Laser full-waveform distance measuring device and method based on correlated double sampling

Abstract

According to the laser full-waveform distance measuring device and method based on correlated double sampling, a high-transmissivity low-reflection spectroscope is adopted to complete light splitting of laser emitted by a laser emitting module, more than 99% of energy of the emitted laser is transmitted to form emitted light which is emitted to a target, and less than 1% of energy is reflected to form reference light which is emitted to the target. The reflected reference light is received by the laser receiving module, and the reflected light after the emitted light is irradiated to the target and the reference light are received by the same laser receiving module. The laser receiving module converts received reference light and emitted light into electric signals and outputs the electric signals to the control and processing module for processing, the control and processing module performs waveform calculation on the electric signals converted from the reference light and the received light, and due to the homology of the emitted light and the returned light, distance measurement errors caused by inconsistent light sources in the distance measurement process are eliminated, and the distance measurement accuracy is improved. Meanwhile, sampling noise of the laser receiving module can be suppressed through correlated double sampling of the emitted light and the received light, so that the sampling signal-to-noise ratio is improved, and the ranging precision is improved.

Description

Technical Field

[0001] The invention relates to a laser full waveform ranging device and method based on correlated double sampling, which is suitable for the field of short-range high-precision laser ranging or laser three-dimensional imaging. Background Art

[0002] The laser three-dimensional sensor uses pulse laser time-of-flight ranging technology. The existing pulse ranging technology uses a high-speed comparator to identify the time of the echo analog pulse, convert it into a termination timing digital signal, and then uses a time-to-digital conversion dedicated chip (TDC) to measure the flight time. The time measurement accuracy of this method is limited by the timing accuracy of the time-to-digital conversion chip and the signal-to-noise ratio of the echo pulse. The ranging accuracy can only reach 0.15m (3σ), and when the signal is saturated, the ranging accuracy drops sharply. In severe cases, the error exceeds 0.5m, which obviously cannot meet the current high-precision three-dimensional scanning ranging accuracy index requirements. In addition to the above technology, there is a literature that uses a reference light laser and a photoelectric detection tube for reference light detection. To a certain extent, it can solve the problem of poor ranging accuracy of the above-mentioned timing TDC chip solution. However, due to the same fluctuation problem of the reference light and the emitted light and the difference in the receiving circuit of the reference light and the echo light in its ranging principle, the ranging error is relatively large. Summary of the invention

[0003] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to design a close-range high-precision laser full-waveform ranging device and method based on correlated double sampling, to solve the problem that the ranging accuracy of traditional laser measurement is poor and the ranging accuracy further decreases when the signal is saturated.

[0004] The technical solution of the present invention is: a laser full waveform ranging device based on correlated double sampling, comprising: a laser transmitting module, a laser receiving module, a control and processing module and a spectroscope;

[0005] After the laser emitting module emits the laser, it is split by a beam splitter, the transmitted part is used as the emitted light to hit the target, and the reflected part is used as the reference light. The reflected reference light is received by the laser receiving module;

[0006] The laser receiving module converts the received reference light and the laser emission return light into electrical signals in real time;

[0007] The control and processing module processes the electrical signal output by the laser receiving module in real time, obtains the distance information and outputs it.

[0008] The beam splitter has the characteristics of high transmittance and low reflection, and completes the beam splitting of the laser emitted by the laser emission module. The transmittance is 99% to 99.5%, and the reflectivity is 0.5% to 1%.

[0009] A method for measuring distance using the device, comprising:

[0010] After the laser transmitting module emits the laser, it is split by the beam splitter. The transmitted part is used as the transmitted light to hit the target, and the reflected part is used as the reference light. The reflected reference light is received by the laser receiving module.

