CN113740948A - Planar diffraction lens, method for manufacturing planar diffraction lens, and optical imaging system - Google Patents
Planar diffraction lens, method for manufacturing planar diffraction lens, and optical imaging system Download PDFInfo
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Abstract
The invention discloses a plane diffraction lens, a manufacturing method thereof and an optical imaging system, which comprise a transparent substrate and a non-transparent metal film, wherein the metal film is provided with semi-ring band groups which are symmetrically distributed on two sides of the substrate, a cutting angle is arranged between the semi-ring band group positioned on one side of the substrate and the semi-ring band group positioned on the other side of the substrate, the two semi-ring band groups respectively comprise a plurality of layers of concentric elliptic semi-ring bands, and a layer of transparent air layer is arranged between every two adjacent layers of concentric elliptic semi-ring bands. The plane diffraction lens has a simple structure and low manufacturing cost, and light beams passing through the plane diffraction lens can generate uniform sub-wavelength transverse light needle light fields (line light sources) on a focal plane.
Description
Technical Field
The invention relates to the technical field of information optics and light field regulation, in particular to a plane diffraction lens, a manufacturing method of the plane diffraction lens and an optical imaging system.
Background
Optical microscopy imaging technology plays an irreplaceable role in modern scientific research and production life. Among the many features of microscopic imaging technology, optical resolution is the most central performance indicator, and among them, the performance of optical lenses is a key factor that limits the resolution of the system. The microscopic imaging system constructed based on the traditional optical lens can not break through the resolution limit determined by the Abbe diffraction limit and the Rayleigh criterion all the time due to the nature of the fluctuation characteristic of light. In addition, the conventional lens based on the optical refraction principle has the disadvantages of large volume, high price and inconvenience for system integration.
The development of current optical technology shows a trend towards light weight and planarization, and is typically represented by a two-dimensional diffractive optical lens instead of a traditional three-dimensional material refractive lens to realize modulation and imaging application of an optical field. The research on diffractive lenses is increasingly becoming a leading field in the direction of current optical theory and optical engineering. As a typical representative of diffractive optical elements, a diffractive lens of a concentric ring zone plate type has many advantages of a two-dimensional planar configuration, a compact size, and a light weight, and is widely used in high-end optical imaging systems. In addition, the diffractive optics principle provides people with a highly free lens design and preparation mode, and the development of the diffractive optics principle also provides a feasible scheme for breaking through the optical diffraction limit. The concept of optical superoscillation was proposed by the british physicist Micheal Berry in 2006. By constructing a precisely designed plane diffraction lens structure, the optical interference effect of different spatial frequency diffraction light fields is reasonably regulated and controlled, and a focusing light spot exceeding the optical diffraction limit can be obtained on a far-field focal plane. A plurality of research teams at home and abroad report that the plane diffraction lens is combined with a confocal microscopic imaging technology to successfully realize optical super-resolution optical imaging. However, in the prior art, a super-diffraction limit point light source generated by a plane diffraction lens is used for scanning a sample point by point, and an electromagnetic radiation signal of each pixel point is used for reconstructing to obtain a plane or stereo image. The imaging speed of the working mode is generally 10-20 frames/second, and the high-speed imaging requirement required by the dynamic imaging of the living organism is difficult to meet. Although the latest commercial line scanning confocal imaging system has a great improvement on the scanning speed (which can exceed 100 frames/second), the line light source required by the scanning system is generated by combining a cylindrical lens and a microscope objective, and is large in size, complex and expensive, and meanwhile, the width of the line light source is limited by the diffraction limit, the resolution is low, and super-resolution optical imaging is difficult to realize.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a planar diffraction lens, a manufacturing method of the planar diffraction lens and an optical imaging system, wherein the generated line light source can exceed the diffraction limit, and the planar diffraction lens has high imaging resolution and low cost.
The purpose of the invention is realized by the following technical scheme:
a first aspect of the present application provides a planar diffractive lens comprising:
a substrate capable of transmitting light; and
the metal film covers in the one side of basement, metal film has and is located basement both sides and symmetric distribution's semi-ring belt group, is located basement one side semi-ring belt group with be located the basement opposite side semi-ring belt group between have the corner cut, two sets of semi-ring belt group all includes a plurality of layers of concentric ellipse semi-ring belt, and adjacent two-layer equal interval one deck can non-light tight air bed between the concentric ellipse semi-ring belt.
