Metasurface lens fused with pupil filtering
By fusing the pupil filtering technology into the metasurface lens and modulating the light field using micro-unit arrays, the problem of insufficient focusing and imaging performance of metasurface lenses in the sub-wavelength field is solved, and a higher precision focusing and imaging effect is achieved.
Patent Information
- Application Number
- CN202510344642.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-24
- Publication Date
- 2025-05-13
AI Technical Summary
Existing metasurface lenses are limited by diffraction limits, making it difficult to achieve high precision focusing and imaging in the subwavelength field.
The pupil filtering technology is fused into the metasurface lens, and the phase, amplitude and polarization of the incident light field are comprehensively modulated through the micro-unit array to achieve super-resolution focus and imaging.
Break through the diffraction limit, achieve a smaller focusing spot, improve focus and imaging performance, and is suitable for micro optical precision measurement instruments and optical nanoprocessing instruments.
Smart Images
Figure CN119986874A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of micro-nano optical technology, and in particular relates to a super-surface lens fused with a pupil filter. Background Art
[0002] With the development of micro-nano optics and integrated optics, more and more optical devices are miniaturized and integrated. As an indispensable key device in the optical system, optical lenses are also continuously miniaturized on the basis of the principle of metasurface optics to form "metasurface lenses", which can also be called "plane lenses". Compared with traditional lenses that rely on optical thickness to modulate the phase distribution of light waves, metasurface lenses rely on micro-units in the structure to regulate the phase of light waves everywhere, thereby achieving the effect of focusing light waves. Compared with traditional lenses, metasurface lenses are small in size and easy to integrate, and can be widely used in various types of micro-optical measurement instruments and optical processing instruments. Like traditional lenses, metasurface lenses are also limited by the diffraction limit, and their focal spot size cannot exceed the half-wavelength level, making them difficult to be applied to sub-wavelength fields such as sub-wavelength optical processing, super-resolution imaging, and ultra-precision measurement. To this end, further improving the focusing and imaging performance of metasurface lenses on the basis of metasurface lenses can greatly expand their application space and promote the development of micro-nano optics and integrated optics.
[0003] Inspired by the traditional pupil filter, by modulating the parameters such as the phase, amplitude and polarization of the incident light field, the size of the lens focal spot can be greatly reduced, and super-resolution focusing and super-resolution imaging can be achieved. Therefore, when designing the metasurface lens, the phase, amplitude and polarization required by the pupil filter are superimposed on each micro-unit in the metasurface device at the same time, so that the pupil filter and the metasurface lens can be perfectly integrated, achieving the effects of super-resolution focusing and super-resolution imaging. Summary of the invention
[0004] Existing metasurface lenses use micro-units to modulate the phase of light waves, forming a spherical wavefront to achieve focusing of light waves, but their focal spot size is still limited by the diffraction limit. In order to break through the diffraction limit and achieve a smaller focused light spot, the present invention applies pupil filtering technology in traditional super-resolution imaging to the design of metasurface lenses, so that the metasurface lens has the effect of pupil filtering while achieving focusing, thereby obtaining a focused light spot beyond the diffraction limit.
[0005] In order to achieve the above object, the technical solution adopted by the present invention is: A metasurface lens with integrated pupil filtering includes a substrate 1 and a micro-unit array 2. The micro-unit array 2 is a nano-columnar array, which is divided into three regions a, b, and c in a concentric circle structure, each with a different additional phase. The radii of the three regions are r1, r2, and r3, respectively, and their sizes can be optimized by performance indicators. The additional phases of the three regions are 0, π, and 0, respectively. The additional phase is achieved by the additional rotation angle of the micro-unit.
[0006] The substrate of the super surface lens is a transparent material SiO2, and the material of the micro unit is Si.
[0007] The three area radii r1, r2 and r3 can be optimized according to the focusing effect.
