Optical system, TOF receiving lens and TOF module

Abstract

The utility model discloses an optical system, a TOF receiving lens and a TOF module. The optical system comprises a super lens; the super lens comprises a substrate and a micro-nano structure, and the micro-nano structure is arranged on the surface, close to the object side, of the substrate and / or the surface, close to the image side, of the substrate. The optical system meets the formula # imgabs0 #, the EPD is the entrance pupil diameter of the optical system, and the fm is the focal length of the super lens. According to the optical system provided by the utility model, only one super lens is used for modulating the light, so that the size of the optical system is relatively small. The super lens is manufactured through a semiconductor process and has good machinability. In addition, the optical system provided by the invention also has the advantages of simple structure and convenient installation.

Description

Technical Field

[0001] The present application relates to the field of optical systems, and in particular to an optical system, a TOF receiving lens and a TOF module. Background Art

[0002] TOF modules are widely used in virtual reality, face recognition, smart home, autonomous driving, machine vision, industrial measurement and other fields. In the prior art, the TOF receiving optical system usually has multiple lenses, which results in a large volume of the TOF receiving optical system. In addition, when the TOF receiving optical system includes multiple lenses, the TOF receiving optical system may have problems such as poor processability and difficulty in installation. Utility Model Content

[0003] In response to the above technical problems, the embodiments of the present application provide an optical system, a TOF receiving lens and a TOF module, aiming to provide an optical system, a TOF receiving lens and a TOF module with small size, good processability and low installation difficulty.

[0004] According to one aspect of an embodiment of the present application, an optical system is disclosed, the optical system comprising: a superlens; the superlens comprises a substrate and a micro-nano structure, the micro-nano structure being arranged on a surface of the substrate close to the object side and / or a surface of the substrate close to the image side;

[0005] The optical system satisfies: Wherein, the EPD is the entrance pupil diameter of the optical system, and the f m is the focal length of the metalens.

[0006] In some embodiments, the optical system satisfies: 0.3 mm < f m <0.6mm.

[0007] In some embodiments, the optical system satisfies: Wherein, Δλ is the difference between the maximum value and the minimum value of the working wavelength of the optical system, is the phase of the superlens, and x is the distance between the point on the superlens and the center of the superlens.

[0008] In some embodiments, the optical system satisfies: 0.7<T<0.8, wherein T is the ratio of the distance from the phase inflection point of the superlens to the center of the superlens to the radius of the superlens, and the phase inflection point is the point where the monotonicity of the derivative of the phase of the superlens changes.

[0009] In some embodiments, the optical system satisfies: Wherein, the F# is the aperture number of the optical system, and the FOV is the maximum field of view angle of the optical system.

[0010] In some embodiments, the optical system satisfies: Wherein, the FOV is the maximum field of view angle of the optical system, and the F# is the aperture number of the optical system.

[0011] In some embodiments, the optical system further comprises an aperture, wherein the aperture is disposed on the object side of the metalens.

[0012] In some embodiments, the optical system satisfies: Wherein, the TTL is the total optical length of the optical system, and the CT is the thickness of the air gap between the super lens and the aperture.

[0013] A second aspect of an embodiment of the present application provides a TOF receiving lens, the TOF receiving lens comprising: an imaging detector and an optical system as described in any one of the above items; the imaging detector is arranged on the image plane of the optical system.

[0014] A third aspect of an embodiment of the present application provides a TOF module, which includes: a TOF transmitting lens and the above-mentioned TOF receiving lens; the TOF transmitting lens and the TOF receiving lens are arranged side by side.

[0015] The optical system provided by the present application includes: a super lens; the super lens includes a substrate and a micro-nano structure, and the micro-nano structure is arranged on the surface of the substrate close to the object side and / or the surface of the substrate close to the image side. The optical system meets: Where EPD is the entrance pupil diameter of the optical system, f m is the focal length of the metalens. The optical system provided by the present application has only one metalens that modulates light, so the volume of the optical system is small. The metalens is manufactured by semiconductor technology and has good machinability. In addition, the optical system provided by the present application also has the advantages of simple structure and easy installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0017] Figure 1 A schematic diagram of the architecture layout of an optical system in an embodiment of the present application is shown.

[0018] Figure 2 The phase diagram of the metalens of the optical system in one embodiment of the present application is shown.

[0019] Figure 3The MTF field of view curve diagram of the optical system in one embodiment of the present application is shown.

[0020] Figure 4 A point diagram of an optical system in an embodiment of the present application is shown.

