CN105259599A - Double-sided Fresnel lens - Google Patents

Abstract

The invention discloses a double-sided Fresnel lens, which comprises an incident surface and an emergent surface. Both the incident surface and the emergent surface are tooth grooves with multiple depressions; the corresponding tooth surface for light concentrating in each tooth groove has an arc surface structure; and the arc surface contour shape of each tooth groove at the lower part changes along with changes of the contour shape of the corresponding tooth groove at the upper part. Through double-sided structure design, the ratio of the focus of the light concentrator to a caliber of the light concentrator is compressed to 0.7; as the tooth surface in each tooth groove adopts an arc surface structure, a tooth distance can be selected randomly, a small light spot can be acquired, and that is, high light concentrating times can be met while a larger tooth distance is used for improving light effects.

Description

A kind of two-sided Fresnel Lenses

Technical field

The invention belongs to technical field of solar utilization technique, particularly the two-sided Fresnel Lenses of one.

Background technology

Current Fresnel Lenses is single-sided structure, namely the plane of incidence is planar structure, exit facet is the tooth slot structure having many to cave in, this structural design makes the Thickness Ratio of concentrating component thicker, the ratio (F/#) of condenser focal length and condenser bore is generally 1.1, and the flank of tooth in existing Fresnel Lenses teeth groove is all set to plane, so just necessarily require Fresnel Lenses itself very thin, namely space width is minimum, usual requirement is at below 0.5mm, if space width is excessive, hot spot will be caused excessive.But due to technique, cause at the bottom of each crown and tooth, i.e. segmentation place of each flank of tooth, will fillet be formed, and in the part of this fillet, light loss will be had, and the loss of tooth less then light efficiency is larger.

Summary of the invention

The object of the invention is to: for above-mentioned Problems existing, a kind of two-sided Fresnel Lenses meeting higher light concentrating times while improving light efficiency is provided.

Technical scheme of the present invention is achieved in that a kind of two-sided Fresnel Lenses, comprise the plane of incidence and exit facet, it is characterized in that: the described plane of incidence and exit facet are the teeth groove being provided with many depressions, in each teeth groove, correspondence is globoidal structure for the flank of tooth playing optically focused effect, the cambered surface contour shape of bottom teeth groove changes with the change of the contour shape of top teeth groove corresponding with it, dispersion of rays is numbered from right to left, be respectively 0, 1, 2, 3 to N, and suppose that the spacing between adjacent two light is Δ X, determine that its institute is by corresponding teeth groove by the light path of each root light, the curvilinear equation of lower curved flank profile shape,

First, determine the equation of the top flank of tooth, its curvilinear equation meets:

$\frac{x_n}{m}=\frac{a}{b}$

y _n＝y _n-1+△x*tanβ

x _n＝x _n-1-△x

$\tan \mathrm{\α}=\frac{h+y_n}{a-(b-m)}$

sinβ＝nsinθ

$\mathrm{\α}-\mathrm{\θ}+\mathrm{\β}=\frac{\mathrm{\π}}{2}$

Wherein, x _nbe the X value of N article of light, m be N article of light by the X value at focus place after this curve, a is lens half bores, and b is focal radius, y _nbe the Y value of N article of light and intersections of complex curve, Δ X is the spacing of adjacent two light, and β is the incident angle of light, and θ is incident angle, and α is the angle of refracted ray and X-axis, and h is the vertical range of x-axis and focus, and n is Refractive Index of Material;

Wherein a, b, Δ X, h, n are known, and Y ₀=0, by above formula, choose suitable x value, the curve point of each tooth can be tried to achieve;

Secondly, after the curvilinear equation of the described top flank of tooth is determined, then determine the equation of the bottom flank of tooth, its curvilinear equation meets:

△ x=[x _n-1-ctg α _n-1* (y _n-1+ h ₀)]-[x _n-ctg α _n(y _n+ h ₀)] ... formula 1

△ x'=△ x-ctg (α _n-1) * (y' _n-1-h ₀)+ctg α _n(y' _n-h ₀) ... formula 2

Y' ₀=y' _n-1-△ x'*tg φ _n-1formula 3

${\mathrm{tg\φ}}_n=\frac{n{\mathrm{cos\α}}_n-{\mathrm{sin\β}}_n}{{\mathrm{cos\β}}_n-n{\mathrm{sin\α}}_n}$ Formula 4

