CN113050114B - Laser speed measuring method and device - Google Patents
Laser speed measuring method and device Download PDFInfo
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- CN113050114B CN113050114B CN202110279498.XA CN202110279498A CN113050114B CN 113050114 B CN113050114 B CN 113050114B CN 202110279498 A CN202110279498 A CN 202110279498A CN 113050114 B CN113050114 B CN 113050114B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/50—Systems of measurement based on relative movement of target
- G01S17/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/36—Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light
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Abstract
The invention relates to the technical field of measurement, and provides a laser speed measuring method and a speed measuring device. When receiving a starting instruction sent by the processing module, the laser receiving and transmitting module transmits laser; the laser and the reflected light of the laser form interference light signals in the laser receiving and transmitting module; the signal acquisition module acquires an acquisition electric signal by detecting an interference light signal in the laser transceiver module; the processing module processes the acquired electric signals in the signal acquisition module to obtain interference frequency, then obtains the speed corresponding to the interference frequency according to the matching relation between the interference frequency and the speed and the interference frequency, and obtains the movement speed of the measured moving object according to the speed and the included angle. And obtaining the motion information of the measured moving object according to the interference light signals of the laser and the reflected light shape, converting the photoelectric signals, processing the electric signals to obtain the interference frequency, and obtaining the speed of the measured moving object based on the matching relation and the included angle, thereby improving the measurement precision.
Description
Technical Field
The invention relates to the technical field of measurement, in particular to a laser speed measuring method and a speed measuring device.
Background
The measurement of the rotation speed is always an important technology in the industrial field, and the current methods for measuring the rotation speed are analog velocimetry such as centrifugal tachometer, synchronous velocimetry such as mechanical or flash stroboscopic velocimetry and counting velocimetry. The counting and speed measuring method comprises a mechanical timing counting method and an electronic timing counting method. In these speed measuring methods, the rotational speeds of a plurality of periods are generally integrated and averaged, so that the instantaneous speed cannot be measured, and the measurement accuracy is low.
Disclosure of Invention
Therefore, the invention aims to provide a laser speed measuring method and a speed measuring device.
In order to achieve the above object, the technical scheme adopted by the embodiment of the invention is as follows:
in a first aspect, the invention provides a laser speed measuring method, which is applied to a speed measuring device, wherein the speed measuring device comprises a processing module, a laser receiving and transmitting module and a signal acquisition module, the processing module is respectively and electrically connected with the laser receiving and transmitting module and the signal acquisition module, and the laser receiving and transmitting module is electrically connected with the signal acquisition module; the method comprises the following steps:
an included angle exists between the optical axis of the laser transceiver module and the moving direction of the measured moving object, and the included angle is an acute angle or an obtuse angle; the measured moving object rotates around a moving shaft;
when receiving a starting instruction sent by the processing module, the laser receiving and transmitting module transmits laser;
the signal acquisition module acquires an acquisition electric signal by detecting an interference light signal in the laser receiving and transmitting module; the interference optical signal is formed by the laser and the reflected light of the laser in the laser receiving and transmitting module;
the processing module processes the acquired electric signals in the signal acquisition module to obtain interference frequencies corresponding to the acquired electric signals;
the processing module obtains the speed corresponding to the interference frequency according to the matching relation between the speed and the interference frequency; the speed represents a speed component of the measured moving object in the optical axis direction;
and the processing module obtains the movement speed of the measured moving object according to the speed and the included angle.
In an alternative embodiment, before the step of obtaining, by the processing module, the speed corresponding to the interference frequency according to the matching relationship between the speed and the interference frequency, the method further includes:
when the processing module obtains each preset speed, obtaining a matching frequency corresponding to the preset speed;
the processing module establishes a matching relation between the speed and the interference frequency according to the obtained multiple preset speeds and the matching frequencies corresponding to the multiple preset speeds.
In an optional embodiment, the step of obtaining the matching frequency corresponding to the preset speed when the processing module obtains each preset speed includes:
when the processing module obtains each preset speed, the processing module controls the laser receiving and transmitting module to emit test laser;
the signal acquisition module acquires a test electric signal by detecting a test optical signal in the laser receiving-transmitting module; the test optical signal is an optical signal formed by the test laser and the reflected light of the test laser;
and the processing module processes the test electric signal, and when the test electric signal meets the preset signal-to-noise ratio, the corresponding matching frequency of the preset speed is obtained.
