CN217821058U - TOF lens and imaging system - Google Patents
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- CN217821058U CN217821058U CN202222003990.7U CN202222003990U CN217821058U CN 217821058 U CN217821058 U CN 217821058U CN 202222003990 U CN202222003990 U CN 202222003990U CN 217821058 U CN217821058 U CN 217821058U
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Abstract
The utility model provides a TOF camera lens and imaging system, wherein, this TOF camera lens includes: the optical lens assembly comprises a first super lens, a first aspheric lens, a second super lens and a second aspheric lens which are sequentially arranged from an object side to an image side along an optical axis; the phase distribution corresponding to the first super lens and the second super lens respectively and the aspheric coefficients corresponding to the first aspheric lens and the second aspheric lens respectively can enable the TOF lens to correct aberration on the basis of meeting imaging requirements. By adopting the structure of combining two super lenses and two aspheric lenses, the TOF lens and the imaging system provided by the embodiment of the utility model reduce the using amount of the aspheric lenses and reduce the processing difficulty and cost of the TOF lens; and the two superlenses are used, so that the TOF lens is lighter in weight, smaller in volume and thinner in thickness, the integral TTL is reduced, and the TOF lens achieves a better imaging effect under the conditions of light and thin volume and lower cost.
Description
Technical Field
The utility model relates to an optical imaging technical field particularly, relates to a TOF camera lens and imaging system.
Background
At present, a Time-of-Flight (TOF) lens is applied to many fields, such as mobile phones, security monitoring, virtual reality, augmented reality, or auto-driving of automobiles, etc. Due to the limitation of the volume of the device, the TOF lens is gradually developed toward more miniaturization, light weight and low cost.
In order to obtain TOF lenses with high imaging quality (e.g. large aperture TOF lenses), multiple spherical lenses or several aspherical lenses are usually required to correct the associated aberrations, which, however, also has a number of negative effects. For example, if a plurality of spherical lenses are used, the size and length of the lens can be increased, and the better the imaging correction is, the more spherical lenses are needed, and the two spherical lenses cannot be well considered; if the aspheric lens is used or the aspheric lens and the spherical lens are mixed for use, the manufacturing cost is greatly improved; the conventional TOF lens is difficult to reach the standard of large aperture and controllable aberration under the conditions of light and thin volume and low cost.
SUMMERY OF THE UTILITY MODEL
In order to solve the above problem, an object of the embodiments of the present invention is to provide a TOF lens and an imaging system.
In a first aspect, an embodiment of the present invention provides a TOF lens, including: the optical lens assembly comprises a first super lens, a first aspheric lens, a second super lens and a second aspheric lens which are sequentially arranged from an object side to an image side along an optical axis; the first super lens and the second super lens respectively satisfy corresponding phase distribution, and the first aspheric lens and the second aspheric lens respectively satisfy corresponding aspheric coefficients; the phase distribution corresponding to the first super lens and the second super lens respectively and the aspheric coefficients corresponding to the first aspheric lens and the second aspheric lens respectively can enable the TOF lens to correct aberration on the basis of meeting imaging requirements.
Optionally, a side surface of each substrate of the first superlens and the second superlens is provided with a nanostructure, and a phase distribution of the nanostructure at least satisfies one of the following formulas:
wherein λ represents an operating wavelength of the TOF lens, and r represents a distance from a center of the nanostructure to a center of the corresponding superlens; (x, y) represents the coordinates of the nanostructure on the corresponding superlens; f represents the focal length of the superlens;
represents an arbitrary constant phase; a is i Represents a coefficient, and a i <0; n denotes the maximum number of terms.
Optionally, the nanostructures of the first superlens and the second superlens are disposed on the image-side surface of the respective substrate.
Optionally, the aspheric coefficients of the first aspheric lens or the second aspheric lens satisfy:
wherein Z represents the rise of the corresponding aspheric lens, c represents the curvature of the vertex of the corresponding aspheric lens, y represents the vertical aperture of the TOF lens, k represents the conic coefficient, A 1 、A 2 、A 3 …A 8 The coefficients are 2, 4, 6, …, respectively, for the corresponding aspheric lens.