Preferably, each layer of the concentric elliptical semi-annular zones has a long axis and a short axis, and the ratio range of the long axis of each layer of the concentric elliptical semi-annular zones to the short axis of each layer of the concentric elliptical semi-annular zones is [ 1.1-1.4 ].
Preferably, the length of the minor axis of the concentric elliptical half-zone located at the outermost side is in the range of 50 μm.
Preferably, the range of the cut angle is [0 °, 60 ° ].
Preferably, the two semi-circular ring belt groups each comprise 40 layers of the concentric elliptical semi-circular ring belts.
Preferably, the annular width of each layer of the concentric elliptical semi-annular zones is [400nm, 900nm ].
A second aspect of the present application provides a method of manufacturing a planar diffraction lens, comprising the steps of:
step S71, covering one side of the substrate with a photoresist layer;
step S72, performing patterning processing on the photoresist layer, etching off part of the photoresist layer, forming semi-ring band groups to be stripped on the positions, located on two sides of the substrate, of the residual photoresist layer, wherein the semi-ring band groups to be stripped are symmetrically distributed, a chamfer is formed between the semi-ring band group to be stripped located on one side of the substrate and the semi-ring band group to be stripped located on the other side of the substrate, two semi-ring band groups to be stripped respectively comprise a plurality of concentric elliptical semi-ring bands to be stripped, and an interval is formed between every two adjacent semi-ring bands to be stripped, so that a part to be plated is obtained;
step S73, coating a film on the piece to be plated so as to cover one surface of the piece to be plated with a metal film layer to obtain a piece to be stripped;
and S74, standing the to-be-stripped part in stripping liquid for a preset standing time, wherein each layer of the concentric elliptical to-be-stripped semi-annular belt automatically falls off from the substrate to form air layers in a one-to-one correspondence manner, and a layer of concentric elliptical semi-annular belt is arranged between every two adjacent layers of the air layers.
Preferably, in the step S71, one surface of the substrate is covered with the photoresist layer by spin coating and spin leveling, a spin coating and spin leveling speed is 2000 rpm, and a thickness of the photoresist layer is [260nm, 280nm ].
Preferably, in step S72, the substrate covered with the photoresist layer is placed in a vacuum dust-free environment, the photoresist layer is patterned by using electron beam direct writing, and a portion of the photoresist layer is etched by chemical development.
A third aspect of the present application provides an optical imaging system, including an optical path module, further including the planar diffraction lens as described above, the optical path module is used for generating light to the planar diffraction lens, and the planar diffraction lens is used for generating a line light source exceeding a diffraction limit.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. compared with the traditional plane diffraction lens, the light field regulation and control characteristics of the traditional diffraction lens such as a Fresnel zone plate and the like can only realize that a focus point is obtained on a far-field focal plane, and the transverse size of the focus is limited by a diffraction limit.
2. Compared with a commercial optical imaging system, the existing commercial line scanning confocal micro-imaging system generates a line light source in a mode of using a cylindrical mirror and a micro objective, the optical imaging system is complex and high in cost, and the width of the line light source is limited by a diffraction limit, so that the imaging resolution is limited by the diffraction limit.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic structural diagram of a planar diffractive lens according to an embodiment of the present invention;
FIG. 2 is a top view of a planar diffractive lens in accordance with an embodiment of the present invention;
FIG. 3 is a flow chart illustrating steps of a method for manufacturing a planar diffractive lens according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a substrate after spin coating, patterning, plating and stripping processes according to an embodiment of the present invention;
FIG. 5 is a diagram illustrating the structure of a planar diffractive lens for generating a transverse sub-wavelength optical needle field according to an embodiment of the present invention;
FIG. 6 is a diagram illustrating two-dimensional light field intensity distribution of a planar diffractive lens according to an embodiment of the present invention at different ratios of the long axis to the short axis;
FIG. 7 is a light field distribution diagram of a planar diffractive lens incorporating different cut angles θ in accordance with an embodiment of the present invention;
fig. 8 is a light field information diagram of a planar diffraction lens according to an embodiment of the present invention.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not represent the only embodiments.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Fig. 1 shows a planar diffraction lens 10 for generating a line light source exceeding a diffraction limit according to an embodiment of the present application, the planar diffraction lens 10 including a substrate 100 and a metal thin film 200. As described above, the substrate 100 is made of a light-transmitting material, most commonly silicon dioxide, and the shape of the substrate 100 is not limited, and may be square, oval, circular, or the like. The metal thin film 200 is made of an opaque material, such as titanium, silver, chromium, or aluminum.
