TOF receiving optical system, TOF receiving lens and TOF module
By using a TOF receiving optical system with a single-chip ultralens, the problem of high installation accuracy of multiple lenses is solved, and low-cost and efficient mass production is achieved.
Patent Information
- Application Number
- CN202421669333.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-15
- Publication Date
- 2025-07-22
- Estimated Expiration
- 2034-07-15
AI Technical Summary
The existing ToF receiving optical systems have high installation accuracy requirements for multi-piece lenses, which leads to high installation difficulty and affects mass production efficiency.
Using a TOF receiving optical system containing an ultralens, the ultralens consists of a substrate and a micro-nano structure, with only one lens, which is manufactured through semiconductor processes, reducing installation accuracy requirements and improving installation tolerance tolerance.
While ensuring imaging quality, the installation accuracy requirements of ultra-lenses are reduced, mass production is promoted, and because the cost of single-chip ultra-lenses is low, it is conducive to reducing production costs.
Smart Images
Figure CN223139838U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical systems, and particularly to a TOF receiving optical system, a TOF receiving lens, and a TOF module. Background Art
[0002] ToF, i.e., Time of Flight, is a technology for distance measurement by measuring the time during the light transmission process. The ToF receiving optical system is an optical system manufactured using the ToF principle, which is used to receive the light reflected by an object.
[0003] In the prior art, the ToF receiving optical system usually has multiple lenses. Since there are certain position errors during the installation of each lens, when the ToF receiving optical system has multiple lenses, in order to ensure its normal use, a relatively high installation accuracy is usually required, resulting in a problem of relatively large installation difficulty for the ToF receiving optical system, which is not conducive to the mass production of the ToF receiving optical system. Summary of the Utility Model
[0004] In view of the above technical problems, embodiments of this application provide a TOF receiving optical system, a TOF receiving lens, and a TOF module, aiming to provide a ToF receiving optical system with relatively low installation difficulty.
[0005] According to one aspect of the embodiments of this application, a TOF receiving optical system is disclosed. The TOF receiving optical system includes: a metalens, the metalens includes a substrate and a micro-nano structure, and the micro-nano structure is provided on at least one of the object side surface and the image side surface of the substrate.
[0006] Wherein, the TOF receiving optical system satisfies: Wherein, f is the effective focal length of the TOF receiving optical system, and TTL is the total optical length of the TOF receiving optical system.
[0007] In some embodiments, the TOF receiving optical system satisfies: Wherein, RFOV is the maximum field of view angle of the TOF receiving optical system, EPD is the entrance pupil diameter of the TOF receiving optical system, and ImgH is the radius of the imaging area on the image plane of the TOF receiving optical system corresponding to the maximum half field of view angle.
[0008] In some embodiments, the TOF receiving optical system satisfies: Wherein, ImgH is the radius of the imaging area on the image plane of the TOF receiving optical system corresponding to the maximum half field of view angle, RFOV is the maximum field of view angle of the TOF receiving optical system, and f is the effective focal length of the TOF receiving optical system.
[0009] In some embodiments, the TOF receiving optical system further includes a diaphragm, and the diaphragm is disposed on the object side of the metalens.
[0010] In some embodiments, the TOF receiving optical system satisfies: 0.03 mm ≤ L ≤ 0.2 mm, where L is the distance between the diaphragm and the object side surface of the metalens.
[0011] In some embodiments, the TOF receiving optical system satisfies: 0.313 mm ≤ L + BFL ≤ 0.414 mm, where L is the distance between the diaphragm and the object side surface of the metalens, and BFL is the back focal length of the TOF receiving optical system.
[0012] In some embodiments, the TOF receiving optical system further includes an antireflection film and a cut-off film. The antireflection film is disposed on either the object side surface or the image side surface of the metalens, and the cut-off film is disposed on the other of the object side surface and the image side surface of the metalens.
[0013] A second aspect of the embodiments of the present application provides a TOF receiving lens. The TOF receiving lens includes an imaging detector and the TOF receiving optical system as described in any one of the above. The imaging detector is disposed on the image plane of the TOF receiving optical system.
[0014] A third aspect of the embodiments of the present application provides a TOF module. The TOF module includes a TOF transmitting lens and the above TOF receiving lens, and the TOF receiving lens and the TOF transmitting lens are arranged side by side.
[0015] In some embodiments, the TOF module satisfies: 3° ≤ TFOV - RFOV ≤ 5°, where TFOV is the maximum field of view angle of the TOF transmitting lens, and RFOV is the maximum field of view angle of the TOF receiving lens.
[0016] The TOF receiving optical system provided by the present application includes a metalens. The metalens includes a substrate and a micro-nano structure, and at least one of the object side surface and the image side surface of the substrate is provided with a micro-nano structure. Among them, the TOF receiving optical system satisfies: Among them, f is the effective focal length of the TOF receiving optical system, and TTL is the total optical length of the TOF receiving optical system. In this application, the TOF receiving optical system only includes one lens. Compared with the TOF receiving optical system including more than two lenses in the prior art, the TOF receiving optical system provided in this application can improve the tolerance of the TOF receiving optical system to the installation tolerance of the metalens while ensuring the imaging quality, can reduce the requirement for the installation accuracy of the metalens, and can ensure that the TOF receiving optical system with low assembly accuracy can also meet the optical performance, which is beneficial to the mass production of the TOF receiving optical system. At the same time, since the metalens can be manufactured by semiconductor processes, the cost of a single metalens is relatively low during mass production. Therefore, the TOF receiving optical system also has the advantage of low cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] By referring to the accompanying drawings and describing in detail its exemplary embodiments, the above and other objectives, features, and advantages of this application will become more apparent.
[0018] Figure 1 FIG. shows a schematic diagram of the architecture layout of the TOF receiving optical system in an embodiment of this application.
[0019] Figure 2 FIG. shows the MTF field curve diagram of the TOF receiving optical system in an embodiment of this application.
[0020] Figure 3 FIG. shows the field curvature diagram of the TOF receiving optical system in an embodiment of this application.
[0021] Figure 4 FIG. shows the distortion diagram of the TOF receiving optical system in an embodiment of this application.