X' _n=x' _n-1-△ x' ... formula 5

${\mathrm{tg\β}}_n=\frac{x_0^{\′}-b+\frac{N}{d}*b}{h^{\′}-y_n^{\′}}$ Formula 6

Wherein, h ₀for thickness of glass, b is the intersection point of Article 1 incident ray and y=h' straight line and the vertical range of Y-axis, and h' is the distance of hot spot to glass top surface, x ₀for Article 1 incident ray is in the starting point in concentrating refractive face, top, α ₀for Article 1 incident ray by behind concentrating refractive face, top with the angle of X-axis, β ₀for Article 1 incident ray is at the refraction angle of concentrating refractive face, bottom xsect, θ ₀for Article 1 incident ray is in the incident angle of concentrating refractive face, bottom xsect, φ ₀for Article 1 incident ray and the normal to curve of concentrating refractive face, bottom xsect point of intersection and the acute angle of y-axis, △ x be Article 1 incident ray and Article 2 incident ray respectively with the distance of lower glass surface intersection point, △ x ' for Article 1 incident ray and Article 2 incident ray respectively with the horizontal range of concentrating refractive face, bottom refraction point, n is Refractive Index of Material; N is a natural number, and the xsect by whole curved surface is divided into N decile, and d is the ratio of light geometric ratio compression, numerically equals formula 1 can be tried to achieve by the top flank of tooth, and formula 2 is substituted into formula 3, tries to achieve y' in conjunction with formula 1 _n, by y' _nsubstitute into formula 6 and try to achieve β _n, by y' _nsubstitute into formula 2 and try to achieve △ x', △ x' is substituted into formula 5 and tries to achieve x' _n, so just obtain each point coordinate (y' in lower teeth face _n, x' _n), namely obtain the curve of the bottom flank of tooth;

Wherein, the upper and lower flank of tooth of corresponding upper and lower teeth groove is equivalent to formation one independently lens, assuming that the radius of whole Fresnel Lenses is R, i.e. X ₀=R, can try to achieve upper and lower two continuous curves by above-mentioned equation, blocks continuous curve at rational height and position H place, and the X value of disconnect position is X ₁, intercepting face width of tooth is W ₁, then X ₁=R-W ₁, in this, as the initial calculation point of the next flank of tooth, when next flank of tooth height is close to H, block curve; By that analogy, until X _nwhen=0, whole Fresnel Lenses calculates complete.

Two-sided Fresnel Lenses of the present invention, the teeth groove on the plane of incidence described in it and the teeth groove on exit facet respectively with the axle center of lens for symcenter rotational symmetry arrange, the teeth groove number on the described plane of incidence is equal with the teeth groove number on exit facet.

The present invention is by two-sided structural design, the ratio of condenser focal length and condenser bore can be compressed to 0.7, the flank of tooth simultaneously in teeth groove adopts globoidal structure, can realize space width can optional while, still can obtain less hot spot, namely use larger space width to meet higher light concentrating times while raising light efficiency.

Accompanying drawing explanation

Fig. 1 is structural representation of the present invention.

Fig. 2 is optically focused schematic diagram of the present invention.

Fig. 3 is sectional view of the present invention.

Fig. 4 is the partial enlarged drawing of section of the present invention.

Fig. 5 is the tooth trace equation schematic diagram of middle and upper part of the present invention teeth groove.

Fig. 6 is the tooth trace equation schematic diagram of middle and lower part of the present invention teeth groove.

Mark in figure: 1 is the plane of incidence, and 2 is exit facet, and 3 is teeth groove, and 4 is the flank of tooth, and 5 is symcenter axle.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in detail.

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

As Figure 1-4, a kind of two-sided Fresnel Lenses, comprise the plane of incidence 1 and exit facet 2, the described plane of incidence 1 and exit facet 2 are the teeth groove 3 being provided with many depressions, in each teeth groove, correspondence is globoidal structure for the flank of tooth 4 playing optically focused effect, teeth groove on the described plane of incidence 1 and the teeth groove on exit facet 2 respectively with the axle center of lens for symcenter axle 5 is arranged symmetrically with, in order to the one_to_one corresponding of light, the teeth groove number on the described plane of incidence 1 is equal with the teeth groove number on exit facet 2.