[0011] After the laser receiving module receives the reference light emitted by the laser, it is converted into an electrical signal by the photoelectric conversion circuit inside the laser receiving module. The electrical signal enters the control and processing module to calculate the time T1 when the reference light is emitted;

[0012] After the laser is emitted to the designated target position, the reflected return light enters the laser receiving module, and is converted into an electrical signal by the photoelectric conversion circuit inside the laser receiving module. The electrical signal enters the control and processing module, and is processed by the peak detection algorithm to calculate the target return light receiving time T2;

[0013] The distance from the device to the target is calculated based on the obtained times T1 and T2.

[0014] After being processed by the peak detection algorithm, the reference light emission time T1 is calculated.

[0015] After being processed by the peak detection algorithm, the target return light receiving time T2 is calculated.

[0016] The distance from the device to the target is d=0.5*C*(T2-T1), where C is the speed of light.

[0017] The spectroscope has high transmittance and low reflection characteristics, and completes the splitting of the laser emitted by the laser emission module, with a transmittance of 99% to 99.5% and a reflectivity of 0.5% to 1%.

[0018] The advantages of the present invention compared with the prior art are:

[0019] 1) The present invention uses a spectroscope reflected light to realize reference light, and the emitted light and the reference light are emitted from the same light source, ensuring the homology and simultaneity of the emitted light and the reference light, thereby eliminating the measurement error caused by the inconsistency between the emitted light and the reference light;

[0020] 2) After the emitted light of the device of the present invention hits the target, the return light and the reference light are received by the same laser receiving module, thereby ensuring the consistency of their reception. Since the sampling moments of the emitted light and the return light are relatively close, with a difference of nanoseconds, the sampling noise of the laser receiving module is correlated in a short time. Therefore, the correlated double sampling of the emitted light and the received light can suppress the sampling noise of the laser receiving module, thereby improving the sampling signal-to-noise ratio and the ranging accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Shown is a system block diagram of a short-range high-precision laser full-waveform ranging device based on correlated double sampling of the present invention;

[0022] Figure 2 The figure shows a waveform schematic diagram of a short-range high-precision laser full-waveform ranging device based on correlated double sampling of the present invention;

[0023] Figure 3 A schematic diagram of the process flow of a short-range high-precision laser full-waveform ranging device based on correlated double sampling provided by the invention; DETAILED DESCRIPTION

[0024] A high-precision laser full-waveform ranging device based on correlated double sampling is designed. Figure 1 The distance measurement principle of the high-precision laser full waveform distance measurement device based on correlated double sampling of the present invention is as follows: Figure 2 As shown, T1 is the moment when the laser emits the laser, and T2 is the moment when the laser returns to the laser receiving module after being reflected by the target. The time difference between T2 and T1 is the laser flight time from the device to the target, d=0.5*C*(T2-T1). The distance from the device to the target can be calculated by the speed of light C.

[0025] The present invention proposes a short-range high-precision laser full-waveform ranging device based on correlated double sampling. The specific implementation steps of the present invention are described below in conjunction with the accompanying drawings:

[0026] 1) The laser emission module emits laser light which is split by a spectroscope, wherein more than 99% of the energy of the emitted laser is transmitted to form the emitted light that hits the target, and less than 1% of the energy is reflected to form the reference light. The reflected reference light is received by the laser receiving module. The return light after the emitted light hits the target and the reference light are received by the same laser receiving module;

[0027] 2) After the laser receiving module receives the reference light emitted by the laser, it is converted into an electrical signal by the photoelectric conversion circuit inside the laser receiving module. The electrical signal enters the control and processing module, and is processed by the peak detection algorithm to calculate the reference light emission time T1;

[0028] 3) After the laser is emitted to the designated target position, the reflected return light enters the laser receiving module, and is converted into an electrical signal by the photoelectric conversion circuit inside the laser receiving module. The electrical signal enters the control and processing module, and is also processed by the peak detection algorithm to calculate the time T2;

[0029] 4) According to the obtained time T2 and time T1, according to the light flight time, the distance from the device to the target is calculated to be d=0.5*C*(T2-T1), where C is the speed of light.