[0022] Figure 5 FIG. shows a schematic diagram of the architecture layout of the TOF receiving optical system in an embodiment of this application.
[0023] Figure 6 FIG. shows the MTF field curve diagram of the TOF receiving optical system in an embodiment of this application.
[0024] Figure 7 FIG. shows the field curvature diagram of the TOF receiving optical system in an embodiment of this application.
[0025] Figure 8 FIG. shows the distortion diagram of the TOF receiving optical system in an embodiment of this application.
[0026] Figure 9 FIG. shows a schematic diagram of the architecture layout of the TOF receiving optical system in an embodiment of this application.
[0027] Figure 10Shows the MTF field of view curve graph of the TOF receiving optical system in an embodiment of the present application.
[0028] Figure 11 Shows the field curvature graph of the TOF receiving optical system in an embodiment of the present application.
[0029] Figure 12 Shows the distortion graph of the TOF receiving optical system in an embodiment of the present application.
[0030] Figure 13 Shows the schematic diagram of the architecture layout of the TOF receiving optical system in an embodiment of the present application.
[0031] Figure 14 Shows the MTF field of view curve graph of the TOF receiving optical system in an embodiment of the present application.
[0032] Figure 15 Shows the field curvature graph of the TOF receiving optical system in an embodiment of the present application.
[0033] Figure 16 Shows the distortion graph of the TOF receiving optical system in an embodiment of the present application.
[0034] Figure 17 Shows the schematic diagram of the structure of the TOF module in an embodiment of the present application.
[0035] Reference numerals
[0036] 1000, TOF module;
[0037] 100, TOF receiving lens;
[0038] 10, TOF receiving optical system;
[0039] 1, meta-lens; 11, substrate; 12, micro-nano structure;
[0040] 2, aperture;
[0041] A, object plane; B, image plane; S, optical axis;
[0042] 20, imaging detector;
[0043] 200, TOF transmitting lens;
[0044] 30, light source; 40, TOF transmitting optical system;
[0045] 300, housing; 3001, receiving cavity. Detailed implementation manners
[0046] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that this application will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The drawings are merely schematic illustrations of the application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repeated description will be omitted.
[0047] In addition, the described features, structures, or characteristics can be combined in any suitable manner in one or more example embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the example embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other modules, components, etc. can be used. In other cases, well-known structures, methods, implementations, or operations are not shown or described in detail to avoid obscuring the aspects of this application.
[0048] Please refer to Figure 1 , Figure 1 which shows a schematic diagram of the architecture layout of the TOF receiving optical system 10 in an embodiment of this application. The TOF receiving optical system 10 includes a metalens 1. Among them, the optical axis S is the center line of the light beam. The object to be measured is located on the left side of the metalens 1, that is, the object side is located on the left side of the metalens 1, and the object surface A is located on the object side. The image formed by the TOF receiving optical system 10 is located on the right side of the metalens 1, that is, the image side is located on the right side of the metalens 1, and the image surface B is located on the image side. For ease of description, in this application, the "object side surface" refers to the surface of the corresponding object close to the object side. Similarly, in this application, the "image side surface" refers to the surface of the corresponding object close to the image side.
[0049] The metalens 1 includes a substrate 11 and a micro-nano structure 12. At least one of the object side surface of the substrate 11 and the image side surface of the substrate 11 is provided with the micro-nano structure 12. According to the adopted phase modulation method, the corresponding phase modulation formula can be adaptively used to configure the parameters of the micro-nano structure 12, so that the metalens 1 can achieve the corresponding optical performance.
[0050] The TOF receiving optical system 10 satisfies Condition 1: Wherein, f is the effective focal length of the TOF receiving optical system 10, TTL is the total optical length of the TOF receiving optical system 10, and TTL is equal to the distance from the object side surface of the metalens 1 to the image plane B on the optical axis S. f and TTL have the same dimension, both being length units, such as millimeters. Conditional formula 1 represents the ratio of the effective focal length of the TOF receiving optical system 10 to the total optical length of the TOF receiving optical system 10. The upper limit of conditional formula 1 indicates the range of the effective focal length of the TOF receiving optical system 10, and the lower limit of conditional formula 1 is used to constrain the total optical length of the TOF receiving optical system 10.
[0051] In this application, the TOF receiving optical system 10 only includes one lens. Compared with the TOF receiving optical system 10 including more than two lenses in the prior art, the TOF receiving optical system 10 provided in this application can improve the tolerance of the TOF receiving optical system 10 to the installation tolerance of the metalens 1 while ensuring the imaging quality, can reduce the requirement for the installation accuracy of the metalens 1, and can ensure that the TOF receiving optical system 10 with low assembly accuracy can also meet the optical performance, which is beneficial to the mass production of the TOF receiving optical system 10. At the same time, since the metalens 1 can be manufactured by semiconductor processes, the cost of a single metalens 1 is relatively low during mass production. Therefore, the TOF receiving optical system 10 also has the advantage of low cost.
[0052] In some embodiments, the TOF receiving optical system 10 satisfies conditional formula 2: The upper limit of conditional formula 2 is used to more precisely limit the range of the effective focal length of the TOF receiving optical system 10, and the lower limit of conditional formula 2 is used to further constrain the total optical length of the TOF receiving optical system 10.
[0053] In some embodiments, the micro-nano structure 12 is disposed on the surface of the substrate 11 close to the object side, that is, the micro-nano structure 12 is disposed on the object side surface of the substrate 11.
[0054] In some embodiments, the micro-nano structure 12 is disposed on both the surface of the substrate 11 close to the object side and the surface of the substrate 11 close to the image side, that is, the micro-nano structure 12 is disposed on both the object side surface and the image side surface of the substrate 11, so that the metalens 1 has a high design freedom.
[0055] In some embodiments, the micro-nano structure 12 is a positive micro-nano structure.
[0056] In some embodiments, the micro-nano structure 12 is a negative micro-nano structure.
[0057] In some embodiments, the micro-nano structure 12 is provided with one layer, so that the processing technology of the metalens 1 is compatible with the existing semiconductor processing technology, which is convenient for the processing and manufacturing of the metalens 1.