Optionally, the TOF lens further satisfies:
1.1≤F/D≤1.5；
80°≤FOV≤85°；
1.12≤f 1 /F≤2.485；
3.24≤f 2 /F≤5.62；
0.02≤d 1 ≤0.5；
0.02≤d 2 ≤0.5；
1.4≤n 1 ≤1.5；
1.4≤n 2 ≤1.5；
wherein F represents an equivalent focal length of the TOF lens; d represents an entrance pupil diameter of the TOF lens; FOV represents the field angle of the TOF lens; f. of 1 Represents a focal length of the first superlens; d 1 Denotes the thickness of the first superlens, n 1 Representing an equivalent refractive index of the first superlens; f. of 2 Represents a focal length of the second superlens; d is a radical of 2 Denotes the thickness, n, of the second superlens 2 Representing the equivalent refractive index of the second superlens.
Optionally, the TOF lens further satisfies:
-3.526≤f 3 /f≤-1.365；
1.525≤f 4 /f≤2.08；
1.6≤n 3 ≤1.7；
1.6≤n 4 ≤1.7；
0.25≤d 3 ≤2.68；
0.31≤d 4 ≤0.67；
wherein f represents an equivalent focal length of the TOF lens; f. of 3 Represents a focal length of the first aspheric lens; d 3 Represents the center thickness, n, of the first aspheric lens 3 Representing the refractive index of the first aspheric lens; f. of 4 Represents a focal length of the second aspheric lens; d 4 Represents the center thickness, n, of the second aspheric lens 4 Representing the refractive index of the second aspherical lens.
Optionally, the material of the first superlens and the second superlens comprises silicon dioxide.
Optionally, the first aspheric lens and the second aspheric lens are of the same material.
Optionally, the operating band of the TOF lens comprises a near infrared band.
In a second aspect, the embodiment of the present invention further provides an imaging system, including: the TOF lens and the filter plate as described in any one of the above; the filter plate is arranged on the light emitting side of the TOF lens.
Optionally, the imaging system further comprises: a diaphragm; the diaphragm is arranged on the light incidence side of the TOF lens and used for limiting the size of the field of view.
In the embodiment of the present invention, in the solution provided by the first aspect, since a structure in which two super lenses and two aspheric lenses are combined is adopted, the number of aspheric lenses used is reduced, and the processing difficulty and cost of the TOF lens are reduced; moreover, the two superlenses used make the TOF lens lighter in weight, smaller in volume and thinner in thickness, and directly reduce the TTL (total system length, e.g., the distance from the light incident side of the first superlens to the image plane) of the TOF lens, so that the TOF lens achieves better imaging effect under the conditions of light and thin volume and lower cost.
In the embodiment of the present invention, since the TOF lens is used for imaging, TTL is small, and the overall thickness is further small; in addition, the adopted TOF lens is simple in processing mode, so that an imaging system comprising the TOF lens is simple to process, and the cost is greatly reduced; in addition, the TOF lens has a good effect of correcting aberration, and can well balance large aperture and small aberration.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 shows a structure diagram of a TOF lens provided in an embodiment of the present invention;
fig. 2 is a diagram illustrating a structure of an imaging system according to an embodiment of the present invention;
fig. 3 is a schematic diagram illustrating a modulation transfer function of an imaging system at a near infrared wavelength of 940nm in embodiment 1 provided by the embodiment of the present invention;
fig. 4 shows a dot-column diagram of an imaging system in embodiment 1 provided by the embodiment of the present invention;
fig. 5 shows a field curvature and distortion diagram of an imaging system in embodiment 1 provided by an embodiment of the present invention;
fig. 6 shows a defocus graph of an imaging system in embodiment 1 provided by the embodiment of the present invention.
Icon:
the optical lens comprises a 1-TOF lens, a 2-filter, a 3-diaphragm, 11-a first super lens, 12-a first aspheric lens, 13-a second super lens and 14-a second aspheric lens.
Detailed Description
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.
In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.
