CN107037512B - High-efficiency diffraction lens - Google Patents
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- CN107037512B CN107037512B CN201710357884.XA CN201710357884A CN107037512B CN 107037512 B CN107037512 B CN 107037512B CN 201710357884 A CN201710357884 A CN 201710357884A CN 107037512 B CN107037512 B CN 107037512B
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- 238000000034 method Methods 0.000 claims description 21
- 239000003989 dielectric material Substances 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 3
- 229920002120 photoresistant polymer Polymers 0.000 claims description 2
- 230000000694 effects Effects 0.000 abstract description 9
- 238000003384 imaging method Methods 0.000 abstract description 6
- 230000003287 optical effect Effects 0.000 description 16
- 238000009826 distribution Methods 0.000 description 14
- 238000010586 diagram Methods 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 3
- 229920002430 Fibre-reinforced plastic Polymers 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 239000011151 fibre-reinforced plastic Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B3/00—Simple or compound lenses
- G02B3/02—Simple or compound lenses with non-spherical faces
- G02B3/08—Simple or compound lenses with non-spherical faces with discontinuous faces, e.g. Fresnel lens
Abstract
The invention discloses a high-efficiency diffraction lens, which comprises a lens body and a lens surface, wherein the lens surface is formed by a plurality of Fresnel zones, the heights of the Fresnel zones are sequentially reduced from the center to the edge, and the widths of the Fresnel zones are sequentially reduced from the center to the edge; compared with the conventional diffraction lens, the high-efficiency diffraction lens provided by the invention can ensure that the light modulated by the lens generates a strict interference superposition effect at the focal position on the axis, has higher peak light intensity, focusing efficiency and smaller light spot size than the conventional diffraction lens, and has better focusing imaging quality because the actual focusing position is closer to the theoretical preset focusing position.
Description
Technical Field
The invention relates to the technical field of diffraction lenses, in particular to a high-efficiency diffraction lens.
Background
The diffraction optical element has the unique advantages of small volume, light weight, low manufacturing cost, higher diffraction efficiency, special dispersion performance, more design freedom, wide material selectivity and the like, is an important component in a micro optical system, and has wide application prospect in the fields of laser beam focusing, optical coupling, wavefront multiplexing, optical sensing, optical storage and the like.
In the prior art, when designing a diffraction lens, a contour model design is generally adopted, namely, a part exceeding 2 pi phase in the refraction lens is removed, so that a conventional diffraction lens with the maximum phase difference of 2 pi is formed. As shown in fig. 1, which is a schematic diagram of the boundary of the lens surface of a conventional diffraction lens, in which the x-axis and y-axis directions are shown, the z-axis is perpendicular to the x-y plane, the positive z-axis direction is defined as being outward perpendicular to the x-y plane, the broken line represents the boundary of the refractive lens, and the solid line represents the boundary of the conventional diffraction lens, which can be considered to be obtained by removing a portion exceeding 2pi phase from the refractive lens. The conventional diffraction lens has an aperture D, is symmetrical about the y-axis, and has an arbitrary length in the z-axis direction. The said normalThe boundary of the gauge diffraction lens divides the whole space into upper and lower parts: the upper half is of refractive index n 1 The lower part of the dielectric is a refractive index n 2 Plane waves polarized by TE (Transverse Electro waves, electromagnetic wave with the vibration direction of the electric field perpendicular to the wave propagation direction) with a wavelength λ are incident on the boundary of the conventional diffraction lens in the-y-axis direction, and after being phase-modulated by the boundary of the conventional diffraction lens, are focused on a point (0, -f) on the y-axis, where f represents a predetermined focal length of the lens.
