TOF receiving optical system and TOF receiving optical lens
The TOF receiving optical system uses a single super lens with micro-nano structures to address the bulkiness and cost issues of multiple lens systems, achieving compact size and high imaging quality with efficient energy collection.
Patent Information
- Application Number
- CN202422438853.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-10
- Publication Date
- 2025-07-15
- Estimated Expiration
- 2034-10-10
AI Technical Summary
The existing TOF receiving optical system has a large size and high cost.
The ultralens is used as the only light modulated lens. The ultralens includes a substrate and micro-nano structure to meet specific optical parameters, combine the aperture and protective glass to optimize the overall optical length and imaging quality.
The TOF receiving optical system is miniaturized and low-cost, maintains good imaging quality, and improves the light inlet and energy collection efficiency.
Smart Images
Figure CN223108148U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical systems, and particularly to a TOF receiving optical system and a TOF receiving optical lens. Background Art
[0002] ToF is the abbreviation of Time of Flight, which is literally translated as flight time. It works by continuously sending light pulses to the target, then using a sensor to receive the light returned from the object, and obtaining the distance of the target object by detecting the flight time of these emitted and received light pulses.
[0003] The TOF receiving lens is an important part of the TOF module, and the TOF receiving optical system is an important part of the TOF receiving lens. In the prior art, the TOF receiving optical system usually includes multiple lenses, resulting in problems such as a large volume and high cost of the TOF receiving optical system. Summary of the Utility Model
[0004] In view of the above technical problems, the embodiments of this application provide a TOF receiving optical system and a TOF receiving optical lens, aiming to provide a TOF receiving optical system and a TOF receiving optical lens with a smaller volume and lower cost.
[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 optical power of the metalens is positive, and the metalens includes a substrate and a micro-nano structure, and the micro-nano structure is disposed on the object side surface and / or the image side surface of the substrate;
[0006] Wherein, the TOF receiving optical system satisfies: -8° ≤ CRA ≤ 6°, where CRA is the main ray incident angle of the maximum field of view ray on the image plane.
[0007] In some embodiments, the TOF receiving optical system satisfies: Where ImgH is the image height corresponding to the maximum field of view angle of the TOF receiving optical system on the image plane, and f m is the focal length of the metalens, and FOV is the maximum field of view angle of the TOF receiving optical system.
[0008] In some embodiments, the TOF receiving optical system satisfies: Where is the maximum phase difference of the metalens in the working wavelength band, and f m is the focal length of the metalens, and r2 is half of the effective diameter of the image side surface of the metalens.
[0009] In some embodiments, the TOF receiving optical system satisfies: Wherein, the TTL is the total optical length of the TOF receiving optical system, the CT is the central thickness of the metalens, and the ImgH is the image height corresponding to the maximum field of view angle on the image plane of the TOF receiving optical system.
[0010] In some embodiments, the TOF receiving optical system satisfies: Wherein, the f m is the focal length of the metalens, and the EPD is the entrance pupil diameter of the TOF receiving optical system.
[0011] In some embodiments, the TOF receiving optical system further includes a diaphragm, and the diaphragm is disposed on the object side of the metalens.
[0012] In some embodiments, the TOF receiving optical system satisfies: Wherein, the TTL is the total optical length of the TOF receiving optical system, the BFL is the back focal length of the TOF receiving optical system, the L is the distance between the diaphragm and the object side surface of the metalens on the optical axis, and the FOV is the maximum field of view angle of the TOF receiving optical system.
[0013] In some embodiments, the TOF receiving optical system satisfies: Wherein, the FOV is the maximum field of view angle of the TOF receiving optical system, the L is the distance between the diaphragm and the object side surface of the metalens on the optical axis, and the CT is the central thickness of the metalens.
[0014] In some embodiments, the TOF receiving optical system satisfies: Wherein, the L is the distance between the diaphragm and the object side surface of the metalens on the optical axis, r1 is half of the effective diameter of the object side surface of the metalens, r2 is half of the effective diameter of the image side surface of the metalens, and the CT is the central thickness of the metalens.
[0015] A second aspect of the embodiments of the present application provides a TOF receiving optical lens, which 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.
