Doppler velocimeter has been used as a method for non-contactly detecting the speed of an object to be measured (for example, Japanese Patent Application Laid-Open No. Hei 7-167965). In this example, the speed is obtained by detecting the frequency change due to the Doppler effect from the reflected light scattered by the measurement object. Therefore, the velocity can be measured at any position if a sufficient light intensity is obtained in the element for detecting the scattered light.

[0003]

However, it is difficult to specify the position where the scattered light is generated, that is, the position of the object to be measured. It is also possible to focus the beam at the measurement point and narrow the measurement position so that the scattered light intensity increases only in the vicinity. However, the longer the distance to the measurement target, the more the light is collected (the higher the scattered light intensity). Will be longer. Therefore, the measurable range is widened, and it is difficult to limit the location where the Doppler frequency is obtained.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the disadvantages of the prior art and, in particular, to provide a laser measuring apparatus capable of determining the position of an object to be measured.
It is another object of the present invention to provide a laser measuring device capable of simultaneously measuring the position and speed of a measurement object with a low-cost and simple configuration.

[0005]

Therefore, according to the present invention, a light emitting section for emitting laser light, a laser light emitted from the light emitting section is divided into two parts, and the two laser lights are crossed at a predetermined crossing angle. A laser beam splitting unit, a light receiving unit that receives, via a laser beam splitting unit and a light emitting unit, reflected light of each laser beam split by the laser beam splitting unit and reflected by an object to be measured, and an output from the light receiving unit. And a frequency analysis unit for analyzing the frequency of the beat waveform and identifying the Doppler frequency of the beat waveform. Further, when a third Doppler frequency other than the Doppler frequency corresponding to the reflected light of each of the two divided laser lights identified by the frequency analysis unit appears, it is determined that the surface of the measurement object exists at the intersection of the laser lights. The configuration is such that a target state determination unit for determination is provided. This aims to achieve the above-mentioned object.

[0006] This is because when a laser beam is split and radiated on a measurement object, the scattered light of one laser beam on the surface of the measurement object reaches the light emitting portion via the optical path of the one laser, and the other laser beam. The scattered light of the laser beam on the surface of the object to be measured reaches the light emitting section via the optical path of the other laser. Then, when the divided laser beams overlap on the surface of the measurement target, the scattered light of the other laser beam returns to the light emitting unit via the optical path of one laser beam. Then, the three types of laser light are self-mixed in the light emitting section (laser resonator). Utilizing this phenomenon, the target state determination unit determines that the surface of the measurement target exists at the intersection of the laser beams when the third Doppler frequency appears. Then, it is possible to measure whether or not the measurement target exists at a certain position, and measure the frequency of the measurement target. Also, when two Doppler frequencies appear,
Even if the angle between the laser light and the direction of the measurement target is unknown, the speed and direction of the measurement target can be obtained.
Then, the target state determination unit can simultaneously measure the position of the measurement target and the speed of the measurement target. Then, it becomes possible to measure the velocity of the measurement object existing at a certain position, and to measure the state of the fluid by simultaneously using a plurality of laser measurement devices. Furthermore, if the intersection angle changing means for changing the intersection angle of the laser beam and outputting the changed angle information is provided, it is possible to measure the distance and the speed of the measurement object at an arbitrary position. Then, for example, the flow rate of the measurement target can be measured.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. The laser measuring apparatus 1 according to the present embodiment divides the laser beam 5 emitted from the light emitting section 2 into two parts and the laser beam 5A, 5B at a predetermined intersection angle Δθ degree. A laser beam splitting unit 8 that intersects with each other, and receives, via the laser beam splitting unit 8 and the light emitting unit 2, the reflected light of each of the laser beams 5 </ b> A and 5 </ b> B reflected by the measurement target 20. And a frequency analysis unit 12 that analyzes the frequency of the beat waveform output from the light reception unit 10 and identifies the Doppler frequency of the beat waveform.

The laser measuring apparatus 1 further detects the intersection of the laser beams when a third Doppler frequency other than the Doppler frequency corresponding to the reflected light of each of the two divided laser beams identified by the frequency analyzer 12 appears. Provided with a target state determination unit 14 having presence confirmation means 16 for determining that the surface of the measurement target exists.

