ToF ranging system

Abstract

The invention discloses a ToF ranging system, and relates to the technical field of ranging, and the ToF ranging system comprises a transmitter, a receiver, a control processing circuit, and a control computer. The receiver comprises a zoom optical lens and a ToF detector; the control computer is connected with the control processing circuit, and the transmitter and the receiver are both connected with the control processing circuit; the control computer is used for inputting a ranging gear instruction, the control processing circuit is used for controlling the power of laser emitted by the emitter according to the ranging gear instruction, the receiver is used for adjusting the focal length of the zoom optical lens according to the ranging gear instruction, and the zoom optical lens is used for receiving light emitted by the laser to a target object and reflected or scattered by the target object. The ToF detector is used for converting the light received by the zoom optical lens into an electric signal and determining the distance between the ToF detector and the target object according to the electric signal. View field reconstruction can be carried out, and long-distance measurement is realized.

Description

Technical Field

[0001] The present application relates to the field of ranging technology, and in particular to a ToF ranging system. Background Art

[0002] The space scenarios currently faced by the field of on-orbit maintenance are becoming increasingly complex. The primary key technology to be solved is how to quickly sense and measure the observed target and provide the service spacecraft with high-precision adjacent position and attitude information of the observed target. The optoelectronic detection system is the main means of sensing, identifying, measuring and navigating space targets. Generally, different measurement technologies are used for different distance ranges from the target to the service spacecraft. Microwave radar or infrared detection technology is used for long distances, lidar technology is used for medium and short distances, and visual measurement technology is used for ultra-close distances. Among them, Time-of-Flight (ToF) ranging technology has the advantages of low cost, high accuracy, small size, light weight and low power consumption, and has great advantages in ultra-close detection of space targets.

[0003] ToF ranging systems have a wide range of applications, such as sensing systems in front of automated teller machines (ATMs) and front-mounted ToF cameras on mobile phones. Limited by size, weight, and application scenarios, ToF ranging systems are primarily used for close distances (less than 10 meters) and have a fixed field of view (the detection range is fixed and the field of view cannot be reconfigured). Furthermore, because the modulation frequency of commonly used ToF camera detectors on the market has a specific modulation range at the factory, it is impossible to achieve longer-range detection by infinitely reducing the modulation frequency. Furthermore, the energy detected by the detector decays rapidly as the square of the distance, resulting in a poor signal-to-noise ratio for long-range measurements. Summary of the Invention

[0004] The purpose of this application is to provide a ToF ranging system that can reconstruct the field of view and achieve long-distance measurement.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides a ToF ranging system, comprising: a transmitter, a receiver, a control processing circuit, and a control computer; the receiver comprises a zoom optical lens and a ToF detector; the control computer is connected to the control processing circuit, and the transmitter and the receiver are both connected to the control processing circuit;

[0007] The control computer is used to input a ranging gear instruction, the control processing circuit is used to control the power of the laser emitted by the transmitter according to the ranging gear instruction, the receiver is used to adjust the focal length of the zoom optical lens according to the ranging gear instruction, the zoom optical lens is used to receive the light reflected or scattered by the target object when the laser hits the target object, and the ToF detector is used to convert the light received by the zoom optical lens into an electrical signal and determine the distance to the target object based on the electrical signal.

[0008] Optionally, the emitter includes a vertical cavity surface emitting laser light source array, a light source driver and a light source power supply, the light source driver and the light source power supply are both connected to the vertical cavity surface emitting laser light source array, the light source driver is used to drive the vertical cavity surface emitting laser light source array, the light source power supply is used to provide power for the vertical cavity surface emitting laser light source array, and the vertical cavity surface emitting laser light source array is used to emit laser to a target object.

[0009] Optionally, the zoom optical lens includes a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens and a sixth lens arranged in sequence; the two surfaces of the first lens are defined as a first surface and a second surface, respectively, the two surfaces of the second lens are defined as a third surface and a fourth surface, respectively, and the two surfaces of the third lens are defined as a fifth surface and a sixth surface, respectively, wherein the second surface is adjacent to the third surface, and the fourth surface is adjacent to the fifth surface; the positions of the first lens, the fourth lens, the fifth lens and the sixth lens are fixed, and the thickness of the second surface, the thickness of the fourth surface, the thickness of the sixth surface, the position of the second lens and the position of the third lens are adjusted according to the ranging gear instruction.

