CN101866056A - Three-dimensional imaging method and system based on LED array common lens TOF depth measurement - Google Patents

Abstract

The invention discloses a three-dimensional imaging method and system based on LED array common-lens TOF depth measurement. A two-dimensional LED array is used as an illumination light source, and only one LED is lit each time, and the modulated light emitted by the LED is projected through a projection lens. To the surface of the target, the photoelectric receiver receives the scattered light of the target surface, measures the round-trip flight time from the light source to the target, and obtains the LED depth pixel value in the lit state from it, and completes the single LED depth pixel value measurement; Time division scans the entire two-dimensional LED array, repeats the measurement process of a single LED depth pixel value, obtains all LED depth pixel values and combines them to generate a depth image of the target; at the same time, the scattered light on the target surface is obtained by the two-dimensional image sensor after passing through the two-dimensional imaging lens The two-dimensional image of the target; the projection lens and the two-dimensional imaging lens are the same lens; the three-dimensional image of the target is generated by fusing the two-dimensional image and the depth image. The invention has fast depth image acquisition speed and high depth measurement resolution.

Description

Three-dimensional imaging method and system based on LED array common lens TOF depth measurement

technical field

The invention relates to the technical fields of ranging imaging and three-dimensional imaging, in particular to a three-dimensional imaging method and system based on LED array common-lens TOF depth measurement.

Background technique

The existing two-dimensional 2D imaging technology based on CCD/CMOS photography and digital image processing has made great progress and has been widely used. However, for the 3D real world, the 2D image obtained by traditional 2D imaging technology is not enough to fully express all the information, thus limiting its application in many fields. In order to solve the above problems, three-dimensional imaging (3D Imaging) technology came into being. Three-dimensional imaging refers to recording the three-dimensional image of the objective world through a special method, and then reproducing the objective real image in the human brain through processes such as processing, compression, transmission, and display. Compared with two-dimensional imaging in the usual sense, three-dimensional imaging contains third-dimensional distance or depth information, which can more fully describe the position and motion information of objects in a real three-dimensional scene, so it has many outstanding advantages. , Physical profiling, industrial testing, biomedicine, reverse engineering, virtual reality and other fields have broad application prospects.

The 3D imaging technology based on optical ranging has gradually become a research hotspot at home and abroad due to its advantages of high resolution and no contact. Most of the currently researched optical 3D imaging systems measure distance based on triangulation or time-of-flight (TOF) principles. Three-dimensional imaging systems based on triangulation ranging, including passive triangulation (such as stereo vision) and active triangulation (such as projected structured light), they all need to deal with the "shadow" effect or "blurring" of projected fringes, so strict limit their scope of application. For example, the stereo vision method can generally only be used for the recognition and analysis of targets in 3D scenes with high contrast, because when this method determines the distance information of the third dimension, it needs to perform feature points on two or more images acquired in different visual directions. Therefore, complex signal processing and a large amount of time-consuming data calculation are required; in addition, in practical applications, the target often lacks characteristic structural information or the reflectivity of each point on the target has no obvious difference, and the matching calculation will become very complicated at this time. Difficulties or even errors, depth measurement accuracy will be seriously affected.

Compared with the triangulation method, the distance measurement method based on time-of-flight TOF will not produce incomplete data because the transmitting unit and the receiving unit are on the same straight line, and there is no "shadow" effect, which makes the time-of-flight based TOF The ranging method has a wider range of applications. However, traditional TOF-based optical 3D imaging systems, such as LiDAR, can actually only measure the distance of a point (one-dimensional ranging). In order to obtain three-dimensional information, it is necessary to use a precise, bulky and expensive mechanical scanning device to mechanically scan the laser beam on the measured scene in the other two directions, so the depth image acquisition speed is slow and the real-time performance is poor; due to the mechanical scanning device itself There are aging and wear phenomena, and the alignment accuracy between the depth image and the 2D image obtained by this method is poor. In addition, it is difficult for the system to achieve breakthrough improvements in terms of vibration resistance, volume, weight and cost.