Fig. 1 shows a metal film 200 according to an embodiment of the present invention, the metal film 200 covers one surface of a substrate 100, the metal film 200 has semi-circular groups 210 located on two sides of the substrate 100 and symmetrically distributed, a cut angle θ (the cut angle θ is the mark 200a shown in fig. 2) is located between the semi-circular group 210 located on one side of the substrate 100 and the semi-circular group 210 located on the other side of the substrate 100, each of the two semi-circular groups 210 includes a plurality of concentric elliptical semi-circular bands 211, and a light-transmissive air layer 212 is spaced between two adjacent concentric elliptical semi-circular bands 211. Thus, when the light is emitted from the optical path module and irradiated to the plane diffraction lens 10, the emitted light can form a line light source exceeding the diffraction limit by virtue of the above structure.
FIG. 2 shows a concentric elliptical half zone 211 in one embodiment of the present application, wherein the concentric elliptical half zone 211 has a major axis CR and a minor axis R, and the ratio of the major axis CR of each layer of the concentric elliptical half zone to the minor axis R of each layer of the concentric elliptical half zone is in the range of [ 1.1-1.4 ]. Thus, it is emphasized that each layer of concentric elliptical half-zone 211 has a major axis CR and a minor axis R.
FIG. 1 shows the outermost concentric elliptical half zone 211 in one embodiment of the present application, where the minor axis length of the outermost concentric elliptical half zone 211 ranges from 50 μm.
Fig. 2 shows a cut angle theta in an embodiment of the present application, which is in the range of 0 deg., 60 deg.. Thus, when the size of the tangent angle θ is equal to 0 °, the concentric elliptical half zones 211 on one side are connected to the concentric elliptical half zones 211 on the other side in a one-to-one correspondence, and the concentric elliptical half zones 211 on one side and the concentric elliptical half zones 211 on the other side are connected into a whole. When the size of the tangent angle θ is not equal to 0 °, for example, the size of the tangent angle θ is equal to 60 °, the concentric elliptical half-zones 211 on one side are not connected with the concentric elliptical half-zones 211 on the other side in a one-to-one correspondence, i.e., not connected into a whole.
Fig. 1 illustrates a half band set 210 according to an embodiment of the present disclosure, where the half band set 210 includes 40 concentric elliptical half bands 211. Thus, it is emphasized that the two sets of half-band groups 210 are identical in number, i.e., that the two sets of half-band groups 210 each include 40 concentric elliptical half-band zones 211. For simplicity of illustration, the concentric elliptical half-zone zones 211 of the planar diffractive lens 10 shown in fig. 1, 2, and 4 do not show 40 layers of concentric elliptical half-zone zones 211.
FIG. 1 illustrates a concentric elliptical half-annulus 211 in one embodiment of the present application, the concentric elliptical half-annulus 211 having an annulus width in the range of [400nm, 900nm ]. Thus, it is emphasized that the width of each layer of concentric elliptical half-annuli 211 ranges from [400nm, 900nm ].
Thus, the specific operation principle of the planar diffraction lens 10 of the present application is described in detail with reference to the above structure, when light is irradiated to the planar diffraction lens 10, due to the introduction of the structural asymmetry, the original focused focal spot tends to extend along the long axis of the ellipse to form a line focus. According to the condition of the ratio of the long axis to the short axis of the non-circular symmetric plane diffraction lens, based on the vector diffraction theory, the width and the position of the ring band of each ring are optimized, so that the width of the transverse light needle on the far-field focal plane can be regulated and controlled to meet the requirement in the length direction, and the width is below the diffraction limit. In order to ensure the uniformity of the transverse light needle in the length direction, in the optimization process, a cut angle which is symmetrical along the X-axis direction and is symmetrical about the Y-axis is introduced into the designed non-circularly symmetrical plane diffraction lens. The design can effectively inhibit a secondary focusing light field which is generated by the diffraction structure near a far field of a set focal plane and is orthogonal to the transverse optical needle of the focal plane in the design optimization process, and is beneficial to the optimization of the uniformity of the transverse optical needle.