[0021] Figure 5 A schematic diagram of the architecture layout of an optical system in an embodiment of the present application is shown.

[0022] Figure 6 The phase diagram of the metalens of the optical system in one embodiment of the present application is shown.

[0023] Figure 7 The MTF field of view curve diagram of the optical system in one embodiment of the present application is shown.

[0024] Figure 8 A point diagram of an optical system in an embodiment of the present application is shown.

[0025] Fig. 9 A schematic diagram of the architecture layout of an optical system in an embodiment of the present application is shown.

[0026] Fig.10 The phase diagram of the metalens of the optical system in one embodiment of the present application is shown.

[0027] Fig.11 The MTF field of view curve diagram of the optical system in one embodiment of the present application is shown.

[0028] Fig.12 A point diagram of an optical system in an embodiment of the present application is shown.

[0029] Fig.13 A schematic diagram of the architecture layout of an optical system in an embodiment of the present application is shown.

[0030] Fig.14 The phase diagram of the metalens of the optical system in one embodiment of the present application is shown.

[0031] Fig.15 The MTF field of view curve diagram of the optical system in one embodiment of the present application is shown.

[0032] Fig.16 A point diagram of an optical system in an embodiment of the present application is shown.

[0033] Reference numerals

[0034] 100. Optical system;

[0035] 10. Super lens; 110. Substrate; 120. Micro-nano structure;

[0036] 20. Aperture;

[0037] 30. Filter;

[0038] A, object plane; B, image plane; S, optical axis. DETAILED DESCRIPTION

[0039] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present application will be more comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0040] In addition, the described features, structures or characteristics may be combined in one or more example embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present application. However, those skilled in the art will appreciate that the technical solution of the present application may be practiced while omitting one or more of the specific details, or other modules, components, etc. may be adopted. In other cases, known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring the present application and making the various aspects of the present application obscure.

[0041] See also Figure 1 , Figure 1 FIG. 1 shows a schematic diagram of the structure layout of an optical system 100 in an embodiment of the present application, wherein the optical axis S is the center line of the light beam. Figure 1 In the figure, the object to be measured is located on the left side of the leftmost optical element, that is, the object side is located on the left side of the leftmost optical element, and the object plane A is located on the object side. The image formed by the optical system 100 is located on the right side of the rightmost optical element, that is, the image side is located on the right side of the rightmost optical element, and the image plane B is located on the image side. Therefore, the direction from the object plane A to the image plane B along the optical axis S is consistent with the direction from the object side to the image side along the optical axis S.

[0042] The optical system 100 includes a metalens 10. The metalens 10 includes a substrate 110 and a micro-nanostructure 120. The micro-nanostructure 120 is a subwavelength structure. The micro-nanostructure 120 is disposed on a surface of the substrate 110 close to the object side and / or a surface of the substrate 110 close to the image side. According to the phase modulation method adopted, the corresponding phase modulation formula can be adaptively used to configure various parameters of the micro-nanostructure 120, so that the metalens 10 can achieve corresponding optical performance, so that the metalens 10 has an expected deflection capability for incident light.

[0043] The optical system 100 satisfies conditional equation 1: Wherein, EPD (Entrance Pupil Diameter, referred to as EPD) is the entrance pupil diameter of the optical system 100, f m is the focal length of the super lens 10. EPD, f m have the same dimension, which is a unit of length, such as millimeter.

[0044] Conditional formula 1 reflects the ratio of the entrance pupil diameter of the optical system 100 and the focal length of the metalens 10. The ratio of conditional formula 1 directly affects the aperture of the optical system 100. By constraining the value of conditional formula 1, it is helpful to constrain the aperture of the optical system 100, so that the volume of the optical system 100 can be compressed, so that the optical system 100 has the advantage of miniaturization.

[0045] The optical system 100 provided by the present application has only one metalens 10 as a lens for modulating light, so the volume of the optical system 100 is relatively small. The metalens 10 is manufactured by semiconductor technology and has good processability. In addition, the optical system 100 provided by the present application also has the advantages of simple structure and easy installation.

[0046] In some embodiments, the micro-nano structure 120 is disposed on a surface of the substrate 110 close to the object side.

[0047] In some embodiments, the micro-nano structure 120 is disposed on a surface of the substrate 110 close to the image side.

[0048] In some embodiments, the surface of the substrate 110 close to the object side and the surface of the substrate 110 close to the image side are both provided with micro-nano structures 120, so that the metalens 10 has a higher degree of design freedom.