From the prior art, the boundary height h of a conventional diffraction lens in the mth Fresnel zone can be found F (x) The method comprises the following steps:
h F (x)＝Mod[h r (x)，Δh]＝h r (x)-|m|Δh，m＝0，±1，±2，...
the 0 th Fresnel zone is a central Fresnel zone, the 1 st and the-1 st Fresnel zones are respectively the first Fresnel zones on the right side and the left side of the central Fresnel zone, and so on; mod [ A, B) =A-Int [ A/B ]]X B represents a remainder function; int [ A/B ]]Representing a rounding function, wherein A and B are integers; m represents the ordinal number of the Fresnel zone in-D/2 is not less than x is not less than D/2,a modulation thickness at 2pi phase corresponding to incident light having a wavelength λ; h is a r (x) The boundary height, which is the refractive lens, can be expressed as:
abscissa at mth Fresnel zone transition position of the conventional diffraction lensCan be expressed as:
it can be seen that the maximum height of a conventional diffractive lens within each fresnel zone is equal. Although the jump height between adjacent fresnel zones corresponds to a phase difference of 2 pi for plane waves parallel to the optical axis, the jump phase difference between adjacent fresnel zones is no longer 2 pi for the focal point, which would not result in an optimal interference superposition effect at the focal point in accordance with conventional contour model designs. In particular, for lenses with smaller focal lengths, the focusing performance of the diffractive lens will drop dramatically because the paraxial approximation is no longer true and the number of fresnel zones is large.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a high-efficiency diffraction lens capable of generating a strict interference superposition effect at a focusing position, and having a higher focusing efficiency and focusing resolution than those of the conventional diffraction lens.
The invention provides a high-efficiency diffraction lens based on the above object, comprising a lens surface and a lens body, wherein the lens surface is composed of a plurality of Fresnel zones, the heights of the Fresnel zones are sequentially reduced from the center to the edge, the widths of the Fresnel zones are sequentially reduced from the center to the edge, and the jump phase difference between two adjacent Fresnel zones is 2 pi.
Optionally, the high-efficiency diffraction lens is a columnar fresnel lens, the lens surface of the high-efficiency diffraction lens is composed of a plurality of laterally symmetrical fresnel regions, and the boundary height h of the position of the high-efficiency diffraction lens with x-axis in the mth fresnel region m (x) The method meets the following conditions:
wherein ,n1 For the refractive index of the high-efficiency diffraction lens, n 2 The refractive index of the dielectric material outside the high-efficiency diffraction lens is f, the predetermined focal length is lambda, and the wavelength of incident light is lambda; the position of the trip point of the mth Fresnel zone of the high-efficiency diffraction lensThe method meets the following conditions:
wherein ,n1 For the refractive index of the high-efficiency diffraction lens, n 2 The refractive index of the dielectric material outside the high-efficiency diffraction lens is f, the predetermined focal length is lambda, and the wavelength of incident light.
Optionally, the high-efficiency diffraction lens is a circular fresnel lens, the lens surface of the high-efficiency diffraction lens is composed of a series of concentric circular fresnel zones, and the boundary height h of the position of the high-efficiency diffraction lens with x in the m-th fresnel zone is equal to the x-axis m (r) satisfies:
wherein ,n 1 for the refractive index of the high-efficiency diffraction lens, n 2 The refractive index of the dielectric material outside the high-efficiency diffraction lens is f, the predetermined focal length is lambda, and the wavelength of incident light is lambda; the position of the trip point of the mth Fresnel zone of said high-efficiency diffractive lens>The method meets the following conditions:
wherein , wherein ,n 1 for said one high efficiency diffractionRefractive index of lens, n 2 The refractive index of the dielectric material outside the high-efficiency diffraction lens is f, the predetermined focal length is lambda, and the wavelength of incident light.
Optionally, the profile of the high-efficiency diffraction lens is set according to actual needs, and the profile comprises a columnar Fresnel lens, a circular Fresnel lens or other shapes.
Optionally, the material of the high-efficiency diffraction lens is photoresist.
As can be seen from the above, compared with the conventional diffraction lens, the high-efficiency diffraction lens provided by the invention has the advantages that the jump phase difference between two adjacent fresnel regions is 2 pi by means of unequal-height design on the boundary of each fresnel region, so that the light modulated by the lens generates a strict interference superposition effect at the on-axis focal position, the high-efficiency diffraction lens has higher peak light intensity, higher focusing efficiency and smaller spot size than the conventional diffraction lens, and the actual focusing position is closer to the theoretical preset focusing position, so that the high-efficiency diffraction lens has better focusing imaging quality.