[0010] Optionally, the refractive index of the first lens is 1.85, the Abbe number is 30.06, and the focal length is 49.47; the refractive index of the second lens is 1.52, the Abbe number is 59.48, and the focal length is -34.17; the refractive index of the third lens is 1.76, the Abbe number is 26.01, and the focal length is -16.09; the refractive index of the fourth lens is 1.80, the Abbe number is 46.57, and the focal length is 11.01; the refractive index of the fifth lens is 1.75, the Abbe number is 52.32, and the focal length is 86.59; the refractive index of the sixth lens is 1.77, the Abbe number is 49.59, and the focal length is 58.93.

[0011] Optionally, two surfaces of the fourth lens are respectively defined as a seventh surface and an eighth surface, two surfaces of the fifth lens are respectively defined as a ninth surface and a tenth surface, and two surfaces of the sixth lens are respectively defined as an eleventh surface and a twelfth surface, wherein the sixth surface is adjacent to the seventh surface, the eighth surface is adjacent to the ninth surface, and the tenth surface is adjacent to the eleventh surface.

[0012] The first surface has a radius of curvature of 37.03 mm and a thickness of 4.49 mm;

[0013] The curvature radius of the second surface is 362.15 and the thickness ranges from 1.42 mm to 15.83 mm;

[0014] The third surface has a radius of curvature of 63.40 mm and a thickness of 2.15 mm;

[0015] The fourth surface has a radius of curvature of 13.62 and a thickness ranging from 15.33 mm to 3.79 mm;

[0016] The fifth surface has a curvature radius of -10.78 and a thickness of 2.97 mm;

[0017] The curvature radius of the sixth surface is -126.44, and the thickness ranges from 3.86 mm to 0.99 mm;

[0018] The seventh surface has a radius of curvature of 222.96 and a thickness of 4.88 mm;

[0019] The eighth surface has a curvature radius of -8.96 and a thickness of 1.76 mm;

[0020] The ninth surface has a curvature radius of -8.32 and a thickness of 4.53 mm;

[0021] The tenth surface has a curvature radius of -9.08 and a thickness of 3.20 mm;

[0022] The eleventh surface has a curvature radius of 19.42 and a thickness of 4.89 mm;

[0023] The curvature radius of the twelfth surface is 30.50 and the thickness is 8.99 mm.

[0024] Optionally, the seventh surface and the ninth surface are both even-order aspheric surfaces;

[0025] The expression of the even-order aspheric surface is:

[0026] Where z is the axial coordinate of the surface, c represents the curvature at the vertex of the surface, r represents the radial coordinate under the lens unit, k represents the cone coefficient, and α1, α2, α3, α4, and α5 are all even-order aspheric coefficients.

[0027] Optionally, for the seventh surface, k=0, α1=0, α2=-7.05E-05, α3=4.56E-06, α4=-3.38E-07, α5=1.02E-08; for the ninth surface, k=0, α1=0, α2=-4.32E-04, α3=-7.72E-06, α4=3.76E-07, α5=-1.78E-08.

[0028] Optionally, the power of the laser emitted by the transmitter is expressed as:

[0029] Among them, P laser The power of the laser emitted by the transmitter, N s T is the number of electrons converted by a single pixel during the integration time. int is the integration time, h is Planck's constant, v is the speed of light, d is the detection distance, H is the number of pixels on the long side of the ToF detector, V is the number of pixels on the short side of the ToF detector, D is the aperture of the receiver optical system, ρ is the reflection coefficient of the target object, η is the transmittance of the receiver optical system, λ is the laser wavelength, QE is the quantum efficiency of the ToF detector, and FF is the filling factor of the ToF detector.

[0030] Optionally, the ranging gear instruction includes a first gear instruction and a second gear instruction, the detection distance range of the first gear instruction is 37.5m to 2m, and the detection distance range of the second gear instruction is 75m to 37.5m.

[0031] Optionally, the receiver further includes a zoom drive motor, and the zoom drive motor is used to adjust the focal length of the zoom optical lens.

[0032] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0033] The present application provides a ToF ranging system, in which a control processing circuit is used to control the power of the laser emitted by the transmitter according to the ranging gear instruction, and a receiver is used to adjust the focal length of the zoom optical lens according to the ranging gear instruction. By controlling the emission power of the laser and the focal length of the zoom optical lens, field of view reconstruction is achieved, thereby solving the problem of fixed detection range and enabling long-distance measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 A schematic structural diagram of a ToF ranging system provided in one embodiment of the present application;

[0036] Figure 2 A schematic diagram of the structure of a zoom optical lens provided in one embodiment of the present application.