[0049] In some embodiments, the micro-nano structure 120 is a positive micro-nano structure.

[0050] In some embodiments, the micro-nano structure 120 is a negative micro-nano structure.

[0051] In some embodiments, the micro-nano structure 120 is provided with a layer to make the processing technology of the superlens 10 compatible with the existing semiconductor processing technology, which can facilitate the processing and manufacturing of the superlens 10.

[0052] In some embodiments, the micro-nano structure 120 has two or more layers, so that the superlens 10 has a larger and expected optical focal length.

[0053] For the superlens 10, the position of the micro-nano structure 120, the positive and negative positions 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 superlens 10 has the expected performance.

[0054] In some embodiments, the phase distribution of the metalens 10 satisfies the following formula:

[0055]

[0056] Wherein, r is the distance from the center of the superlens 10 to any micro-nanostructure 120, λ is the central wavelength of the working band of the superlens 10, is the phase constant, (x, y) is the two-dimensional coordinate of the surface of the metalens 10, and ai and bi are real coefficients. m is the focal length of the metalens 10. In the present application, since the metalens 10 is the only optical element in the optical system 100 that has the ability to deflect light, the focal length of the metalens 10 is also the effective focal length of the optical system 100.

[0057] Furthermore, the optical system 100 satisfies conditional equation 2: The meanings of the parameters in the conditional expression 2 can refer to the conditional expression 1, and will not be repeated here. The volume of the optical system 100 can be further compressed by the conditional expression 2, so that the optical system 100 can be miniaturized.

[0058] In some embodiments, the optical system 100 satisfies the conditional equation 3: 0.3 mm < f m <0.6mm, where f m is the focal length of the superlens 10.

[0059] Conditional formula three is used to limit the focal length of the metalens 10, and the lower limit of conditional formula three is used to ensure that the metalens 10 has a certain optical focal length to achieve light adjustment of the incident light within the system length. The upper limit of conditional formula three can avoid the optical focal length provided by the metalens 10 being too large. The greater the optical focal length of the metalens 10, the greater the dispersion will be brought to the optical system 100. If the optical focal length of the metalens 10 is too large, it will cause the problem of excessive aberration, and the upper limit of conditional formula three controls the optical focal length of the metalens 10 to control the aberration of the optical system 100 within an acceptable range.

[0060] In some embodiments, the optical system 100 satisfies Condition 4: Δλ is the difference between the maximum and minimum values ​​of the working wavelength of the optical system 100. For example, if the working wavelength of the optical system 100 is from a nanometer to b nanometer, and b is greater than a, then Δλ=ba nanometers. The unit of "2π" in conditional expression 4 is rad. is the phase of the superlens 10, The unit of is 2πrad. x is the distance between a point on the metalens 10 and the center of the metalens 10. The dimension of Δλ is the same as that of x, both of which are length units, such as millimeters.

[0061] is the change in the phase of the superlens 10, dx is the change in the distance between a point on the superlens 10 and the center of the superlens 10, is the phase gradient of the superlens 10, The unit is 2πrad / mm. represents the maximum value of the phase gradient of the metalens 10, and the magnitude of the phase gradient represents the magnitude of the negative chromatic aberration introduced by the metalens 10. The lower limit of conditional formula 4 can ensure that the metalens 10 has sufficient and expected refractive power, and the upper limit of conditional formula 4 can avoid the metalens 10 from introducing excessive chromatic aberration, thereby ensuring the imaging quality of the optical system 100.

[0062] In some embodiments, the optical system 100 satisfies conditional formula 5: 0.7<T<0.8, where T is the ratio of the distance between the phase inflection point of the metalens 10 and the center of the metalens 10 to the radius of the metalens 10. In the present application, the phase inflection point is a point where the monotonicity of the derivative of the phase of the metalens 10 changes, and the derivative of the phase of the metalens 10 is equal to the ratio of the change in the phase of the metalens 10 to the change in the distance between a point on the metalens 10 and the center of the metalens 10.

[0063] In the present application, the edge and center of the field of view of the optical system 100 require different aberration correction capabilities, and the metalens 10 has a phase inflection point, so that the metalens 10 can correct aberrations at different positions. Conditional formula 5 can be used to balance the degree of aberration correction at the edge and center of the field of view of the optical system 100 to form a good optical system 100.