[0016] The TOF receiving optical system provided by this application includes: a metalens; the optical power of the metalens is positive, and the metalens includes a substrate and a micro-nano structure, and the micro-nano structure is arranged on the object side and / or the image side of the substrate; wherein, the TOF receiving optical system satisfies: -8° ≤ CRA ≤ 6°, where CRA is the incident angle of the chief ray of the maximum field-of-view light ray on the image plane. The imaging quality of the TOF receiving optical system provided by this application is relatively good. Moreover, in the TOF receiving optical system provided by this application, there is only one metalens that has a modulation effect on light rays. Therefore, the volume of the TOF receiving optical system is relatively small. The metalens can be generated by semiconductor technology, and the cost of a single metalens is relatively low during mass production, so that the TOF receiving optical system also has the advantage of relatively low production cost. Description of the Drawings
[0017] By referring to the accompanying drawings and describing its exemplary embodiments in detail, 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-of-view curve graph of the TOF receiving optical system in an embodiment of this application.
[0020] Figure 3 Fig. shows the field curvature graph of the TOF receiving optical system in an embodiment of this application.
[0021] Figure 4 Fig. shows the distortion graph 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-of-view curve graph of the TOF receiving optical system in an embodiment of this application.
[0024] Figure 7 Fig. shows the field curvature graph of the TOF receiving optical system in an embodiment of this application.
[0025] Figure 8 Fig. shows the distortion graph 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 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] Reference numerals
[0031] 100, TOF receiving optical system;
[0032] 10, metalens; 110, substrate; 120, micro-nano structure;
[0033] 20, aperture;
[0034] 30, protective glass;
[0035] A, object plane; B, image plane; S, optical axis. Detailed implementation manners
[0036] 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 more complete and comprehensive, and will fully convey the concept of the example embodiments to those skilled in the art. The drawings are merely schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures denote the same or similar parts, and thus their repeated description will be omitted.
[0037] 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 the present application. However, those skilled in the art will realize that the technical solutions of the present 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 various aspects of the present application.
[0038] Please refer to Figure 1 , Figure 1 shows a schematic diagram of the architecture layout of the TOF receiving optical system 100 in an embodiment of the present application. The TOF receiving optical system 100 includes a metalens 10, where the optical axis S is the center line of the light beam. In Figure 1In this case, the object is located on the left side of the metalens 10, that is, the object side is on the left side of the metalens 10, and the object surface A is on the object side. The image formed by the TOF receiving optical system 100 is located on the right side of the metalens 10, that is, the image side is on the right side of the metalens 10, and the image surface B is on the image side. Therefore, the direction along the optical axis S from the object surface A to the image surface B is consistent with the direction along the optical axis S from the object side to the image side.
[0039] For each optical element of the TOF receiving optical system 100, the side close to the object side is the object side of the corresponding optical element, and the side close to the image side is the image side of the corresponding optical element. For example, the side of the metalens 10 close to the object side is the object side of the metalens 10. For each optical element of the TOF receiving optical system 100, the surface close to the object side is the object side surface of the corresponding optical element, and the surface close to the image side is the image side surface of the corresponding optical element. For example, the surface of the metalens 10 close to the image side is the image side surface of the metalens 10.
[0040] The diopter of the metalens 10 is positive. The metalens 10 includes a substrate 110 and a micro-nano structure 120. The micro-nano structure 120 is disposed on the object side surface and / or the image side surface of the substrate 110. 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 120, so that the metalens 10 has the expected optical performance.
[0041] The TOF receiving optical system 100 satisfies Condition 1: -8° ≤ CRA ≤ 6°, where CRA (Chief Ray Angle, abbreviated as CRA) is the main ray incident angle of the maximum field of view ray on the image surface B. The main ray incident angle directly affects the imaging quality. When the main ray incident angle is too large or too small, it may cause excessive aberration and relatively low relative illumination of the TOF receiving optical system 100. The upper and lower limits of Condition 1 control the main ray incident angle of the maximum field of view ray on the image surface B within a reasonable range, which can ensure that the TOF receiving optical system 100 has small aberration and relatively high relative illumination, and further ensure that the TOF receiving optical system 100 has good imaging quality.
[0042] The TOF receiving optical system 100 provided by the present application has good imaging quality. Moreover, in the TOF receiving optical system 100 provided by the present application, there is only one metalens 10 among the lenses that have a modulation effect on light. Therefore, the TOF receiving optical system 100 has a small volume. The metalens 10 can be generated by semiconductor technology, and the cost of a single metalens 10 is low during mass production, so that the TOF receiving optical system 100 also has the advantage of low production cost.
[0043] Further, in some embodiments, the TOF receiving optical system 100 satisfies Condition 2: -5° ≤ CRA ≤ 5°, where CRA is the principal ray incidence angle of the maximum field-of-view ray on the image plane B. Condition 2 can more precisely constrain the magnitude of the principal ray incidence angle of the maximum field-of-view ray on the image plane B, which is beneficial to further controlling the magnitude of the aberration of the TOF receiving optical system 100, thereby further improving the imaging quality of the TOF receiving optical system 100.