The laser beam splitting unit 8 may be any unit as long as it divides the laser beam emitted from the light emitting unit 2 into two, and reflects the laser beam reflected from the object to be measured to the light emitting unit 2 through the same route. The example shown in FIG. 1 includes a half mirror 4 that transmits a part of the laser light, and a mirror 6 that reflects the laser light transmitted or reflected by the half mirror 4 to an object to be measured. The configuration of the laser beam splitting section 8 is not limited to this, and various beam splitters satisfying the above conditions can be used.

As the frequency analysis unit, for example, a DSP can be used. In this case, the output of the photodiode is amplified and then converted to digital data. Further, the target state determination unit can be realized by a microprocessor and a program. The frequency analysis unit and the target state determination unit 14 may be realized by a special logic circuit according to the purpose.

FIG. 2 is a diagram showing an example in which the laser light intersects on the surface of the measurement object 20, and FIG. 3 is a diagram showing an example in which the measurement object 20 exists before the intersection position of the laser light. is there. As shown in FIG. 2, when the laser beam crosses the surface of the measurement target 20, a Doppler frequency f3 shown in FIG. 4 is generated. In the example shown in FIG. 3, the Doppler frequencies f1 and f2
Only happens. Whether or not they intersect is determined according to the length of the range 2a where the incident light intensity is high as shown in FIG. That is,
When the target state determination unit 14 determines that the surface of the measurement object exists at the “crossing position of the laser light”, the “crossing position of the laser light” is within the high incident light intensity range 2a shown in FIG. Say. In order to improve the accuracy of position measurement, it is only necessary to shorten the range where the intensity of incident light is high as shown in FIG. 5 (A). On the other hand, when measuring whether or not the object to be measured is within a certain range In this case, as shown in FIG. 5B, the range in which the intensity of the incident light is high may be increased.

When the surface of the measuring object 20 exists within the range where the incident light intensity is high, as shown in FIG. 6, the scattered light of one laser beam (beam 1) 5A is changed to the optical path of the one laser beam 5A. 5A1 that returns to the light receiving unit 10 via the optical path, a similar path 5B1 of the other laser beam, and 2
If three beams intersect, a third path exists. That is, a path 5A2 in which the scattered light of one laser light 5A returns to the light receiving section 10 via the optical path of the other laser light 5B.
Similarly, a path 5B2 occurs in which the scattered light of the other laser light 5B returns to the light receiving unit 10 via the optical path of the one laser light.

By intersecting the two split beams on the surface of the object to be measured, third paths 5A2 and 5B
2 to obtain the third Doppler frequency f3 shown in FIG. This third path and the third Doppler frequency only occur when the beams intersect at the surface of the measurement object. For this reason, the existence check unit 16 determines whether or not the measurement target is at a predetermined position according to the presence or absence of the third Doppler frequency.

As disclosed in Japanese Patent Application No. 9-86087, when two Doppler frequencies f1 and f2 are used by intersecting laser beams, angles θ1 and θ2 between the direction of the object to be measured and the laser beam are used. Even if it is not clear, if the difference (intersection angle) between these two angles is known, the speed of the object to be measured can be obtained. In the embodiment for calculating the speed, the target state determination unit 14 determines the values of the Doppler frequencies f1 and f2 according to the reflected light of each of the two divided laser beams, and the laser wavelength of the laser beam 5 emitted from the light emitting unit 2. and the expected intersection angle Δθ of each laser beam split by the laser beam splitting unit.
Speed calculating means 18 for calculating the speed of the measuring object based on the above.

The laser beam splitter irradiates the object to be measured with two laser beams by crossing the two laser beams at a predetermined crossing angle, and the laser beams returned on the respective paths 5A1 and 5B1 emit light. The velocity component of each laser beam is mixed in the unit 2 and further self-mixes with the component at the time of light emission. When the output (beat wave) of the light receiving unit is subjected to frequency analysis, the first and second Doppler frequencies f1 and f2 are observed.

The detected Doppler frequencies are f 1 and f 2, and the angles between the surface of the object to be measured and the laser beam are θ 1 and θ.
2. Assuming that the speed of the measurement object is V, the speed V is expressed by the following equation (1).