[0058] In some embodiments, the micro-nano structure 12 has two or more layers, so that the superlens 1 has a large and expected optical power.
[0059] For the superlens 1, the position where the micro-nano structure 12 is arranged, the positive and negative of the micro-nano structure 12, and the number of layers of the micro-nano structure 12 can be freely combined, as long as the superlens 1 has the expected performance.
[0060] In some embodiments, the specific structure of the superlens 1 is as follows: the micro-nano structure 12 is arranged on the surface of the substrate 11 close to the image side, and the micro-nano structure 12 is a negative micro-nano structure 12, and the micro-nano structure 12 has only one layer, so that the superlens 1 has good processability and also has an expected optical power. It should be noted that this is only for illustrative purposes here and should not be construed as a limitation on the specific structure of the superlens 1.
[0061] In some embodiments, the phase distribution of the superlens 1 satisfies the following formula:
[0062]
[0063] where r is the distance from the center of the superlens to any micro-nano structure, λ is the central wavelength of the working band of the superlens, is the phase constant, (x, y) is the two-dimensional coordinate of the surface of the superlens, and ai and bi are real coefficients. f m is the focal length of the superlens. Since the TOF receiving optical system 10 provided in this application only includes one superlens 1, therefore, the focal length f of the superlens 1 m is also the effective focal length f of the TOF receiving optical system 10, that is, the focal length f of the superlens 1 m is equal to the effective focal length f of the TOF receiving optical system 10.
[0064] In some embodiments, the TOF receiving optical system 10 satisfies Conditional Equation Three: where RFOV is the maximum field of view angle of the TOF receiving optical system 10, and its unit is degree. EPD (Entrance Pupil Diameter, abbreviated as EPD) is the entrance pupil diameter of the TOF receiving optical system 10, and ImgH is the radius of the imaging region of the TOF receiving optical system 10 on the image plane B corresponding to the maximum half field of view angle. The dimensions of EPD and ImgH are the same, both are length units, such as millimeters.
[0065] Conditional formula three characterizes the relationship between the maximum field of view angle of the TOF receiving optical system 10, the entrance pupil diameter of the TOF receiving optical system 10, and the image height. Since, for the same optical system, the ratio of the maximum field of view angle to the image height is directly proportional to the effective focal length of the optical system, therefore, the ratio of conditional formula three is positively correlated with the f-number of the TOF receiving optical system 10. The smaller the value of conditional formula three, the smaller the f-number of the TOF receiving optical system 10, and the larger the amount of incident light of the TOF receiving optical system 10. Therefore, the upper limit of conditional formula three can ensure that the TOF receiving optical system 10 has sufficient incident light, thereby ensuring the response rate of the TOF receiving optical system 10. The lower limit of conditional formula three can avoid the entrance pupil diameter or the field of view angle of the TOF receiving optical system 10 from being too large. If the entrance pupil diameter or the field of view angle of the TOF receiving optical system 10 is too large, it will cause uncorrectable aberrations introduced by the single ultra-lens 1, that is, the lower limit of conditional formula three can ensure that the TOF receiving optical system 10 has good imaging quality.
[0066] Further, in some embodiments, the TOF receiving optical system 10 satisfies conditional formula four: The parameters characterized by RFOV, EPD, and ImgH can refer to conditional formula three, which will not be elaborated here. The upper limit of conditional formula four can more accurately ensure that the TOF receiving optical system 10 has sufficient incident light, and the upper limit of conditional formula four can further ensure that the TOF receiving optical system 10 has better imaging quality.
[0067] In some embodiments, the TOF receiving optical system 10 satisfies conditional formula five: Wherein, ImgH is the radius of the imaging area of the TOF receiving optical system 10 corresponding to the maximum half field of view angle on the image plane B. RFOV is the maximum field of view angle of the TOF receiving optical system 10, and its unit is degree. f is the effective focal length of the TOF receiving optical system 10. ImgH and f have the same dimension, both are length units, such as millimeters.
[0068] Conditional formula five reflects the distortion of the TOF receiving optical system 10 through the gap between the real image height and the theoretical image height. Since the ultra-lens 1 has a high degree of design freedom, the distortion of the TOF receiving optical system 10 can be controlled within 8%, which is beneficial to improving the imaging quality of the TOF receiving optical system 10.
[0069] Further, in some embodiments, the TOF receiving optical system 10 satisfies conditional formula six: Wherein, the parameters characterized by ImgH, RFOV, and f can refer to conditional formula five, which will not be elaborated here. Since conditional formula six can further control the distortion of the TOF receiving optical system 10, it is beneficial to further improve the imaging quality of the TOF receiving optical system 10.
[0070] In some embodiments, the TOF receiving optical system 10 further includes a diaphragm 2, which is used to control the light incident amount of the TOF receiving optical system 10, and can ensure that the TOF receiving optical system 10 can work effectively and generate high-quality images. The diaphragm 2 is disposed on the object side of the metalens 1. Specifically, the position where the diaphragm 2 is disposed can be any of the following cases:
[0071] (1) The diaphragm 2 is disposed on the object side of the metalens 1, that is, there is a preset distance between the diaphragm 2 and the metalens 1.
[0072] (2) The diaphragm 2 is disposed on the object side surface of the metalens 1, that is, the diaphragm 2 is attached to the surface of the metalens 1 close to the object side.
[0073] In some embodiments, when the diaphragm 2 is disposed on the object side of the metalens 1, the TOF receiving optical system 10 satisfies Conditional Expression Seven: 0.03 mm ≤ L ≤ 0.2 mm, where L is the distance between the diaphragm 2 and the object side surface of the metalens 1.
[0074] Conditional Expression Seven is used to control the distance between the diaphragm 2 and the object side surface of the metalens 1. Since the diaphragm 2 is relatively thick, the diaphragm 2 blocks the marginal incident light of the TOF receiving optical system 10. Therefore, the upper limit of Conditional Expression Seven can avoid the diaphragm 2 being too thick, can avoid the diaphragm 2 blocking too much marginal light, and can ensure that the TOF receiving optical system 10 has a relatively high relative illuminance. The lower limit of Conditional Expression Seven can ensure that the diaphragm 2 has good processability and can ensure that the processing process requirements of the diaphragm 2 are compatible with the existing processing processes.