[0008] The micro-unit structure is a quadrangular prism, and its parameters include length, width, height and rotation angle. By controlling the rotation angle of the micro-unit, the phase of the light field at that location can be controlled.
[0009] A metasurface lens that integrates pupil filtering can achieve super-resolution focusing effects through comprehensive regulation of the light field by micro-units, and can be applied to optical nano-processing and nano-imaging equipment.
[0010] Compared with the prior art, the present invention has the following beneficial effects: 1. Compared with the existing metasurface lens, the metasurface lens with integrated pupil filtering proposed in the present invention can achieve the comprehensive modulation capability of the phase, amplitude and polarization of the incident light field. Therefore, reasonable design and parameter optimization can greatly improve the focusing ability of the lens.
[0011] 2. Compared with the pupil filter in the traditional super-resolution imaging optical path, the fusion metasurface lens proposed in the present invention has the effects of both lens and pupil filter, realizing the fusion of the two. Therefore, the device is more integrated and can be applied to various types of micro-optical imaging instruments and micro-optical processing instruments.
[0012] In summary, compared with the existing metasurface lens, the present invention integrates the light field control principle of the pupil filter, and can use the micro-units in the metasurface structure to achieve comprehensive light field parameter control, thereby obtaining a finer focal spot. The present invention can be applied to miniaturized optical precision measurement instruments and optical nano-processing instruments. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 This is the relationship between the micro-unit rotation angle and phase modulation of the metasurface lens.
[0014] Figure 2 Micro-unit structural parameters and micro-unit spatial arrangement of the metasurface lens.
[0015] Figure 3The working principle and structural diagram of pupil filter super-resolution focusing.
[0016] Figure 4 This is a schematic diagram of a metasurface lens structure that incorporates pupil filtering proposed in the present invention.
[0017] Figure 5 Comparison of the focal spot size of a traditional metasurface lens and a metasurface lens with fused pupil filtering.
[0018] Figure 6 Comparison of the focus spot intensity curves and their half-maximum full width of the two lenses. DETAILED DESCRIPTION
[0019] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the present invention. The detailed description is as follows.
[0020] Reference Figure 1 , the correspondence between the rotation angle of the micro-unit in the metasurface lens and the phase modulation. The appropriate micro-unit structural parameters are selected so that the phase of the micro-unit changes by 2π within the range of 180° rotation. Therefore, when designing a metasurface device, the rotation angle of the micro-unit at that position can be determined according to the required phase.
[0021] See also Figure 2 , the micro-unit structural parameters of the metasurface lens and the arrangement of the micro-unit array. Each micro-unit is a nano-quadrangular prism, and its parameters are composed of length, width, height and rotation angle. The length, width and height can adjust its phase modulation amplitude, while the rotation angle can be used to modulate the phase information of the outgoing light field. After the plane wave is phase modulated by the metasurface lens, a converging spherical wave front can be formed, which then converges at the focal spot.
[0022] Reference Figure 3 , the super-resolution imaging optical path of traditional pupil filtering and the structure of pupil filter. After the plane wave ① passes through the pupil filter ②, its phase distribution is modulated to form a specific incident light field, which is converged by the objective lens ③ to form a smaller focal spot on the focal plane ④. The structure of the pupil filter is shown in the figure on the right. It is a phase-type three-zone structure. The thickness of the three zones is slightly different. The three rings are concentric circles with radii of r1, r2 and r3 respectively. , the light passing through the area between r1 and r2 will obtain an additional π phase difference.
[0023] Reference Figure 4The metasurface lens with integrated pupil filtering designed by the present invention has the same structure as the existing metasurface lens, and is composed of a substrate ① and a micro-unit array ②. The arrangement of the micro-unit array is also the same as that of the existing metasurface lens. The only difference lies in the rotation angle of each micro-unit. We divide the microlens array into three areas, namely a, b and c, according to the structural parameters of the pupil filter. The rotation angles of the micro-units in areas a and c are consistent with those of traditional metasurface lenses, while each of the micro-units in area b needs to add an additional π phase, that is, each micro-unit needs to be rotated another 90°. The metasurface lens formed in this way realizes the regulation of the incident light field while realizing wavefront convergence, so that a finer focused light spot can be obtained.
