A laser distance measurement system based on beam diameter variation

Abstract

The present invention belongs to the field of laser distance measurement technology, and in particular, relates to a laser distance measurement system based on the change of beam diameter, including a laser emitting unit, a beam quality analysis unit and a distance calculation unit, wherein the laser emitting unit is used to emit a distance measurement laser, the beam quality analysis unit is used to analyze the beam quality factor of the beam, and the distance calculation unit is used to calculate the distance between the laser emission position and the receiving position through the diameter of the beam. The present invention emits a distance measurement laser through the laser emitting unit, and the distance measurement laser will have a certain degree of divergence when propagating through the distance at one end. The beam diameter after the laser propagation is measured according to the receiving position, and the distance parameter value is obtained by three groups of known distance measurements, and then the average value of the distance parameter is calculated to obtain a more accurate distance parameter, and the distance is accurately calculated again through the distance parameter and the beam diameter.

Description

Technical Field

[0001] The invention belongs to the technical field of laser distance measurement, and in particular relates to a laser distance measurement system based on the change of beam diameter. Background Art

[0002] With the rapid development of laser detection technology, the application of laser detection technology for distance measurement is becoming more and more extensive. For example, laser distance measuring devices for intelligent driving are receiving more and more attention. Existing laser distance measuring devices can include mechanical scanning laser distance measuring devices, micro-electromechanical system scanning laser distance measuring devices and MEMS laser distance measuring devices. Mechanical scanning laser distance measuring devices and micro-electromechanical system scanning laser distance measuring devices have the advantages of long detection distance and high image resolution. However, due to the existence of rotating parts, the scanning laser distance measuring device has a short service life and poor stability. MEMS laser distance measuring devices can only achieve distance measurement scanning at a certain viewing angle.

[0003] The existing method of measuring distance by measuring laser propagation time cannot accurately measure the laser propagation time. Often, a small time difference will lead to a large measurement error under the influence of the extremely high laser propagation speed. In view of this, we propose a laser distance measurement system based on the change of beam diameter. Summary of the invention

[0004] The object of the present invention is to provide a laser ranging system based on the change of beam diameter to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A laser ranging system based on beam diameter change comprises a laser emitting unit, a beam quality analysis unit and a distance calculation unit. The laser emitting unit is used to emit ranging laser, the beam quality analysis unit is used to analyze the beam quality factor of the beam, and the distance calculation unit is used to calculate the distance between the laser emitting position and the receiving position according to the diameter of the beam.

[0007] Preferably, the laser emitting unit includes a single-chip microcomputer, a laser diode group, a capacitor, a resistor, a diode and an inductor, wherein the single-chip microcomputer IN+ pin pulls up R1 to 3.3V and pulls down R5 to the power ground, the single-chip microcomputer IN- pin pulls up R2 to 3.3V and pulls down R6 to the power ground, the pin BEN+ pulls up R3 to 3.3V and pulls down R7 to the power ground, the pin BEN- pulls up R4 to 3.3V and pulls down R8 to the power ground, the OUT+ pin is connected to the resistor R12, the resistor R12 is connected in series with the resistor R8 and the capacitor C3 to ground, the negative pole of D1 is connected to R11, R9 and L1 are connected in parallel, the positive pole of D1 is connected to the inductor L1, the other end of the inductor L1 is connected to the 3.3V power supply and C2 at the same time, the other end of C2 is connected to the power ground, and the laser diode group is respectively connected to the positive pole of D1, R11 and the pin MD.

[0008] Preferably, the laser diode group is composed of two LED lamps, and the positive electrode of one LED lamp is connected to the negative electrode of the other LED lamp to form the laser diode group.

[0009] Preferably, the R1, R2, R3 and R4 are 130Ω resistors, the R5, R6, R7 and R8 are 82Ω resistors, the C1 and C2 are 0.1uF capacitors, and the L1 is a 10nH inductor.

[0010] Preferably, the beam quality analysis unit calculates the beam quality factor x of the light beam using the following calculation formula:

[0011]

[0012] Where D is the beam waist width, θ is the far-field divergence angle, and ρ is the base film waist width.