[0064] In some embodiments, the optical system 100 satisfies Conditional Formula 6: Wherein, F# is the aperture number of the optical system 100, that is, the F number. FOV (Field of View, abbreviated as FOV) is the maximum field of view of the optical system 100, and the unit of FOV is degree.

[0065] Conditional formula six reflects the ratio of the aperture number of the optical system 100 to the tangent value of the maximum half field angle. Conditional formula six is ​​used to constrain the aperture of the optical system 100. At the same time, conditional formula six also ensures the position of the incident light at a certain angle on the image plane B after reaching the image plane B.

[0066] In some embodiments, the optical system 100 satisfies conditional equation 7: Wherein, FOV is the maximum field of view of the optical system 100, and the unit of FOV is degree. F# is the aperture number of the optical system 100, f m is the focal length of the superlens 10, in millimeters.

[0067] Conditional equation 7 constrains the deflection angle of the light by the metalens 10, ensuring that the metalens 10 has the expected refractive power, while also constraining the position of the image height in the direction perpendicular to the optical axis S.

[0068] In some embodiments, the optical system 100 further includes an aperture 20, which is used to control the amount of light entering the optical system 100 to ensure that the optical system 100 can work effectively and generate high-quality images. The aperture 20 is disposed on the object side of the metalens 10. Specifically, the position where the aperture 20 is disposed is any one of the following:

[0069] (1) The aperture 20 is located on the object side of the super lens 10, and the aperture 20 and the super lens 10 are spaced apart;

[0070] (2) The aperture 20 is provided on the surface of the super lens 10 close to the object side. That is, the aperture 20 is attached to the surface of the super lens 10 close to the object side.

[0071] In some embodiments, the aperture 20 is located on the object side of the metalens 10, and the aperture 20 is spaced apart from the metalens 10, and the optical system 100 satisfies conditional formula eight: Wherein, TTL (Total Track Length, abbreviated as TTL) is the total optical length of the optical system 100, and CT is the thickness of the air gap between the metalens 10 and the aperture 20. For the convenience of description, it is hereinafter referred to as the air gap thickness.

[0072] The upper limit of conditional formula eight is used to limit the ratio of the total optical length to the thickness of the air gap, which can ensure that the thickness of the air gap is not too large, and can leave enough space for the metalens 10 and the optical back focal length. The lower limit of conditional formula eight can ensure that there is a suitable spacing between the metalens 10 and other optical elements, which can make the assembly of the optical system 100 smoother.

[0073] In some embodiments, the optical system 100 further includes a filter 30, which is used to filter light outside the working band. The filter 30 is disposed at any position in the light path. The position of the filter 30 can be any of the following:

[0074] (1) The filter 30 is disposed on the side of the aperture 20 away from the superlens 10;

[0075] (2) The filter 30 is disposed between the aperture 20 and the super lens 10, and the filter 30 is spaced apart from the aperture 20 and the super lens 10;

[0076] (3) The filter 30 is disposed on the surface of the superlens 10 close to the object side, that is, the filter 30 is attached to the surface of the superlens 10 close to the object side;

[0077] (4) The filter 30 is disposed on the surface of the superlens 10 close to the image side, that is, the filter 30 is attached to the surface of the superlens 10 close to the image side;

[0078] (5) The optical filter 30 is provided on the surface of the super lens 10 close to the image side, and the optical filter 30 is provided at a distance from the super lens 10 .

[0079] The filter 30 may be a sheet structure made of glass, plastic (acrylic), quartz, colored glass or plastic resin, etc. The filter 30 may also be a coating structure. It is understood that the specific material of the filter 30 is not limited, as long as it has a filtering effect on light outside the 930nm-950nm band. In addition, the thickness of the filter is not specifically limited. Since the thickness of the filter can affect the size of the total optical length, it is sufficient as long as the thickness of the filter does not cause the total optical length to be too large.

[0080] The optical system 100 provided in this application has the following benefits:

[0081] (1) The total optical length is less than 1.2 mm;

[0082] (2) F# (F number) ≤ 1;

[0083] (3) The maximum field of view has a MTF (Modulation Transfer Function) of greater than 0.8 at the cutoff frequency of 10 lp / mm.

[0084] The present application illustratively provides four optical systems 100 that meet usage requirements in four embodiments. Next, the optical system 100 provided by each embodiment of the present application is described in detail.