An embodiment of the utility model provides a TOF camera lens, it is shown to see figure 1, and this TOF camera lens includes: a first super lens 11, a first aspheric lens 12, a second super lens 13, and a second aspheric lens 14 arranged in order from an object side to an image side; fig. 1 shows the TOF lens with its left side as its object side and its right side as its image side.
As shown in fig. 1, the first and second superlenses 11 and 13 respectively satisfy the corresponding phase distributions, and the first and second aspherical mirror plates 12 and 14 respectively satisfy the corresponding aspherical coefficients; the phase distribution corresponding to the first superlens 11 and the second superlens 13, respectively, and the aspheric coefficients corresponding to the first aspheric lens 12 and the second aspheric lens 14, respectively, enable the TOF lens to correct aberrations on the basis of meeting imaging requirements.
In the embodiment of the present invention, the TOF lens may include 2 super lenses (e.g. a first super lens 11 and a second super lens 13) and 2 aspheric lenses (e.g. a first aspheric lens 12 and a second aspheric lens 14), and the 4 lenses are sequentially arranged from an object side (left side of the TOF lens shown in fig. 1, i.e. light incident side) to an image side (right side of the TOF lens shown in fig. 1, i.e. light emergent side), for example, a lens close to the object side in fig. 1 is the first super lens 11, a first aspheric lens 12 is disposed on the light emergent side of the first super lens 11, a second super lens 13 is disposed on the light emergent side of the first aspheric lens 12, and a second aspheric lens 14 is disposed on the light emergent side of the second super lens 13, i.e. the second aspheric lens 14 is the lens closest to the image side in the TOF lens; the 4 lenses are coaxially arranged.
Each super lens corresponds to one phase distribution, and each aspheric lens corresponds to one aspheric coefficient; incident light sequentially passes through the four lenses, such as a first super lens 11, a first aspheric lens 12, a second super lens 13 and a second aspheric lens 14 which are coaxially arranged, and the incident light can be subjected to two-time phase modulation sequentially by the first super lens 11 and the second super lens 13 in the four lenses (such as phase modulation based on phase distribution corresponding to the two super lenses); and may also be modulated twice by the first aspheric lens 12 and the second aspheric lens 14 of the four lenses (e.g., based on the aspheric coefficients of each aspheric lens), and when the incident light is modulated four times and exits the TOF lens, the incident light can better correct the aberration generated by the incident light through the different lenses based on the image generated at the image plane (shown at the far right in fig. 1).
The TOF lens in the embodiment of the utility model adopts the structure of combining two super lenses and two aspheric lenses, so that the using number of the aspheric lenses is reduced, and the processing difficulty and cost of the TOF lens are reduced; moreover, the two superlenses used make the TOF lens lighter in weight, smaller in volume and thinner in thickness, and directly reduce the TTL (total system length, e.g., the distance from the light incident side of the first superlens 11 to the image plane) of the TOF lens, so that the TOF lens achieves better imaging effect under the conditions of light and thin volume and lower cost.
Optionally, one side surface of each substrate of the first superlens 11 and the second superlens 13 is provided with a nanostructure, and a phase distribution of the nanostructure satisfies at least one of the following formulas:
wherein λ represents an operating wavelength of the TOF lens, optionally, an operating band of the TOF lens includes a near-infrared band; for example, the incident light entering the TOF lens may be near-infrared light, i.e. electromagnetic waves between visible light and mid-infrared light, and the near-infrared band may be electromagnetic waves with wavelengths in the range of 780nm to 2526 nm; specifically, common near infrared wavelengths include 850nm, 940nm, and the like. In the above-mentioned formula,r denotes the distance from the center of the nanostructure to the center of the corresponding superlens, such as the distance from the center of the nanostructure on the first superlens 11 to the center of the first superlens 11; (x, y) represents the coordinates of the nanostructures on the corresponding superlens, e.g., the coordinates of the nanostructures on the first superlens 11 (e.g., substrate) on the first superlens 11; f denotes a focal length of the superlens, such as the focal length of the first superlens 11, or the focal length of the second superlens 13;
represents an arbitrary constant phase; a is i Represents a coefficient, and a i <0; n represents the maximum number of terms, i.e., the maximum number of terms of the above equations (1-1) to (1-4) (i.e., 4 fitting polynomials).