In an alternative embodiment, the method further comprises:
when the test electric signal does not meet the preset signal to noise ratio, the processing module sends an adjusting instruction;
when receiving the adjusting instruction sent by the processing module, the laser receiving and transmitting module adjusts the optical power of the test laser so that the test electric signal meets the preset signal-to-noise ratio.
In an optional embodiment, when receiving the adjustment instruction sent by the processing module, the laser transceiver module adjusts the optical power of the test laser, so that the test electrical signal meets the preset signal-to-noise ratio, and the method includes:
when the signal to noise ratio of the test electric signal is smaller than the preset signal to noise ratio, the signal acquisition module increases the optical power of the test laser.
In a second aspect, the invention provides a speed measuring device, which comprises a processing module, a laser receiving and transmitting module and a signal acquisition module, wherein the processing module is respectively and electrically connected with the laser receiving and transmitting module and the signal acquisition module, and the laser receiving and transmitting module is electrically connected with the signal acquisition module;
the laser receiving and transmitting module is used for transmitting laser when receiving a starting instruction sent by the processing module;
the signal acquisition module is used for acquiring an acquisition electric signal by detecting an interference light signal in the laser receiving and transmitting module; the interference optical signal is formed by the laser and the reflected light of the laser in the laser receiving and transmitting module;
the processing module is used for processing the acquired electric signals in the signal acquisition module to obtain corresponding interference frequencies of the acquired electric signals; and obtaining the speed corresponding to the interference frequency according to the matching relation between the speed and the interference frequency.
In an alternative embodiment, the processing module is further configured to:
when each preset speed is obtained, obtaining a matching frequency corresponding to the preset speed;
and establishing a matching relation between the speed and the interference frequency according to the obtained multiple preset speeds and the matching frequencies corresponding to the multiple preset speeds.
In an alternative embodiment, the laser transceiver module comprises a driving unit and a semiconductor laser unit, the driving unit is electrically connected with the semiconductor laser unit, and the driving unit is electrically connected with the processing module;
the driving unit is used for controlling the optical power of the laser;
the semiconductor laser unit is used for emitting laser.
In an alternative embodiment, the signal acquisition module comprises a photoelectric detection unit, a signal amplification unit and an acquisition unit, and the photoelectric detection unit, the signal amplification unit and the acquisition unit are electrically connected in sequence;
the photoelectric detection unit is used for converting the detected interference light signals into electric signals;
the signal amplifying unit is used for amplifying the electric signals in the photoelectric detection unit;
the acquisition unit is used for acquiring the electric signals amplified in the signal amplification unit to obtain acquired electric signals.
In an alternative embodiment, the apparatus further comprises a focusing module;
the focusing module is used for focusing the laser in the laser receiving and transmitting module.
The embodiment of the invention provides a laser speed measuring and discharging method and a speed measuring device. When receiving a starting instruction sent by the processing module, the laser receiving and transmitting module transmits laser; the laser and the reflected light of the laser form interference light signals in the laser receiving and transmitting module; the signal acquisition module acquires an acquisition electric signal by detecting an interference light signal in the laser transceiver module; the processing module processes the acquired electric signals in the signal acquisition module to obtain interference frequency, then obtains the speed corresponding to the interference frequency according to the matching relation between the interference frequency and the speed and the interference frequency, and obtains the movement speed of the measured moving object according to the speed and the included angle. And obtaining the motion information of the measured moving object according to the interference light signals of the laser and the reflected light shape, converting the photoelectric signals, processing the electric signals to obtain the interference frequency, and obtaining the speed of the measured moving object based on the matching relation and the included angle, thereby improving the measurement precision.