Contents of the invention

The purpose of the present invention is to propose a three-dimensional imaging method based on LED array common lens TOF depth measurement for the shortcomings of the existing three-dimensional imaging method and system, such as slow depth image acquisition speed and poor alignment accuracy between the depth image and the two-dimensional image. And the system is used to realize fast and high-precision three-dimensional imaging, which meets the urgent demand for high-performance three-dimensional imaging in many existing fields.

The technical scheme that the present invention solves its technical problem to take is:

The present invention is based on the three-dimensional imaging method of LED array common lens TOF depth measurement, and its characteristics are:

A two-dimensional LED array modulated by optical power is used as an illumination source, and only one LED in the two-dimensional LED array is turned on each time, and the modulated light emitted by the LED is projected onto the surface of the target through a projection lens, and is used The photoelectric receiver receives the scattered light from the surface of the target, measures the round-trip time of flight TOF from the light source to the target, calculates the depth pixel value of the LED in the lit state according to the round-trip time of flight TOF, and completes a single LED Measurement of depth pixel values;

Time division scans the entire two-dimensional LED array, repeats the measurement process of the single LED depth pixel value, obtains all LED depth pixel values and combines them to generate a depth image of the target; at the same time, the scattered light on the target surface passes through the two-dimensional imaging lens The CCD/CMOS image sensor receives and obtains the two-dimensional image of the target; the projection lens and the two-dimensional imaging lens are set as the same lens, so that the depth image and the two-dimensional image are aligned in real time;

The 2D image and the depth image are fused to generate a 3D image of the target.

The feature of the three-dimensional imaging method based on LED array common lens TOF depth measurement of the present invention is that a beam splitter is set, and the modulated light emitted by the LED light source is transmitted through the beam splitter to reach the projection lens; the scattered light on the target surface passes through two After the three-dimensional imaging lens, it is reflected by the beam splitter mirror to reach the two-dimensional CCD/CMOS image sensor.

The characteristics of the three-dimensional imaging system based on LED array common lens TOF depth measurement of the present invention are:

Set the photoelectric modulation scanning circuit to modulate and time-division scan the output light power of the N×M LED array. At any time, only one LED in the entire LED array is lit; the modulated light emitted by the LED reaches the beam splitter and is divided into Transmitted light and reflected light, the transmitted light is projected on the surface of the target through the lens, and the scattered light generated by the target surface is received by the photoelectric receiver PD1; the reflected light is directly received by the photoelectric receiver PD2;

The TOF depth measurement circuit (8) is set, and the photoelectric signals output by the photoelectric receiver PD1 and the photoelectric receiver PD2 are processed respectively with the TOF depth measurement circuit (8), and each LED depth pixel value is calculated in turn, and the depth pixel value of the LED is Values are combined in the PC to generate the depth image of the target; at the same time, the scattered light on the target surface is received by the two-dimensional CCD/CMOS image sensor after being reflected by the lens and the beam splitter mirror, and obtained by the two-dimensional image signal processing circuit. A two-dimensional image of the target to which the image is aligned in real time;

The depth image and the two-dimensional image are fused in the PC to generate a three-dimensional image of the target.

The system of the present invention is also characterized in that a feedback automatic gain control AGC circuit is included in the TOF depth measurement circuit, and the feedback AGC circuit uses a square amplitude detection circuit to detect the amplitude of the input signal, and the output signal is passed through the second After the fixed gain amplifier circuit, it is sent to the inductance resistance LR low-pass filter to filter out the high-order harmonics generated, and the output DC level is used to control the gain of the variable gain amplifier circuit; the input signal is passed through the variable gain After being amplified by the amplifying circuit and the first fixed gain amplifying circuit, the output signal of the feedback AGC circuit is obtained.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

1. The present invention uses fast electronically scanned two-dimensional LED arrays as the lighting source, and imaging does not require any mechanical moving and rotating parts;

2. The present invention builds a feedback AGC circuit with high gain control precision and fast response by using a high-precision, fast square amplitude detection circuit and an LR low-pass filter with a short response time, and uses it for fast TOF depth measurement, The depth image acquisition speed of the imaging system is fast, and the depth measurement resolution is high;

3. In the present invention, the two-dimensional image and the depth image share the same lens for imaging, which can overcome the inherent aberration problem caused by using different lenses for imaging, and can realize real-time high-precision alignment between the depth image and the two-dimensional image;

4. A high-density two-dimensional LED array can be obtained by densely packaging the LED dies. Therefore, the imaging system of the present invention has a large number of depth image pixels and high spatial resolution;

5. The imaging system in the present invention filters out the DC component generated by the action of ambient light in the received photoelectric signal through the AC coupling of a small capacitor, so the imaging system has a strong ability to resist ambient light interference.