F1: Doppler frequency detected by one laser beam f2: Doppler frequency detected by the other laser beam V: speed θ1: angle between the direction of the object to be measured and one laser beam θ2: object to be measured Angle of the angle between the direction of the object and the other laser beam Δθ: Offset angle (crossing angle) λ: Wavelength of laser beam

[0018]

(Equation 1)

The speed calculating means 18 calculates the speed of the object to be measured based on the equation (1). The speed can be calculated not only in the state shown in FIG. 2 where the laser light intersects on the surface of the measurement target object, but also in the state shown in FIG. 3 existing before the intersection position. Also, it may exist before the intersection position.

When such a speed calculating means 18 is provided,
It is organically coupled to the existence position confirming means 16 to calculate the speed of the measurement target at a predetermined position, always calculate the speed, and furthermore, the period at which the measurement target passes through the predetermined position. Can be measured.

In the above-described example, the intersection angle Δθ is a predetermined value. However, the intersection angle may be changed. Then, the distance from the laser beam splitting section 8 to the object to be measured changes. When the presence or absence of the third Doppler frequency is confirmed while changing the distance, the distance to the measurement target can be measured. In order to measure the distance to the object to be measured in this way, the laser beam splitting unit 8 changes the crossing angle of the laser beam and outputs the changed angle information (for example, the mirror driving unit 13).
Is provided. The target state determination unit 14 includes a distance calculation unit 24 that calculates a distance to the surface of the measurement target based on the angle information when the third Doppler frequency appears.

Referring to FIG. 1 again, the example shown in FIG. 1 includes a mirror driving unit 13 for changing the angle of the mirror 6. As a specific configuration of the mirror 6 and the mirror driving unit 13, for example, a configuration in which a laser beam is repeatedly scanned in a certain range using a galvano scanner, a polygon mirror, and a stepping motor may be used.
By performing the frequency analysis 12 while changing the intersection angle Δθ, the intersection angle Δθ when the Doppler frequency f3 occurs
Alternatively, the distance to the measurement target can be obtained based on the angle information of the mirror 6.

Then, the position and speed of the moving measuring object can be measured in the mirror scanning cycle. Once the position and speed of the moving measuring object are known,
Measure the flow rate, and also measure the state of vibration,
Its application range expands.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a self-mixing type laser measuring device, the configuration of an optical part for detecting the Doppler frequency is simple, so that the sensor head can be dramatically reduced in cost and size as compared with other systems. Then, when the laser beam is divided into two and intersected by the configuration shown in FIG. 1, a third frequency (f3) is generated in addition to the Doppler frequencies (f1, f2) for each beam. This third frequency f3 occurs between f1 and f2 only when the beams overlap on the object to be measured, as shown in FIG. This is because when an object to be measured is present at the position where the beams overlap, the light scattered by one of the beams on the target surface passes through the optical path of the other beam different from the incident optical path to the resonator (laser element). It is thought that it returned and self-mixed. Therefore, if the object to be measured is not at the position where the beams overlap, f3 is not observed.

By utilizing this, it is possible to realize inexpensive multipoint simultaneous measurement using a large number of laser measuring devices simultaneously. For this reason, it is possible to accurately and inexpensively measure the state of a fluid, recognize the shape of a three-dimensional object during operation, measure the abnormal state of operation of a motor or the like, and measure the amount of a displaced measurement object. Can be. Hereinafter, representative embodiments will be described with reference to the drawings.

[Measurement of Velocity Distribution] By adopting f1 and f2 only when f3 is measured, it is possible to select only the velocity occurring at the position where the laser beam is divided into two and crossed. That is, it is possible to measure only the speed of the movement of the measurement target occurring at the predetermined position. FIG. 7 shows a circuit configuration for measuring the velocity distribution. A semiconductor laser 2 on which scattered light is incident via a split optical path;
A photodiode 10 for photoelectrically converting the laser light;
A beat wave detection circuit 11A for detecting a beat wave from the output of the photodiode;
A waveform amplifying circuit 11B for amplifying the output of A, a frequency analyzing circuit for frequency-analyzing the waveform amplified by the waveform amplifying circuit 11B, a frequency calculating circuit 12 for identifying the Doppler frequency and calculating the value of the frequency, An arithmetic processing circuit 14 is provided as a target state determination unit that calculates the presence and speed of the measurement target based on the output of the calculation circuit 12.

FIG. 8 is an explanatory diagram showing an example of an object for measuring the velocity distribution. Here, first to third laser measuring devices 1A to 1C that intersect laser beams at respective positions of three transport lines are installed. Then, the speeds of the packages 10A to 20C moving on the respective lines are measured by the respective laser measuring devices 1A to 1C.