In order to make the above objects, features and advantages of the present invention more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 shows a schematic block diagram of a speed measuring device according to an embodiment of the present invention;
FIG. 2 is a diagram showing an example of a laser velocimetry method provided by an embodiment of the present invention;
fig. 3 is a schematic flow chart of a laser speed measurement method according to an embodiment of the present invention;
fig. 4 is a schematic flow chart of another laser speed measurement method according to an embodiment of the present invention;
FIG. 5 is a diagram showing another example of a laser velocimetry method provided by an embodiment of the present invention;
FIG. 6 is a diagram showing another example of a laser velocimetry method provided by an embodiment of the present invention;
fig. 7 is a schematic flow chart of another laser speed measurement method according to an embodiment of the present invention;
FIG. 8 is a diagram showing another example of a laser velocimetry method provided by an embodiment of the present invention;
fig. 9 shows a block schematic diagram of another speed measuring device according to an embodiment of the present invention.
Icon: 100-a speed measuring device; 110-a processing module; 130-a laser transceiver module; 150-a signal acquisition module; 170-a focusing module; 131-a driving unit; 133-a semiconductor laser unit; 135-direct current power supply; 151-a photodetection unit; 153-a signal amplifying unit; 155-acquisition unit.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without making any inventive effort, are intended to be within the scope of the present invention.
It is noted that relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
In the prior art, a method of calculating an average value based on the accumulation of the rotational speeds of a plurality of periods is generally adopted for the measurement of the rotational speeds, but under the condition of higher measurement accuracy requirements, the actual requirements cannot be met by adopting the method. With the rapid development of laser technology, lasers are widely used in various industrial fields. Since the laser has good optical characteristics, the method is very suitable for the field of high-precision measurement. Therefore, the invention provides a speed measuring device based on good coherence of laser.
Fig. 1 is a schematic block diagram of a speed measuring device according to an embodiment of the present invention. The speed device 100 includes a processing module 110, a laser transceiver module 130, and a signal acquisition module 150. The processing module 110 is electrically connected to the laser transceiver module 130 and the signal acquisition module 150, and the laser transceiver module 130 and the signal acquisition module 150 are electrically connected.
The laser transceiver module 130 is configured to emit laser, and when the emitted laser is reflected, reflected light is formed, and the reflected light enters the laser transceiver module 130 to interfere with the original laser to form an interference light signal, that is, self-mixing interference (Self-mixing Interference, SMI).
The signal acquisition module 150 is configured to convert an optical signal into an electrical signal, and perform filtering, denoising, amplifying, and acquisition recording on the electrical signal.
The processing module 110 is configured to send out an instruction, control the laser transceiver module 130 and the signal acquisition module 150 to work, and perform processing operation on an electrical signal output by the signal acquisition module 150.
It can be appreciated that the focusing module 170 can be used to focus the laser light emitted by the laser transceiver module 130, concentrate the energy of the laser light, and reduce the loss when measuring the object. Accordingly, the speed measuring device 100 may further include a focusing module 170.
It will be appreciated by those skilled in the art that the configuration shown in fig. 1 is merely illustrative and is not intended to limit the configuration of the speed measuring device 100. The speed measuring device 100 may also include more or fewer components than shown in fig. 1, or have a different configuration than shown in fig. 1.
The following takes the speed measuring device in fig. 1 as an execution main body to implement each step of the laser speed measuring method provided in the embodiment of the present application.
Referring to fig. 2, an exemplary diagram is provided in an embodiment of the present application. Fig. 2 (a 1) is an exemplary diagram of a side view angle, wherein a represents a measured moving object, Y represents a moving axis of the measured moving object, X represents an optical axis of the laser transceiver module, M represents laser light emitted by the laser transceiver module, N represents reflected light of the laser light M, and F represents a focal point of the focusing module. The optical axis X passes through the focal point F; the object a to be measured rotates counterclockwise around the movement axis Y.
Fig. 2 (a 2) is a top view of the object a. Wherein S represents the intersection point of the optical axis X and the surface of the measured moving object; v represents the speed of the intersection point; the moving direction of the measured moving object, namely the speed direction at the intersection point, r represents the included angle between the optical axis X and the moving direction of the measured moving object.
The following describes a laser velocity measurement method provided by the embodiment of the present invention with reference to fig. 2 and 3. Fig. 3 is a schematic flow chart of a laser speed measurement method according to an embodiment of the present invention.