The super lens is an artificially designed imaging lens which modulates the characteristics of light such as phase, amplitude, polarization and the like through a sub-wavelength nano structure on the surface of the super lens. Different from the traditional optical spherical lens or aspheric lens, the super lens only needs to design a certain structure and a periodically arranged nano structure array on a plane, and can realize the deflection of light rays which can be realized by designing different curvatures, thicknesses and selected material characteristics of the lens of the traditional lens.
In the embodiment of the present invention, any one side of each super lens (the first super lens 11 and the second super lens 13) is provided with a plurality of nano structures, and the nano structures are arranged in an array. Optionally, the nanostructures of each of the first superlens 11 and the second superlens 13 are disposed on the image-side surface of each of the corresponding substrates. As shown in fig. 1, the nanostructure of the first superlens 11 can be disposed on the right surface of the substrate of the first superlens 11 (i.e. the image side surface of the first superlens 11), and the nanostructure of the second superlens 13 can also be disposed on the right surface of the substrate of the second superlens 13 (i.e. the image side surface of the second superlens 13).
In particular, the refraction of a conventional lens conforms to Snell's law of refraction, i.e., n i sinθ i ＝n t sinθ t (ii) a Wherein n is i And n t Are respectively lightRefractive index of the line in two media, θ i And theta t The incident angle and the refraction angle of the light ray on the incident interface are respectively. Whereas the refraction of a superlens is described by the generalized Snell's law, i.e.
Wherein λ is 0 Which is indicative of the wavelength of the incident light,
represents a phase distribution of light at an incident surface; based on this, the phase distribution (e.g., the phase distribution corresponding to the nanostructure of each superlens) corresponding to each superlens (e.g., the first superlens 11 and the second superlens 13) at least satisfies any one of the above equations (1-1) to (1-5). For example, the phase distribution of the first superlens 11 may satisfy the formula (1-1); the phase distribution of the second superlens 13 may satisfy both equations (1-4) and (1-5).
Optionally, the aspheric coefficients of the first aspheric lens 12 or the second aspheric lens 14 satisfy:
wherein Z represents a rise of a corresponding aspheric lens, e.g., a surface vector parallel to a Z-axis, which is an optical axis of a TOF lens provided by an embodiment of the present invention; c denotes the curvature of the vertex of the corresponding aspherical lens, for example, the vertex curvature of the first aspherical lens 12 or the vertex curvature of the second aspherical lens 14; y represents the vertical aperture of the TOF lens, and k represents the cone coefficient; a. The 1 、A 2 、A 3 …A 8 Coefficients of 2, 4 and 6 times … times, namely, high-order coefficients, of the corresponding aspheric lens respectively; since the TOF lens mainly images incident light of a single wavelength, correction of chromatic aberration is not required, and a second-order coefficient (quadratic coefficient) a among higher-order coefficients (aspherical coefficients) is used 1 The effect of (A) is to correct the chromatic aberration, so that the embodiment of the present invention 1 Is equal to 0; based on this, the aspheric coefficients corresponding to the two aspheric lenses respectively should satisfy:
optionally, the TOF lens further satisfies:
1.1≤F/D≤1.5 (2-1)；
80°≤FOV≤85° (2-2)；
1.12≤f 1 /F≤2.485 (2-3)；
3.24≤f 2 /F≤5.62 (2-4)；
0.02≤d 1 ≤0.5 (2-5)；
0.02≤d 2 ≤0.5 (2-6)；
1.4≤n 1 ≤1.5 (2-7)；
1.4≤n 2 ≤1.5 (2-8)；
wherein, F represents an Equivalent Focal Length (EFL) of the TOF lens; d represents the entrance pupil diameter of the TOF lens; F/D represents the ratio of the equivalent focal length of the TOF lens to the diameter of the entrance pupil of the TOF lens; FOV represents the field angle of the TOF lens; f. of 1 Denotes the focal length of the first superlens 11; d 1 Denotes the thickness, n, of the first superlens 11 1 Represents the equivalent refractive index of the first superlens 11; f. of 2 Denotes the focal length of the second superlens 13; d 2 Denotes the thickness, n, of the second superlens 13 2 Representing the equivalent refractive index of the second superlens 13. When the TOF lens satisfies the 8 relations (2-1) to (2-8), the TOF lens can effectively increase the amount of light entering (for example, the TOF lens is a large aperture lens), and meanwhile, aberration can be controlled within a reasonable range, so that the imaging effect is better.