[0085] Example 1

[0086] Figure 1 FIG. 1 shows a schematic diagram of the architecture layout of the optical system 100 provided in Example 1. Figure 1 The optical system 100 includes, from the object plane A to the image plane B along the optical axis S, an aperture 20, a super lens 10, and a filter 30, wherein the micro-nano structure 120 is located on the surface of the substrate 110 close to the image side. Some parameters of the optical system 100 provided in Example 1 are shown in Table 1-1.

[0087] Table 1-1. Partial parameters of the optical system 100 provided in Example 1

[0088] parameter data Total optical length (TTL) 1.12mm Maximum field of view (2ω) 71.2° F-number 1 Effective focal length 0.483mm Working band Near infrared (930nm-950nm)

[0089] As can be seen from Table 1-1, the working band of the optical system 100 is near infrared, specifically, the working band is 930 nanometers to 950 nanometers. The total optical length of the optical system 100 is relatively short, only 1.12 mm, so the volume of the optical system 100 provided in Example 1 is relatively small. The F number of the optical system 100 is 1, which can greatly increase the amount of light entering the optical system 100, and when the image sensor has a low response to light energy, the energy entering the optical system 100 is collected as much as possible, thereby ensuring excellent imaging quality.

[0090] Along the optical axis S from the object plane A to the image plane B, starting from the aperture 20, each surface in the optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 1-2.

[0091] Table 1-2. Parameters of various surfaces in the optical system 100 provided in Example 1

[0092] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Aperture unlimited 0.25 - 2 Spherical unlimited 0.3 Silicon dioxide 3 Structural surface unlimited 0.26 - 4 Spherical unlimited 0.21 D263TECO 5 Spherical unlimited 0.1 - 6 Image plane unlimited - -

[0093] For each surface in Table 1-2, surface 1 is the aperture 20, surface 2 is the surface of the super lens 10 close to the object side, surface 3 is the surface of the super lens 10 close to the image side, and since the micro-nano structure 120 is located on the surface of the substrate 110 close to the image side, surface 3 is recorded as the structural surface. Surface 4 is the surface of the filter 30 close to the object side, surface 5 is the surface of the filter 30 close to the image side, and surface 6 is the image surface B.

[0094] 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 0.25 mm, and the material between surface 1 and surface 2 is air. The radius of curvature of surface 2 is infinite, so surface 2 is a plane, the distance between surface 2 and surface 3 is 0.3 mm, and the material between surface 2 and surface 3 is silicon dioxide. 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 0.26 mm, and the material between surface 3 and surface 4 is air. The radius of curvature of surface 4 is infinite, so surface 4 is a plane, the distance between surface 4 and surface 5 is 0.21 mm, and the material between surface 4 and surface 5 is D263TECO. The radius of curvature of surface 4 is infinite, so surface 5 is a plane, the distance between surface 5 and surface 6 is 0.1 mm, and the material between surface 5 and surface 6 is air.

[0095] See also Figure 2 , Figure 2 : shows a phase diagram of the metalens 10 of the optical system 100 provided in Example 1, Figure 2 A two-dimensional coordinate system is established with the center of the superlens 10 as the origin. Figure 2, the horizontal axis represents the distance from the center of the super lens 10 in the X direction, and its unit is millimeter; the horizontal axis represents the distance from the center of the super lens 10 in the Y direction, and its unit is millimeter.

[0096] See also Figure 3 , Figure 3 FIG. 1 shows the MTF field curve of the optical system 100 provided in Example 1. Figure 3 The horizontal axis in is the X-axis field of view angle, and its unit is degree; Figure 3 The vertical axis is the MTF value. Figure 3 The sagittal curve S1 and the meridional curve T1 of the MTF with 10lp / mm spatial frequency as the field of view changes, and the sagittal curve S2 and the meridional curve T2 of the MTF with 20lp / mm spatial frequency as the field of view changes are listed in the table. Figure 3 It can be seen that at a spatial frequency of 20lp / mm, within the entire field of view, the MTF is greater than 0.55, and the imaging quality of the optical system 100 is excellent.

[0097] See also Figure 4 , Figure 4 FIG. 1 shows a point diagram of the optical system 100 provided in Example 1. The pixel size of the image sensor adapted to the optical system 100 provided in Example 1 is 25 micrometers. Figure 4 It can be seen that in the whole field of view, the spot diagram is smaller than one pixel, and the light converges more concentratedly. It is worth mentioning that the pixel size of the image sensor that the optical system 100 provided in this embodiment can adapt to is not limited to 25 microns. The optical system 100 can adapt to image sensors with a pixel size greater than 20 microns. The same is true for the optical system 100 provided in other embodiments of the present application. Therefore, it will not be repeated in other embodiments.