[0044] In some embodiments, the micro-nano structure 120 is disposed on the object side of the substrate 110.
[0045] In some embodiments, the micro-nano structure 120 is disposed on the image side of the substrate 110.
[0046] In some embodiments, both the object side of the substrate 110 and the image side of the substrate 110 are provided with the micro-nano structure 120, so that the metalens 10 has a high design freedom.
[0047] In some embodiments, the micro-nano structure 120 is a positive micro-nano structure.
[0048] In some embodiments, the micro-nano structure 120 is a negative micro-nano structure.
[0049] In some embodiments, the micro-nano structure 120 is provided with one layer, so that the processing technology of the metalens 10 is compatible with the existing semiconductor processing technology, which is convenient for the processing and manufacturing of the metalens 10.
[0050] In some embodiments, the micro-nano structure 120 is provided with two or more layers, so that the metalens 10 has a large and expected optical power.
[0051] For the metalens 10, the arrangement of the micro-nano structure 120 on the surface of the substrate 110, the positive or negative of the micro-nano structure 120, and the number of layers of the micro-nano structure 120 can be freely combined, as long as the metalens 10 has the expected performance.
[0052] In some embodiments, the phase distribution of the metalens 10 satisfies one of the following formulas:
[0053]
[0054] where, r is the distance from the center of the metalens 10 to any micro-nano structure 120, λ is the central wavelength of the working band of the metalens 10, is the phase constant, (x, y) is the two-dimensional coordinate on the surface of the metalens 10, a i b i a ij b ij are all real coefficients, N is the number of phase coefficient terms, f mis the focal length of the metalens 10.
[0055] In some embodiments, the TOF receiving optical system 100 satisfies Condition III: where ImgH is the image height corresponding to the maximum field of view angle of the TOF receiving optical system 100 on the image plane B, that is, ImgH is half of the diagonal length of the effective pixel region of the imaging plane B. f m is the focal length of the metalens 10, and FOV (Field of View, abbreviated as FOV) is the maximum field of view angle of the TOF receiving optical system 100. The dimensions of ImgH and f m are the same, both being length units, such as millimeters. The unit of FOV is an angular unit, such as degrees.
[0056] Condition III reflects the distortion magnitude of the TOF receiving optical system 100. From Condition III, it can be seen that the distortion of the TOF receiving optical system 100 meets the expected requirements for distortion.
[0057] In some embodiments, the TOF receiving optical system 100 satisfies Condition IV: where TTL (Total Track Length, abbreviated as TTL) is the total optical length of the TOF receiving optical system 100, CT is the central thickness of the metalens 10, and ImgH is the image height corresponding to the maximum field of view angle of the TOF receiving optical system 100 on the image plane B, that is, ImgH is half of the diagonal length of the effective pixel region of the imaging plane B. The dimensions of TTL, CT, and ImgH are the same, all being length units, such as millimeters.
[0058] Condition IV reflects the compactness of the TOF receiving optical system 100 on the premise that the central thickness of the metalens 10 is different. When the TOF receiving optical system 100 satisfies Condition IV, the miniaturization advantage of the TOF receiving optical system 100 can be ensured.
[0059] In some embodiments, the TOF receiving optical system 100 satisfies Condition V: where is the maximum phase difference of the metalens 10 in the working band, that is is the difference between the maximum phase and the minimum phase of the metalens 10 in the working band, and the unit of m is rad. f is the focal length of the metalens 10, and r2 is half of the effective diameter of the image side of the metalens 10. In this application, the effective diameter of a certain side of the metalens 10 is the diameter of the maximum light passing region of the metalens 10 on that side. The dimensions of f m and r2 are the same, both being length units, such as millimeters.
[0060] The lower limit of Conditional Formula Five represents the minimum phase difference that the metalens 10 can satisfy per unit length, and the upper limit of the conditional formula represents the maximum phase difference that the metalens 10 can satisfy per unit length.
[0061] In some embodiments, the TOF receiving optical system 100 satisfies Conditional Formula Six: where f m is the focal length of the metalens 10, and EPD (Entrance Pupil Diameter, abbreviated as EPD) is the entrance pupil diameter of the TOF receiving optical system 100. f m and EPD have the same dimension, both being length units, such as millimeters.
[0062] Conditional Formula Six reflects the range of the F number of the TOF receiving optical system 100. From Conditional Formula Six, it can be seen that the F number of the TOF receiving optical system 100 is relatively small, which can greatly increase the light incident amount of the TOF receiving optical system 100, and can collect the energy entering the TOF receiving optical system 100 as much as possible when the imaging detector has a low response to light energy, thereby ensuring excellent imaging quality.