Optionally, the TOF lens further satisfies:
-3.526≤f 3 /F≤-1.365；
1.525≤f 4 /F≤2.08；
1.6≤n 3 ≤1.7；
1.6≤n 4 ≤1.7；
0.25≤d 3 ≤2.68；
0.31≤d 4 ≤0.67；
wherein F denotes an equivalent focal length of the TOF lens; f. of 3 Denotes the focal length of the first aspherical lens 12; d 3 Denotes the center thickness, n, of the first aspherical lens 12 3 Denotes the refractive index of the first aspherical lens 12; f. of 4 Denotes the focal length of the second aspherical lens 14; d 4 Denotes the center thickness, n, of the second aspherical lens 14 4 The refractive index of the second aspherical lens 14 is shown.
Optionally, the material of the first and second superlenses 11 and 13 includes silicon dioxide; the embodiment of the present invention adopts silicon dioxide (organic silicon material) to make the first super lens 11 and the second super lens 13, so that the first super lens 11 and the second super lens 13 can have high refractive index in the working wave band (near infrared wave band); moreover, the first super lens 11 and the second super lens 13 can have lower thermal expansion coefficient, longer service life and higher stability.
Optionally, the materials of the first aspheric lens 12 and the second aspheric lens 14 are the same. Wherein, the material of the two aspheric lenses can be optical glass, such as crown glass, flint glass, quartz glass, etc.; and various optical plastics can be used. When optical plastic is used as the material of the first aspheric lens 12 and the second aspheric lens 14, the aspheric lenses can be produced in a large scale at low cost by injection molding, and the process difficulty and cost of the whole TOF lens are reduced.
The embodiment of the utility model provides a still provide an imaging system, see fig. 2 and show, this imaging system includes: the TOF lens 1 and the filter 2; the filter 2 is arranged on the light-emitting side of the TOF lens 1.
Wherein, fig. 2 shows for its light-emitting side with the right side of TOF camera lens 1, the embodiment of the utility model can set up filter 2 between the light-emitting side of TOF camera lens 1 and image plane, this filter 2 can be near infrared filter (Nir filter), this filter 2 can filter the light outside the working wavelength, only the light of the working wavelength is passed through, is favorable to improving the imaging quality of this optical system in the near infrared band (working wavelength); for example, the filter 2 can be arranged to filter background light well, improving the image purity at the operating wavelength.
In the imaging system provided by the embodiment of the utility model, the TOF lens 1 is adopted for imaging, the TTL is smaller, and the overall thickness is further reduced; moreover, the adopted TOF lens 1 is simple in processing mode, so that an imaging system comprising the TOF lens is simple in processing, and the cost is greatly reduced; in addition, the TOF lens 1 has a good effect of correcting aberrations, and can well balance large apertures and small aberrations.
Optionally, as shown in fig. 2, the imaging system further comprises: a diaphragm 3; a diaphragm 3 is arranged on the light entrance side of the TOF lens 1 for limiting the field size.
In the embodiment of the present invention, the aperture 3 may be disposed on the light incident side of the TOF lens 1, for example, on the left side of the TOF lens 1 in fig. 2, and the aperture 3 may limit the size of the field of view, for example, limit the edge light to enter the field of view, limit stray light, etc.; the aperture 3 may comprise a field stop.