[0037] Figure markings: 1-first lens, 2-second lens, 3-third lens, 4-fourth lens, 5-fifth lens, 6-sixth lens, ST-aperture, S1-first surface, S2-second surface, S3-third surface, S4-fourth surface, S5-fifth surface, S6-sixth surface, S7-seventh surface, S8-eighth surface, S9-ninth surface, S10-tenth surface, S11-eleventh surface, S12-twelfth surface, S13-image plane. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0039] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0040] Typically, a ToF ranging system consists of three components: a transmitter, a receiver, and a processing circuit. For short-range (less than 20 meters) ToF ranging systems, the transmitter is typically a low-power LED or laser transmitter without beam shaping, and the receiver is a fixed-focus optical lens. This system can only detect short-range distances and three-dimensional objects, and the receiving field of view cannot be reconfigured.

[0041] This application provides a ToF ranging system, such as Figure 1 As shown, the ToF ranging system includes: a transmitter, a receiver, a control processing circuit and a control computer; the receiver includes a zoom optical lens and a ToF detector; the control computer is connected to the control processing circuit, and the transmitter and the receiver are both connected to the control processing circuit.

[0042] The control computer is used to input a ranging gear instruction, the control processing circuit is used to control the power of the laser emitted by the transmitter according to the ranging gear instruction, the receiver is used to adjust the focal length of the zoom optical lens according to the ranging gear instruction, the zoom optical lens is used to receive the light reflected or scattered by the target object when the laser hits the target object, and the ToF detector is used to convert the light received by the zoom optical lens into an electrical signal and determine the distance to the target object based on the electrical signal.

[0043] The present application realizes field of view reconstruction by controlling the emission power of the laser and the focal length of the zoom optical lens, thereby solving the problem of fixed detection range and short measurement distance, and can realize long-distance measurement.

[0044] The principle of the ToF ranging system is to measure the distance based on the flight time of the emitted modulated light source.

[0045] The transmitter includes a vertical-cavity surface-emitting laser (VCSEL) light source array, a light source driver, and a light source power supply. The light source driver and the light source power supply are both connected to the VCSEL light source array. The light source driver is used to drive the VCSEL light source array, and the light source power supply is used to provide power for the VCSEL light source array. The VCSEL light source array is used to emit laser light toward a target object. A control processing circuit controls the light source power supply to power the VCSEL light source array. The control processing circuit drives the VCSEL light source array to work through a drive signal, thereby emitting an adjusted laser toward the target object.

[0046] Vertical cavity surface emitting lasers (VCSELs) combine the advantages of high output power, high conversion efficiency, and high-quality beams. Compared with light emitting diodes (LEDs) and edge emitting lasers, they have advantages in terms of precision, miniaturization, low power consumption, and reliability.

[0047] A zoom optical lens is an optical lens with moving optical components. Its focal length is variable and it can change the field of view when used with a photodetector.

[0048] The receiver also includes a zoom drive motor, a motor drive, a motor power supply, a detector drive, and a detector power supply. The zoom drive motor is used to adjust the focal length of the zoom optical lens through a control processing circuit. The control computer uploads instructions to the control processing circuit through an interface, and the control processing circuit is connected to the motor power supply to power the zoom drive motor; the control computer uploads instructions to the processing circuit through an interface, and the control processing circuit sends a motor drive signal to drive the zoom drive motor to work, and the zoom drive motor drives the zoom optical lens to achieve zooming of the zoom optical lens; the control computer uploads instructions to the control processing circuit through an interface, and the control processing circuit is connected to the detector power supply to power the ToF detector; the control computer uploads instructions to the processing circuit through an interface, and the control processing circuit sends a detector drive signal to drive the ToF detector to work.

[0049] The control processing circuit consists of a control processing chip, memory, processing board power supply, drive master control, power master control, and interface; the memory is used to store the target information received by the receiver; the processing board power supply is used to power the processing circuit; the drive master control controls the motor drive, light source drive, and detector drive; the power master control controls the motor power supply, light source power supply, detector power supply, and processing board power supply; the interface is connected to the control computer as the entrance for information and instruction exchange.

[0050] The control computer serves as the overall control of the entire system. It controls and processes data of the entire ToF ranging system through command input.

