Time-slotted laser tof array ranging imaging system based on pseudo-random sequences

Abstract

The application belongs to the technical field of laser array ranging imaging detection, and relates to a pseudo-random sequence time-slot laser TOF array ranging imaging system, which comprises a semiconductor laser, an adjustable laser light source controller, a laser receiving and converging lens, an APD light intensity detector, a distance solving and imaging system and a computer. The semiconductor laser generates a composite laser beam with different waveforms. The strong autocorrelation and weak cross-correlation of the pseudo-random sequence are used to solve the laser signals emitted by corresponding devices and eliminate irrelevant signals, so that the anti-interference purpose is achieved. The proportion of time-slot signals of the laser signals can be flexibly adjusted, or more laser signals with different waveforms can be modulated. The advantages of various laser waveforms in ranging imaging are fully utilized, so that the purpose of imaging different distance targets is achieved. If the image optimization algorithm is combined, the signal-to-noise ratio and definition of the reconstructed image can be further improved, and high-resolution and long-distance array laser ranging imaging is realized.

Description

Technical Field

[0001] This invention, a time-slotted laser TOF array ranging and imaging system based on pseudo-random sequences, belongs to the field of laser array ranging and imaging detection technology. Background Technology

[0002] Laser ranging and imaging technology is an important technology in laser detection, with wide applications in target recognition, tracking, and space exploration. When imaging a target, different laser types and frequencies emphasize different aspects of the distance and target details obtained. Using a single-waveform laser for target ranging makes it impossible to simultaneously achieve both image quality and imaging distance. These effects are more pronounced in complex detection environments, making it difficult for traditional laser ranging and imaging systems to obtain high-quality distance images of the target.

[0003] Continuous wave lasers are the most commonly used waveform in laser ranging and imaging, but they are subject to interference from factors such as natural light at longer distances, resulting in shorter measured distances and thus having certain limitations. Pseudo-random sequence pulse lasers have better anti-interference capabilities in ranging, but they may collect less detailed information about the target object, resulting in lower imaging resolution. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides a time-slotted laser TOF array ranging and imaging system based on pseudo-random sequences. This system can utilize an adjustable laser source controller to flexibly adjust the proportion of time slot signals of two different waveform laser beams, thereby improving the imaging quality of laser array ranging and imaging technology by combining the precision and reliability of the TOF ranging principle.

[0005] The objective of this invention is achieved as follows:

[0006] A time-slotted laser TOF array ranging and imaging system based on pseudo-random sequences includes a semiconductor laser, an adjustable laser source controller, a laser receiving and converging lens, an APD light intensity detector, a distance calculation and imaging system, and a computer.

[0007] The semiconductor laser is used to emit lasers of different waveforms and / or frequencies toward a target and match different targets in time slots to form a composite laser beam.

[0008] The adjustable laser source controller is used to control the semiconductor laser to emit lasers of different waveforms and / or different frequencies.

[0009] The laser receiving and converging lens is used to converge the composite laser beam reflected by the target to the effective sensing and receiving area of ​​the APD light intensity detector.

[0010] The APD light intensity detector is used to collect the intensity information of the light beam after it has been focused by the laser receiving and converging lens.

[0011] The distance calculation and imaging system is used to calculate the beam intensity information detected by the APD light intensity detector and convert it into a distance image of array ranging.

[0012] The computer is connected at one end to the adjustable laser source controller and at the other end to the distance calculation and imaging system.

[0013] The aforementioned time-slotted laser TOF array ranging and imaging system based on pseudo-random sequences emits two different waveforms of laser beams from a semiconductor laser; the continuous wave has a working wavelength of 1550nm or 1064nm, and the pseudo-random sequence pulse laser has a sequence length between 64 and 128.

[0014] The proportion of the time slot signals of two different waveform laser beams is adjusted according to the different distances from the semiconductor laser to the target.

[0015] or / and

[0016] Depending on the required imaging details, the proportion of the time slot signals of the two different waveform laser beams is adjusted.

[0017] The aforementioned time-slotted laser TOF array ranging and imaging system based on pseudo-random sequences utilizes the TOF principle for distance measurement in its distance calculation and imaging system.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] First, the target is illuminated by the characteristics of laser beam ranging with different waveforms and frequencies. The semiconductor laser is controlled by an adjustable laser source controller to generate composite laser beams with different waveforms. The strong autocorrelation and weak cross-correlation of the pseudo-random sequence are used to calculate the laser signal emitted by the corresponding device to the maximum extent, while eliminating other irrelevant signals to achieve the purpose of anti-interference.