Example 1:
as shown in fig. 2, the present embodiment provides a four-chip imaging system based on two super lenses and two aspheric lenses. Wherein, the nanostructures of the two superlenses are respectively located on the image-side surface of the first superlens 11 (such as the right-side surface of the first superlens 11 in fig. 2) and the image-side surface of the second superlens 13 (such as the right-side surface of the second superlens 13 in fig. 2); for convenience of description and distinction, the present embodiment 1 names both sides of each lens piece in the imaging system, for example, a left side surface of the first superlens 11 is referred to as a first surface, and a right side surface of the first superlens 11 is referred to as a second surface; the left surface of the first aspherical lens 12 is referred to as a third surface, and the right surface of the first aspherical lens 12 is referred to as a fourth surface; a left side surface of the second superlens 13 is referred to as a fifth surface, and a right side surface of the second superlens 13 is referred to as a sixth surface; the left surface of the second aspherical lens 14 is referred to as a seventh surface, and the right surface of the second aspherical lens 14 is referred to as an eighth surface. As shown in FIG. 2, the second surface and the sixth surface of the present embodiment 1 can be arranged in an arrayA nanostructure. In this embodiment, the phase distributions of the two super lenses at least satisfy any one of the formulas (1-1) to (1-5), and the aspheric coefficients of the two aspheric lenses satisfy the corresponding formulas:
specifically, the specific optical index of the imaging system used in this embodiment 1 can be found in table 1 below:
TABLE 1
Wherein 2P represents two aspheric lenses (e.g., the first aspheric lens 12 and the second aspheric lens 14), and 2M represents two superlenses (e.g., the first superlens 11 and the second superlens 13); the whole thickness of this imaging system is only 4mm, can satisfy the requirement of miniaturized device, for example devices such as cell-phone, lock, VR/AR. Meanwhile, the field of view (FOV) reaches 80 degrees, so that the application in a relatively wide-angle field of view can be met; the aperture (F number) of the lens is as high as 1.3, so that the collection of reflected light energy can be effectively improved, and more detailed information of an object can be obtained.
Specific parameters for the various surfaces of the imaging system are shown in table 2 below:
TABLE 2
In the table, M1 denotes a first super lens 11, P1 denotes a first aspherical mirror 12, M2 denotes a second super lens 13, and P2 denotes a second aspherical mirror 14; filter denotes a Filter 2, such as a near-infrared Filter; the serial numbers sequentially represent an object plane, a diaphragm 3, first to tenth planes, and an image plane, wherein the serial numbers 1 to 8 represent two side surfaces of four lenses (i.e., the first to eighth planes of the TOF lens 1), respectively; numbers 9 to 10 indicate two side surfaces of the filter 2 in the imaging system (i.e. the object side surface and the image side surface of the filter 2, which are the ninth surface and the tenth surface of the imaging system, respectively); the standard plane refers to a plane without nanostructures; a super-surface then means a surface with nanostructures. Note that, in table 2, the thickness refers to the center thickness, for example, the center thickness of the diaphragm is 0.102mm; the thicknesses of the first surface, the third surface, the fifth surface and the seventh surface respectively represent the distances from the light-in side surface to the light-out side surface of the first super lens 11, the first aspheric lens 12, the second super lens 13 and the second aspheric lens 14, namely the central thickness of the corresponding lens along the main optical axis; the thicknesses of the second surface, the fourth surface, the sixth surface and the eighth surface respectively represent the distance between the light-emitting side surface of each of the first super lens 11, the first aspheric lens 12, the second super lens 13 and the second aspheric lens 14 and the distance between the next lens and the next lens; the thickness of the ninth surface is the center thickness of the filter 2 itself, and the thickness of the tenth surface is the distance (i.e., back intercept, BFL) from the filter 2 to the image plane.
In this imaging system, specific aspheric coefficients of the two aspheric lenses are shown in table 3 below, where a 1 Equal to 0 (not shown in table 3).
| Serial number | k | A 2 | A 3 | A 4 | A 5 | A 6 | A 7 | A 8 |
| 3 | -2.513 | 0.065 | -0.133 | -0.022 | 0.038 | -0.001132 | -0.001499 | -0.001607 |
| 4 | 0.005172 | -0.094 | -0.047 | -0.016 | 0.007856 | 0.004892 | -0.001352 | -0.0007964 |
| 7 | -6032.556 | 0.084 | 0.003212 | -0.004333 | 0.0001201 | 0.0001596 | 0.0001652 | -0.00009044 |
| 8 | -0.583 | 0.049 | 0.011 | 0.014 | -0.0009268 | -0.001552 | -0.0003914 | 0.0001534 |
TABLE 3
As shown in fig. 3, fig. 3 shows a Modulation Transfer Function (MTF) diagram of the imaging system provided in this embodiment 1 at a near infrared wavelength of 940 nm. As can be seen from FIG. 4, the MTF of the imaging system is still greater than 0.3 in the full field when the spatial frequency reaches 70 lp/mm; under the spatial frequency of 50lp/mm, the MTF is still about 0.5, the resolution of the imaging system is good, and the excellent imaging quality can be ensured.