Drawings
FIG. 1 is a schematic diagram of a lens surface boundary of a conventional diffraction lens;
FIG. 2 is a perspective view of a high-efficiency diffraction lens according to embodiment 1 of the present invention;
FIG. 3 is a schematic diagram of a boundary of a lens surface of a high-efficiency diffraction lens according to embodiment 1 of the present invention;
FIG. 4 is a schematic diagram showing the comparison of boundary profiles of lens surfaces of a high-efficiency diffraction lens and a conventional diffraction lens according to embodiment 2 of the present invention;
FIG. 5 is a graph of a conventional diffraction lens light intensity profile;
FIG. 6 is a graph showing the intensity distribution of a high-efficiency diffraction lens according to embodiment 2 of the present invention;
FIG. 7 is a graph showing the intensity distribution of a high-efficiency diffraction lens and a conventional diffraction lens in a focal plane according to example 2 of the present invention;
FIG. 8 is a graph showing the contrast of the intensity distribution of a high-efficiency diffraction lens and a conventional diffraction lens on the optical axis according to embodiment 2 of the present invention;
FIG. 9 is a schematic diagram of a test platform of a high-efficiency diffraction lens and a conventional diffraction lens according to embodiment 3 of the present invention;
FIG. 10 is a graph showing the intensity distribution of the focal plane of a high-efficiency diffraction lens according to embodiment 3 of the present invention;
FIG. 11 is a graph showing the focal plane intensity distribution of a conventional diffraction lens of example 3 of the present invention;
FIG. 12 is a graph showing the contrast of the intensity distribution of a high-efficiency diffraction lens and a conventional diffraction lens in a focal plane according to example 3 of the present invention;
FIG. 13 is a graph showing the contrast of the intensity distribution of a high-efficiency diffraction lens and a conventional diffraction lens on the optical axis according to example 3 of the present invention;
FIG. 14 is a perspective view of a high-efficiency diffraction lens according to embodiment 4 of the present invention;
FIG. 15 is a schematic radial longitudinal cross-sectional view of a high efficiency diffractive lens according to embodiment 4 of the present invention;
FIG. 16 is a schematic view of the boundary of the lens surface of a radial slit of a high-efficiency diffraction lens according to embodiment 4 of the present invention.
Detailed Description
The present invention will be further described in detail below with reference to specific embodiments and with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent.
Example 1:
an embodiment 1 of the present invention provides a high-efficiency diffractive lens, which is configured as a columnar fresnel lens, as shown in fig. 2, and is a perspective view of the high-efficiency diffractive lens of embodiment 1 of the present invention, where the high-efficiency diffractive lens includes a lens body 2 and a lens surface 1, the lens surface 1 is formed by a plurality of fresnel regions distributed symmetrically from left to right, the heights of the plurality of fresnel regions decrease sequentially from the middle to both sides, and the widths of the plurality of fresnel regions decrease sequentially from the middle to both sides.
As shown in fig. 3, which is a schematic view of the boundary of the lens surface of a high-efficiency diffraction lens according to embodiment 1 of the present invention, the x-axis and y-axis directions are shown, the z-axis is perpendicular to the x-y plane, the positive z-axis direction is defined as being perpendicular to the x-y plane,the dashed line represents the boundary of the refractive lens and the solid line represents the boundary of the one high-efficiency diffractive lens. The high-efficiency diffraction lens is symmetrical about a y-axis and has any length in the z-axis direction, and the boundary height of the high-efficiency diffraction lens is h m (x) A. The invention relates to a method for producing a fibre-reinforced plastic composite The boundary of the high-efficiency diffraction lens divides the whole space into an upper part and a lower part: the upper half is of refractive index n 1 The dielectric of the high-efficiency diffraction lens is n 1 The method comprises the steps of carrying out a first treatment on the surface of the The lower half is of refractive index n 2 The refractive index of the other dielectric outside the high-efficiency diffraction lens is n 2 Plane waves of TE polarization with a wavelength lambda are incident on the boundary of the conventional diffraction micro-cylindrical lens along the-y axis direction, and are focused on one point (0, -f) on the y axis after being subjected to phase modulation of the boundary of the high-efficiency diffraction lens, wherein f represents the preset focal length of the lens.