Step S202, when receiving a starting instruction sent by a processing module, a laser receiving and transmitting module transmits laser;
wherein the start instruction is an instruction to start measurement.
The processing module sends a starting instruction to the laser receiving and transmitting module, and the laser receiving and transmitting module transmits laser M after receiving the starting instruction; the focusing module focuses the laser M, the laser M irradiates the measured moving object A, and reflection occurs, so that reflected light N is formed.
The reflected light N returns along the light path of the laser M, enters the laser receiving and transmitting module through the focusing module, and forms interference light signals of the laser M and the reflected light N in the laser receiving and transmitting module according to the self-mixing interference principle.
Optionally, when the reflected light formed by the measured moving object is weaker, a reflective material may be disposed on the surface of the measured moving object, so as to increase the reflection intensity, obtain stronger reflected light, and form a good interference light signal. A reflective material with a reflectivity of 3% -100% for the laser wavelength may be selected.
Alternatively, when the measured moving object is not in effective contact with the laser light, such as when the surface area is small, the reflected light formed is weak, and the connection shaft and the reflecting object may be used. The reflecting object is a cylindrical object with a good reflecting effect. The reflecting object and the measured moving object can be connected by adopting the connecting shaft, so that the reflecting object and the measured moving object realize coaxial rotation. The laser is irradiated to the reflecting object to form good reflected light.
Step S204, a signal acquisition module acquires an acquisition electric signal by detecting an interference light signal in the laser transceiver module;
the interference optical signal is an optical signal formed by the laser light M and the reflected light N of the laser light.
The signal acquisition module detects the interference light signal, converts the interference light signal into an electric signal, and because the electric signal converted from the light signal is weak, the electric signal is required to be filtered, part of noise signals are removed, the electric signal is amplified, the strength and the signal to noise ratio of the electric signal are increased, then the enhanced electric signal is acquired and recorded, and the acquired electric signal is transmitted to the processing module.
Step S206, the processing module processes the acquired electric signals in the signal acquisition module to obtain interference frequencies corresponding to the acquired electric signals;
the acquired electric signals are time domain signals, the processing module carries out Fourier transform on the time domain signals and converts the time domain signals into frequency domain signals, and the frequency can be calculated according to the frequency domain signals, so that the interference frequency of the acquired electric signals can be obtained.
Step S208, the processing module obtains the speed corresponding to the interference frequency according to the matching relation between the speed and the interference frequency;
the matching relationship is a pre-obtained speed and interference frequency, and may be a relationship table, a functional relationship, or the like.
After the processing module obtains the interference frequency, the corresponding speed can be calculated according to the matching relation.
Step S210, a processing module obtains the movement speed of a measured moving object according to the speed and the included angle;
it will be appreciated that if the velocity at the intersection S is set aside by the optical axis X, an orthogonal decomposition is performed. A velocity component is obtained on the optical axis X, and the included angle between the direction of the velocity component and the moving direction of the measured moving object a is r.
The velocity calculated by the processing module from the interference frequency is the velocity component. The movement speed of the measured moving object can be obtained according to the included angle r and the speed component.
It can be understood that as long as the moving direction of the measured moving object has an included angle with the optical axis, and the included angle is an acute angle or an obtuse angle, then the velocity of the measured moving object has a component on the optical axis, and then the actual velocity of the measured moving object can be obtained according to the included angle.
It can be understood that when the measured moving object moves in a displacement manner relative to the speed measuring device, as long as an included angle exists between the moving direction of the measured moving object and the optical axis, the included angle is an obtuse angle or an acute angle, that is, when the included angle is not a right angle, a velocity component exists on the optical axis of the measured moving object, and then the moving velocity of the measured moving object can also be measured.
Through the steps, when receiving the starting instruction sent by the processing module, the laser receiving and transmitting module transmits laser; the laser and the reflected light of the laser form interference light signals in the laser receiving and transmitting module; the signal acquisition module acquires an acquisition electric signal by detecting an interference light signal in the laser transceiver module; the processing module processes the acquired electric signals in the signal acquisition module to obtain interference frequency, then obtains the speed corresponding to the interference frequency according to the matching relation between the interference frequency and the speed and the interference frequency, and obtains the movement speed of the measured moving object according to the speed and the included angle. And obtaining the motion information of the measured moving object according to the interference light signals of the laser and the reflected light shape, converting the photoelectric signals, processing the electric signals to obtain the interference frequency, and obtaining the speed of the measured moving object based on the matching relation and the included angle, thereby improving the measurement precision.