6. The imaging system of the present invention has simple structure, small volume and low cost.

Description of drawings

Fig. 1 is a schematic diagram of the structure principle of the present invention.

Figure 2 is a block diagram of the feedback AGC circuit structure.

Fig. 3 is a specific implementation of depth image acquisition.

Detailed ways

In this embodiment, the three-dimensional imaging method based on LED array common lens TOF depth measurement is carried out as follows:

1. A two-dimensional LED array modulated by optical power is used as the lighting source. Only one LED in the two-dimensional LED array is lit at a time, and the modulated light emitted by the LED is projected onto the surface of the target 1 through the projection lens. The receiver 6 receives the scattered light on the surface of the target 1, measures the round-trip time of flight TOF from the light source to the target 1, calculates the depth pixel value of the LED in the lit state according to the round-trip time of flight TOF, and completes the depth pixel value of a single LED. Measurement;

2. Scan the entire two-dimensional LED array in time division, repeat the measurement process of the depth pixel value of a single LED, obtain all the depth pixel values of the LED and combine them to generate the depth image of the target 1; at the same time, the scattered light on the surface of the target 1 passes through the two-dimensional imaging lens. The two-dimensional CCD/CMOS image sensor 9 receives and obtains the two-dimensional image of the target 1; the projection lens and the two-dimensional imaging lens are set as the same lens 2, so that the depth image and the two-dimensional image are aligned in real time;

3. The 2D image and the depth image are fused to generate a 3D image of the target 1 .

In the specific implementation, the beam splitter 3 is set, and the modulated light emitted by the LED light source is transmitted through the beam splitter 3 and reaches the projection lens; the scattered light on the surface of the target 1 passes through the two-dimensional imaging lens, and then is reflected by the beam splitter 3 to reach the two-dimensional imaging lens. Dimensional CCD/CMOS image sensor9.

In this embodiment, the specific implementation of the three-dimensional imaging system based on LED array common lens TOF depth measurement is as follows:

Referring to Fig. 1, the photoelectric modulation scanning circuit 5 is set to modulate and time-divisionally scan the output optical power of the N×M LED array 4. At any time, only one LED in the entire LED array 4 is lit; the modulated light emitted by the LED After reaching the beam splitter 3, it is divided into transmitted light and reflected light. The transmitted light is projected on the surface of the target 1 through the lens 2, and the scattered light generated by the surface of the target 1 is received by the PD1 photoelectric receiver 6; the reflected light is directly sent by the PD2 photoelectric receiver 7 Receive; set the TOF depth measurement circuit 8, process the photoelectric signals output by the PD1 photoelectric receiver 6 and the PD2 photoelectric receiver 7 respectively with the TOF depth measurement circuit 8, and calculate the depth pixel value of each LED in turn, and the depth pixel value of the LED is in the PC 11 The depth image of the target 1 is generated in combination; at the same time, the scattered light on the surface of the target 1 is received by the two-dimensional CCD/CMOS image sensor 9 after being reflected by the lens 2 and then beam splitter 3, and obtained by the two-dimensional image signal processing circuit 10. The depth image is aligned with the two-dimensional image of the target 1 in real time; the depth image and the two-dimensional image are fused in the PC to generate a three-dimensional image of the target 1.

In this embodiment, a feedback automatic gain control AGC circuit is included in the TOF depth measurement circuit 8. The feedback automatic gain control AGC circuit uses the square amplitude detection circuit 15 to detect the amplitude of the input signal, and the output signal is fixed by the first After the gain amplifying circuit 16, it is sent to the inductance-resistor LR low-pass filter 14 to filter out the high-order harmonics generated, and the output DC level is used to control the gain of the variable gain amplifying circuit 12 . After the input signal is amplified by the variable gain amplifier circuit 12 and the second fixed gain amplifier circuit 13 , the output signal of the feedback AGC circuit 22 is finally obtained.