[0075] In some embodiments, when the diaphragm 2 is disposed on the object side of the metalens 1, the TOF receiving optical system 10 satisfies Conditional Expression Eight: 0.313 mm ≤ L + BFL ≤ 0.414 mm, where L is the distance between the diaphragm 2 and the object side surface of the metalens 1, and BFL (Back focal length, abbreviated as BFL) is the optical back focal length of the TOF receiving optical system 10.
[0076] For the convenience of description, the sum of the distance between the diaphragm 2 and the object side surface of the metalens 1 and the optical back focal length of the TOF receiving optical system 10 is denoted as the sum of the free thicknesses. Conditional Expression Eight characterizes the sum of the free thicknesses. The upper limit of Conditional Expression Eight is used to control the overall optical length of the TOF receiving optical system 10 and can avoid the overall optical length being too large. The lower limit of Conditional Expression Eight can ensure that there is enough space to install the diaphragm 2. At the same time, the lower limit of Conditional Expression Eight can also ensure that the TOF receiving optical system 10 has enough optical back focal length and can ensure that the optical lens corresponding to the TOF receiving optical system 10 can be assembled smoothly.
[0077] In some embodiments, the defocus MTF (Modulation Transfer Function, abbreviated as MTF) symmetry of each field of view of the TOF receiving optical system 10 is relatively good, and the MTF value is relatively high, indicating that the optical back focal length of the TOF receiving optical system 10 has a relatively high tolerance capacity. Even when the optical back focal length deviation reaches ±40 microns, the MTF value can still remain above 0.4 at a spatial frequency of 12.5 lp / mm.
[0078] In some embodiments, the TOF receiving optical system 10 further includes an antireflection film and a cut-off film. The antireflection film is used to reduce the reflection of the incident light by the TOF receiving optical system 10, thereby improving the transmittance of the incident light. The antireflection film is disposed on either the object side or the image side of the metalens 1. The cut-off film is used to filter the incident light outside the working wavelength band, and the cut-off film is disposed on the other side of the object side and the image side of the metalens 1.
[0079] In some embodiments, the antireflection film is a coating provided on the metalens 1.
[0080] In some embodiments, the antireflection film is a metasurface.
[0081] Exemplarily, this application provides four TOF receiving optical systems 10 that meet the usage requirements in four embodiments. Next, the TOF receiving optical systems 10 provided by each embodiment of this application will be introduced in detail.
[0082] Embodiment 1
[0083] Figure 1 Fig. shows a schematic diagram of the architecture layout of the TOF receiving optical system 10 provided by Embodiment 1. Figure 1 In the TOF receiving optical system 10, along the optical axis S from the object plane A to the image plane B, it successively includes: a diaphragm 2 and a metalens 1, wherein the diaphragm 2 and the metalens 1 are spaced apart. Some parameters of the TOF receiving optical system 10 provided by Embodiment 1 are shown in Table 1-1.
[0084] Table 1-1. Some parameters of the TOF receiving optical system 10 provided by Embodiment 1
[0085] Parameter Data Total Track Length (TTL) 0.708 mm Maximum Field of View (2ω) 64° F Number 0.82 Effective Focal Length 0.3 mm Operating Wavelength Band 940 ± 10 nm
[0086] As can be seen from Table 1-1, the working wavelength band of the TOF receiving optical system 10 is near-infrared light. Specifically, its working wavelength band is from 930 nanometers to 950 nanometers. The total optical length of the TOF receiving optical system 10 is relatively short, only 0.708 millimeters. Therefore, the volume of the TOF receiving optical system 10 provided in Embodiment 1 is relatively small. The F number of the TOF receiving optical system 10 is 0.82, which can greatly improve the light input amount of the TOF receiving optical system 10 and collect as much energy entering the TOF receiving optical system 10 as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.
[0087] Starting from the aperture 2, along the optical axis S from the object surface A to the image surface B direction, each surface in the TOF receiving optical system 10 is numbered, and after summarizing the parameters of each surface, the following Table 1-2 is obtained.
[0088] Table 1-2. Parameters of each surface in the TOF receiving optical system 10 provided in Embodiment 1
[0089] Surface Number Surface Type Radius of Curvature (mm) Thickness (mm) Material (nd, vd) 1 Aperture Stop Infinity 0.109 - 2 Structural Surface Infinity 0.300 1.46，67.8 3 Spherical Surface Infinity 0.299 - 4 Image Plane Infinity -- --
[0090] For each surface in Table 1-2, surface 1 is the aperture 2. Surface 2 is the surface of the superlens 1 close to the object side. Since the micro-nano structure 12 is provided on surface 2, surface 2 is denoted as the structured surface. Surface 3 is the surface of the superlens 1 close to the image side. Surface 4 is the image surface B.
[0091] As can be seen from Table 1-2, the radius of curvature of surface 1 is infinite, that is, surface 1 is a plane. The distance between surface 1 and surface 2 is 0.109 millimeters, and the material between surface 1 and surface 2 is air. The radius of curvature of surface 2 is infinite, that is, surface 2 is a plane. The distance between surface 2 and surface 3 is 0.300 millimeters, and the refractive index (nd) and Abbe number (vd) of the material between surface 2 and surface 3 are 1.46 and 67.8 respectively. The radius of curvature of surface 3 is infinite, that is, surface 3 is a plane. The distance between surface 3 and surface 4 is 0.299 millimeters, and the material between surface 3 and surface 4 is air.
[0092] Please refer to Figure 2 , Figure 2 which shows the MTF field-of-view curve graph of the TOF receiving optical system 10 provided in Embodiment 1. Figure 2 The abscissa in Figure 2 is the Y-axis field-of-view angle, and its unit is degree; Figure 2 The ordinate in Figure 2It can be seen that at a spatial frequency of 12.5 lp / mm, the MTF value of the TOF receiving optical system 10 within the full field of view is greater than 0.75, and the imaging quality of the TOF receiving optical system 10 is excellent.