It is emphasized that, in the planar diffraction lens 10 of the present application, the ratio of the major axis to the minor axis of each layer of the concentric elliptical half-zone 211, the range of the cut angle θ, the range of the width of each layer of the concentric elliptical half-zone 211, and the number of the concentric elliptical half-zone 211 can be flexibly designed according to the actual situation, and the numerical ranges listed in the present application are proved to be capable of enabling the light beam passing through the planar diffraction lens 10 to generate a uniform sub-wavelength transverse light needle light field (line light source) on the focal plane in the experimental process. Compared with the traditional plane diffraction lens, the plane diffraction lens 10 provided by the application has the advantages that the light field regulation and control characteristics of the traditional diffraction lens such as a Fresnel zone plate and the like can only realize that a focus point can be obtained on a far-field focal plane, and the transverse size of the focus is limited by a diffraction limit. In addition, the existing commercial optical imaging system generates the line light source by using a cylindrical lens and a microscope objective, the optical imaging system is complex and high in cost, the width of the line light source is limited by a diffraction limit, and the imaging resolution is limited by the diffraction limit.
Referring to fig. 3, a method for manufacturing a planar diffraction lens is described, which includes the steps of:
step S71 is to cover one side of the substrate 100 with a photoresist layer 30.
In this way, the substrate 100 is made of a transparent material, and the substrate 100 may be made of a silicon dioxide material in consideration of the cost and performance of the substrate 100. Firstly, one side of a substrate 100 is covered with a photoresist layer 30, one side of the substrate 100 is covered with a photoresist layer 30 by adopting a spin coating and glue homogenizing mode, the substrate 100 is covered with the photoresist layer 30 with certain thickness at the speed of 2000 r/s, the photoresist layer 30 is a hierarchical structure which needs to be etched subsequently, the actual thickness of the photoresist layer 30 can be flexibly selected according to the actual situation, and the preferred thickness range is 260 nm-280 nm.
Step S72, performing patterning processing on the photoresist layer 30, etching off a part of the photoresist layer 30, forming half-ring band groups 31 to be peeled symmetrically on the remaining photoresist layer 30 at positions on two sides of the substrate 100, forming a cut angle θ between the half-ring band group 31 to be peeled on one side of the substrate 100 and the half-ring band group 31 to be peeled on the other side of the substrate 100, wherein both half-ring band groups 31 to be peeled include a plurality of concentric elliptical half-ring bands 31a to be peeled, and a space is formed between two adjacent half-ring bands 31a to be peeled, thereby obtaining a to-be-plated part.
Thus, the substrate 100 covered with the photoresist layer 30 is placed in a vacuum dust-free environment, the photoresist layer 30 is patterned by electron beam direct writing (the patterning process is to perform patterning process on the photoresist layer 30 according to a preset image), a part of the photoresist layer 30 is etched by chemical development, the remaining photoresist layer 30 forms half-ring groups 31 to be peeled symmetrically on two sides of the substrate 100, a cutting angle θ (the cutting angle θ is the 200a mark shown in fig. 2) is formed between the half-ring group 31 to be peeled on one side of the substrate 100 and the half-ring group 31 to be peeled on the other side of the substrate 100, each half-ring group 31 to be peeled includes a plurality of concentric elliptical half-ring bands 31a to be peeled (the concentric elliptical half-ring bands 31a to be peeled are portions to be subsequently peeled from the substrate), and a space is formed between two adjacent half-ring bands 31a to be peeled, at this time, the piece to be plated is obtained.
And step S73, coating a film on the piece to be plated so as to cover one surface of the piece to be plated with a metal film layer to obtain the piece to be stripped.
Thus, after the piece to be plated is obtained, the piece to be plated is plated by adopting a plating process, so that one surface of the piece to be plated is covered with a layer of metal film 200, the metal film 200 is made of a light-tight material, and when the piece to be plated is emphasized, after the film is plated, the substrate 100 is covered with a layer of metal film 200, and the top of each concentric oval half-band to be stripped is also covered with a layer of metal film 200.