[0063] In some embodiments, the TOF receiving optical system 100 further includes a diaphragm 20, and the diaphragm 20 is used to control the light incident amount of the TOF receiving optical system 100 to ensure that the TOF receiving optical system 100 can work effectively and generate high-quality images. The diaphragm 20 is disposed on the object side of the metalens 10. Specifically, the position where the diaphragm 20 is disposed satisfies any one of the following conditions:
[0064] (1) The diaphragm 20 is disposed on the object side of the metalens 10, and the diaphragm 20 is spaced apart from the metalens 10;
[0065] (2) The diaphragm 20 is disposed on the object side of the metalens 10, and the diaphragm 20 is disposed in contact with the metalens 10, that is, the diaphragm 20 is disposed on the object side surface of the metalens 10.
[0066] In some embodiments, the TOF receiving optical system 100 satisfies Conditional Formula Seven: where TTL is the total optical length of the TOF receiving optical system 100; BFL (Backfocal length, abbreviated as BFL) is the optical back focal length of the TOF receiving optical system 100. In this application, BFL is the distance between the image side surface of the metalens 10 and the image plane B on the optical axis S. L is the distance between the diaphragm 20 and the object side surface of the metalens 10 on the optical axis S; TTL, BFL, and L have the same dimension, all being length units, such as millimeters. FOV is the maximum field of view angle of the TOF receiving optical system 100, and the dimension of FOV is an angular unit, such as degrees.
[0067] The lower limit of Conditional Formula Seven represents the minimum total optical length of the TOF receiving optical system 100 under the constraints of the size of the optical back focal length and the aperture 20. The upper limit of Conditional Formula Seven represents the maximum total optical length of the TOF receiving optical system 100 under the constraints of the size of the optical back focal length and the aperture 20. The total optical length of the TOF receiving optical system 100 can be restricted by Conditional Formula Seven, which is beneficial to reducing the volume of the TOF receiving optical system 100.
[0068] In some embodiments, the TOF receiving optical system 100 satisfies Conditional Formula Eight: where FOV is the maximum field of view angle of the TOF receiving optical system 100, CRA is the principal ray incident angle of the maximum field of view ray on the image plane B. CRA and FOV have the same dimension, both in angular units, such as degrees. L is the distance between the aperture 20 and the object side of the meta-lens 10 on the optical axis S, CT is the central thickness of the meta-lens 10. L and CT have the same dimension, both in length units, such as millimeters.
[0069] Conditional Formula Eight represents the influence of the position of the aperture 20 and the central thickness of the meta-lens 10 on the principal ray incident angle of the maximum field of view ray on the image plane B. The principal ray incident angle of the maximum field of view ray on the image plane B can be controlled within a suitable range by Conditional Formula Eight to improve the imaging quality of the TOF receiving optical system 100.
[0070] In some embodiments, the TOF receiving optical system 100 satisfies Conditional Formula Nine: where CRA is the principal ray incident angle of the maximum field of view ray on the image plane B, and the dimension of CRA is in angular units, such as degrees. L is the distance between the aperture 20 and the object side of the meta-lens 10 on the optical axis S, r1 is half of the effective diameter of the object side of the meta-lens 10, r2 is half of the effective diameter of the image side of the meta-lens 10, and CT is the central thickness of the meta-lens 10. L, r1, r2, and CT have the same dimension, all in length units, such as millimeters.
[0071] Conditional Formula Nine represents the influence of the position of the aperture 20 and the central thickness of the meta-lens 10 on the principal ray incident angle of the maximum field of view ray on the image plane B, the effective diameter of the object side of the meta-lens 10, and the effective diameter of the image side of the meta-lens 10. The principal ray incident angle of the maximum field of view ray on the image plane B can be made to be within a suitable range by Conditional Formula Nine, and the effective diameters of the object side and the image side of the meta-lens 10 can be controlled, so that the aperture size of the meta-lens 10 can be made more appropriate.
[0072] In some embodiments, the TOF receiving optical system 100 satisfies Conditional Formula Ten: 0.4mm ≤ f m ≤ 0.6mm, where f mis the focal length of the metalens 10. In the TOF receiving optical system 100 provided in this application, the only lens that modulates light is the metalens 10. Therefore, the focal length of the metalens 10 is also the effective focal length of the TOF receiving optical system 100. Conditional formula ten controls the effective focal length of the TOF receiving optical system 100 within a reasonable range.
[0073] In some embodiments, the TOF receiving optical system 100 satisfies Conditional formula eleven: FOV≥100°. Conditional formula eleven reflects that the TOF receiving optical system 100 has a large field of view and can meet the requirements of large-field imaging.