[0051] The VCSEL light source array is controlled by the control processing circuit to emit a modulated laser beam and record the instantaneous phase of the emitted laser beam. The recorded instantaneous phase is recorded in the memory and recorded as the initial phase. When the light beam emitted by the light source hits the target object, it is reflected or scattered by the target object and received by the zoom optical lens, generating an electrical signal on the ToF detector. The phase information collected by the ToF detector is subtracted from the initial phase of the emitted beam. Through the formula Calculate the distance to the target object. By obtaining the difference in signals from different pixels of the ToF detector, the target object can be reconstructed in three dimensions. Where d represents the distance between the target object and the ToF ranging system, v represents the speed of light, is the phase difference between the transmitted and received beams, f is the frequency of the modulated light, and n represents the number of integer cycles. As can be seen, when the target distance is within one cycle, there is a typical conflict between detection range and accuracy. Reducing the modulation frequency increases the detection range, but measurement accuracy decreases as f decreases. However, the phase recorded by a ToF detector is within 2π. When the modulation frequency remains unchanged and the phase difference corresponding to the actual distance exceeds one cycle, it is impossible to confirm the integer cycle after the difference, that is, it is impossible to determine the value of n. This phenomenon is called distance ambiguity.

[0052] The design of this application measures a distance of 75m to 2m, a modulation frequency of 4MHz, and a full-scale ranging range of 37.5m for one-cycle phase difference, dividing the measuring distance into two gears. The first ranging gear has a ranging range of 37.5m to 2m, n=0, and adjusts the light source output power to normal exposure, while adjusting the focal length of the zoom optical lens to the set value; the second ranging gear has a ranging range of 75m to 37.5m, n=1, and adjusts the light source output power and the focal length of the zoom optical lens in the same way. When measuring, the integer period of the phase difference corresponding to the target distance can be determined based on the given initial measurement distance to resolve the problem of distance ambiguity.

[0053] This application can determine the zoom optical lens parameters according to the detection requirements. The pixel size of the ToF detector is δ, the detection distance is d0, N represents the number of pixels occupied by the image plane size, y is the target size, and the position of the image plane S13 is as follows: Figure 2 As shown, the number of pixels N occupied by the image plane of the target object will change with the distance of the target and the zoom lens gear. According to the formula for calculating the image height at infinity, the focal length f' of the optical system can be expressed as:

[0054] After analysis and calculation, the design parameters of the zoom optical lens are shown in Table 1.

[0055] Table 1 Design parameters of zoom optical lens

[0056]

[0057]

[0058] In an exemplary embodiment, the zoom optical lens is designed using ZEMAX software according to the design parameters, and the three-dimensional diagram of the lens design is as follows: Figure 2The zoom optical lens comprises a first lens 1, a second lens 2, a third lens 3, an aperture ST, a fourth lens 4, a fifth lens 5 and a sixth lens 6 arranged in sequence, wherein the first lens 1 is a front fixed group, the fourth lens 4, the fifth lens 5 and the sixth lens 6 are a rear fixed group, the second lens 2 is a zoom group, and the third lens 3 is a compensation group; two surfaces of the first lens 1 are respectively defined as a first surface S1 and a second surface S2, two surfaces of the second lens 2 are respectively defined as a third surface S3 and a fourth surface S4, and two surfaces of the third lens 3 are respectively defined as a fifth surface S5 and a sixth surface S6, wherein the second surface S2 is adjacent to the third surface S3, and the fourth surface S4 is adjacent to the fifth surface S5; the positions of the first lens 1, the fourth lens 4, the fifth lens 5 and the sixth lens 6 are fixed, and the thickness of the second surface S2, the thickness of the fourth surface S4, the thickness of the sixth surface S6, the position of the second lens 2 and the position of the third lens 3 are adjusted according to the ranging gear instruction.

[0059] The second and third lenses 2 and 3 are mechanically connected to the zoom drive motor. Different focal lengths correspond to different positions, and the drive motor can be controlled by a computer to adjust the positions of the second and third lenses 2 and 3. The air gaps between the two gears correspond to the endpoint values ​​of the three variable thicknesses: For the 37.5m gear, the thickness intervals of the second surface S2 are 1.42, the thickness intervals of the fourth surface S4 are 15.33, and the thickness intervals of the sixth surface S6 are 3.86; for the 75m gear, the thickness intervals of the second surface S2 are 15.83, the thickness intervals of the fourth surface S4 are 3.79, and the thickness intervals of the sixth surface S6 are 0.99.