First, for the focal position (0, -f) on the optical axis, if the phase difference between two adjacent Fresnel zones of the one high-efficiency diffraction lens is 2 pi, the position of the trip point of the mth Fresnel zoneThe following should be satisfied:
wherein the 0 th Fresnel zone is a central Fresnel zone; the 1 st and the-1 st Fresnel zone are respectively the first Fresnel zone on the right side and the left side of the central Fresnel zone, are symmetrical about the central Fresnel zone and so on; the location of the trip point of the mth fresnel zoneThe method comprises the following steps:
secondly, in order to produce the most ideal interference superposition effect at the focal position (0, -f), it is also necessary to ensure that all boundary points within the same fresnel zone have the same phase, i.e. the two rays in fig. 3 have equal optical paths, according to the fermat principle, this relationship being expressed as:
thereby, the boundary height h of the high-efficiency diffraction lens in the mth Fresnel zone can be obtained m (x) The method comprises the following steps:
compared with the conventional diffraction micro-cylindrical lens, the high-efficiency diffraction lens provided by the embodiment 1 of the invention adopts an unequal-height design method, ensures that the phase difference of adjacent Fresnel zones is strictly 2 pi, can ensure that light modulated by the lens generates a strict interference superposition effect at the focal position on the axis, and has higher imaging quality and accuracy than the conventional diffraction micro-cylindrical lens.
Example 2:
embodiment 2 of the present invention provides a high-efficiency diffraction lens, which is a cylindrical Fresnel lens having an aperture D of 20 μm and a refractive index n of a dielectric material of an upper half space, and uses theoretical derivation to verify a focusing imaging effect of the high-efficiency diffraction lens on light 1 =1.5, i.e. refractive index n of the one high-efficiency diffraction lens provided in embodiment 2 of the present invention 1 Refractive index n of lower half-space dielectric material =1.5 2 =1.0, the predetermined focal length f=4 μm.
Fig. 4 is a schematic diagram showing the comparison of the boundary profiles of the lens surfaces of a high-efficiency diffraction lens according to embodiment 2 of the present invention and a conventional diffraction lens. The conventional diffractive lens is also a cylindrical Fresnel lens having the same caliber, predetermined focal length and refractive index as the one high-efficiency diffractive lens, i.e., the caliber D of the conventional diffractive lens is 20 μm, the upper half spaceRefractive index n of dielectric material 1 Refractive index n of lower half-space dielectric material =1.5 2 =1.0, the predetermined focal length f=4 μm.
As can be seen from fig. 4, the maximum height of the fresnel zone of the one type of high-efficiency diffraction lens is lower than that of the conventional diffraction lens, and the heights of the fresnel zones of the one type of high-efficiency diffraction lens gradually decrease in the direction from the center to the both sides, unlike the conventional diffraction lens in which the heights of the fresnel zones are equal.
The performance of the one high-efficiency diffraction lens and the conventional diffraction lens was analyzed by using a TE polarized plane wave with a wavelength of 0.633 μm as incident light, and by using a strict electromagnetic theory and a boundary element method, respectively. The performance indexes of the high-efficiency diffraction lens and the conventional diffraction lens comprise: the focusing efficiency is the percentage of the energy focused in the main lobe on the actual focal plane to the total incident energy; the light spot size is the distance between the lowest light intensity positions on the two sides of the main lobe on the actual focal plane; the actual focusing position is the position corresponding to the maximum light intensity on the optical axis.
As shown in fig. 5, the light intensity profile of a conventional diffraction lens is shown; fig. 6 shows a light intensity distribution diagram of a high-efficiency diffraction lens according to embodiment 2 of the present invention. It can be seen that the high-efficiency diffraction lens of the embodiment of the invention has only one focus, and stray light does not exist around the focus; the conventional diffraction lens has a plurality of focuses, cannot be imaged strictly at predetermined focus positions, and there is a large amount of stray light around each focus.