[0098] Example 2

[0099] Figure 5 FIG. 1 shows a schematic diagram of the architecture layout of the optical system 100 provided in Example 2. Figure 5 The optical system 100 includes, along the optical axis S, from the object plane A to the image plane B, an aperture 20, a super lens 10, and a filter 30, wherein the micro-nano structure 120 is located on the surface of the substrate 110 close to the image side. Some parameters of the optical system 100 provided in Example 2 are shown in Table 2-1.

[0100] Table 2-1. Partial parameters of the optical system 100 provided in Example 2

[0101]

[0102]

[0103] As can be seen from Table 2-1, the working band of the optical system 100 is near infrared, specifically, the working band is 930 nanometers to 950 nanometers. The total optical length of the optical system 100 is relatively short, only 1.12 mm, so the volume of the optical system 100 provided in Example 2 is relatively small. The F number of the optical system 100 is 1, which can greatly increase the amount of light entering the optical system 100, and when the image sensor has a low response to light energy, the energy entering the optical system 100 is collected as much as possible, thereby ensuring excellent imaging quality.

[0104] Along the optical axis S from the object plane A to the image plane B, starting from the aperture 20, each surface in the optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 2-2.

[0105] Table 2-2. Parameters of various surfaces in the optical system 100 provided in Example 2

[0106] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Aperture unlimited 0.25 - 2 Spherical unlimited 0.3 Silicon dioxide 3 Structural surface unlimited 0.26 - 4 Spherical unlimited 0.21 D263TECO 5 Spherical unlimited 0.1 - 6 Image plane unlimited - -

[0107] The analysis of each surface in Table 2-2 can refer to Example 1 and will not be analyzed here.

[0108] See also Figure 6 , Figure 6 : shows a phase diagram of the metalens 10 of the optical system 100 provided in Example 2, Figure 6 A two-dimensional coordinate system is established with the center of the superlens 10 as the origin. Figure 6 , the horizontal axis represents the distance from the center of the super lens 10 in the X direction, and its unit is millimeter; the horizontal axis represents the distance from the center of the super lens 10 in the Y direction, and its unit is millimeter.

[0109] See also Figure 7 , Figure 7 FIG. 2 shows the MTF field curve of the optical system 100 provided in Example 2. Figure 7 The horizontal axis in is the X-axis field of view angle, and its unit is degree; Figure 7 The vertical axis is the MTF value. Figure 7 The sagittal curve S1 and the meridional curve T1 of the MTF with 10lp / mm spatial frequency as the field of view changes, and the sagittal curve S2 and the meridional curve T2 of the MTF with 20lp / mm spatial frequency as the field of view changes are listed in the table. Figure 7 It can be seen that at a spatial frequency of 20lp / mm, the MTF is greater than 0.8 in the entire field of view, and the imaging quality of the optical system 100 is excellent.

[0110] See also Figure 8 , Figure 8FIG. 1 shows a point diagram of the optical system 100 provided in Example 2. The pixel size of the image sensor adapted to the optical system 100 provided in Example 2 is 25 micrometers. Figure 8 It can be seen that within the entire field of view, the spot diagram is smaller than one pixel, and the light converges more concentratedly.

[0111] Example 3

[0112] Fig. 9 FIG. 1 shows a schematic diagram of the architecture layout of the optical system 100 provided in Example 3. Fig. 9 The optical system 100 includes, along the optical axis S, from the object plane A to the image plane B, an aperture 20, a super lens 10, and a filter 30, wherein the micro-nano structure 120 is located on the surface of the substrate 110 close to the image side. Some parameters of the optical system 100 provided in Example 3 are shown in Table 3-1.

[0113] Table 3-1. Partial parameters of the optical system 100 provided in Example 3

[0114] parameter data Total optical length (TTL) 0.85mm Maximum field of view (2ω) 101° F-number 0.98 Effective focal length 0.351mm Working band Near infrared (930nm-950nm)

[0115] As can be seen from Table 3-1, the working band of the optical system 100 is near infrared, specifically, the working band is 930 nanometers to 950 nanometers. The total optical length of the optical system 100 is relatively short, only 0.85 mm, so the volume of the optical system 100 provided in Example 3 is relatively small. The F number of the optical system 100 is 0.98, which can greatly increase the amount of light entering the optical system 100, and when the image sensor has a low response to light energy, the energy entering the optical system 100 is collected as much as possible, thereby ensuring excellent imaging quality.