TOF ranging is to obtain the measured distance by applying the constant speed of light c and measuring the flight time t of light. The depth value of each LED pixel in the LED array can be obtained by the photoelectric phase-shift TOF ranging method, that is, the output optical power of the LEDs in the array is modulated by a continuous sine wave with frequency f _m , and the round-trip of light will be directly measured The time of flight t is transformed into an indirect measurement of the phase shift ΔΦ of the modulated electrical signal corresponding to t to obtain the measured distance d:

$\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; ct</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span>\frac{\mathrm{<span\; class="notranslate">\; \&Delta;\&Phi;</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; 4</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&Delta;\&Phi;</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Since the flight speed of light is very fast, this method can avoid the difficulty of directly measuring the extremely short flight time of light, and at the same time can obtain high ranging resolution.

FIG. 3 is a specific implementation of depth image acquisition, which is also an embodiment of the TOF depth measurement circuit 8 . First use the continuous sine wave generated by the modulation source 17 with a frequency of f _m to modulate the output light power of the LEDs in the N×M LED array 4 through the driver 18, and project the output modulated light onto the target 1 through the lens 2, Then, the photoelectric receiver PD1 is used to receive the scattered light signal on the surface of the target 1, and after converting it into a corresponding electrical signal, the AC coupling effect of a small capacitor is used to filter out the signal that is mainly generated by the ambient light and affects the resolution of the depth measurement. frequency DC component, then use the low noise amplifier 19 to amplify the AC component in the signal, and perform frequency difference processing with the f _o local oscillator 21 to obtain the low intermediate frequency signal f _I ; then use the fast feedback AGC circuit 22 to it Perform automatic gain control and send it to the bandpass filter 23 for filtering processing, and finally use the "four-point" phase algorithm in the phase shift detection module 24 to perform phase detection on the obtained intermediate frequency signal f _I with high SNR.

Another PD2 receiving and processing channel in the imaging system is used as a reference channel to directly receive the LED light signal without lens projection. The signal processing flow of this reference channel is exactly the same as that of the previous one. Drift is the error introduced by the phase shift measurement. In specific implementation, if the temperature drift of the circuit does not introduce much error to the phase shift measurement, the photoelectric receiver PD2 and its corresponding receiving processing channel can also be removed from the system, and the sinusoidal modulation signal generated by the modulation source 17 can be directly used as the phase measurement the reference signal.

In addition, the two PD receiving channels adopt the weak photoelectric signal processed by the full differential method, the purpose is to suppress the common mode interference signal, improve the signal-to-noise ratio of the imaging system, and improve the final depth measurement resolution.

After the phases of the two intermediate frequency signals are respectively measured, the phase shift ΔΦ corresponding to the time of flight of the light can be obtained by making a difference between the two in the phase shift detection module 24 . Finally, the obtained phase shift ΔΦ is brought into the formula (1), and the final measured distance d can be obtained through the processing unit circuit, and the corresponding result is sent to the PC 11. After obtaining the distance of a single LED depth pixel, the acquisition of the entire depth image is finally realized by time-division scanning of the two-dimensional LED array.

Time division scanning control process:

When the imaging system is working, each LED in the array is turned on sequentially at a certain time interval until the entire LED array is traversed. At any moment, only one LED in the entire array is on, while the other LEDs are off, and the duration of each LED is also fixed, which is based on the number of pixels in the depth image of the imaging system determined by the needs of practical applications. For example, N=M=10, that is, for an LED array with a depth of 10×10 pixels, if the actual application requires a dynamic measurement speed of 10 frames per second, then the fixed duration of each LED in the array is 1ms; during this 1ms time Inside, the imaging system needs to complete the fast TOF distance measurement of an LED depth pixel and the sending of the result. After that, the imaging system turns off the LED, lights up the next adjacent LED light, and enters the next 1ms cycle depth pixel measurement. And the result is sent; and so on, until the entire LED array is traversed to complete the measurement of the depth image of one frame and enter the cycle measurement of the next frame.