Further, fig. 4 shows a stippling diagram of the imaging system; FIG. 5 shows a field curvature and distortion map of the imaging system; fig. 6 shows a defocus plot of the imaging system. The point diagram shown in fig. 4 can see the convergence of the light rays of different fields (angles) on the image plane, the smaller the light spot is, the better the imaging quality is, and the RMS (Rate-Monotonic Scheduling) radius is smaller than or close to the airy disk radius, which indicates that the imaging quality is excellent; therefore, as shown in fig. 4, the maximum RMS radius of the present embodiment 1 is 10.081 μm, which can satisfy the excellent imaging effect; as can be seen from fig. 5 (left part), the field curvature of the imaging system is small, i.e. less than 0.02mm; as can be seen in fig. 5 (right), the distortion of the imaging system is approximately 5%, e.g., the optical maximum distortion is 5.0689%; the defocus graph shown in fig. 6 indicates the MTF variation when the image plane deviates from the design value (parameter), that is, the allowable error range of the imaging system, theoretically deviates from the design value greatly but the MTF variation is small, which indicates that the allowable error of the imaging system is large, and the imaging system is beneficial to assembly. If the imaging system deviates slightly from the design value, the MTF drops rapidly, which indicates that the system is sensitive and no large deviation is allowed in the assembly, otherwise the imaging quality is reduced. As can be seen from fig. 6, the MTF is all at a higher position within ± 0.02mm of the design value, which indicates that the design of embodiment 1 allows a certain deviation, which is beneficial to the actual assembly.
The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the technical solutions of the changes or replacements within the technical scope of the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (11)
1. A TOF lens, comprising: a first super lens (11), a first aspheric lens (12), a second super lens (13), and a second aspheric lens (14) arranged in order from the object side to the image side;
the first superlens (11) and the second superlens (13) each satisfy a respective phase profile, the first aspheric lens (12) and the second aspheric lens (14) each satisfy a respective aspheric coefficient;
the phase distribution corresponding to the first super lens (11) and the second super lens (13) respectively and the aspheric coefficients corresponding to the first aspheric lens (12) and the second aspheric lens (14) respectively can enable the TOF lens to correct aberration on the basis of meeting imaging requirements.
2. TOF lens according to claim 1, wherein a side surface of the respective substrate of the first superlens (11) and the second superlens (13) is provided with nanostructures having a phase distribution satisfying at least one of the following formulae:
wherein λ represents an operating wavelength of the TOF lens, and r represents a distance from a center of the nanostructure to a center of the corresponding superlens; (x, y) represents the coordinates of the nanostructure on the corresponding superlens; f represents the focal length of the superlens;
represents an arbitrary constant phase; a is i Represents a coefficient, and a i <0; n represents the maximum number of terms.
3. The TOF lens according to claim 2, wherein the respective nanostructures of the first superlens (11) and the second superlens (13) are each arranged on the image-side surface of the respective substrate.
4. The TOF lens according to claim 1, characterized in that the aspheric coefficients of the first aspheric lens (12) or the second aspheric lens (14) satisfy:
wherein Z represents the rise of the corresponding aspheric lens, c represents the curvature of the vertex of the corresponding aspheric lens, y represents the vertical aperture of the TOF lens, k represents the conic coefficient, A 1 、A 2 、A 3 …A 8 The coefficients are 2, 4, 6, …, respectively, for the corresponding aspheric lens.