The difficult point of two-sided Fresnel Lenses is: in order to obtain less hot spot, upper and lower two-layer Fresnel Lenses needs coupling mutually, namely the cambered surface contour shape of bottom teeth groove changes with the change of the contour shape of top teeth groove corresponding with it, in order to make upper and lower two-layer Fresnel Lenses coupling, by dispersion of rays during design, simultaneously due to symmetrical centered by condenser, only consider an xsect by this symcenter during design, finally this xsect is selected to obtain required condenser along this symcenter.

Concrete grammar is: on xsect as shown in Figure 4, dispersion of rays is numbered from right to left, be respectively 0,1,2,3 to N, and suppose that the spacing between adjacent two light is Δ X, by the light path of each root light determine its by the curvilinear equation of arc-shaped tooth contour shape in upper and lower part in corresponding teeth groove.

As shown in Figure 5, first, determine the equation of the top flank of tooth, its curvilinear equation meets:

$\frac{x_n}{m}=\frac{a}{b}$

y _n＝y _n-1+△x*tanβ

x _n＝x _n-1-△x

$\tan \mathrm{\α}=\frac{h+y_n}{a-(b-m)}$

sinβ＝nsinθ

$\mathrm{\α}-\mathrm{\θ}+\mathrm{\β}=\frac{\mathrm{\π}}{2}$

Wherein, x _nbe the X value of N article of light, m be N article of light by the X value at focus place after this curve, a is lens half bores, and b is focal radius, y _nbe the Y value of N article of light and intersections of complex curve, Δ X is the spacing of adjacent two light, and β is the incident angle of light, and θ is incident angle, and α is the angle of refracted ray and X-axis, and h is the vertical range of x-axis and focus, and n is Refractive Index of Material;

Wherein a, b, Δ X, h, n are known, and Y ₀=0, by above formula, choose suitable x value, the curve point of each tooth can be tried to achieve.In addition, the curvilinear equation of the top flank of tooth also can be obtained by method for designing disclosed in patent CN201210534148.4.

As shown in Figure 6, secondly, after the curvilinear equation of the described top flank of tooth is determined, then determine the equation of the bottom flank of tooth of its correspondence, the curvilinear equation of contour shape in the plane coordinate system forming top flank profile shape of the described bottom flank of tooth meets:

△ x=[x _n-1-ctg α _n-1* (y _n-1+ h ₀)]-[x _n-ctg α _n(y _n+ h ₀)] ... formula 1

△ x'=△ x-ctg (α _n-1) * (y' _n-1-h ₀)+ctg α _n(y' _n-h ₀) ... formula 2

Y' ₀=y' _n-1-△ x'*tg φ _n-1formula 3

${\mathrm{tg\φ}}_n=\frac{n{\mathrm{cos\α}}_n-{\mathrm{sin\β}}_n}{{\mathrm{cos\β}}_n-n{\mathrm{sin\α}}_n}$ Formula 4

X' _n=x' _n-1-△ x' ... formula 5

${\mathrm{tg\β}}_n=\frac{x_0^{\′}-b+\frac{N}{d}*b}{h^{\′}-y_n^{\′}}$ Formula 6

Wherein, h ₀for thickness of glass, b is the intersection point of Article 1 incident ray and y=h' straight line and the vertical range of Y-axis, and h' is the distance of hot spot to glass top surface, x ₀for Article 1 incident ray is in the starting point in concentrating refractive face, top, α ₀for Article 1 incident ray by behind concentrating refractive face, top with the angle of X-axis, β ₀for Article 1 incident ray is at the refraction angle of concentrating refractive face, bottom xsect, θ ₀for Article 1 incident ray is in the incident angle of concentrating refractive face, bottom xsect, φ ₀for Article 1 incident ray and the normal to curve of concentrating refractive face, bottom xsect point of intersection and the acute angle of y-axis, △ x be Article 1 incident ray and Article 2 incident ray respectively with the distance of lower glass surface intersection point, △ x ' for Article 1 incident ray and Article 2 incident ray respectively with the horizontal range of concentrating refractive face, bottom refraction point, n is Refractive Index of Material; N is a natural number, and the xsect by whole curved surface is divided into N decile, and d is the ratio of light geometric ratio compression, numerically equals formula 1 can be tried to achieve by the top flank of tooth, and formula 2 is substituted into formula 3, tries to achieve y' in conjunction with formula 1 _n, by y' _nsubstitute into formula 6 and try to achieve β _n, by y' _nsubstitute into formula 2 and try to achieve △ x', △ x' is substituted into formula 5 and tries to achieve x' _n, so just obtain each point coordinate (y' in lower teeth face _n, x' _n), namely obtain the curve of the bottom flank of tooth.