[0093] Please refer to Figure 3 , Figure 3 which shows the field curvature diagram of the TOF receiving optical system 10 provided in Embodiment 1. Figure 3 In it, the horizontal axis is the field curvature, and its unit is millimeter; Figure 3 the vertical axis is the field of view angle, and its unit is degree. In Figure 3 it, S1 is the field curvature of the near-infrared light with a wavelength of 930 nm in the sagittal direction, T1 is the field curvature of the near-infrared light with a wavelength of 930 nm in the meridional direction; S2 is the field curvature of the near-infrared light with a wavelength of 940 nm in the sagittal direction, T2 is the field curvature of the near-infrared light with a wavelength of 940 nm in the meridional direction; S3 is the field curvature of the near-infrared light with a wavelength of 950 nm in the sagittal direction, T3 is the field curvature of the near-infrared light with a wavelength of 950 nm in the meridional direction. It can be seen from Figure 3 that the maximum field curvature of the TOF receiving optical system 10 in the sagittal direction is 0.05 mm, and the maximum field curvature of the TOF receiving optical system 10 in the meridional direction is 0.13 mm, meeting the requirements for field curvature in the excellent imaging quality standard.
[0094] Please refer to Figure 4 , Figure 4 which shows the distortion diagram of the TOF receiving optical system 10 provided in Embodiment 1. Figure 4 In it, the horizontal axis is the distortion, and its unit is percentage, Figure 4 the vertical axis is the field of view angle, and its unit is degree. In Figure 4 it, M1 is the distortion of the near-infrared light with a wavelength of 930 nm, M2 is the distortion of the near-infrared light with a wavelength of 940 nm, and M3 is the distortion of the near-infrared light with a wavelength of 950 nm. It can be seen from Figure 4 that the maximum distortion of the TOF receiving optical system 10 is 2.5%, and the distortion of the TOF receiving optical system 10 is small, meeting the requirements for distortion in the excellent imaging quality standard.
[0095] Embodiment 2
[0096] Figure 5 which shows a schematic diagram of the architecture layout of the TOF receiving optical system 10 provided in Embodiment 2. Figure 5 In the TOF receiving optical system 10 along the optical axis S from the object plane A to the image plane B, it successively includes: a diaphragm 2, a metalens 1, where the diaphragm 2 and the metalens 1 are arranged at intervals. Some parameters of the TOF receiving optical system 10 provided in Embodiment 2 are shown in Table 2-1.
[0097] Table 2-1. Some parameters of the TOF receiving optical system 10 provided in Embodiment 2
[0098] Parameter Data Total Track Length (TTL) 0.620 mm Maximum Field of View (2ω) 65° F Number 0.77 Effective Focal Length 0.278 mm Operating Wavelength Band 940 ± 10 nm
[0099] As can be seen from Table 2-1, the working band of the TOF receiving optical system 10 is near-infrared light. Specifically, its working band is from 930 nanometers to 950 nanometers. The total optical length of the TOF receiving optical system 10 is relatively short, only 0.620 millimeters. Therefore, the volume of the TOF receiving optical system 10 provided in Embodiment 2 is relatively small. The F number of the TOF receiving optical system 10 is 0.77, which can greatly increase the light input amount of the TOF receiving optical system 10, and can collect the energy entering the TOF receiving optical system 10 as much as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.
[0100] Starting from the diaphragm 2 and along the optical axis S from the object surface A to the image surface B direction, each surface in the TOF receiving optical system 10 is numbered, and after summarizing the parameters of each surface, the following Table 2-2 is obtained.
[0101] Table 2-2. Parameters of each surface in the TOF receiving optical system 10 provided in Embodiment 2
[0102] Surface Number Surface Type Radius of Curvature (mm) Thickness (mm) Material (nd, vd) 1 Aperture Stop Infinity 0.050 - 2 Structural Surface Infinity 0.300 1.46，67.8 3 Spherical Surface Infinity 0.270 - 4 Image Plane Infinity -- --
[0103] For the analysis of each surface in Table 2-2, reference can be made to Embodiment 1, which will not be elaborated here.
[0104] Please refer to Figure 6 , Figure 6 shows the MTF field curve graph of the TOF receiving optical system 10 provided in Embodiment 2. Figure 6 The abscissa in Figure 6 is the field angle of the Y axis, and its unit is degree; Figure 6 The ordinate in Figure 6 is the MTF value. The sagittal curve S1 and meridional curve T1 of the MTF varying with the field of view at a spatial frequency of 6 lp / mm, and the sagittal curve S2 and meridional curve T2 of the MTF varying with the field of view at a spatial frequency of 12.5 lp / mm are listed in
[0105] Please refer to Figure 7 , Figure 7 shows the field curvature graph of the TOF receiving optical system 10 provided in Embodiment 2. Figure 7 The horizontal axis in Figure 7 is the field curvature, and its unit is millimeter; Figure 7Among them, S1 is the field curvature of near-infrared light with a wavelength of 930 nm in the sagittal direction, and T1 is the field curvature of near-infrared light with a wavelength of 930 nm in the meridional direction; S2 is the field curvature of near-infrared light with a wavelength of 940 nm in the sagittal direction, and T2 is the field curvature of near-infrared light with a wavelength of 940 nm in the meridional direction; S3 is the field curvature of near-infrared light with a wavelength of 950 nm in the sagittal direction, and T3 is the field curvature of near-infrared light with a wavelength of 950 nm in the meridional direction. From Figure 7 It can be seen that the maximum field curvature of the TOF receiving optical system 10 in the sagittal direction is 0.05 mm, and the maximum field curvature of the TOF receiving optical system 10 in the meridional direction is 0.13 mm, meeting the requirements for field curvature in the excellent imaging quality standard.