FIG. 9 is a flowchart showing an example of the measurement process in this case. First, each laser measurement device,
The intersection positions of the two divided laser beams are set in accordance with the passing points of the cargo line of interest (step S1). Then, the beat wave generated by the self-mixing method is detected by the photodiode (step S2),
Amplify (step S3).

Next, the amplified detection signal is subjected to frequency analysis to identify the Doppler frequency. Then, the speed is calculated from the Doppler frequencies f1 and f2 (step S5). Further, it is determined whether or not the third Doppler frequency f3 has been detected. If the third Doppler frequency f3 has been detected, the speed calculated in step S5 is output as the speed of the measurement target (step S7). On the other hand, if the third frequency is not detected, the process returns to step S2 without outputting speed information because the speed is not the speed of the measurement target existing at the predetermined position. By performing this for each of the laser measurement devices 1A to 1C, it is possible to calculate the speed of each of the shipping lines shown in FIG.

[Detection of Position and Speed of Measurement Object] FIG. 10
By controlling the mirror as shown in FIG. 7, the point at which the beams intersect can be changed. If the object is not at the measurement point, f3 is not observed, so that f1 and f2 measured at that time are not used. The measurement point was changed, and when f3 was observed, the position of the measurement point was determined by the mirror angle, and the beam angle and f
The speed is calculated from 1 and f2. In this case, as shown in FIG. 11, a mirror driving unit 13 is added to the configuration shown in FIG. As an example, there is a flow rate measurement of sand or the like flowing in a pipe. As shown in FIG. 12, the distance d to the intersection point changes according to the mirror drive angles θ3 and θ4.

As shown in FIG.
When 0 flows, the laser measurement device 1 is placed above the observation window 22 of the pipe, and the angle of the mirror is controlled to change the measurement point. Then, the flow rate is calculated from the speed information and the distance information at the position where f3 is obtained. At this time,
The distance information is the height h of the sand. Such a flow rate measurement may be performed not only on the pipe 21 but also on a culvert.

In this case, as shown in FIG. 14, the laser measuring device 1 is set (step S11), and after a predetermined process (steps S2 to S5), it is confirmed whether or not the Doppler frequency f3 has been detected (step S11). Step S6). If the Doppler frequency f3 is not detected, the mirror angle is changed (Step S12), and the process returns to Step S2. On the other hand, when the Doppler frequency f3 is detected, the intersection position of the beam is grasped from the mirror angle information (step S13). Subsequently, the height of the object to be measured is calculated based on the intersection position of the beams, and the flow rate is calculated from the height and the position of the object to be measured (step S14).
Thus, the flow rate can be accurately measured without contact. In addition, since the height information and the speed information can be continuously obtained, it is possible to analyze the transition of the state of the fluid.

[Proximity Sensor] As shown in FIG. 15, it is possible to detect that a rotating object has moved and reached a predetermined position. As shown in FIG. 16, first, an intersection position of two beams is set at a predetermined point (step S21).
Then, when the rotating body moves to a predetermined point,
Light is scattered on the surface of the rotating object to generate f3. At this time, f1 and f2 are not particularly required, and only f3 is detected to determine that the rotating object has approached (step S22).

[Position Sensor] As shown in FIG. 17, it is possible to detect that the object to be processed is located at the focal position in the laser beam machine by observing f3. At the time of laser processing, if the position of the surrounding object is displaced from the position where the laser is focused, the accuracy of welding and cutting is reduced. For this reason, it is set to the optimum position of the beam surrounding the intersection of the two beams, and by detecting f3, it is detected that the position of the processing target has shifted. Since there are few methods for directly measuring the position where the beam is illuminated in a non-contact manner, the detection of the positional deviation by using this f3 is very effective. In laser welding, the accuracy of welding is determined by the state of the keyhole.However, when measuring the state of the object to be measured with the divided laser light, the speed of the object to be measured can be obtained. The speed of the components of the melted workpiece can be measured. Depending on the welding material, the state of the keyhole changes periodically or may be constant, so if the speed information of the workpiece on the keyhole surface can be obtained continuously, the quality of the welding can be determined. It can be measured in real time.