[0020] Secondly, for targets at different distances, the proportion of different time slots of the laser signal can be flexibly adjusted, or more waveforms of laser signal can be modulated to adapt to more application scenarios. Compared with the current method of using a single laser waveform for ranging, this invention can flexibly adjust the working mode and make full use of the ranging and imaging advantages of various laser waveforms. If combined with image optimization algorithms, it will help to further improve the signal-to-noise ratio and clarity of the reconstructed image, and realize high-resolution, long-distance array laser ranging imaging. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the composition and ranging imaging process of the laser array ranging system provided by the present invention.

[0022] Figure 2 This is a schematic diagram of the composite time-slot laser beam described in this invention, i.e., laser types with different proportions.

[0023] Figure 3 This is a schematic diagram of a pseudo-random sequence.

[0024] Figure 4 This is a schematic diagram of the autocorrelation of a pseudo-random sequence.

[0025] In the diagram: 1 Semiconductor laser, 2 Adjustable laser source controller, 3 Laser receiving and converging lens, 4 APD light intensity detector, 5 Distance calculation and imaging system, 6 Computer, 7 Target. Detailed Implementation

[0026] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Method 1

[0028] The time-slot laser TOF array ranging and imaging system based on pseudo-random sequences in this specific implementation is as follows: Figure 1 As shown, it includes a semiconductor laser 1, an adjustable laser source controller 2, a laser receiving and converging lens 3, an APD light intensity detector 4, a distance calculation and imaging system 5, and a computer 6.

[0029] The semiconductor laser 1 is used to emit lasers of different waveforms and / or different frequencies toward the target 7, and to match different targets 7 in time slots to form a composite laser beam.

[0030] The adjustable laser source controller 2 is used to control the semiconductor laser 1 to emit lasers of different waveforms and / or different frequencies;

[0031] The laser receiving and converging lens 3 is used to converge the composite laser beam reflected by the target 7 to the effective sensing and receiving area of ​​the APD light intensity detector 4.

[0032] The APD light intensity detector 4 is used to collect the intensity information of the light beam after it has been focused by the laser receiving and converging lens 3.

[0033] The distance calculation and imaging system 5 is used to calculate the beam intensity information detected by the APD light intensity detector 4 and convert it into a distance image of array ranging.

[0034] The computer 6 is connected at one end to the adjustable laser light source controller 2 and at the other end to the distance calculation and imaging system 5.

[0035] First, fix the semiconductor laser 1 and install it in front of the adjustable laser source controller 2. Then, connect the adjustable laser source controller 2 to the computer 6 to perform laser modulation for matching the relevant target. Next, fix the reflected beam receiving device and place the laser receiving converging lens 3 between the target 7 and the APD light intensity detector 4, so that the beam reflected by the target 7 is focused into the effective receiving area of ​​the APD light intensity detector 4. Then, the photoelectric signal detected by the APD light intensity detector 4 is transmitted to the subsequent distance calculation and imaging system 5 to obtain specific array distance information. Finally, the information is converted and presented on the computer 6 to show the final distance image.

[0036] Method 2

[0037] The time-slotted laser TOF array ranging and imaging system based on pseudo-random sequences in this specific embodiment, based on specific embodiment one, is further defined as follows: the semiconductor laser 1 emits two different waveforms of laser beams; the continuous wave operates at a wavelength of 1550nm or 1064nm, and the sequence length of the pseudo-random sequence pulsed laser is between 64 and 128. Figure 2 As shown.

[0038] The pseudo-random sequence and its autocorrelation diagram are shown below. Figure 3 , Figure 4 As shown in the figure. It can be seen from the figure that... Figure 4 The signal is most correlated at the position with the largest autocorrelation coefficient, that is, at the correlation peak. From this, the time delay between the echo signal and the original reference signal can be obtained, and the distance information of the target can be calculated.

[0039] Method 3

[0040] The time-slot laser TOF array ranging and imaging system based on pseudo-random sequences in this specific embodiment is further defined based on the first embodiment:

[0041] Depending on the distance between semiconductor laser 1 and target 7, adjust the proportion of the time slot signals of two different waveform laser beams; or / and

[0042] Depending on the required imaging details, the proportion of the time slot signals of the two different waveform laser beams is adjusted.