[0024] Reference Figure 5 Comparison of the focused spots of a traditional metasurface lens and a metasurface lens integrated with pupil filtering proposed in the present invention. The left side shows the focusing effect of the traditional metasurface lens, and the right side shows the light intensity distribution on the focal plane of the metasurface lens integrated with pupil filtering design.
[0025] Reference Figure 6 To further compare the changes in the size of the focal spots of the two, we use a curve to represent the intensity distribution on their center lines, where the center intensity of the metasurface lens that incorporates the pupil filtering function is about half of that without the pupil filter added. Comparing the intensity distribution curves of the two, the half-height full width of the light spot is calculated, which are 376 nm (188.0*2) and 325.4 nm (162.7*2), respectively, which are 0.59λ and 0.51λ, respectively, compared to the incident wavelength of 632.8 nm. It can be seen that the metasurface lens that incorporates pupil filtering can obtain a finer focal spot size. The above is only an example. If the parameters of the pupil filter are further optimized, its focusing effect can be further improved. In addition, if the phase, amplitude and polarization of the incident light field are modulated simultaneously, better super-resolution focusing performance can be obtained.
[0026] Therefore, the metasurface lens with integrated pupil filtering involved in the present invention fully integrates the phase modulation function of the pupil filter, and can achieve a better focusing effect by modulating the phase of the incident light field. Compared with the existing metasurface lens, the metasurface lens with integrated pupil filtering involved in the present invention can achieve simultaneous regulation of the phase, amplitude and polarization of the incident light field, thereby further reducing the focal spot size and achieving the effects of super-resolution focusing and super-resolution imaging. Compared with traditional pupil filtering technology, the present invention integrates the lens and the pupil filter, and simultaneously realizes the functions of light convergence and light field regulation, with a smaller volume and higher integration. The present invention can be widely used in micro-nano optical systems, laying the foundation for the development of micro-optical imaging systems and high-precision optical instruments.
[0027] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.
Claims
1. A metasurface lens integrating pupil filtering, comprising a substrate (1) and a micro-unit array (2), characterized in that: The substrate (1) is an optically transparent material, such as SiO2, and the micro-unit array (2) is a two-dimensional periodic arrangement of micro-unit structures, and its material is a non-metallic material, such as Si.
2. The metasurface lens for pupil filtering according to claim 1, characterized in that: The micro-unit array is arranged in a circle, and each micro-unit is a quadrangular prism structure. The length, width and height of the micro-unit structure parameters can be used to adjust the amplitude of phase modulation, and the azimuth angle of the micro-unit can be used to modulate the phase information of the light field.
3. The metasurface lens with integrated pupil filtering according to claim 1, characterized in that: The circular micro-unit array can be divided into three areas according to the length of the point from the center point, wherein the area with a distance less than r1 from the center is the central area, the area with a distance greater than r1 and less than r2 is the middle area, and the area with a distance greater than r2 and less than r3 is the edge area, wherein r3 is the radius of the metasurface lens, and r1 and r2 are the structural parameters of the pupil filter.
4. According to the micro-unit array of claim 3, the rotation direction of the micro-units located in the central area and the edge area is consistent with the general metasurface lens of the unfused pupil filter, while the micro-units located in the middle area have an additional rotation angle compared to the general metasurface lens to achieve an additional π phase change.
5. The metasurface lens integrating pupil filtering according to claim 1, characterized in that: Through comprehensive control of the micro-unit structural parameters in the metasurface lens, the phase, amplitude and polarization information in the incident light field can be independently modulated, thereby greatly improving the focusing and imaging performance of the lens, and further achieving super-resolution focusing and super-resolution imaging.