5. The TOF lens of claim 1, wherein the TOF lens further satisfies:
1.1≤F/D≤1.5；
80°≤FOV≤85°；
1.12≤f 1 /F≤2.485；
3.24≤f 2 /F≤5.62；
0.02≤d 1 ≤0.5；
0.02≤d 2 ≤0.5；
1.4≤n 1 ≤1.5；
1.4≤n 2 ≤1.5；
wherein F represents an equivalent focal length of the TOF lens; d represents an entrance pupil diameter of the TOF lens; FOV represents the field angle of the TOF lens; f. of 1 Represents the focal length of the first superlens (11); d 1 Represents the thickness, n, of the first superlens (11) 1 Represents the equivalent refractive index of the first superlens (11); f. of 2 Represents the focal length of the second superlens (13); d 2 Represents the thickness, n, of the second superlens (13) 2 Representing the equivalent refractive index of the second superlens (13).
6. The TOF lens of claim 1, wherein the TOF lens further satisfies:
-3.526≤f 3 /f≤-1.365；
1.525≤f 4 /f≤2.08；
1.6≤n 3 ≤1.7；
1.6≤n 4 ≤1.7；
0.25≤d 3 ≤2.68；
0.31≤d 4 ≤0.67；
wherein f represents an equivalent focal length of the TOF lens; f. of 3 Represents the focal length of the first aspheric lens (12); d is a radical of 3 Represents the center thickness, n, of the first aspherical lens (12) 3 Represents the refractive index of the first aspherical lens (12); f. of 4 Represents the focal length of the second aspherical lens (14); d 4 Represents the central thickness, n, of the second aspherical lens (14) 4 Represents the refractive index of the second aspherical lens (14).
7. The TOF lens according to claim 1, characterized in that the material of the first superlens (11) and the second superlens (13) comprises silicon dioxide.
8. TOF lens according to claim 1, characterized in that the material of the first aspheric lens (12) and the second aspheric lens (14) is the same.
9. The TOF lens of claim 1 wherein the operating band of the TOF lens comprises a near infrared band.
10. An imaging system, comprising: a TOF lens (1) and filter plate (2) according to any one of claims 1 to 9; the filter (2) is arranged on the light outgoing side of the TOF lens (1).
11. The imaging system of claim 10, further comprising: a diaphragm (3); the diaphragm (3) is arranged on the light incidence side of the TOF lens (1) and used for limiting the size of a view field.
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| US11927769B2 (en) | 2022-03-31 | 2024-03-12 | Metalenz, Inc. | Polarization sorting metasurface microlens array device |
| CN117706738A (en) * | 2024-02-05 | 2024-03-15 | 武汉二元科技有限公司 | External long-focus lens of folding and super-mixing mobile phone |
| CN117930472A (en) * | 2024-03-25 | 2024-04-26 | 武汉宇熠科技有限公司 | Infrared confocal security lens |
| US11978752B2 (en) | 2019-07-26 | 2024-05-07 | Metalenz, Inc. | Aperture-metasurface and hybrid refractive-metasurface imaging systems |
| US11988844B2 (en) | 2017-08-31 | 2024-05-21 | Metalenz, Inc. | Transmissive metasurface lens integration |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US11988844B2 (en) | 2017-08-31 | 2024-05-21 | Metalenz, Inc. | Transmissive metasurface lens integration |
| US11978752B2 (en) | 2019-07-26 | 2024-05-07 | Metalenz, Inc. | Aperture-metasurface and hybrid refractive-metasurface imaging systems |
| US11927769B2 (en) | 2022-03-31 | 2024-03-12 | Metalenz, Inc. | Polarization sorting metasurface microlens array device |
| CN117706738A (en) * | 2024-02-05 | 2024-03-15 | 武汉二元科技有限公司 | External long-focus lens of folding and super-mixing mobile phone |
| CN117706738B (en) * | 2024-02-05 | 2024-04-09 | 武汉二元科技有限公司 | External long-focus lens of folding and super-mixing mobile phone |
| CN117930472A (en) * | 2024-03-25 | 2024-04-26 | 武汉宇熠科技有限公司 | Infrared confocal security lens |
| CN117930472B (en) * | 2024-03-25 | 2024-05-28 | 武汉宇熠科技有限公司 | Infrared confocal security lens |
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