[0116] Along the optical axis S from the object plane A to the image plane B, starting from the aperture 20, each surface in the optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 3-2.

[0117] Table 3-2. Parameters of various surfaces in the optical system 100 provided in Example 3

[0118]

[0119]

[0120] The analysis of each surface in Table 3-2 can refer to Example 1 and will not be further analyzed here.

[0121] See also Fig.10 , Fig.10 : shows a phase diagram of the metalens 10 of the optical system 100 provided in Example 3, Fig.10 A two-dimensional coordinate system is established with the center of the superlens 10 as the origin. Fig.10 , the horizontal axis represents the distance from the center of the super lens 10 in the X direction, and its unit is millimeter; the horizontal axis represents the distance from the center of the super lens 10 in the Y direction, and its unit is millimeter.

[0122] See also Fig.11 , Fig.11 FIG. 4 shows the MTF field curve of the optical system 100 provided in Example 3. Fig.11 The horizontal axis in is the X-axis field of view angle, and its unit is degree; Fig.11 The vertical axis is the MTF value. Fig.11 The sagittal curve S1 and the meridional curve T1 of the MTF with 10lp / mm spatial frequency as the field of view changes, and the sagittal curve S2 and the meridional curve T2 of the MTF with 20lp / mm spatial frequency as the field of view changes are listed in the table. Fig.11 It can be seen that at a spatial frequency of 20lp / mm, within the entire field of view, the MTF is greater than 0.52, and the imaging quality of the optical system 100 is excellent.

[0123] See also Fig.12 , Fig.12 FIG. 1 shows a point diagram of the optical system 100 provided in Example 3. The pixel size of the image sensor adapted to the optical system 100 provided in Example 3 is 25 micrometers. Fig.12 It can be seen that within the entire field of view, the spot diagram is smaller than one pixel, and the light converges more concentratedly.

[0124] Example 4

[0125] Fig.13 FIG. 1 shows a schematic diagram of the architecture layout of the optical system 100 provided in Example 4. Fig.13 The optical system 100 includes, in order from the object plane A to the image plane B along the optical axis S: an aperture 20, a super lens 10, and a filter 30, wherein the micro-nano structure 120 is located on the surface of the substrate 110 close to the image side. Some parameters of the optical system 100 provided in Example 4 are shown in Table 4-1.

[0126] Table 4-1. Partial parameters of the optical system 100 provided in Example 4

[0127] parameter data Total optical length (TTL) 0.85mm Maximum field of view (2ω) 102.2° F-number 0.97 Effective focal length 0.432mm Working band Near infrared (930nm-950nm)

[0128] As can be seen from Table 4-1, the working band of the optical system 100 is near infrared, specifically, the working band is 930 nanometers to 950 nanometers. The total optical length of the optical system 100 is relatively short, only 0.85 mm, so the volume of the optical system 100 provided in Example 1 is relatively small. The F number of the optical system 100 is 0.97, which can greatly increase the amount of light entering the optical system 100, and when the image sensor has a low response to light energy, collect as much energy as possible entering the optical system 100, thereby ensuring excellent imaging quality.

[0129] Along the optical axis S from the object plane A to the image plane B, starting from the aperture 20, each surface in the optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 4-2.

[0130] Table 4-2. Parameters of various surfaces in the optical system 100 provided in Example 4

[0131] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Aperture unlimited 0.1 - 2 Spherical unlimited 0.3 Silicon dioxide 3 Structural surface unlimited 0.14 - 4 Spherical unlimited 0.21 D263TECO 5 Spherical unlimited 0.1 - 6 Image plane unlimited - -

[0132] The analysis of each surface in Table 4-2 can refer to Example 1 and will not be further analyzed here.

[0133] See also Fig.14 , Fig.14 : shows a phase diagram of the metalens 10 of the optical system 100 provided in Example 4, Fig.14 A two-dimensional coordinate system is established with the center of the superlens 10 as the origin. Fig.14 , the horizontal axis represents the distance from the center of the super lens 10 in the X direction, and its unit is millimeter; the horizontal axis represents the distance from the center of the super lens 10 in the Y direction, and its unit is millimeter.