[Vibration Measuring Apparatus] FIG. 18 shows an example of measuring the vibration of an object to be measured using the laser measuring apparatus 1 according to the present embodiment. In the first example of the vibration measurement, the target state determination unit 14 has a function of measuring a time interval at which the third Doppler frequency appears. If the laser crossover position is set to the initial position before the oscillation starts, this time interval becomes
The value indicates the frequency and the period of the vibration. And since the self-mixing type laser measurement device can be realized at low cost and small size,
When the laser light is set so as to intersect at multiple points on the vibration surface, the transition of the vibration of the measurement object can be observed.

In the second example of the vibration measurement, the measurement object 2
The laser beam is scanned at a speed higher than the vibration speed of 0, and the displacement speed of the measurement object is measured while sequentially changing the intersection position of the laser beam. When the speed of the measurement object is measured, the displacement amount can be calculated. FIG. 19 shows a processing example in this case.
Shown in First, the two divided laser beams are set so as to intersect at an arbitrary point on the surface of the vibrating body by controlling the angle of the mirror (step S31). After a predetermined process (steps S2 to S5), it is confirmed whether or not the Doppler frequency f3 has been detected (step S6).

If the Doppler frequency f3 is not detected, the mirror angle is changed and the process returns to step S2 (step S32). On the other hand, if the Doppler frequency f3 is detected, the intersection position is calculated based on the mirror angle information (step S33), and the speed at the intersection position is adopted. Then, the state of the vibration is analyzed from the speed and the position of the measurement object.

In addition, the present invention can be applied to various measurements such as inspection of the shape of a three-dimensional object, detailed inspection of paint defects, measurement of the movement and shape of a moving object, and means for inputting information to a computer or the like. it can. In the above-described embodiment, an example has been described in which the presence or absence of the Doppler frequency f3 is checked after calculating the speed of the measurement target. However, the speed of the measurement target is calculated only when the presence of the Doppler frequency f3 is checked. You may do so.

As described above, according to the present embodiment, speed measurement and position detection can be performed simultaneously, so that it is not necessary to prepare a plurality of sensors. Since the position where the velocity is measured is known, the velocity distribution can be three-dimensionally analyzed for the flow of the fluid, the generation of the vortex, and the like. To measure the velocity distribution three-dimensionally, it is necessary to measure the velocity at many points at the same time. However, since the self-mixing method can be made inexpensive and small due to the simplicity of the configuration, it measures many points. This method, which is optimal as a speed detector and can measure at a limited location in this self-mixing method, is very important in realizing multipoint speed measurement.

According to the present embodiment, speed measurement using a parallel beam becomes possible. When a parallel beam is used in the self-mixing method, the incident light intensity can be kept constant over a wide range, so that it can be used without limiting the distance to the measurement point, but in this case, where the speed is measured I don't know. Of these contradictory elements, since the surface of limiting the measurement location is heavily used, a method is used in which the beam is converged and reflected light is obtained only in a location where the light intensity is high. Therefore, it is necessary to adjust the focal length when changing the measurement location, which is difficult to achieve.

On the other hand, according to the present embodiment, the speed at the place where the two beams intersect can be selected from the speeds measured using the parallel beams by detecting f3. By changing the angle of the mirror for adjusting the irradiation position of the laser without changing the focal length, it is possible to change the measurement location. Further, when it is desired to limit the position accurately, the position can be limited by using an optical fiber.

[0042]

The present invention is constructed and functions as described above. According to this, the laser beam is divided and irradiated on the object to be measured. The scattered light of the other laser light returns to the light emitting unit via the optical path of one laser light, and then the three types of laser light are self-mixed in the light emitting unit. When the Doppler frequency of 3 appears, it can be determined that the surface of the object to be measured exists at the intersection of the laser beams. This makes it possible to measure the position of the object to be measured with a self-mixing type inexpensive and compact configuration. It is possible to provide an unprecedented excellent laser measurement device that can be used. In the case of dividing the laser light, even if the angle between the direction of the measurement target and the laser light is unknown, if the intersection angle is clear, the speed of the measurement target can be calculated. When combined with the measurement of the position of the measurement target, it is possible to measure only the speed of the object that moves at a predetermined position, and by using a large number of the devices,
It is possible to provide an unprecedented excellent laser measurement device capable of obtaining velocity information and position information at multiple points such as a fluid vibration surface.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example in which lasers cross on the surface of a measurement target.