Step S74, standing the to-be-peeled piece in the peeling liquid for a predetermined standing time, wherein each layer of the concentric elliptical to-be-peeled half band 31a will automatically fall off from the substrate 100 to form the air layers 212 in a one-to-one correspondence manner, and a layer of the concentric elliptical half band 211 is spaced between two adjacent air layers 212.
After the piece to be stripped is obtained, the piece to be stripped is placed in a container loaded with stripping liquid for 10 h-12 h, each layer of concentric oval half-ring belt 31a to be stripped falls off in a one-to-one correspondence mode under the action of the stripping liquid, the position corresponding to the bottom of the fallen concentric oval half-ring belt 31a to be stripped is not covered with the metal film 200, the fallen concentric oval half-ring belt 31a to be stripped forms an air layer 212 at the corresponding position, the metal film 200 is covered between two adjacent air layers 212, and the metal film 200 between two adjacent air layers 212 is the corresponding concentric oval half-ring belt 211.
After steps S71 to S74, the planar diffraction lens 10 shown in fig. 1 can be manufactured, and the planar diffraction lens 10 can generate a line light source (i.e., a transverse light needle light field) exceeding the diffraction limit.
Fig. 5 is a schematic diagram of a planar diffraction lens 10 for generating a transverse subwavelength optical needle light field, which employs the planar diffraction lens 10 structure and introduces a cut angle θ along the X-axis direction and symmetrical with respect to the Y-axis. As can be seen from fig. 5, when the incident wavelength is 633nm, a uniform sub-wavelength transverse optical needle light field (line light source) can be generated in the far field.
Fig. 6 is a simulation result of the two-dimensional light field intensity distribution of the planar diffraction lens 10 on the focal plane under different values of the ratio of the long axis to the short axis. As can be seen from fig. 6, as the ratio of the major axis to the minor axis increases, the length of the transverse light needle light field increases, but the intensity decreases significantly.
Fig. 7 is a light field distribution diagram of the planar diffraction lens 10 after introducing different cut angles θ. The planar diffraction lens 10 in fig. 7 introduces the cut angles θ of 0 °, 20 °, 40 °, and 60 °, and then performs simulation calculation on the light field, and as a result of comparison, it can be found that the introduction of the cut angle θ can significantly suppress the secondary focused light field generated in the far field, and after the introduction of the cut angle θ of 60 °, the intensity of the secondary focused light field is substantially eliminated, so that the preferred value of the cut angle θ is 60 ° in order to eliminate the secondary focused light field.
Fig. 3 and 4 are process flow diagrams of the planar diffraction lens 10. The corresponding working procedures of I to IV are spin coating, direct writing by electron beams, film coating and stripping respectively. Each half-ring zone group 210 of the manufactured plane diffraction lens 10 includes 40 layers of concentric elliptical half-ring zones 211, the ratio of the major axis of the outermost concentric elliptical half-ring zone 211 to the minor axis of the outermost concentric elliptical half-ring zone 211 is 1.2, a tangential angle θ of 60 ° is introduced, and the minor axis of the outermost concentric elliptical half-ring zone 211 has a dimension of 50 μm.
Fig. 8 is a graph of light field information for the designed and processed planar diffraction lens 10. Graphs (a) and (b) are simulation results and experimental results, respectively, in which graphs (i) and (ii) show two-dimensional light field distribution at the focal plane and longitudinal light field distribution along the optical axis, respectively. As can be seen by comparison, the experimental results are substantially consistent with the simulation results. Graphs (c) and (d) show the information of the one-dimensional optical field distribution along the dotted line of graphs (a) and (b), the characteristic dimension of the maximum central optical field intensity along the optical needle direction is measured by the experimental characterization to be 0.46 λ/NA, the error of 0.45 λ/NA from the simulation result is within the allowable range, and the diffraction limit is exceeded. It is easy to observe the axial one-dimensional light field information, the plane diffraction lens 10 can generate a focused light field at a position of 30 μm along the optical axis direction, which is designed in advance, and the intensity of the secondary focused light field is effectively inhibited. And (e) and (f) are characteristic diagrams of the uniformity of the transverse light needle light field at the focal plane and the longitudinal characteristic dimension of each point along the light needle direction. It can be seen that the planar diffractive lens 10 can produce a uniform optical field of about 4 μm in length at the far field focal plane, and the longitudinal characteristic dimension (full height half width) of each point along that direction is significantly smaller than the diffraction limited focused spot size under the rayleigh criterion. In summary, the machined planar diffractive lens 10 is designed to achieve a uniform optical needle field beyond the diffraction limit in the far field (i.e., the planar diffractive lens 10 achieves a line source beyond the diffraction limit in the far field).