[0030] like Figure 3 As shown in the figure, it is a close-range high-precision laser full-waveform ranging device based on correlated double sampling. The specific process is as follows:

[0031] (1) Control the power supply of the device through an external power supply;

[0032] (2) Initialize the configuration of the device;

[0033] (3) The device enters standby mode;

[0034] (4) Sending ranging instructions externally;

[0035] (5) After receiving the ranging command, the device emits laser through the laser emission module;

[0036] (6) The laser emission module in step 5 emits laser light which is split by a spectroscope, wherein more than 99% of the energy of the emitted laser light is transmitted to form emission light that hits the target, and less than 1% of the energy is reflected to form reference light;

[0037] (7) After the reference light in step 5 and step 6 reaches the laser receiving module, the laser receiving module receives the reference light and converts it into an electrical signal;

[0038] (8) The laser receiving module described in step 7 receives the reference light and converts it into an electrical signal and then outputs it to the control and processing module. The control and processing module completes the peak detection of the reference photoelectric signal to obtain the time T1;

[0039] (9) The laser transmitting module in step 5 and step 6 transmits light that reaches the measurement target and is reflected as return light, and the laser receiving module receives the return light and converts it into an electrical signal;

[0040] (10) The laser receiving module described in step 9 receives the return light and converts it into an electrical signal and then outputs it to the control and processing module. The control and processing module completes the peak detection of the return optical signal and calculates the time T2;

[0041] (11) The control and processing module calculates the distance information d according to the light speed flight time formula d=0.5*C*(T2-T1), where C is the speed of light.

[0042] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A laser full waveform ranging device based on correlated double sampling, characterized in that: It includes: laser emission module, laser receiving module, control and processing module and spectroscope; After the laser emitting module emits the laser, it is split by a beam splitter, the transmitted part is used as the emitted light to hit the target, and the reflected part is used as the reference light. The reflected reference light is received by the laser receiving module; The laser receiving module converts the received reference light and the laser emission return light into electrical signals in real time; The control and processing module processes the electrical signal output by the laser receiving module in real time, obtains the distance information and outputs it.

2. The device according to claim 1, characterized in that The beam splitter has the characteristics of high transmittance and low reflection, and completes the beam splitting of the laser emitted by the laser emission module. The transmittance is 99% to 99.5%, and the reflectivity is 0.5% to 1%.

3. A method for measuring distance using the device of claim 1, characterized in that: include: After the laser transmitting module emits the laser, it is split by the beam splitter. The transmitted part is used as the transmitted light to hit the target, and the reflected part is used as the reference light. The reflected reference light is received by the laser receiving module. After the laser receiving module receives the reference light emitted by the laser, it is converted into an electrical signal by the photoelectric conversion circuit inside the laser receiving module. The electrical signal enters the control and processing module to calculate the time T1 when the reference light is emitted; After the laser is emitted to the designated target position, the reflected return light enters the laser receiving module, and is converted into an electrical signal by the photoelectric conversion circuit inside the laser receiving module. The electrical signal enters the control and processing module, and is processed by the peak detection algorithm to calculate the target return light receiving time T2; The distance from the device to the target is calculated based on the obtained times T1 and T2.

4. The method according to claim 3, characterized in that After being processed by the peak detection algorithm, the reference light emission time T1 is calculated.

5. The method according to claim 3, characterized in that: After being processed by the peak detection algorithm, the target return light receiving time T2 is calculated.

6. The method according to claim 3, characterized in that The distance from the device to the target is d=0.5*C*(T2-T1), where C is the speed of light.

7. The method according to claim 3, characterized in that The beam splitter has the characteristics of high transmittance and low reflection, and completes the beam splitting of the laser emitted by the laser emission module. The transmittance is 99% to 99.5%, and the reflectivity is 0.5% to 1%.

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