In the above step S208, there is a matching relationship between the interference frequency and the velocity. This matching relationship can be understood as scaling and calibration prior to measurement, and embodiments of the present invention provide a way in which it is possible to obtain a matching relationship between interference frequency and speed. Referring to fig. 4, the steps for obtaining the matching relationship between the interference frequency and the velocity will be described.
Step S212, when the processing module obtains each preset speed, obtaining a matching frequency corresponding to the preset speed;
in step S214, the processing module establishes a matching relationship between the speed and the interference frequency according to the obtained multiple preset speeds and the matching frequencies corresponding to the multiple preset speeds.
It will be appreciated that a test object may be pre-arranged, which test object has a good reflection effect. The preset speed is the preset speed of rotation of the test object.
The motor drives the test object to rotate according to a plurality of preset speeds, such as speeds u1, u2, u3 and u4; when the processing module obtains a preset speed, such as u1, a starting instruction is sent; the speed measuring device is started, the matching frequency f1 corresponding to the preset speed u1 can be tested, and then the corresponding matching frequencies f2, f3 and f4 are obtained according to u2, u3 and u4 respectively.
And then, according to preset speeds u1, u2, u3 and u4 and corresponding matching frequencies f1, f2, f3 and f4, linear fitting is carried out, so that a functional relation can be obtained, wherein the functional relation is the matching relation of the speeds and the interference frequencies. As shown in FIG. 5, a linear fitting graph provided by an embodiment of the present invention is shown, the abscissa represents a velocity value, the ordinate represents a frequency value, and a functional relationship between velocity and interference frequency can be obtained according to linear fitting.
In the following, please refer to fig. 6 and fig. 7, the matching frequency corresponding to the preset speed in the above steps is described.
Please refer to fig. 6, which is an exemplary diagram provided in an embodiment of the present application. Fig. 6 (B1) is an example diagram of a side view angle, where B represents a test object, Z represents a movement axis of the test object, X represents an optical axis of the laser transceiver module, O represents test laser light emitted from the laser transceiver module, P represents reflected light of the laser light O, and F represents a focal point of the focusing module. The optical axis X passes through the focal point F; the test object B is rotated clockwise about the axis of motion Z.
Fig. 6 (B2) is a top view of the test object B. Wherein W represents the intersection point of the optical axis X and the surface of the test object; u represents the velocity at the intersection point; the direction of movement of the test animal, i.e. the direction of velocity at the intersection point, t represents the angle of the optical axis X with the direction of movement of the test animal, which is 45 °.
Referring to fig. 7, in step S212-1, when the processing module obtains each preset speed, the processing module controls the laser transceiver module to emit the test laser;
when the processing module obtains a preset speed, a starting instruction is sent to the laser receiving and transmitting module, the laser receiving and transmitting module sends out test laser O, the focusing module focuses the test laser O, the test laser O irradiates the test object B and is reflected, and reflected light P is formed.
The reflected light P returns along the light path of the test laser O, enters the laser receiving and transmitting module through the focusing module, and forms test light signals of the test laser O and the reflected light P in the laser receiving and transmitting module according to the self-mixing interference principle.
Step S212-3, the signal acquisition module acquires a test electric signal by detecting a test optical signal in the laser transceiver module;
the signal acquisition module detects the test optical signal, converts the test optical signal into an electric signal, amplifies and acquires the electric signal to obtain the test electric signal, and transmits the acquired test electric signal to the processing module.
Step S212-5, the processing module processes the test electric signal, and when the test electric signal meets the preset signal-to-noise ratio, the corresponding matching frequency of the preset speed is obtained;
the preset snr is a preset snr and can be understood as a critical value.