The application also protects an optical imaging system, which comprises the optical path module and the planar diffraction lens 10, wherein the optical path module is used for generating light irradiating the planar diffraction lens 10, and the planar diffraction lens 10 is used for generating a line light source exceeding the diffraction limit.
It should also be emphasized that it is within the scope of the present application to apply the planar diffractive lens 10 of the present application to other devices and apparatus to generate line light sources beyond the diffraction limit.
The above embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A planar diffraction lens for generating a line light source beyond the diffraction limit, comprising:
a substrate capable of transmitting light; and
the metal film covers in the one side of basement, metal film has and is located basement both sides and symmetric distribution's semi-ring belt group, is located basement one side semi-ring belt group with be located the basement opposite side semi-ring belt group between have the corner cut, two sets of semi-ring belt group all includes a plurality of layers of concentric ellipse semi-ring belt, and adjacent two-layer equal interval one deck can non-light tight air bed between the concentric ellipse semi-ring belt.
2. The planar diffraction lens of claim 1 wherein each layer of the concentric elliptical half zones has a major axis and a minor axis, and the ratio of the major axis of each layer of the concentric elliptical half zones to the minor axis of each layer of the concentric elliptical half zones is in the range of [ 1.1-1.4 ].
3. The planar diffraction lens as claimed in claim 2, wherein the length of the minor axis of the concentric elliptical half zone located at the outermost side is in the range of 50 μm.
4. The planar diffraction lens of claim 1, wherein the range of the cut angles is [0 °, 60 ° ].
5. The planar diffraction lens of claim 1 wherein the two sets of half zones each comprise 40 layers of the concentric elliptical half zones.
6. The planar diffraction lens of claim 5 wherein the annular width of each layer of the concentric elliptical half zones is in the range of [400nm, 900nm ].
7. A method of manufacturing a planar diffraction lens, comprising the steps of:
step S71, covering one side of the substrate with a photoresist layer;
step S72, performing patterning processing on the photoresist layer, etching off part of the photoresist layer, forming semi-ring band groups to be stripped on the positions, located on two sides of the substrate, of the residual photoresist layer, wherein the semi-ring band groups to be stripped are symmetrically distributed, a chamfer is formed between the semi-ring band group to be stripped located on one side of the substrate and the semi-ring band group to be stripped located on the other side of the substrate, two semi-ring band groups to be stripped respectively comprise a plurality of concentric elliptical semi-ring bands to be stripped, and an interval is formed between every two adjacent semi-ring bands to be stripped, so that a part to be plated is obtained;
step S73, coating a film on the piece to be plated so as to cover one surface of the piece to be plated with a metal film layer to obtain a piece to be stripped;
and S74, standing the to-be-stripped part in stripping liquid for a preset standing time, wherein each layer of the concentric elliptical to-be-stripped semi-annular belt automatically falls off from the substrate to form air layers in a one-to-one correspondence manner, and a layer of concentric elliptical semi-annular belt is arranged between every two adjacent layers of the air layers.
8. The method for manufacturing a planar diffraction lens as claimed in claim 7, wherein in the step S71, one surface of the substrate is covered with the photoresist layer by spin coating with a spin coating speed of 2000 rpm, and the thickness of the photoresist layer is in the range of [260nm, 280nm ].
9. The method for manufacturing a planar diffraction lens as claimed in claim 7, wherein in step S72, the substrate covered with the photoresist layer is placed in a vacuum environment, the photoresist layer is patterned by electron beam direct writing, and a portion of the photoresist layer is etched by chemical development.
10. An optical imaging system comprising an optical path module, and further comprising the planar diffraction lens of any one of claims 1 to 6, wherein the optical path module is configured to generate light to irradiate the planar diffraction lens.
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| JP7406971B2 (en) | 2019-12-05 | 2023-12-28 | 株式会社トプコン | measuring device |
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