[0013] Preferably, the calculation formula of the far-field divergence angle θ is:

[0014]

[0015] Where λ is the laser wavelength and D0 is the beam waist diameter.

[0016] Preferably, the distance calculation unit includes a coefficient calibration unit and a calculation output unit.

[0017] Preferably, the calculation formula of the coefficient calibration unit is:

[0018]

[0019] When the distance parameters are calculated for the first time, the beam diameter D1 and the distance L1 are known; when the distance parameters are calculated for the second time, the beam diameter D2 and the distance L2 are known; and when the distance parameters are calculated for the third time, the beam diameter D3 and the distance L3 are known.

[0020] Preferably, the calculation formula used by the calculation output unit to calculate the distance S is:

[0021] S = ρ·D;

[0022] Where ρ is the distance parameter and D is the beam diameter.

[0023] Preferably, the working steps of the distance calculation unit are:

[0024] Step S1: Given a known distance L and a known diameter D, calculate the distance parameters three times;

[0025] Step S2: taking the average of the three sets of distance parameters to obtain a more accurate parameter ρ;

[0026] Step S3: Calculate the distance S according to the beam diameter and the distance parameter ρ.

[0027] Compared with the prior art, the beneficial effect of the present invention is that the present invention calculates and grasps that the diameter of the laser beam will change with the change of distance, and grasps the relationship between the changes of the two to measure and calculate the distance between the receiving and transmitting positions.

[0028] The present invention emits a distance measuring laser through a laser emitting unit. The distance measuring laser will diverge to a certain extent when propagating through one end distance. The beam diameter after the laser propagation is measured according to the receiving position. The laser quality analysis unit analyzes the beam, calculates the quality factor of the beam, obtains the beam waist width, far divergence angle and basement membrane beam waist width of the beam, and conveniently obtains the beam diameter after the laser propagation directly through the laser quality analysis unit.

[0029] In the process of calculating the distance parameter, the distance parameter value is obtained by measuring three groups of known distances, and then the average value of the distance parameter is calculated to obtain a more accurate distance parameter. The distance is then accurately calculated using the distance parameter and the beam diameter.

[0030] The present invention avoids the problem of large error in measuring laser propagation time due to the high speed of light during use. The measurement time error will make the measurement inaccurate due to the influence of the speed of light. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0032] Figure 2 This is a schematic diagram of the laser emission unit circuit in the present invention;

[0033] Figure 3 It is the working flow diagram of the system in the present invention;

[0034] Figure 4 Schematic diagram of the distance calculation unit structure in the present invention;

[0035] Figure 5 This is a workflow diagram of the distance calculation unit in the present invention.

[0036] In the figure: 1 laser emission unit, 2 beam quality analysis unit, 3 distance calculation unit, 301 coefficient calibration unit, 302 calculation output unit. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] See also Figure 1-5 , the present invention provides a technical solution:

[0039] A laser ranging system based on beam diameter change includes a laser emitting unit 1, a beam quality analysis unit 2 and a distance calculation unit 3. The laser emitting unit 1 is used to emit a ranging laser, the beam quality analysis unit 2 is used to analyze the beam quality factor of the beam, and the distance calculation unit 3 is used to calculate the distance between the laser emitting position and the receiving position according to the diameter of the beam.

[0040] In the present invention, the laser emitting unit 1 includes a single chip microcomputer, a laser diode group, a capacitor, a resistor, a diode and an inductor, wherein the single chip microcomputer IN+ pin pulls up R1 to 3.3V and pulls down R5 to the power supply ground, the single chip microcomputer IN- pin pulls up R2 to 3.3V and pulls down R6 to the power supply ground, the pin BEN+ pulls up R3 to 3.3V and pulls down R7 to the power supply ground, the pin BEN- pulls up R4 to 3.3V and pulls down R8 to the power supply ground, the OUT+ pin is connected to the resistor R12, the resistor R12 is connected to the ground in series with the resistor R8 and the capacitor C3, the cathode of D1 is connected to R11, R9 and L1 are connected in parallel, the anode of D1 is connected to the inductor L1, the other end of the inductor L1 is connected to the 3.3V power supply and C2 at the same time, the other end of C2 is connected to the power supply ground, and the laser diode group is connected to the anode of D1, R11 and the pin MD respectively. The laser diode group is composed of two LED lamps, and the anode of one LED lamp is connected to the cathode of the other LED lamp to form the laser diode group. R1, R2, R3 and R4 are 130Ω resistors, R5, R6, R7 and R8 are 82Ω resistors, C1 and C2 are 0.1uF capacitors, and L1 is a 10nH inductor.