[0134] See also Fig.15 , Fig.15 FIG. 4 shows the MTF field curve of the optical system 100 provided in Example 4. Fig.15 The horizontal axis in is the X-axis field of view angle, and its unit is degree; Fig.15 The vertical axis is the MTF value. Fig.15 The sagittal curve S1 and the meridional curve T1 of the MTF with 10lp / mm spatial frequency as the field of view changes, and the sagittal curve S2 and the meridional curve T2 of the MTF with 20lp / mm spatial frequency as the field of view changes are listed in the table. Fig.15 It can be seen that at a spatial frequency of 20lp / mm, within the entire field of view, the MTF is greater than 0.78, and the imaging quality of the optical system 100 is excellent.

[0135] See also Fig.16 , Fig.16FIG. 1 shows a point diagram of the optical system 100 provided in Example 4. The pixel size of the image sensor adapted to the optical system 100 provided in Example 4 is 25 micrometers. Fig.16 It can be seen that within the entire field of view, the spot diagram is smaller than one pixel, and the light converges more concentratedly.

[0136] After summarizing the various parameters of the optical system 100 provided by the above four embodiments, the following Table 5 is obtained. Table 5 is mainly used to illustrate that various conditions satisfied by the optical system 100 provided by the present application are all verified and supported by experiments.

[0137] Table 5. Parameters of the optical system 100 provided in various embodiments

[0138]

[0139] The present application also provides a TOF receiving lens (not shown), which includes an imaging detector and the above-mentioned optical system 100. The architecture of the optical system 100 can be found above and will not be repeated here. The imaging detector is arranged on the image plane B of the optical system 100, and the imaging detector includes but is not limited to CMOS (Complementary Metal Oxide Semiconductor, referred to as CMOS, complementary metal oxide semiconductor) and CCD (Charge Coupled Device, referred to as CCD, charge coupled device).

[0140] The present application also provides a TOF module (not shown), the TOF module includes a TOF transmitting lens and the above-mentioned TOF receiving lens. The TOF transmitting lens plays the role of uniform light to form a uniform light field in the environment. The specific architecture of the TOF transmitting lens can refer to the prior art, and the present application does not limit its specific architecture. The TOF transmitting lens and the TOF receiving lens are arranged side by side and close to each other. Objects in the environment reflect the light emitted by the TOF transmitting lens, and the TOF receiving lens is used to receive the light reflected back by objects in the environment to obtain environmental information.

[0141] In some embodiments, the maximum field of view of the TOF transmitting lens is 3 to 5° larger than the maximum field of view of the TOF receiving lens to avoid dark corners of the TOF receiving lens.

[0142] Those skilled in the art will readily appreciate 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 modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the appended claims.

Claims

1. An optical system, characterized in that: The optical system comprises: a superlens; the superlens comprises a substrate and a micro-nano structure, wherein the micro-nano structure is arranged on a surface of the substrate close to the object side and / or a surface of the substrate close to the image side; The optical system satisfies: Wherein, the EPD is the entrance pupil diameter of the optical system, and the f m is the focal length of the metalens.

2. The optical system according to claim 1, characterized in that The optical system satisfies: 0.3mm<f m <0.6mm.

3. The optical system according to claim 1, characterized in that The optical system satisfies: Wherein, Δλ is the difference between the maximum value and the minimum value of the working wavelength of the optical system, is the phase of the superlens, and x is the distance between the point on the superlens and the center of the superlens.

4. The optical system according to claim 1, characterized in that The optical system satisfies: 0.7<T<0.8, wherein T is the ratio of the distance between the phase inflection point of the superlens and the center of the superlens to the radius of the superlens, and the phase inflection point is the point where the monotonicity of the derivative of the phase of the superlens changes.

5. The optical system according to claim 1, characterized in that The optical system satisfies: Wherein, the F# is the aperture number of the optical system, and the FOV is the maximum field of view angle of the optical system.

6. The optical system according to claim 1, characterized in that The optical system satisfies: Wherein, the FOV is the maximum field of view angle of the optical system, and the F# is the aperture number of the optical system.

7. The optical system according to claim 1, characterized in that The optical system further includes an aperture, which is disposed on the object side of the super lens.

8. The optical system according to claim 7, characterized in that The optical system satisfies: Wherein, the TTL is the total optical length of the optical system, and the CT is the thickness of the air gap between the super lens and the aperture.

9. A TOF receiving lens, characterized in that: The TOF receiving lens comprises: an imaging detector and an optical system according to any one of claims 1 to 8; the imaging detector is arranged on the image plane of the optical system.

10. A TOF module, characterized in that: The TOF module comprises: a TOF transmitting lens and a TOF receiving lens as claimed in claim 9; the TOF transmitting lens and the TOF receiving lens are arranged side by side.

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