[0043] Method 4

[0044] The time-slotted laser TOF array ranging and imaging system based on pseudo-random sequences in this specific embodiment, based on the first embodiment, is further defined as follows: the distance calculation and imaging system 5 utilizes the TOF (Time-of-Flight) principle for ranging. The TOF principle formula is as follows:

[0045]

[0046] Among them, H f T represents the distance from the laser emission location to target 7. t T represents the time interval between the transmitter emitting a laser signal and the receiver receiving a response signal. r This represents the time interval between the receiver receiving the laser signal from the transmitter and sending a response signal, where c represents the laser propagation speed.

[0047] It should be noted that the above is only the ranging information for one channel. To achieve imaging capabilities, multiple similar channels need to be arranged in an array. In this specific implementation, a 320×240 array with a number of channels is used.

[0048] In this invention:

[0049] First, the target 7 is irradiated by using the rangefinding characteristics of laser beams with different waveforms and frequencies. The semiconductor laser 1 is controlled by the adjustable laser source controller 2 to generate composite laser beams with different waveforms. The strong autocorrelation and weak cross-correlation of the pseudo-random sequence are used to calculate the laser signal emitted by the corresponding device to the maximum extent, while eliminating other irrelevant signals to achieve the purpose of anti-interference.

[0050] Strong autocorrelation means that the emitted original reference signal and the received echo signal have a good correlation, which can be "selected" from many complex signals; while weak cross-correlation is relative to strong autocorrelation, where the echo signal has a poor correlation with other different types of signals, that is, the cross-correlation is weak, which is beneficial for the differentiation between signals.

[0051] Secondly, for targets 7 at different distances, the proportion of different time slots of the laser signal can be flexibly adjusted, or more waveforms of laser signal can be modulated to adapt to more application scenarios. Therefore, compared with the current method of using a single laser waveform for ranging, this invention can flexibly adjust the working mode and make full use of the ranging and imaging advantages of various laser waveforms. If combined with image optimization algorithms, it will help to further improve the signal-to-noise ratio and clarity of the reconstructed image, and realize high-resolution, long-distance array laser ranging imaging.

[0052] In specific experiments, it was found that using continuous wave laser signals, due to the complexity of the signal, can obtain more information about target 7. However, continuous wave signals are easily interfered with by natural light and other signals, so the transmission distance is relatively short. On the other hand, PN sequence pulsed lasers are not easily interfered with, but because the signal is relatively simple, the information about target 7 carried is relatively less. Therefore, the specific time slot allocation can be flexibly adjusted according to the requirements for the amount of information about target 7, the distance requirements, the accuracy requirements, and the anti-interference requirements.

[0053] It should be noted that the above are merely specific embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0054] It should also be noted that all the technical features listed in the above specific embodiments can be arranged and combined, as long as they are not contradictory. Those skilled in the art can exhaustively calculate the result of each arrangement and combination based on the mathematical knowledge of permutations and combinations learned in high school. All the results of permutations and combinations should be understood as being disclosed in this application.

Claims

1. A time-slotted laser TOF array ranging and imaging system based on pseudo-random sequences, characterized in that: It includes a semiconductor laser (1), an adjustable laser source controller (2), a laser receiving and converging lens (3), an APD light intensity detector (4), a distance calculation and imaging system (5), and a computer (6). The semiconductor laser (1) is used to emit lasers of different waveforms toward the target (7) and match different targets (7) in time slots to form a composite laser beam; The adjustable laser source controller (2) is used to control the semiconductor laser (1) to emit lasers of different waveforms; The proportion of the time slot signals of two different waveform laser beams is adjusted according to the different distances from the semiconductor laser (1) to the target (7); or / and The proportion of the time slot signals of the two different waveform laser beams is adjusted according to the different imaging detail requirements; The laser receiving converging lens (3) is used to converge the composite laser beam reflected by the target (7) to the effective sensing and receiving area of ​​the APD light intensity detector (4). The APD light intensity detector (4) is used to collect the intensity information of the beam after it has been focused by the laser receiving focusing lens (3); The distance calculation and imaging system (5) is used to calculate the beam intensity information detected by the APD light intensity detector (4) and convert it into a distance image of array ranging. The computer (6) is connected at one end to the adjustable laser light source controller (2) and at the other end to the distance calculation and imaging system (5).

2. The time-slotted laser TOF array ranging and imaging system based on pseudo-random sequences according to claim 1, characterized in that: The semiconductor laser (1) emits two different waveforms of laser beams; the continuous wave has a working wavelength of 1550nm or 1064nm, and the pseudo-random sequence pulse laser has a sequence length between 64 and 128.

3. The time-slotted laser TOF array ranging and imaging system based on pseudo-random sequences according to claim 1, characterized in that: The distance calculation and imaging system (5) uses the TOF principle to measure distance.

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