[0041] The MAX3656 is a burst-mode laser driver that operates at data rates from 155Mbps to 2.5Gbps. The laser driver accepts either positive-emitter-coupled logic or current-mode logic data inputs and provides bias and modulation currents for the laser diode. The device switches the laser diode from a completely non-communication state to a fully communication state in less than 2ns. The MAX3656 laser driver is DC-coupled to the laser diode and operates from a single supply voltage as low as +3.0V. A digital automatic power control (APC) loop maintains average optical power constant over the entire temperature range and operating life. The APC loop operates with a minimum burst-on time of 576ns and a minimum burst-off time of 96ns; there is no limit on the maximum burst-on or -off time. A failure monitor indicates that the APC loop can no longer maintain a constant average power. The MAX3656 can be used in a non-burst-mode system (continuous mode) by connecting the burst-enable terminal (BEN) high. To save power, the MAX3656 provides enable and disable functions. Modulation current setting range: 10mA to 85mA; bias current setting range: 1mA to 70mA. Pulse laser is directly emitted through high-speed digital circuit, and the emission power can be automatically adjusted through input signal. Each item of driving current can be programmed by simply setting different resistors as needed, and the design is simple. The driving power circuit composed of MAX3656 operates stably and reliably.

[0042] In addition, the beam quality analysis unit 2 calculates the beam quality factor x of the beam as follows:

[0043]

[0044] Where D is the beam waist width, θ is the far-field divergence angle, and ρ is the base film waist width. The calculation formula for the far-field divergence angle θ is:

[0045]

[0046] Wherein, λ is the laser wavelength, and D0 is the beam waist diameter. The laser emitting unit emits a ranging laser, and the ranging laser will diverge to a certain extent when propagating through one end distance. The beam diameter after the laser propagation is measured according to the receiving position. The laser quality analysis unit 2 analyzes the beam, calculates the quality factor of the beam, obtains the beam waist width, far divergence angle and basement membrane waist width of the beam, and conveniently obtains the beam diameter after the laser propagation directly through the laser quality analysis unit. The laser quality analysis unit 2 can directly analyze the received laser through the laser mass analyzer, and directly read the diameter of the laser beam from the laser mass analyzer to calculate the distance S.

[0047] The distance calculation unit 3 includes a coefficient calibration unit 301 and a calculation output unit 302. The calculation formula of the coefficient calibration unit 301 is:

[0048]

[0049] The beam diameter D1 and the distance L1 are known when the distance parameters are calculated for the first time, the beam diameter D2 and the distance L2 are known when the distance parameters are calculated for the second time, and the beam diameter D3 and the distance L3 are known when the distance parameters are calculated for the third time. The calculation formula for calculating the distance S by the calculation output unit 302 is:

[0050] S = ρ·D;

[0051] Where ρ is the distance parameter and D is the beam diameter.

[0052] The working steps of the distance calculation unit (3) are:

[0053] Step S1: Given a known distance L and a known diameter D, calculate the distance parameters three times;

[0054] Step S2: taking the average of the three sets of distance parameters to obtain a more accurate parameter ρ;

[0055] Step S3: Calculate the distance S according to the beam diameter and the distance parameter ρ.

[0056] Before calculating the distance S, the distance parameter ρ needs to be calculated. The calculated distance parameter ρ is calculated and verified by measuring three sets of known distances, and then the average value of the distance parameter ρ is obtained to make the calculated value of the distance parameter ρ more accurate. After the value of the distance parameter ρ is calculated, the distance value can be obtained by measuring the beam diameter, and the value of the distance S is calculated by the formula S = ρ·D.