The feedback AGC circuit 22 is used in the TOF depth measurement circuit 8 to process the mixed intermediate frequency signal, which can prevent the photoelectric signal received by the photoelectric receiver PD1 from introducing phase shift or distance measurement error due to its own amplitude difference. Since the automatic gain control of the intermediate frequency signal needs to be performed in a very short time, the AGC circuit is required to have a very short response time. For example, for an LED array with a depth pixel of 10×10, if the actual application requires a dynamic measurement speed of 10 frames per second, then the measurement time t _S of each LED depth pixel = 1ms. In order to ensure a high depth measurement resolution, the AGC circuit The response time t _R should be much shorter than t _S , for example, t _R =t _S /10 = 0.1 ms. And the traditional feedback AGC circuit often needs longer response time (generally greater than the second level), such as using diode detection, RC filter AGC circuit, does not meet the application requirements here; although the existing feedforward AGC circuit has many Short response time, but because of its poor gain control accuracy, it cannot be used in high-precision phase shift or distance detection occasions.

Figure 2 is a block diagram of a feedback AGC circuit with high gain control precision and fast response, in which the amplitude and frequency of the input intermediate frequency signal are about 0.5-20mV _pp and 10KHz-1MHz. The square amplitude detection circuit 15 that detects the amplitude of the input signal can be a double-balanced analog multiplier with a short response time, and the variable gain amplifier circuit 12 can use a differential current mode gain control circuit, the first fixed gain amplifier circuit 13 and the second The two fixed-gain amplifying circuits 16 are common differential amplifiers. The signal output by the second fixed-gain amplifying circuit 16 is sent to the LR low-pass filter 14 to filter out the high-order harmonics generated, which utilizes the characteristic that the inductive reactance of the inductor increases as the frequency of the input signal increases , so the filter has a very short response time in addition to a good low-pass filtering effect, which is obviously better than 0.1ms. The output DC level of the LR low pass filter 14 is used to control the gain of the variable gain amplifier circuit 12 . After the input signal is amplified by the variable gain amplifier circuit 12 and the first fixed gain amplifier circuit 13 , the output signal of the feedback AGC circuit 22 can be finally obtained.

The two-dimensional CCD/CMOS image sensor 9 can be selected from the mature two-dimensional image sensor MI360, and the two-dimensional image signal processing circuit 10 can use the existing dedicated image processing chip ZC0301 to jointly complete a real-time high-pixel two-dimensional image of acquisition.

By using the beam splitter 3 to transmit the projected light of the N×M LED array 4 and to reflect the scattered light on the surface of the three-dimensional target 1 to be measured, the lens 2 is not only used as a projection lens for the depth measurement of the LED array, but also as a projection lens for the depth measurement of the LED array. The scattered light on the surface of the target 1 is collected and used as the two-dimensional imaging lens of the target 1 to realize the imaging of the depth image and the two-dimensional image with the same lens 2, so as to overcome the inherent aberration problem caused by the use of different lenses for imaging, and realize the two-dimensional image and Real-time high-precision alignment between depth images, the detailed optical path structure is shown in Figure 1.

Figure 1 shows an optical path structure in which the depth image and the two-dimensional image share the same lens 2 for imaging. In specific implementation, there may be at least another optical path structure: keep the placement position and angle of the beam splitter 3 in Figure 1 Invariably, the positions of the N×M LED array 4 and the two-dimensional CCD/CMOS image sensor 9 in Fig. 1 are exchanged so that the modulated light emitted by the LED light source is reflected by the beam splitter 3 and reaches the lens 2; the scattering on the surface of the target 1 After passing through the lens 2 , the light is transmitted through the beam splitter 3 and reaches the two-dimensional CCD/CMOS image sensor 9 .

In order to meet the requirements of shared lens imaging, the beam splitter 3 needs to provide the same field of view for the N×M LED array 4 and the two-dimensional CCD/CMOS image sensor 9 after installation, and the area size of the N×M LED array 4 must be the same as The two-dimensional CCD/CMOS image sensors 9 have the same area size. The existing mature microelectronics technology can be used to densely package small-volume LED dies to form LED array chips with high pixels and small area. This is not only an effective way to reduce the area of LED arrays, but also to increase the depth of LED images. The number of pixels is an effective way to improve the spatial resolution of the imaging system. The densely packaged small-area LED array can also ensure that all modulated emission LED dies in the array have the same temperature environment during depth measurement, which can reduce the impact of temperature effects on depth measurement resolution, and at the same time reduce The diameter of the projection imaging lens 2 reduces the volume of the entire optical imaging system. In addition, if some simple LED array row and column gating and driving circuits are integrated while the LED dies are densely packaged, the integration level of the system can be further improved and a more compact and compact 3D imaging system can be constructed.