The acquired electric signals are time domain signals, the processing module carries out Fourier transform on the time domain signals and converts the time domain signals into frequency domain signals, and the intensity distribution map of the signals with different frequencies can be obtained; the method comprises the steps of smoothing and filtering signals, carrying out full frequency domain scanning to obtain the strongest spectrum wave crest, namely the wave crest with the largest amplitude, then fitting the spectrum wave crest by adopting a Gaussian function, and obtaining the peak frequency according to the fitted wave crest.
And calculating the signal-to-noise ratio according to the frequency, wherein when the signal-to-noise ratio is equal to or greater than the preset signal-to-noise ratio, the frequency is the matching frequency corresponding to the preset speed.
As shown in fig. 8, an intensity distribution diagram of a frequency signal according to an embodiment of the present invention is shown. The abscissa represents a frequency value, the ordinate represents an amplitude value, namely a voltage value, the peak with the largest amplitude is in a dotted line area, the frequency corresponding to the peak is f0, the signal to noise ratio of the frequency is in a preset signal to noise ratio range, and the frequency f0 is a matching frequency corresponding to a preset speed.
In actual measurement, there are many measurement factors, and a situation may occur that the signal to noise ratio of the test electrical signal does not meet the preset signal to noise ratio, and the frequency obtained under the situation is inaccurate.
Step S212-7, when the test electric signal does not meet the preset signal to noise ratio, the processing module sends an adjusting instruction;
in step S212-9, when receiving the adjustment command sent by the processing module, the laser transceiver module adjusts the optical power of the test laser.
When the test electrical signal does not meet the preset signal-to-noise ratio, it is possible that the test electrical signal is weak. The processing module can compare the obtained signal-to-noise ratio with a preset signal-to-noise ratio, and then the laser receiving and transmitting module is controlled to adjust the optical power of the test laser, so that the signal-to-noise ratio of the test electric signal meets the preset signal-to-noise ratio.
When the signal-to-noise ratio is smaller than the preset signal-to-noise ratio, the test electric signal is weaker, the processing module sends an adjusting instruction to the laser receiving and transmitting module, optionally, the adjusting instruction comprises an adjusting parameter, and after the laser receiving and transmitting module receives the adjusting instruction, the power of the test laser is increased according to the adjusting parameter.
According to the adjusted test laser, the adjusted interference frequency is obtained, whether the signal-to-noise ratio of the adjusted interference frequency is equal to or larger than a preset signal-to-noise ratio is calculated, if the signal-to-noise ratio is smaller than the preset signal-to-noise ratio, the processing module sends an adjusting instruction again, the power of the test laser is adjusted again, after multiple adjustments are carried out, when the signal-to-noise ratio of the interference frequency is equal to or larger than the preset signal-to-noise ratio, the interference frequency obtained at the moment is the matching frequency, and adjustment is not needed.
The embodiment of the invention also provides a speed measuring device. The device structure shown in fig. 1 can be adopted by the speed measuring device, and the steps can be executed to realize the laser speed measuring method disclosed by the embodiment of the invention. It should be noted that, the basic principle and the technical effects of the speed measuring device provided by the embodiment of the present invention are the same as those of the above embodiment, and for brevity, the details of the description of the embodiment are not mentioned in the section of the present embodiment, and reference may be made to the corresponding content of the above embodiment. The speed measuring device 100 includes: the device comprises a processing module 110, a laser receiving and transmitting module 130, a signal acquisition module 150 and a focusing module 170.
The laser transceiver module 130 is configured to emit laser when receiving the start command sent by the processing module;
the signal acquisition module 150 is configured to obtain an acquired electrical signal by detecting an interference optical signal in the laser transceiver module; the interference optical signal is formed by laser and reflected light of the laser;
the processing module 110 is configured to process the collected electrical signal in the signal collection module, so as to obtain a corresponding interference frequency of the collected electrical signal; obtaining a speed corresponding to the interference frequency according to the matching relation between the speed and the interference frequency;
the focusing module 170 is used for focusing the laser light in the laser transceiver module.
Optionally, the processing module 110 is further configured to: when each preset speed is obtained, obtaining a matching frequency corresponding to the preset speed; and establishing a matching relation between the speed and the interference frequency according to the obtained multiple preset speeds and the matching frequencies corresponding to the multiple preset speeds.