[0106] Please refer to Figure 8 , Figure 8 which shows the distortion diagram of the TOF receiving optical system 10 provided in Embodiment 2. Figure 8 In it, the horizontal axis is distortion, and its unit is percentage. Figure 8 In it, the vertical axis is the field of view angle, and its unit is degree. In Figure 8 it, M1 is the distortion of near-infrared light with a wavelength of 930 nm, M2 is the distortion of near-infrared light with a wavelength of 940 nm, and M3 is the distortion of near-infrared light with a wavelength of 950 nm. From Figure 8 it can be seen that the maximum distortion of the TOF receiving optical system 10 is -1.7%, and the distortion of the TOF receiving optical system 10 is small, meeting the requirements for distortion in the excellent imaging quality standard.
[0107] Embodiment 3
[0108] Figure 9 which shows the schematic diagram of the architecture layout of the TOF receiving optical system 10 provided in Embodiment 3. Figure 9 In the TOF receiving optical system 10 along the optical axis S from the object plane A to the image plane B, it successively includes: a diaphragm 2 and a metalens 1, where the diaphragm 2 and the metalens 1 are arranged at intervals. Some parameters of the TOF receiving optical system 10 provided in Embodiment 3 are shown in Table 3-1.
[0109] Table 3-1. Some parameters of the TOF receiving optical system 10 provided in Embodiment 3
[0110] Parameter Data Total Track Length (TTL) 0.613 mm Maximum Field of View (2ω) 65° F Number 0.76 Effective Focal Length 0.274 mm Operating Wavelength Band 940 ± 10 nm
[0111] As can be seen from Table 3-1, the operating wavelength band of the TOF receiving optical system 10 is near-infrared light. Specifically, its operating wavelength band is from 930 nm to 950 nm. The total optical length of the TOF receiving optical system 10 is relatively short, only 0.613 mm. Therefore, the volume of the TOF receiving optical system 10 provided in Embodiment 3 is relatively small. The F number of the TOF receiving optical system 10 is 0.76, which can greatly increase the amount of incident light of the TOF receiving optical system 10, and can collect as much energy entering the TOF receiving optical system 10 as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.
[0112] Starting from the aperture 2, along the optical axis S from the object plane A to the image plane B direction, each surface in the TOF receiving optical system 10 is numbered, and after summarizing the parameters of each surface, the following Table 3-2 is obtained.
[0113] Table 3-2. Parameters of each surface in the TOF receiving optical system 10 provided in Embodiment 3
[0114] Surface Number Surface Type Radius of Curvature (mm) Thickness (mm) Material (nd, vd) 1 Aperture Stop Infinity 0.040 - 2 Structural Surface Infinity 0.300 1.46，67.8 3 Spherical Surface Infinity 0.273 - 4 Image Plane Infinity -- --
[0115] For the analysis of each surface in Table 3-2, reference can be made to Embodiment 1, which will not be elaborated here.
[0116] Please refer to Figure 10 , Figure 10 which shows the MTF field curve graph of the TOF receiving optical system 10 provided in Embodiment 3. Figure 10 The abscissa in Figure 10 is the Y-axis field angle, and its unit is degree; Figure 10 The ordinate in Figure 10 is the MTF value. Figure 10 lists the sagittal curve S1 and meridional curve T1 of the MTF varying with the field for the 6 lp / mm spatial frequency, and the sagittal curve S2 and meridional curve T2 of the MTF varying with the field for the 12.5 lp / mm spatial frequency. As can be seen from Figure 10 , at the 12.5 lp / mm spatial frequency, the MTF values of the TOF receiving optical system 10 within the full field range are all greater than 0.7, and the imaging quality of the TOF receiving optical system 10 is excellent.
[0117] Please refer to Figure 11 , Figure 11 which shows the field curvature graph of the TOF receiving optical system 10 provided in Embodiment 3. Figure 11 The horizontal axis in Figure 11 is the field curvature, and its unit is mm; Figure 11 The vertical axis in Figure 11Among them, S1 is the field curvature of the near-infrared light with a wavelength of 930 nm in the sagittal direction, and T1 is the field curvature of the near-infrared light with a wavelength of 930 nm in the meridional direction; S2 is the field curvature of the near-infrared light with a wavelength of 940 nm in the sagittal direction, and T2 is the field curvature of the near-infrared light with a wavelength of 940 nm in the meridional direction; S3 is the field curvature of the near-infrared light with a wavelength of 950 nm in the sagittal direction, and T3 is the field curvature of the near-infrared light with a wavelength of 950 nm in the meridional direction. From Figure 11 It can be seen that the maximum field curvature of the TOF receiving optical system 10 in the sagittal direction is 0.06 mm, and the maximum field curvature of the TOF receiving optical system 10 in the meridional direction is 0.14 mm, meeting the requirements for field curvature in the excellent imaging quality standard.
[0118] Please refer to Figure 12 , Figure 12 which shows the distortion diagram of the TOF receiving optical system 10 provided in Embodiment 3. Figure 12 In it, the horizontal axis is distortion, and its unit is percentage. Figure 12 In it, the vertical axis is the field of view angle, and its unit is degree. In Figure 12 it, M1 is the distortion of the near-infrared light with a wavelength of 930 nm, M2 is the distortion of the near-infrared light with a wavelength of 940 nm, and M3 is the distortion of the near-infrared light with a wavelength of 950 nm. From Figure 12 it can be seen that the maximum distortion of the TOF receiving optical system 10 is 2.4%, and the distortion of the TOF receiving optical system 10 is small, meeting the requirements for distortion in the excellent imaging quality standard.
[0119] Embodiment 4
[0120] Figure 13 which shows the schematic diagram of the architecture layout of the TOF receiving optical system 10 provided in Embodiment 4. Figure 13 In the TOF receiving optical system 10 along the optical axis S from the object plane A to the image plane B, it successively includes: a diaphragm 2 and a metalens 1, where the diaphragm 2 and the metalens 1 are arranged at intervals. Some parameters of the TOF receiving optical system 10 provided in Embodiment 4 are shown in Table 4-1.