In the PC, based on mature image processing algorithms, the obtained 2D image and depth image data are "fused" together to obtain the final high-performance real-time 3D image. In addition, if the number of pixels of the depth image obtained in the actual imaging system is less than the number of pixels of the two-dimensional image, the interpolation processing of the depth image can be performed first, and then the data fusion processing of the two can be performed.

Claims (4)

1. A three-dimensional imaging method based on LED array common lens TOF depth measurement, characterized in that: A two-dimensional LED array modulated by optical power is used as an illumination light source, and only one LED in the two-dimensional LED array is turned on each time, and the modulated light emitted by the LED is projected to the target (1) through a projection lens. surface, use a photoelectric receiver (6) to receive the scattered light on the surface of the target (1), measure the round-trip time-of-flight TOF from the light source to the target (1), and calculate the point according to the round-trip time-of-flight TOF The depth pixel value of the LED in the bright state, to complete the measurement of the depth pixel value of a single LED; Scan the entire two-dimensional LED array in time division, repeat the measurement process of the single LED depth pixel value, obtain all LED depth pixel values and combine them to generate the depth image of the target (1); at the same time, the scattered light on the surface of the target (1) is passed through the two-dimensional After the imaging lens is received by a two-dimensional CCD/CMOS image sensor (9), the two-dimensional image of the target (1) is obtained; the projection lens and the two-dimensional imaging lens are set as the same lens (2), so that the depth image and the two-dimensional image real-time alignment; The two-dimensional image and the depth image are fused to generate a three-dimensional image of the target (1). 2. The three-dimensional imaging method based on LED array common lens TOF depth measurement according to claim 1, characterized in that: a beam splitter (3) is set, and the modulated light emitted by the LED light source is transmitted through the beam splitter (3) Reaching the projection lens; the scattered light on the surface of the target (1) passes through the two-dimensional imaging lens, and then is reflected by the beam splitter (3) to reach the two-dimensional CCD/CMOS image sensor (9). 3. A three-dimensional imaging system based on LED array common lens TOF depth measurement, characterized in that: The photoelectric modulation scanning circuit (5) is set to modulate and time-divisionally scan the output optical power of the N×M LED array (4), at any moment, only one LED is lit in the entire LED array (4); After the modulated light reaches the beam splitter (3), it is divided into transmitted light and reflected light. The transmitted light is projected on the surface of the target (1) through the lens (2), and received by the photoelectric receiver PD1 (6) on the surface of the target (1) The scattered light produced; the reflected light is directly received by the photoelectric receiver PD2 (7); The TOF depth measurement circuit (8) is set, and the photoelectric signals output by the photoelectric receiver PD1 (6) and the photoelectric receiver PD2 (7) are processed respectively with the TOF depth measurement circuit (8), and each LED depth pixel value is calculated in turn, The depth pixel values of the LEDs are combined in the PC (11) to generate a depth image of the target (1); at the same time, the scattered light on the surface of the target (1) is reflected by the lens (2) and the beam splitter (3). The three-dimensional CCD/CMOS image sensor (9) receives, and obtains the two-dimensional image of the target (1) aligned with the described depth image in real time through the two-dimensional image signal processing circuit (10); The depth image and the two-dimensional image are fused in the PC (11) to generate a three-dimensional image of the target (1). 4. the three-dimensional imaging system based on the LED array common lens TOF depth measurement according to claim 3, is characterized in that a feedback type automatic gain control AGC circuit (22) is included in the TOF depth measurement circuit (8), Described feedback type AGC circuit (22) adopts square amplitude detection circuit (15) to carry out amplitude detection to input signal, and its output signal is sent into inductance resistance LR low-pass filter ( 14) to filter out the higher harmonics produced, the direct current level of its output is used to control the gain of the variable gain amplifier circuit (12); The input signal is amplified through the variable gain amplifier circuit (12) and the first fixed gain After the circuit (13) is amplified, the output signal of the feedback AGC circuit (22) is obtained.

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