[0074] In some embodiments, the TOF receiving optical system 100 further includes a protective glass 30, which is used to protect other optical elements in the TOF receiving optical system 100 to reduce the probability of damage to other optical elements in the TOF receiving optical system 100. The protective glass 30 is disposed at any position in the TOF receiving optical system 100. Specifically, the setting position of the protective glass 30 satisfies any of the following conditions:
[0075] (1) The protective glass 30 is disposed on the side of the aperture stop 20 away from the metalens 10, that is, the TOF receiving optical system 100 includes, along the optical axis S from the object side to the image side: the protective glass 30, the aperture stop 20, and the metalens 10. It should be noted that in this case, the aperture stop 20 can be spaced apart from the metalens 10, or the aperture stop 20 can be disposed in contact with the object side surface of the metalens 10;
[0076] (2) The protective glass 30 is disposed between the aperture stop 20 and the metalens 10, that is, the TOF receiving optical system 100 includes, along the optical axis S from the object side to the image side: the aperture stop 20, the protective glass 30, and the metalens 10;
[0077] (3) The protective glass 30 is disposed between the metalens 10 and the image plane B, that is, the TOF receiving optical system 100 includes, along the optical axis S from the object side to the image side: the aperture stop 20, the metalens 10, and the protective glass 30.
[0078] The TOF receiving optical system 100 provided in this application has the following advantages:
[0079] (1) TTL<1.3mm, and the overall optical length is small, so that the TOF receiving optical system 100 has the advantage of miniaturization;
[0080] (2) The MTF (Modulation Transfer Function, abbreviated as MTF) of the full field of view at 30 lp / mm is greater than 0.5;
[0081] (3) The only lens with a light modulation effect is the metalens 10, and the number of lenses is small, resulting in a low cost of the TOF receiving optical system 100.
[0082] Exemplarily, this application provides three TOF receiving optical systems 100 that meet the usage requirements in three embodiments. Next, the TOF receiving optical systems 100 provided by each embodiment of this application will be introduced in detail.
[0083] Embodiment 1
[0084] Figure 1 Fig. 10 shows a schematic diagram of the architecture layout of the TOF receiving optical system 100 provided by Embodiment 1. Figure 1 In the TOF receiving optical system 100, along the optical axis S from the object plane A to the image plane B, it sequentially includes: a diaphragm 20, a metalens 10, and a protective glass 30. Among them, the micro-nano structure 120 is located on the image side of the substrate 110. Some parameters of the TOF receiving optical system 100 provided by Embodiment 1 are shown in Table 1-1.
[0085] Table 1-1. Some parameters of the TOF receiving optical system 100 provided by Embodiment 1
[0086] Parameter Data Optical Total Length (TTL) 1.298 mm Maximum Field of View Angle (2ω) 100° F - number 1.03 Effective Focal Length 0.51 mm Operating Wavelength Band Near - Infrared (930 - 950 nm)
[0087] As can be seen from Table 1-1, the working wavelength band of the TOF receiving optical system 100 is the near-infrared band from 930 nm to 950 nm. The total optical length of the TOF receiving optical system 100 is relatively short, only 1.298 mm. Therefore, the volume of the TOF receiving optical system 100 provided by Embodiment 1 is relatively small. The maximum field of view angle of the TOF receiving optical system 100 is 100°, which can meet the requirements of large-field imaging. The F number of the TOF receiving optical system 100 is 1.03, which can greatly increase the light input of the TOF receiving optical system 100 and collect as much energy entering the TOF receiving optical system 100 as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.
[0088] Along the direction of the optical axis S from the object plane A to the image plane B, starting from the diaphragm 20, each surface in the TOF receiving optical system 100 is numbered, and after summarizing the parameters of each surface, the following Table 1-2 is obtained.
[0089] Table 1-2. Parameters of each surface in the TOF receiving optical system 100 provided by Embodiment 1
[0090] Surface Serial Number Surface Type Radius of Curvature (mm) Thickness (mm) Refractive Index of Material 1 Aperture Stop Infinity 0.000 - 2 Spherical Surface Infinity 0.725 1.45 3 Structural Surface Infinity 0.089 - 4 Spherical Surface Infinity 0.210 1.52 5 Spherical Surface Infinity 0.274 - 6 Image Plane Infinity - -
[0091] For each surface in Table 1-2, surface 1 is the aperture stop 20, surface 2 is the object side of the metalens 10, surface 3 is the image side of the metalens 10. Since the micro-nano structure 120 is located on the image side of the substrate 110, surface 3 is denoted as the structured surface. Surface 4 is the object side of the protective glass 30, surface 5 is the image side of the protective glass 30, and surface 6 is the image plane B.