FIG. 7 is a graph showing the contrast of the light intensity distribution in the focal plane of a high-efficiency diffraction lens according to example 2 of the present invention and a conventional diffraction lens; the peak light intensity of the high-efficiency diffraction lens is 54.3V/m, the focusing efficiency is 38.61%, and the light spot size is 0.557 mu m; the peak intensity of the conventional diffraction lens was 18.4V/m, the focusing efficiency was 19.85%, and the spot size was 0.897. Mu.m. It can be seen that the high efficiency diffraction lens provided in embodiment 2 of the present invention has a much larger peak light intensity than the conventional diffraction lens, and has a smaller spot size and a higher focusing efficiency.
As shown in fig. 8, a graph is shown showing the light intensity distribution on the optical axis of a high-efficiency diffraction lens according to embodiment 2 of the present invention compared with that of a conventional diffraction lens. The actual focal position of the one high-efficiency diffraction lens is 4.06 μm, and only one focal point is provided; the actual focal position of the conventional diffractive lens is 3.93 μm, but there are two more foci on either side of the maximum intensity position. It can be seen that the high efficiency diffraction lens provided in embodiment 2 of the present invention has a better focusing quality than the conventional diffraction lens, and the actual focusing position is closer to the predetermined focusing position and has only a single intersection point.
In summary, the high-efficiency diffraction lens provided in embodiment 2 of the present invention adopts an unequal-height design method, ensures that the phase difference between adjacent fresnel regions is 2pi, has higher focusing efficiency and smaller spot size than conventional diffraction lenses, and has a practical focusing position closer to a theoretical predetermined focusing position and better focusing imaging quality.
Example 3
FIG. 9 is a schematic diagram showing a test platform of a high-efficiency diffraction lens and a conventional diffraction lens according to embodiment 3 of the present invention; embodiment 3 of the present invention provides a high-efficiency diffractive lens, and the high-efficiency diffractive lens and the conventional diffractive lens are actually tested by using the test platform, wherein the high-efficiency diffractive lens and the conventional diffractive lens are cylindrical Fresnel lenses, the caliber D is 20 μm, and the refractive index n of the upper half-space dielectric material 1 Refractive index n of lower half-space dielectric material =1.5 2 =1.0, the predetermined focal length f=4 μm.
FIG. 10 is a graph showing the intensity distribution of the focal plane of a high-efficiency diffraction lens according to embodiment 3 of the present invention; as shown in fig. 11, the focal plane light intensity distribution of the conventional diffraction lens of example 3 of the present invention is shown; it can be seen that the one high efficiency diffraction lens presents a clear and bright spot at the predetermined focus position, with a spot size much smaller than that of the conventional diffraction lens.
FIG. 12 is a graph showing the contrast of the intensity distribution of a high-efficiency diffraction lens and a conventional diffraction lens in a focal plane according to example 3 of the present invention; the peak light intensity of the high-efficiency diffraction lens is 203V/m, the light spot size is 1.10 mu m, and the experimental focusing efficiency is 16.23%; the peak light intensity of the conventional diffraction lens is 99V/m, the light spot size is 1.38 mu m, and the experimental focusing efficiency is 11.42%.
Fig. 13 is a graph showing the light intensity distribution on the optical axis of a high-efficiency diffraction lens according to example 3 of the present invention compared with that of a conventional diffraction lens. The axial peak light intensity of the high-efficiency diffraction lens is 207V/m, and the actual focusing position is 4 mu m; the axial peak light intensity of the conventional diffraction lens was 103V/m, and the actual focusing position was 2. Mu.m. It can be seen that the one high efficiency diffraction lens has higher axial peak light intensity and axial resolution than the conventional diffraction lens, and the actual focal position is closer to the predetermined focal position.