[0057] The specific working process of the present invention is as follows: when in use, a ranging laser is first emitted through the laser emitting unit 1. The ranging laser will diverge to a certain extent when propagating through the distance at one end. The laser quality analysis unit 2 is at the position where the laser is received. The laser quality analysis unit 2 measures the beam diameter after the laser propagates according to the receiving position. The laser quality analysis unit 2 analyzes the light beam, calculates the quality factor of the light beam, obtains the beam waist width, the far divergence angle and the basement membrane beam waist width of the light beam, and conveniently obtains the beam diameter after the laser propagates directly through the laser quality analysis unit. After measuring the beam diameter, the distance parameter value is obtained through three groups of known distances, and then the average value of the distance parameter is calculated to obtain a more accurate distance parameter. After obtaining the distance parameter, the distance S between the laser emitting position and the receiving position can be calculated by a calculation formula. Multiple groups of distances S can be calculated by moving the laser emitting unit 1 and the receiving position in parallel, and then the distance average is obtained to obtain a more accurate distance S.

[0058] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A laser distance measurement system based on beam diameter change, comprising a laser emission unit (1), a beam quality analysis unit (2) and a distance calculation unit (3), characterized in that: The laser emitting unit (1) is used to emit a distance-measuring laser, the beam quality analysis unit (2) is used to analyze the beam quality factor of the beam, and the distance calculation unit (3) is used to calculate the distance between the laser emitting position and the receiving position according to the diameter of the beam; the laser emitting unit (1) comprises a single-chip microcomputer, a laser diode group, a capacitor, a resistor, a diode and an inductor, wherein the single-chip microcomputer IN+ pin pulls up R1 to 3.3V and pulls down R5 to a power ground, the single-chip microcomputer IN- pin pulls up R2 to 3.3V and pulls down R6 to a power ground, the pin BEN+ pulls up R3 to 3.3V and pulls down R7 to a power ground, the pin BEN- pulls up R4 to 3.3V and pulls down R8 to a power ground, and the OUT+ pin is connected to a resistor R12, the resistor R12 is connected to the resistor R8 and the inductor Capacitor C3 is connected to the ground in series, the cathode of D1 is connected to R11, R9 and L1 are connected in parallel, the anode of D1 is connected to the inductor L1, the other end of the inductor L1 is connected to the 3.3V power supply and C2 at the same time, the other end of C2 is connected to the power supply ground, and the laser diode group is connected to the anode of D1, R11 and the pin MD respectively; the laser diode group is composed of two LED lamps, the anode of one LED lamp is connected to the cathode of the other LED lamp to form the laser diode group; R1, R2, R3 and R4 are 130Ω resistors, R5, R6, R7 and R8 are 82Ω resistors, C1 and C2 are 0.1uF capacitors, and L1 is a 10nH inductor; the beam quality analysis unit (2) calculates the beam quality factor × of the beam as follows: Where D is the beam waist width, θ is the far-field divergence angle, and ρ is the base film waist width; The calculation formula of the far-field divergence angle θ is: Where λ is the laser wavelength and DO is the beam waist diameter.

2. The laser ranging system based on beam diameter variation according to claim 1, characterized in that: The distance calculation unit (3) includes a coefficient calibration unit (301) and a calculation output unit (302).

3. The laser ranging system based on beam diameter variation according to claim 2, characterized in that: The calculation formula of the coefficient calibration unit (301) is: When the distance parameters are calculated for the first time, the beam diameter D1 and the distance L1 are known; when the distance parameters are calculated for the second time, the beam diameter D2 and the distance L2 are known; and when the distance parameters are calculated for the third time, the beam diameter D3 and the distance L3 are known.

4. The laser ranging system based on beam diameter variation according to claim 3, characterized in that: The calculation formula used by the calculation output unit (302) to calculate the distance S is: S = p·D; Where p is the distance parameter and D is the beam diameter.

5. The laser ranging system based on beam diameter variation according to claim 4, characterized in that: The working steps of the distance calculation unit (3) are: Step S1: Given a known distance L and a known diameter D, calculate the distance parameters three times; Step S2: taking the average of the three sets of distance parameters to obtain a more accurate distance parameter p; Step S3: Calculate the distance S according to the beam diameter and the distance parameter p.

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