[0092] 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 mm, 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 0.725 mm, and the refractive index of the material between surface 2 and surface 3 is 1.45. 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 0.089 mm, and the material between surface 3 and surface 4 is air. The radius of curvature of surface 4 is infinite, that is, surface 4 is a plane. The distance between surface 4 and surface 5 is 0.210 mm, and the refractive index of the material between surface 4 and surface 5 is 1.52. The radius of curvature of surface 5 is infinite, that is, surface 5 is a plane. The distance between surface 5 and surface 6 is 0.274 mm, and the material between surface 5 and surface 6 is air.
[0093] Please refer to Figure 2 , Figure 2 which shows the MTF field curve graph of the TOF receiving optical system 100 provided in Embodiment 1. Figure 2 The abscissa in Figure 2 is the X-axis field of view, and its unit is degree; Figure 2 The ordinate in Figure 2 is the MTF value. In
[0094] Please refer to Figure 3 , Figure 3 which shows the field curvature graph of the TOF receiving optical system 100 provided in Embodiment 1. Figure 3 The horizontal axis in Figure 3 is the field curvature, and its unit is millimeter; Figure 3Among 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 3 It can be seen that the maximum field curvature of the TOF receiving optical system 100 in the sagittal direction under the near-infrared light with a wavelength of 940 nm is 0.030 mm, and the maximum field curvature of the TOF receiving optical system 100 in the meridional direction under the near-infrared light with a wavelength of 940 nm is 0.055 mm, meeting the requirements for field curvature in the excellent imaging quality standard.
[0095] Please refer to Figure 4 , Figure 4 which shows the distortion diagram of the TOF receiving optical system 100 provided in Embodiment 1. Figure 4 In , the horizontal axis is distortion, and its unit is percentage; Figure 4 in , the vertical axis is the field of view angle, and its unit is degree. Figure 4 In , the distortion curves of the TOF receiving optical system 100 under the near-infrared light with wavelengths of 930 nm, 940 nm, and 950 nm are respectively shown. Since the three curves almost completely overlap, therefore, the three curves are not distinguished in this embodiment. From Figure 4 It can be seen that the maximum distortion of the TOF receiving optical system 100 provided in Embodiment 1 is -31%.
[0096] Embodiment 2
[0097] Figure 5 which shows the schematic diagram of the architecture layout of the TOF receiving optical system 100 provided in Embodiment 2. Figure 5 In , the TOF receiving optical system 100 along the optical axis S from the object plane A to the image plane B successively includes: a diaphragm 20, a metalens 10, and a protective glass 30. Among them, the micro-nano structure 120 is located on the image side of the substrate 110. Some parameters of the TOF receiving optical system 100 provided in Embodiment 2 are shown in Table 2-1.
[0098] Table 2-1. Some parameters of the TOF receiving optical system 100 provided in Embodiment 2
[0099] Parameter Data Optical Total Length (TTL) 1.02 mm Maximum Field of View Angle (2ω) 102° F - number 1.0 Effective Focal Length 0.56 mm Operating Wavelength Band Near - Infrared (930 - 950 nm)
[0100] As can be seen from Table 2-1, the operating wavelength band of the TOF receiving optical system 100 is the near-infrared band from 930 nm to 950 nm. The total optical length of the TOF receiving optical system 100 is relatively short, only 1.02 mm. Therefore, the volume of the TOF receiving optical system 100 provided in Embodiment 2 is relatively small. The maximum field of view angle of the TOF receiving optical system 100 is 102°, which can meet the requirements of large-field imaging. The F number of the TOF receiving optical system 100 is 1.0, which can greatly improve the amount of incident light of the TOF receiving optical system 100 and collect as much energy entering the TOF receiving optical system 100 as possible under the condition that the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.
[0101] Along the optical axis S from the object plane A to the image plane B, starting from the aperture 20, each surface in the TOF receiving optical system 100 is numbered, and after summarizing the parameters of each surface, the following Table 2-2 is obtained.
[0102] Table 2-2. Parameters of each surface in the TOF receiving optical system 100 provided in Embodiment 2
[0103] Surface Serial Number Surface Type Radius of Curvature (mm) Thickness (mm) Refractive Index of Material 1 Aperture Stop Infinity 0.150 - 2 Spherical Surface Infinity 0.3 1.45 3 Structural Surface Infinity 0.201 - 4 Spherical Surface Infinity 0.210 1.52 5 Spherical Surface Infinity 0.159 - 6 Image Plane Infinity - -
[0104] For the analysis of each surface in Table 2-2, reference can be made to Embodiment 1, and this embodiment will not be analyzed again.