FIG. 3 is an explanatory diagram showing an example in which lasers do not intersect on the surface of a measurement object.

FIG. 4 is a spectrum diagram showing an example of a frequency spectrum in which a third Doppler frequency appears.

FIG. 5 is an explanatory diagram illustrating a range of high incident intensity;
FIG. 5A is a diagram showing an example where the range is short.
(B) is a diagram showing an example of a case where the range is long.

FIG. 6 is an explanatory diagram showing a relationship between an optical path of laser light and a return path of reflected light.

FIG. 7 is a block diagram illustrating a configuration of a control system according to the present embodiment.

FIG. 8 is an explanatory diagram showing an example of measuring the speed of each of the measurement objects moving on a plurality of lines.

FIG. 9 is a flowchart illustrating an example of a process for calculating the speed of the measurement target illustrated in FIG. 8;

FIG. 10 is an explanatory diagram showing an example in which the mirror shown in FIG. 1 is driven to change the intersection position of a laser beam.

11 is a block diagram showing a configuration of a control system corresponding to the configuration shown in FIG.

12 is an explanatory diagram that defines a distance d to an intersection point in the configuration shown in FIG. 10;

FIG. 13 is an explanatory diagram showing an example of measuring a flow rate using the laser measuring device of the present embodiment.

14 is a flowchart illustrating an example of a process for calculating the flow rate of the measurement target illustrated in FIG.

FIG. 15 is an explanatory diagram illustrating an example of measuring whether or not a moving measurement target has reached a predetermined position using the laser measurement device of the present embodiment.

16 is a flowchart illustrating an example of a process of measuring the position of the measurement target illustrated in FIG.

FIG. 17 is an explanatory diagram illustrating an example of inspecting the position of a welding target using the laser measurement device of the present embodiment.

FIG. 18 is an explanatory diagram illustrating an example of measuring vibration of a measurement target using the laser measurement device of the present embodiment.

FIG. 19 is a flowchart illustrating an example of a vibration measurement process illustrated in FIG. 18;

[Explanation of symbols]

 Reference Signs List 2 light emitting unit (laser diode) 4 half mirror 6 mirror 8 laser beam splitting unit 10 light receiving unit (photodiode) 12 frequency analyzing unit (for example, DSP) 13 mirror driving unit (for example, motor) 14 target state determining unit (for example, Microcomputer)

Claims (5)

[Claims] 1. A light emitting section for emitting a laser beam, a laser beam splitting section for splitting a laser beam emitted from the light emitting section into two and intersecting the two laser beams at a predetermined crossing angle, and the laser beam A light receiving unit that receives, via the laser light splitting unit and the light emitting unit, reflected light of each laser beam split by the splitting unit and reflected by the object to be measured, and performs a frequency analysis on a beat waveform output from the light receiving unit. A frequency analysis unit for identifying a Doppler frequency of the beat waveform, and a third Doppler frequency other than the Doppler frequency corresponding to the reflected light of each of the two divided laser lights identified by the frequency analysis unit appears. And a target state determination unit that determines that the surface of the measurement object is present at the intersection of the laser beams when the laser light crosses. 2. The apparatus according to claim 1, wherein the target state determination unit is configured to determine a Doppler frequency value corresponding to the reflected light of each of the two divided laser lights, a laser wavelength of the laser light emitted from the light emitting unit, and the laser light division. 2. The apparatus according to claim 1, further comprising a speed calculating unit configured to calculate a speed of the object to be measured based on a scheduled intersection angle of each laser beam divided by the unit.
The laser measuring device as described in the above. 3. The laser beam splitting unit further includes a crossing angle changing unit that changes a crossing angle of the laser beam and outputs changed angle information, wherein the target state determination unit determines that the third Doppler frequency is not higher than the third Doppler frequency. 3. The laser measurement apparatus according to claim 2, further comprising a distance calculation unit that calculates a distance to a surface of the measurement target based on the angle information when the measurement object appears. 4. The apparatus according to claim 1, wherein the target state determination unit includes a flow rate calculating unit that calculates a flow rate of the measurement target from the distance to the measurement target calculated by the distance calculation unit and the speed of the measurement target. 4. The laser measuring means according to claim 3, wherein: 5. The laser measurement apparatus according to claim 1, wherein the target state determination unit has a function of measuring a time interval at which the third Doppler frequency appears.