[0060] The curvature radius, thickness interval, refractive index, Abbe number and focal length of each lens surface in the zoom optical lens are shown in Table 2.

[0061] Table 2 Lens parameters

[0062]

[0063]

[0064] The refractive index of the first lens 1 is 1.85, the Abbe number is 30.06, and the focal length is 49.47; the refractive index of the second lens 2 is 1.52, the Abbe number is 59.48, and the focal length is -34.17; the refractive index of the third lens 3 is 1.76, the Abbe number is 26.01, and the focal length is -16.09; the refractive index of the fourth lens 4 is 1.80, the Abbe number is 46.57, and the focal length is 11.01; the refractive index of the fifth lens 5 is 1.75, the Abbe number is 52.32, and the focal length is 86.59; and the refractive index of the sixth lens 6 is 1.77, the Abbe number is 49.59, and the focal length is 58.93.

[0065] Two surfaces of the fourth lens 4 are respectively defined as a seventh surface S7 and an eighth surface S8, two surfaces of the fifth lens 5 are respectively defined as a ninth surface S9 and a tenth surface S10, and two surfaces of the sixth lens 6 are respectively defined as an eleventh surface S11 and a twelfth surface S12, wherein the sixth surface S6 is adjacent to the seventh surface S7, the eighth surface S8 is adjacent to the ninth surface S9, and the tenth surface S10 is adjacent to the eleventh surface S11.

[0066] The first surface S1 has a radius of curvature of 37.03 and a thickness of 4.49 mm; the second surface S2 has a radius of curvature of 362.15 and a thickness range of 1.42 mm to 15.83 mm; the third surface S3 has a radius of curvature of 63.40 and a thickness range of 2.15 mm; the fourth surface S4 has a radius of curvature of 13.62 and a thickness range of 15.33 mm to 3.79 mm; the fifth surface S5 has a radius of curvature of -10.78 and a thickness range of 2.97 mm; the sixth surface S6 has a radius of curvature of -126.44 and a thickness range of 3.86mm~0.99mm; the curvature radius of the seventh surface S7 is 222.96, and the thickness is 4.88mm; the curvature radius of the eighth surface S8 is -8.96, and the thickness is 1.76mm; the curvature radius of the ninth surface S9 is -8.32, and the thickness is 4.53mm; the curvature radius of the tenth surface S10 is -9.08, and the thickness is 3.20mm; the curvature radius of the eleventh surface S11 is 19.42, and the thickness is 4.89mm; the curvature radius of the twelfth surface S12 is 30.50, and the thickness is 8.99mm.

[0067] The focal length of the zoom optical lens ranges from 9.4mm to 18.8mm. When zooming, the front fixed group and the rear fixed group are fixed, and the magnification group and the compensation group change with the focal length, involving changes in the air thickness of three surfaces, namely the second lens 2, the fourth lens 4, and the sixth lens 6. The thickness of the second lens 2 surface varies from 1.42mm to 15.83mm, the thickness of the fourth lens 4 surface varies from 15.33mm to 3.79mm, and the thickness of the sixth lens 6 surface varies from 3.86mm to 0.99mm.

[0068] The seventh surface S7 and the ninth surface S9 are both even-order aspherical surfaces.

[0069] The expression of the even-order aspheric surface is:

[0070] Among them, z is the axial coordinate of the surface, which represents the curvature at the vertex of the surface. The vertex of the surface is the intersection of the optical axis (axis of symmetry) and each surface. r is the radial coordinate under the lens unit. k is the cone coefficient. α1, α2, α3, α4 and α5 are all even-order aspheric coefficients. The lens unit refers to the unit used to describe the size and length of the lens. Millimeters are used here. The unit of r is also millimeters.

[0071] For the seventh surface S7, k=0, α1=0, α2=-7.05E-05, α3=4.56E-06, α4=-3.38E-07, α5=1.02E-08; for the ninth surface S9, k=0, α1=0, α2=-4.32E-04, α3=-7.72E-06, α4=3.76E-07, α5=-1.78E-08.

[0072] The calculation and analysis of the light source power for this application are as follows: There are two main factors that determine the light source power: the light source power required to produce a certain number of photons per pixel; and the number of photons required at each sampling point to achieve a certain accuracy. Assuming that the object being observed is a Lambertian body, the light power obtained by the detector is:

[0073] Where D is the aperture of the receiver optical system, P lens is the optical power obtained by the detector, P obj is the transmitter optical power received by the target, The optical system is a general term for the zoom optical lens and ToF detector.