[0105] Please refer to Figure 6 , Figure 6 which shows the MTF field curve graph of the TOF receiving optical system 100 provided in Embodiment 2. Figure 6 The abscissa in Figure 6 is the X-axis field of view, 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 15 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 30 lp / mm are listed in
[0106] Please refer to Figure 7 , Figure 7 which shows the field curvature graph of the TOF receiving optical system 100 provided in Embodiment 2. Figure 7 The horizontal axis in Figure 7 is the field curvature, and its unit is mm; Figure 7Among 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 7 It can be seen that the maximum field curvature of the TOF receiving optical system 100 in the sagittal direction under the near-infrared light with a wavelength of 940 nm is 0.027 mm, and the maximum field curvature of the TOF receiving optical system 100 in the meridional direction under the near-infrared light with a wavelength of 940 nm is 0.053 mm, meeting the requirements for field curvature in the excellent imaging quality standard.
[0107] Please refer to Figure 8 , Figure 8 which shows the distortion diagram of the TOF receiving optical system 100 provided in Embodiment 2. Figure 8 In , the horizontal axis is distortion, and its unit is percentage; Figure 8 in , the vertical axis is the field of view angle, and its unit is degree. Figure 8 shows the distortion curves of the TOF receiving optical system 100 under the near-infrared light with wavelengths of 930 nm, 940 nm, and 950 nm respectively. Since the three curves almost completely overlap, therefore, the three curves are not distinguished in this embodiment. From Figure 8 It can be seen that the maximum distortion of the TOF receiving optical system 100 provided in Embodiment 1 is -39%.
[0108] Embodiment 3
[0109] Figure 9 shows the schematic diagram of the architecture layout of the TOF receiving optical system 100 provided in Embodiment 3. Figure 9 In , the TOF receiving optical system 100 along the optical axis S from the object plane A to the image plane B sequentially includes: a diaphragm 20, a metalens 10, and a protective glass 30. Among them, the micro-nano structure 120 is located on the image side of the substrate 110. Some parameters of the TOF receiving optical system 100 provided in Embodiment 3 are shown in Table 3-1.
[0110] Table 3-1. Some parameters of the TOF receiving optical system 100 provided in Embodiment 3
[0111] Parameter Data Optical Total Length (TTL) 1.095 mm Maximum Field of View Angle (2ω) 101° F - number 1.05 Effective Focal Length 0.5 mm Operating Wavelength Band Near - Infrared (930 - 950 nm)
[0112] As can be seen from Table 3-1, the working wavelength band of the TOF receiving optical system 100 is the near-infrared band from 930 nm to 950 nm. The total optical length of the TOF receiving optical system 100 is relatively short, only 1.095 mm. Therefore, the volume of the TOF receiving optical system 100 provided in Embodiment 3 is relatively small. The maximum field of view angle of the TOF receiving optical system 100 is 101°, which can meet the requirements of large field of view imaging. The F number of the TOF receiving optical system 100 is 1.05, which can greatly improve the amount of incident light of the TOF receiving optical system 100 and collect as much energy entering the TOF receiving optical system 100 as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.
[0113] Along the optical axis S from the object plane A to the image plane B direction, starting from the aperture 20, each surface in the TOF receiving optical system 100 is numbered, and after summarizing the parameters of each surface, the following Table 3-2 is obtained.
[0114] Table 3-2. Parameters of each surface in the TOF receiving optical system 100 provided in Embodiment 3
[0115] Surface Serial Number Surface Type Radius of Curvature (mm) Thickness (mm) Refractive Index of Material 1 Aperture Stop Infinity 0.22 - 2 Spherical Surface Infinity 0.30 1.45 3 Structural Surface Infinity 0.05 - 4 Spherical Surface Infinity 0.210 1.52 5 Spherical Surface Infinity 0.315 - 6 Image Plane Infinity - -
[0116] For the analysis of each surface in Table 3-2, reference can be made to Embodiment 1, and this embodiment will not be analyzed again.
[0117] Please refer to Figure 10 , Figure 10 which shows the MTF field curve graph of the TOF receiving optical system 100 provided in Embodiment 3. Figure 10 The abscissa in Figure 10 is the X-axis field of view, and its unit is degree; Figure 10 The ordinate in Figure 10 is the MTF value.