In summary, the high-efficiency diffraction lens provided in embodiment 3 of the present invention adopts an unequal-height design method, ensures that the phase difference between adjacent fresnel regions is 2pi, has higher peak light intensity and focusing efficiency than conventional diffraction lenses, and has smaller focused spot size and better optical performance.
Example 4
The embodiment 4 of the present invention provides a high-efficiency diffraction lens, which is a circular fresnel lens, as shown in fig. 14, and is a schematic perspective view of the high-efficiency diffraction lens in the embodiment 4 of the present invention; fig. 15 is a schematic radial longitudinal cross-sectional view of a high-efficiency diffraction lens according to embodiment 4 of the present invention. The high-efficiency diffraction lens is a cylinder, one bottom surface is set to be a lens surface, the lens surface is composed of a plurality of concentric circular Fresnel zones, the heights of the Fresnel zones are sequentially reduced from inside to outside, and the widths of the Fresnel zones are sequentially reduced from inside to outside.
Fig. 16 is a schematic view showing a boundary of a lens surface of a radial slit section of a high-efficiency diffraction lens according to embodiment 4 of the present invention. Wherein the directions of the x-axis and the y-axis are as shown, the z-axis is perpendicular to the x-y plane, and the positive direction of the z-axis is defined as being outward perpendicular to the x-y plane, said oneThe boundary height of the high-efficiency diffraction lens is h m (x) A. The invention relates to a method for producing a fibre-reinforced plastic composite Since the one high-efficiency diffraction lens is centered about the y-axis, only the lens boundary portion in the first quadrant in fig. 16 will be described. The boundary of the high-efficiency diffraction lens divides the whole space into an upper part and a lower part: the upper half is of refractive index n 1 The dielectric of the high-efficiency diffraction lens is n 1 The method comprises the steps of carrying out a first treatment on the surface of the The lower half is of refractive index n 2 The refractive index of the other dielectric outside the high-efficiency diffraction lens is n 2 Plane waves of TE polarization having a wavelength lambda are incident on the boundary of the conventional diffraction lens in the-y-axis direction, and after being phase-modulated by the boundary of the one high-efficiency diffraction lens, are focused on a point (0, -f) on the y-axis, where f represents a predetermined focal length of the lens.
First, for the focal position (0, -f) on the optical axis, if the phase difference between two adjacent Fresnel zones of the one high-efficiency diffraction lens is 2 pi, the position of the trip point of the mth Fresnel zone in the radial longitudinal section of the one high-efficiency diffraction lensThe following should be satisfied:
the location of the trip point of the mth fresnel zone in the radial longitudinal section of the high efficiency diffractive lensThe method comprises the following steps:
secondly, in order to produce the most ideal interference superposition effect at the focal position (0, -f), it is also necessary to ensure that all boundary points within the same fresnel zone have the same phase, i.e. that the two rays in fig. 16 have equal optical paths, according to the fermat principle, this relationship being expressed as:
the boundary height h of the radial longitudinal section of the high-efficiency diffraction lens in the mth Fresnel zone can be obtained m (x) The method comprises the following steps:
the boundary height h of the position of the high-efficiency diffraction lens with x on the abscissa in the mth Fresnel zone m (r) satisfies:
wherein ,
the position of the trip point of the mth Fresnel zone of the high-efficiency diffraction lensThe method comprises the following steps:
wherein ,
compared with the conventional diffraction lens, the high-efficiency diffraction lens provided by the embodiment 4 of the invention adopts an unequal-height design method, ensures that the phase difference of adjacent Fresnel zones is 2 pi, can ensure that light modulated by the lens generates a strict interference superposition effect at the focal position on the axis, and has higher imaging quality and accuracy than the conventional diffraction lens.
Those of ordinary skill in the art will appreciate that: the foregoing is merely illustrative of specific embodiments of the present invention, and the columnar fresnel lens and the circular fresnel lens illustrated in the embodiments should not be construed as limiting the present invention, and any modification, equivalent replacement, improvement, application to diffraction lenses of different specifications and shapes, optimization improvement to diffraction lenses of different specifications and shapes, etc. that are obtained by adopting the unequal height design method provided by the present invention so that the phase difference between adjacent fresnel sections is 2 pi are included in the protection scope of the present invention.