[0074] Among them, A obj is the target surface area, A field is the irradiation area of ​​the transmitter at the detection distance d, P laser is the transmitter laser pump power, and ρ is the reflection coefficient of the target.

[0075] Assuming the transmittance of the receiver optical system is η, the optical power on a single pixel is: P image =P lens ×η. Among them, P image is the optical power on a single pixel.

[0076] During the integration time, the number of electrons converted by a single pixel is:

[0077] From this we can conclude that at a certain N s The power of the laser emitted by the transmitter is expressed as: According to this formula, the laser emission power required at different ranging positions can be calculated, and the laser power can be adjusted in real time to ensure normal system exposure.

[0078] Among them, P laser The power of the laser emitted by the transmitter, N s T is the number of electrons converted by a single pixel during the integration time. int is the integration time, h is Planck's constant, c is the speed of light, d is the detection distance, H is the number of pixels on the long side of the ToF detector, V is the number of pixels on the short side of the ToF detector, D is the aperture of the receiver optical system, ρ is the reflection coefficient of the target object, k is the transmittance of the receiver optical system, λ is the laser wavelength, QE is the quantum efficiency of the ToF detector, and FF is the filling factor of the ToF detector.

[0079] The ranging gear instructions include a first gear instruction and a second gear instruction. The detection range of the first gear instruction is 37.5m to 2m, and the detection range of the second gear instruction is 75m to 37.5m. This application is designed to measure distances at different distances and has two ranging gears. The transmitter power and receiver field of view of each ranging gear are different. The transmitter power is adjusted by the VCSEL laser array, and the focal length of the receiver zoom lens is adjusted to switch the field of view.

[0080] The field of view of this application is reconfigurable: an optical zoom lens with two zoom levels is used as the receiver, which can theoretically achieve a maximum receiving field of view of 47.4°. This allows the ranging system to reconstruct the receiver field of view according to the distance of the measured target and obtain more comprehensive and accurate target distance information.

[0081] This application boasts a longer detection range: Using a VCSEL laser array as a transmitter, the transmitter power can be adjusted according to the detection distance. Theoretically, the longer the measurement distance, the greater the transmitter power required. Compared to a single VCSEL laser transmitter, a VCSEL array can emit higher laser power and a longer transmission distance, making it more suitable for long-distance ranging. Long-distance detection requires a larger relative aperture of the receiver to achieve higher energy capture efficiency. Using a large relative aperture zoom lens as the receiver can improve energy capture efficiency. This application is designed to meet detection requirements up to 75 meters, with applications in aerospace ranging and three-dimensional measurement.

[0082] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A ToF ranging system, characterized in that: The ToF ranging system comprises: a transmitter, a receiver, a control processing circuit and a control computer; the receiver comprises a zoom optical lens and a ToF detector; the control computer is connected to the control processing circuit, and the transmitter and the receiver are both connected to the control processing circuit; The control computer is used to input a ranging gear instruction, the control processing circuit is used to control the power of the laser emitted by the transmitter according to the ranging gear instruction, the receiver is used to adjust the focal length of the zoom optical lens according to the ranging gear instruction, the zoom optical lens is used to receive the light reflected or scattered by the target object when the laser hits the target object, and the ToF detector is used to convert the light received by the zoom optical lens into an electrical signal, and determine the distance to the target object according to the electrical signal.

2. The ToF ranging system according to claim 1, characterized in that: The transmitter includes a vertical cavity surface emitting laser light source array, a light source driver and a light source power supply. The light source driver and the light source power supply are both connected to the vertical cavity surface emitting laser light source array. The light source driver is used to drive the vertical cavity surface emitting laser light source array, and the light source power supply is used to provide power for the vertical cavity surface emitting laser light source array. The vertical cavity surface emitting laser light source array is used to emit laser to a target object.

3. The ToF ranging system according to claim 1, characterized in that: The zoom optical lens comprises a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens and a sixth lens arranged in sequence; two surfaces of the first lens are respectively defined as a first surface and a second surface, two surfaces of the second lens are respectively defined as a third surface and a fourth surface, two surfaces of the third lens are respectively defined as a fifth surface and a sixth surface, wherein the second surface is adjacent to the third surface, and the fourth surface is adjacent to the fifth surface; the positions of the first lens, the fourth lens, the fifth lens and the sixth lens are fixed, and the thickness of the second surface, the thickness of the fourth surface, the thickness of the sixth surface, the position of the second lens and the position of the third lens are adjusted according to the ranging gear instruction.