[0121] Table 4-1. Some parameters of the TOF receiving optical system 10 provided in Embodiment 4
[0122] Parameter Data Total Track Length (TTL) 0.714 mm Maximum Field of View (2ω) 60.8° F Number 0.83 Effective Focal Length 0.299 mm Operating Wavelength Band 940 ± 10 nm
[0123] As can be seen from Table 4-1, the working wavelength band of the TOF receiving optical system 10 is near-infrared light. Specifically, its working wavelength band is from 930 nanometers to 950 nanometers. The total optical length of the TOF receiving optical system 10 is relatively short, only 0.714 millimeters. Therefore, the volume of the TOF receiving optical system 10 provided in Embodiment 4 is relatively small. The F number of the TOF receiving optical system 10 is 0.83, which can greatly improve the light input amount of the TOF receiving optical system 10, and can collect as much energy entering the TOF receiving optical system 10 as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.
[0124] Starting from the aperture 2, along the optical axis S from the object surface A to the image surface B direction, each surface in the TOF receiving optical system 10 is numbered, and after summarizing the parameters of each surface, the following Table 4-2 is obtained.
[0125] Table 4-2. Parameters of each surface in the TOF receiving optical system 10 provided in Embodiment 4
[0126] Surface Number Surface Type Radius of Curvature (mm) Thickness (mm) Material (nd, vd) 1 Aperture Stop Infinity 0.110 - 2 Structural Surface Infinity 0.300 1.46，67.8 3 Spherical Surface Infinity 0.304 - 4 Image Plane Infinity -- --
[0127] For the analysis of each surface in Table 4-2, reference can be made to Embodiment 1, which will not be elaborated here.
[0128] Please refer to Figure 14 , Figure 14 shows the MTF (Modulation Transfer Function, abbreviated as MTF) field curve graph of the TOF receiving optical system 10 provided in Embodiment 4. Figure 14 The abscissa in [] is the field angle of the Y axis, and its unit is degree; Figure 14 The ordinate in [] is the MTF value. Figure 14 lists the sagittal curve S1 and meridional curve T1 of the MTF varying with the field for a spatial frequency of 6 lp / mm, and the sagittal curve S2 and meridional curve T2 of the MTF varying with the field for a spatial frequency of 12.5 lp / mm. As can be seen from Figure 14 , at a spatial frequency of 12.5 lp / mm, the MTF values of the TOF receiving optical system 10 within the full field range are all greater than 0.75, and the imaging quality of the TOF receiving optical system 10 is excellent.
[0129] Please refer to Figure 15 , Figure 15 shows the field curvature graph of the TOF receiving optical system 10 provided in Embodiment 4. Figure 15 The horizontal axis in [] is the field curvature, and its unit is millimeter; Figure 15 The vertical axis in [] is the field angle, and its unit is degree. In Figure 15Among them, S1 is the field curvature of the near-infrared light with a wavelength of 930 nm in the sagittal direction, and T1 is the field curvature of the near-infrared light with a wavelength of 930 nm in the meridional direction; S2 is the field curvature of the near-infrared light with a wavelength of 940 nm in the sagittal direction, and T2 is the field curvature of the near-infrared light with a wavelength of 940 nm in the meridional direction; S3 is the field curvature of the near-infrared light with a wavelength of 950 nm in the sagittal direction, and T3 is the field curvature of the near-infrared light with a wavelength of 950 nm in the meridional direction. From Figure 15 It can be seen that the maximum field curvature of the TOF receiving optical system 10 in the sagittal direction is 0.05 mm, and the maximum field curvature of the TOF receiving optical system 10 in the meridional direction is 0.15 mm, meeting the requirements for field curvature in the excellent imaging quality standard.
[0130] Please refer to Figure 16 , Figure 16 which shows the distortion diagram of the TOF receiving optical system 10 provided in Embodiment 4. Figure 16 In Figure 16 , the horizontal axis is distortion, and its unit is percentage. Figure 16 In Figure 16 , the vertical axis is the field of view angle, and its unit is degree. Among them, M1 is the distortion of the near-infrared light with a wavelength of 930 nm, M2 is the distortion of the near-infrared light with a wavelength of 940 nm, and M3 is the distortion of the near-infrared light with a wavelength of 950 nm. From
[0131] After summarizing the parameters of the TOF receiving optical system 10 provided in the above 4 embodiments, Table 5 as shown below is obtained. The display of Table 5 is mainly used to illustrate that the various conditions satisfied by the TOF receiving optical system 10 provided in the present application are all experimentally verified and supported.
[0132] Table 5. Parameters of the TOF receiving optical system 10 provided in each embodiment
[0133]
[0134] Please refer to Figure 17 , the present application also provides a TOF receiving lens 100. The TOF receiving lens 100 includes an imaging detector 20 and the above TOF receiving optical system 10. The imaging detector 20 is arranged on the image plane B of the TOF receiving optical system 10. The imaging detector 20 includes, but is not limited to, CMOS (Complementary Metal Oxide Semiconductor, abbreviated as CMOS, complementary metal oxide semiconductor) and CCD (Charge Coupled Device, abbreviated as CCD, charge coupled device).
[0135] Please refer toFigure 17 In addition, the present application also provides a TOF module 1000. The TOF module 1000 includes the above-mentioned TOF emission lens 200 and the above-mentioned TOF reception lens 100, and the TOF emission lens 200 and the TOF reception lens 100 are arranged side by side. Among them, the TOF emission lens 200 includes a light source 30 and a TOF emission optical system 40. The TOF emission optical system 40 functions to homogenize light, so as to form a uniform light field with the light emitted by the light source 30. The TOF reception lens 100 is used to receive the reflected light of a human body or other objects.
[0136] It should be noted that the number of lenses included in the TOF emission optical system 40 can be one, two or more than two, and the present application does not limit the number of lenses of the TOF emission optical system 40.
[0137] Please refer to again Figure 17 In some embodiments, the TOF module 1000 further includes a housing 300. The housing 300 is provided with a receiving cavity 3001 for providing an installation space. The TOF emission lens 200 is received in the receiving cavity 3001, and the TOF reception lens 100 is disposed in the receiving cavity 3001 and is arranged side by side with the TOF emission lens 200. The housing 300 is provided with a first light-transmitting hole (not shown in the figure) corresponding to the TOF emission lens 200, or the housing 300 is made of a material transparent to the working wavelength band of the TOF emission lens 200 at the position corresponding to the TOF emission lens 200. Similarly, the housing 300 is provided with a second light-transmitting hole (not shown in the figure) corresponding to the TOF reception lens 100, or the housing 300 is made of a material transparent to the working wavelength band of the TOF reception lens 100 at the position corresponding to the TOF emission lens 200.