Fig. 9 is a block diagram of another speed measuring device according to an embodiment of the invention. The speed measuring device 100 comprises a processing module 110, a laser transceiver module 130, a signal acquisition module 150 and a focusing module 170.
The laser transceiver module 130 includes a driving unit 131 and a semiconductor laser unit 133, and may further include a dc power source 135, where the driving unit 131, the semiconductor laser unit 133 and the dc power source 135 are electrically connected in sequence.
The dc power supply 135 is used to supply power to the driving unit 131;
the semiconductor laser unit 133 is for emitting laser light;
the driving unit 131 is used to control the optical power of the laser light.
Alternatively, the wavelength of the laser light of the semiconductor laser unit 133 may be 850nm,940nm,1380nm, or the like, and the optical power range controlled by the driving unit 131 may be 0.1mW to 100mW.
Because of the complex structure, the gas laser has larger volume and is inconvenient to carry. The semiconductor laser unit 133 of the embodiment of the present invention adopts a semiconductor laser, and the semiconductor laser has the advantages of simple manufacture, easy mass production, low cost, wide wavelength coverage, small volume, long service life, low energy consumption, high electro-optical conversion efficiency, etc. Such as a Vertical-Cavity Surface-Emitting Laser (VCSEL), a semiconductor with a Laser light perpendicular to the top Surface.
It is understood that the driving unit 131 is electrically connected to the processing module 110, and the driving unit 131 controls the optical power of the laser emitted by the semiconductor laser unit 133 by controlling the magnitude of the current value after receiving the instruction of the processing module 110.
It can be understood that the laser light emitted from the semiconductor laser unit 133 and the reflected light of the laser light are subjected to self-mixing interference in the cavity of the semiconductor laser unit 133, forming an interference optical signal.
The signal acquisition module 150 includes a photodetection unit 151, a signal amplification unit 153, and an acquisition unit 155. The photoelectric detection unit 151, the signal amplification unit 153, and the acquisition unit 155 are electrically connected in this order.
The photoelectric detection unit 151 is used for converting the detected interference optical signal into an electrical signal;
the signal amplifying unit 153 is configured to amplify the electrical signal in the photodetecting unit;
the acquisition unit 155 is configured to acquire the electrical signal amplified in the signal amplifying unit, and obtain an acquired electrical signal.
Alternatively, the photodetection unit 151 may be connected to the semiconductor laser unit 133 to convert the detected interference light signal into an electrical signal.
The acquisition unit 155 may be an ADC acquisition card or an oscilloscope.
In summary, the invention provides a laser speed measuring method and a speed measuring device. Transmitting laser through a speed measuring device to obtain reflected light, and obtaining an interference light signal of the laser and the reflected light by utilizing a self-mixing coherence principle; converting the interference light signal into an acquisition electric signal; processing the acquired electric signals to obtain interference frequency; according to the matching relation, the speed corresponding to the interference frequency is obtained, so that the speed of the tested object is obtained, and the technical effect of improving the measurement accuracy is achieved.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. The laser speed measuring method is characterized by being applied to a speed measuring device, wherein the speed measuring device comprises a processing module, a laser receiving and transmitting module and a signal acquisition module, the processing module is respectively and electrically connected with the laser receiving and transmitting module and the signal acquisition module, and the laser receiving and transmitting module is electrically connected with the signal acquisition module; the method comprises the following steps:
an included angle exists between the optical axis of the laser transceiver module and the moving direction of the measured moving object, and the included angle is an acute angle or an obtuse angle; the measured moving object rotates around a moving shaft; the movement direction of the measured moving object is the speed direction at the intersection point of the optical axis and the surface of the measured moving object;
when receiving a starting instruction sent by the processing module, the laser receiving and transmitting module transmits laser;
the signal acquisition module acquires an acquisition electric signal by detecting an interference light signal in the laser receiving and transmitting module; the interference optical signal is formed by the laser and the reflected light of the laser in the laser receiving and transmitting module;
the processing module processes the acquired electric signals in the signal acquisition module to obtain interference frequencies corresponding to the acquired electric signals;
the processing module obtains the speed corresponding to the interference frequency according to the matching relation between the speed and the interference frequency; the speed represents a speed component of the measured moving object in the optical axis direction;
the processing module obtains the movement speed of the measured moving object according to the speed and the included angle;
before the step of obtaining the speed corresponding to the interference frequency by the processing module according to the matching relation between the speed and the interference frequency, the method further comprises the following steps:
when the processing module obtains each preset speed, obtaining a matching frequency corresponding to the preset speed;
the processing module carries out linear fitting according to the obtained multiple preset speeds and the matching frequencies corresponding to the multiple preset speeds to obtain a functional relation, and the functional relation represents the matching relation between the speeds and the interference frequencies.