[0118] Please refer to Figure 11 , Figure 11 which shows the field curvature graph of the TOF receiving optical system 100 provided in Embodiment 3. Figure 11 The horizontal axis in Figure 11 is the field curvature, and its unit is millimeter; Figure 11Among 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 11 It can be seen that the maximum field curvature of the TOF receiving optical system 100 in the sagittal direction under near-infrared light with a wavelength of 940 nm is 0.034 mm, and the maximum field curvature of the TOF receiving optical system 100 in the meridional direction under near-infrared light with a wavelength of 940 nm is 0.080 mm, meeting the requirements for field curvature in the excellent imaging quality standard.
[0119] Please refer to Figure 12 , Figure 12 which shows the distortion diagram of the TOF receiving optical system 100 provided in Embodiment 3. Figure 12 In , the horizontal axis is distortion, and its unit is percentage; Figure 12 in , the vertical axis is the field of view angle, and its unit is degree. Figure 12 In , the distortion curves of the TOF receiving optical system 100 under near-infrared light with wavelengths of 930 nm, 940 nm, and 950 nm are respectively shown. Since the three curves almost completely overlap, therefore, the three curves are not distinguished in this embodiment. From Figure 12 It can be seen that the maximum distortion of the TOF receiving optical system 100 provided in Embodiment 1 is -32%.
[0120] After summarizing the various parameters of the TOF receiving optical system 100 provided in the above three embodiments, Table 4 as shown below is obtained. The display of Table 4 is mainly used to illustrate that the various conditions satisfied by the TOF receiving optical system 100 provided in this application are all experimentally verified and supported.
[0121] Table 4. Various parameters of the TOF receiving optical system 100 provided in each embodiment
[0122]
[0123]
[0124] The present application also provides a TOF receiving optical lens (not shown in the figure), the TOF receiving optical lens includes an imaging detector (not shown in the figure) and the above-mentioned TOF receiving optical system 100. For the specific architecture of the TOF receiving optical system 100, reference may be made to the above text and will not be elaborated here. The imaging detector is disposed on the image plane B of the TOF receiving optical system 100, and the imaging detector 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).
[0125] 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 knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and examples are only regarded 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 optical power of the metalens is positive, and the metalens includes a substrate and a micro-nano structure, and the micro-nano structure is disposed on the object side and / or the image side of the substrate; Wherein, the TOF receiving optical system satisfies: -8° ≤ CRA ≤ 6°, where CRA is the incident angle of the chief ray of the maximum field-of-view ray on the image plane.
2. The TOF receiving optical system according to claim 1, wherein The TOF receiving optical system satisfies the following: where ImgH is the image height corresponding to the maximum field of view angle on the image plane of the TOF receiving optical system, and f m is the focal length of the metalens, and FOV is the maximum field of view angle 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: wherein, the is the maximum phase difference of the metalens at the working wavelength band, the f m is the focal length of the metalens, and r2 is half of the effective diameter of the image side of the metalens.
4. The TOF receiving optical system according to claim 1, wherein The TOF receiving optical system satisfies: Wherein, the TTL is the total optical length of the TOF receiving optical system, the CT is the central thickness of the metalens, and the ImgH is the image height corresponding to the maximum field of view angle on the image plane of the TOF receiving optical system.
5. The TOF receiving optical system according to claim 1, characterized in that The TOF receiving optical system satisfies the following: wherein the f m is the focal length of the metalens, and the EPD is the entrance pupil diameter of the TOF receiving optical system.
6. The TOF receiving optical system according to any one of claims 1-5, characterized in that, The TOF receiving optical system further includes a diaphragm, and the diaphragm is disposed on the object side of the metalens.
7. The TOF receiving optical system according to claim 6, wherein The TOF receiving optical system satisfies the following: Wherein, the TTL is the total optical length of the TOF receiving optical system, the BFL is the back focal length of the TOF receiving optical system, the L is the distance between the aperture and the object side of the metalens on the optical axis, and the FOV is the maximum field of view angle of the TOF receiving optical system.
8. The TOF receiving optical system according to claim 6, wherein The TOF receiving optical system satisfies: wherein, the FOV is the maximum field of view angle of the TOF receiving optical system, the L is the distance between the aperture and the object side surface of the metalens on the optical axis, and the CT is the central thickness of the metalens.
9. The TOF receiving optical system according to claim 6, characterized in that, The TOF receiving optical system satisfies: wherein, L is the distance between the diaphragm and the object side of the metalens on the optical axis, r1 is half of the effective diameter of the object side of the metalens, r2 is half of the effective diameter of the image side of the metalens, and CT is the central thickness of the metalens.
10. A TOF receiving optical lens, characterized in that, The TOF receiving optical lens includes: an imaging detector and the TOF receiving optical system according to any one of claims 1-9; the imaging detector is disposed on the image plane of the TOF receiving optical system.