Claims (4)
1. A high-efficiency diffraction lens, characterized in that the high-efficiency diffraction lens comprises a lens surface and a lens body, wherein the lens surface is composed of a plurality of fresnel zones, the heights of the fresnel zones are sequentially reduced from center to edge, the widths of the fresnel zones are sequentially reduced from center to edge, and a jump phase difference between two adjacent fresnel zones is 2 pi;
the high-efficiency diffraction lens is a columnar Fresnel lens, the lens surface of the high-efficiency diffraction lens is composed of a plurality of Fresnel zones which are bilaterally symmetrical, and all boundary points of the high-efficiency diffraction lens in the same Fresnel zone have the same phase, and the high-efficiency diffraction lens is expressed as:
,
the boundary height of the position of the high-efficiency diffraction lens with x-axis in the mth Fresnel zoneThe method meets the following conditions:
,/>
wherein ,refractive index for said one high efficiency diffractive lens, +.>Refractive index of the dielectric material outside the high-efficiency diffraction lens>For a predetermined focal length>For the wavelength of incident light, +.>The position of the trip point of the mth Fresnel zone;
or the high-efficiency diffraction lens is a circular Fresnel lens, the lens surface of the high-efficiency diffraction lens is formed by a series of concentric circular Fresnel zones, and all boundary points of the high-efficiency diffraction lens in the same Fresnel zone are identical and expressed as:
,
the boundary height of the position of the high-efficiency diffraction lens with x-axis in the mth Fresnel zoneThe method meets the following conditions:
,/>
wherein ,,/>refractive index for said one high efficiency diffractive lens, +.>Refractive index of the dielectric material outside the high-efficiency diffraction lens>For a predetermined focal length>For the wavelength of incident light, +.>Is the location of the trip point of the mth fresnel zone.
2. A high efficiency diffractive lens according to claim 1, wherein when said high efficiency diffractive lens is a cylindrical fresnel lens, the location of the trip point of the mth fresnel zone thereofThe method meets the following conditions:
,/>
wherein ,refractive index for said one high efficiency diffractive lens, +.>Refractive index of the dielectric material outside the high-efficiency diffraction lens>For a predetermined focal length>Is the wavelength of incident light.
3. A high efficiency diffractive lens according to claim 1, wherein when said high efficiency diffractive lens is a circular fresnel lens, the location of the trip point of the mth fresnel zone thereofThe method meets the following conditions:
,/>
wherein ,，/>refractive index for said one high efficiency diffractive lens, +.>Refractive index of the dielectric material outside the high-efficiency diffraction lens>For a predetermined focal length>Is the wavelength of incident light.
4. The high efficiency diffraction lens of claim 1, wherein the material of the high efficiency diffraction lens is photoresist.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH564783A5 (en) * | 1972-08-05 | 1975-07-31 | Agfa Gevaert Ag | |
| JPS61189504A (en) * | 1985-02-19 | 1986-08-23 | Matsushita Electric Ind Co Ltd | Preparation of fresnel lens |
| US5132843A (en) * | 1989-03-16 | 1992-07-21 | Omron Corporation | Grating lens and focusing grating coupler |
| CN206757083U (en) * | 2017-05-19 | 2017-12-15 | 首都师范大学 | A kind of high efficiency diffraction lens |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070216851A1 (en) * | 2006-03-01 | 2007-09-20 | Citizen Watch Co., Ltd. | Liquid crystal lens and imaging lens device |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH564783A5 (en) * | 1972-08-05 | 1975-07-31 | Agfa Gevaert Ag | |
| JPS61189504A (en) * | 1985-02-19 | 1986-08-23 | Matsushita Electric Ind Co Ltd | Preparation of fresnel lens |
| US5132843A (en) * | 1989-03-16 | 1992-07-21 | Omron Corporation | Grating lens and focusing grating coupler |
| CN206757083U (en) * | 2017-05-19 | 2017-12-15 | 首都师范大学 | A kind of high efficiency diffraction lens |
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