2. The method of claim 1, wherein the step of obtaining a matching frequency corresponding to each preset speed when the processing module obtains the preset speed comprises:
when the processing module obtains each preset speed, the processing module controls the laser receiving and transmitting module to emit test laser;
the signal acquisition module acquires a test electric signal by detecting a test optical signal in the laser receiving-transmitting module; the test optical signal is an optical signal formed by the test laser and the reflected light of the test laser;
and the processing module processes the test electric signal, and when the test electric signal meets the preset signal-to-noise ratio, the corresponding matching frequency of the preset speed is obtained.
3. The method according to claim 2, wherein the method further comprises:
when the test electric signal does not meet the preset signal to noise ratio, the processing module sends an adjusting instruction;
when receiving the adjusting instruction sent by the processing module, the laser receiving and transmitting module adjusts the optical power of the test laser so that the test electric signal meets the preset signal-to-noise ratio.
4. A method according to claim 3, wherein the step of the laser transceiver module adjusting the optical power of the test laser to enable the test electrical signal to meet the preset signal-to-noise ratio when receiving the adjustment command sent by the processing module comprises:
when the signal to noise ratio of the test electric signal is smaller than the preset signal to noise ratio, the signal acquisition module increases the optical power of the test laser.
5. The device is characterized by comprising a processing module, a laser receiving and transmitting module and a signal acquisition module, wherein the processing module is respectively and electrically connected with the laser receiving and transmitting module and the signal acquisition module, and the laser receiving and transmitting module is electrically connected with the signal acquisition module;
an included angle exists between the optical axis of the laser transceiver module and the moving direction of the measured moving object, and the included angle is an acute angle or an obtuse angle; the measured moving object rotates around a moving shaft; the movement direction of the measured moving object is the speed direction at the intersection point of the optical axis and the surface of the measured moving object;
the laser receiving and transmitting module is used for transmitting laser when receiving a starting instruction sent by the processing module;
the signal acquisition module is used for acquiring an acquisition electric signal by detecting an interference light signal in the laser receiving and transmitting module; the interference optical signal is formed by the laser and the reflected light of the laser in the laser receiving and transmitting module;
the processing module is used for processing the acquired electric signals in the signal acquisition module to obtain corresponding interference frequencies of the acquired electric signals; obtaining a speed corresponding to the interference frequency according to the matching relation between the speed and the interference frequency; the speed represents a speed component of the measured moving object in the optical axis direction; obtaining the movement speed of the measured moving object according to the speed and the included angle;
the processing module is further configured to:
when each preset speed is obtained, obtaining a matching frequency corresponding to the preset speed;
and performing linear fitting according to the obtained multiple preset speeds and the matching frequencies corresponding to the multiple preset speeds to obtain a functional relationship, wherein the functional relationship represents the matching relationship between the speeds and the interference frequency.
6. The apparatus of claim 5, wherein the laser transceiver module comprises a drive unit and a semiconductor laser unit, the drive unit being electrically connected to the processing module;
the driving unit is used for controlling the optical power of the laser;
the semiconductor laser unit is used for emitting laser.
7. The device according to claim 5, wherein the signal acquisition module comprises a photoelectric detection unit, a signal amplification unit and an acquisition unit, which are electrically connected in sequence;
the photoelectric detection unit is used for converting the detected interference light signals into electric signals;
the signal amplifying unit is used for amplifying the electric signals in the photoelectric detection unit;
the acquisition unit is used for acquiring the electric signals amplified in the signal amplification unit to obtain acquired electric signals.
8. The apparatus of claim 5, further comprising a focusing module;
the focusing module is used for focusing the laser in the laser receiving and transmitting module.
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