4. The ToF ranging system according to claim 3, characterized in that: The refractive index of the first lens is 1.85, the Abbe number is 30.06, and the focal length is 49.47; the refractive index of the second lens is 1.52, the Abbe number is 59.48, and the focal length is -34.17; the refractive index of the third lens is 1.76, the Abbe number is 26.01, and the focal length is -16.09; the refractive index of the fourth lens is 1.80, the Abbe number is 46.57, and the focal length is 11.01; the refractive index of the fifth lens is 1.75, the Abbe number is 52.32, and the focal length is 86.59; the refractive index of the sixth lens is 1.77, the Abbe number is 49.59, and the focal length is 58.

93.

5. The ToF ranging system according to claim 4, characterized in that: The two surfaces of the fourth lens are respectively defined as a seventh surface and an eighth surface, the two surfaces of the fifth lens are respectively defined as a ninth surface and a tenth surface, and the two surfaces of the sixth lens are respectively defined as an eleventh surface and a twelfth surface, wherein the sixth surface is adjacent to the seventh surface, the eighth surface is adjacent to the ninth surface, and the tenth surface is adjacent to the eleventh surface; The first surface has a radius of curvature of 37.03 and a thickness of 4.49 mm; The radius of curvature of the second surface is 362.15, and the thickness ranges from 1.42 mm to 15.83 mm; The third surface has a radius of curvature of 63.40 and a thickness of 2.15 mm; The fourth surface has a radius of curvature of 13.62 and a thickness ranging from 15.33 mm to 3.79 mm; The fifth surface has a radius of curvature of -10.78 and a thickness of 2.97 mm; The radius of curvature of the sixth surface is -126.44, and the thickness ranges from 3.86 mm to 0.99 mm; The seventh surface has a radius of curvature of 222.96 and a thickness of 4.88 mm; The eighth surface has a radius of curvature of -8.96 and a thickness of 1.76 mm; The ninth surface has a radius of curvature of -8.32 and a thickness of 4.53 mm; The tenth surface has a radius of curvature of -9.08 and a thickness of 3.20 mm; The eleventh surface has a radius of curvature of 19.42 and a thickness of 4.89 mm; The curvature radius of the twelfth surface is 30.50 and the thickness is 8.99 mm.

6. The ToF ranging system according to claim 5, characterized in that: The seventh surface and the ninth surface are both even-order aspherical surfaces; The expression of the even-order aspheric surface is: Among them, z is the axial coordinate of the surface, c represents the curvature at the vertex of the surface, r represents the radial coordinate under the lens unit, k represents the cone coefficient, and α1, α2, α3, α4 and α5 are all even-order aspheric coefficients.

7. The ToF ranging system according to claim 6, characterized in that: For the seventh surface, k=0, α1=0, α2=-7.05E-05, α3=4.56E-06, α4=-3.38E-07, α5=1.02E-08; for the ninth surface, k=0, α1=0, α2=-4.32E-04, α3=-7.72E-06, α4=3.76E-07, α5=-1.78E-08.

8. The ToF ranging system according to claim 1, characterized in that: The power of the laser emitted by the transmitter is expressed as: Among them, P laser is the power of the laser emitted by the transmitter, N s is the number of electrons converted by a single pixel during the integration time, T int is the integration time, h is Planck's constant, v is the speed of light, d is the detection distance, H is the number of pixels on the long side of the ToF detector, V is the number of pixels on the short side of the ToF detector, D is the aperture of the receiver optical system, ρ is the reflection coefficient of the target object, η is the transmittance of the receiver optical system, λ represents the laser wavelength, QE is the quantum efficiency of the ToF detector, and FF is the filling factor of the ToF detector.

9. The ToF ranging system according to claim 1, characterized in that: The ranging gear position instruction includes a first gear position instruction and a second gear position instruction. The detection distance range of the first gear position instruction is 37.5m to 2m, and the detection distance range of the second gear position instruction is 75m to 37.5m.

10. The ToF ranging system according to claim 1, characterized in that: The receiver also includes a zoom drive motor, which is used to adjust the focal length of the zoom optical lens.

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