[0138] In some embodiments, the TOF module 1000 satisfies conditional formula nine: 3° ≤ TFOV - RFOV ≤ 5°, where TFOV is the maximum field of view angle of the TOF emission lens 200, and the maximum field of view angle of the TOF emission lens 200 is the maximum field of view angle of the TOF emission optical system 40. RFOV is the maximum field of view angle of the TOF reception lens 100, and the maximum field of view angle of the TOF reception lens 100 is the maximum field of view angle of the TOF reception optical system 10. The units of TFOV and RFOV are both degrees.
[0139] Conditional formula nine indicates that the maximum field of view angle of the TOF emission lens 200 needs to be larger than the maximum field of view angle of the TOF reception lens 100, which can avoid the occurrence of vignetting in the field of view due to eccentricity caused by the assembly error of the TOF emission lens 200. The lower limit of conditional formula nine is used to ensure that there is enough margin for the field of view angle of the TOF emission lens 200 and no vignetting will occur. The upper limit of conditional formula nine is to avoid excessive margin for the field of view angle of the TOF emission lens 200. If the margin for the field of view angle of the TOF emission lens 200 is too large, some light energy will be wasted, resulting in a low light energy utilization rate.
[0140] In a specific embodiment, the maximum field of view angle of the TOF receiving lens 100 of the TOF module 1000 is 64 degrees, and the maximum field of view angle of the TOF transmitting lens 200 is 68 degrees.
[0141] In a specific embodiment, the maximum field of view angle of the TOF receiving lens 100 of the TOF module 1000 is 65 degrees, and the maximum field of view angle of the TOF transmitting lens 200 is 69 degrees.
[0142] In a specific embodiment, the maximum field of view angle of the TOF receiving lens 100 of the TOF module 1000 is 65 degrees, and the maximum field of view angle of the TOF transmitting lens 200 is 70 degrees.
[0143] In a specific embodiment, the maximum field of view angle of the TOF receiving lens 100 of the TOF module 1000 is 60.8 degrees, and the maximum field of view angle of the TOF transmitting lens 200 is 65.8 degrees.
[0144] After summarizing the maximum field of view angles of the TOF receiving lens 100 and the maximum field of view angles of the TOF transmitting lens 200 of the TOF module 1000 provided in the above 4 embodiments, Table 6 as shown below is obtained. The display of Table 6 is mainly used to illustrate that the various conditions satisfied by the TOF module 1000 provided in the present application are all experimentally verified and supported.
[0145] Table 6. The maximum field of view angles of the TOF receiving lens 100 and the maximum field of view angles of the TOF transmitting lens 200 of the TOF module 1000 provided in each embodiment
[0146] Conditional Expression Example 1 Example 2 Example 3 Example 4 RFOV 64° 65° 65° 60.8° TFOV 68° 69° 70° 65.8° TFOV - RFOV 4° 4° 5° 5°
[0147] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the utility model disclosed herein. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include known common general knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and embodiments are only to be considered as exemplary, and the true scope and spirit of the present application are pointed out by the appended claims.
Claims
1. A TOF receiving optical system, characterized in that, The TOF receiving optical system includes: a metalens, the metalens includes a substrate and a micro-nano structure, and the micro-nano structure is provided on at least one of the object side surface and the image side surface of the substrate; Among them, the TOF receiving optical system satisfies: wherein, f is the effective focal length of the TOF receiving optical system, and TTL is the total optical length of the TOF receiving optical system.
2. The TOF receiving optical system according to claim 1, wherein The TOF receiving optical system satisfies the following: where the RFOV is the maximum field of view angle of the TOF receiving optical system, the EPD is the entrance pupil diameter of the TOF receiving optical system, and the ImgH is the imaging region radius corresponding to the maximum half field of view angle on the image plane of the TOF receiving optical system.
3. The TOF receiving optical system according to claim 1, characterized in that The TOF receiving optical system satisfies the following: where ImgH is the radius of the imaging area corresponding to the maximum half field of view angle on the image plane of the TOF receiving optical system, RFOV is the maximum field of view angle of the TOF receiving optical system, and f is the effective focal length of the TOF receiving optical system.
4. The TOF receiving optical system according to claim 1, wherein The TOF receiving optical system further includes a diaphragm, and the diaphragm is arranged on the object side of the metalens.
5. The TOF receiving optical system according to claim 4, wherein The TOF receiving optical system satisfies: 0.03mm ≤ L ≤ 0.2mm, where L is the distance between the diaphragm and the object side surface of the metalens.
6. The TOF receiving optical system according to claim 5, characterized in that, The TOF receiving optical system satisfies: 0.313mm ≤ L + BFL ≤ 0.414mm, where L is the distance between the diaphragm and the object side surface of the metalens, and BFL is the back focal length of the TOF receiving optical system.
7. The TOF receiving optical system according to claim 1, characterized in that, The TOF receiving optical system further includes an anti-reflection film and a cut-off film, the anti-reflection film is arranged on any one of the object side surface and the image side surface of the metalens, and the cut-off film is arranged on the other of the object side surface and the image side surface of the metalens.
8. A TOF receiving lens, characterized in that, Comprising: an imaging detector and the TOF receiving optical system according to any one of claims 1-7; The imaging detector is arranged on the image plane of the TOF receiving optical system.
9. A TOF module, characterized in that, Comprising: a TOF transmitting lens and the TOF receiving lens according to claim 8, and the TOF receiving lens and the TOF transmitting lens are arranged side by side.
10. The TOF module according to claim 9, wherein The TOF module satisfies: 3° ≤ TFOV - RFOV ≤ 5°, where TFOV is the maximum field of view angle of the TOF transmitting lens, and RFOV is the maximum field of view angle of the TOF receiving lens.