Wherein, the upper and lower flank of tooth of corresponding upper and lower teeth groove is equivalent to formation one independently lens, assuming that the radius of whole Fresnel Lenses is R, i.e. X ₀=R, can try to achieve upper and lower two continuous curves by above-mentioned equation, blocks continuous curve at rational height and position H place, and the X value of disconnect position is X ₁, intercepting face width of tooth is W ₁, then X ₁=R-W ₁, in this, as the initial calculation point of the next flank of tooth, when next flank of tooth height is close to H, block curve; By that analogy, until X _nwhen=0, whole Fresnel Lenses calculates complete.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (2)

1. a two-sided Fresnel Lenses, comprise the plane of incidence and exit facet, it is characterized in that: the described plane of incidence and exit facet are the teeth groove being provided with many depressions, in each teeth groove, correspondence is globoidal structure for the flank of tooth playing optically focused effect, the cambered surface contour shape of bottom teeth groove changes with the change of the contour shape of top teeth groove corresponding with it, dispersion of rays is numbered from right to left, be respectively 0, 1, 2, 3 to N, and suppose that the spacing between adjacent two light is Δ X, determine that its institute is by corresponding teeth groove by the light path of each root light, the curvilinear equation of lower curved flank profile shape,

First, determine the equation of the top flank of tooth, its curvilinear equation meets:

$\frac{x_n}{m}=\frac{a}{b}$

y _n＝y _n-1+△x*tanβ

x _n＝x _n-1-△x

$\tan \mathrm{\α}=\frac{h+y_n}{a-(b-m)}$

sinβ＝nsinθ

$\mathrm{\α}-\mathrm{\θ}+\mathrm{\β}=\frac{\mathrm{\π}}{2}$

Wherein, x _nbe the X value of N article of light, m be N article of light by the X value at focus place after this curve, a is lens half bores, and b is focal radius, y _nbe the Y value of N article of light and intersections of complex curve, Δ X is the spacing of adjacent two light, and β is the incident angle of light, and θ is incident angle, and α is the angle of refracted ray and X-axis, and h is the vertical range of x-axis and focus, and n is Refractive Index of Material;

Wherein a, b, Δ X, h, n are known, and Y ₀=0, by above formula, choose suitable x value, the curve point of each tooth can be tried to achieve;

Secondly, after the curvilinear equation of the described top flank of tooth is determined, then determine the equation of the bottom flank of tooth, its curvilinear equation meets:

△ x=[x _n-1-ctg α _n-1* (y _n-1+ h ₀)]-[x _n-ctg α _n(y _n+ h ₀)] ... formula 1

△ x'=△ x-ctg (α _n-1) * (y' _n-1-h ₀)+ctg α _n(y' _n-h ₀) ... formula 2

Y' ₀=y' _n-1-△ x'*tg φ _n-1formula 3

${\mathrm{tg\φ}}_n=\frac{n{\mathrm{cos\α}}_n-{\mathrm{sin\β}}_n}{{\mathrm{cos\β}}_n-n{\mathrm{sin\α}}_n}$ Formula 4

X' _n=x' _n-1-△ x' ... formula 5

${\mathrm{tg\β}}_n=\frac{x_0^{\′}-b+\frac{N}{d}*b}{h^{\′}-y_n^{\′}}$ Formula 6

Wherein, h ₀for thickness of glass, b is the intersection point of Article 1 incident ray and y=h' straight line and the vertical range of Y-axis, and h' is the distance of hot spot to glass top surface, x ₀for Article 1 incident ray is in the starting point in concentrating refractive face, top, α ₀for Article 1 incident ray by behind concentrating refractive face, top with the angle of X-axis, β ₀for Article 1 incident ray is at the refraction angle of concentrating refractive face, bottom xsect, θ ₀for Article 1 incident ray is in the incident angle of concentrating refractive face, bottom xsect, φ ₀for Article 1 incident ray and the normal to curve of concentrating refractive face, bottom xsect point of intersection and the acute angle of y-axis, △ x be Article 1 incident ray and Article 2 incident ray respectively with the distance of lower glass surface intersection point, △ x ' for Article 1 incident ray and Article 2 incident ray respectively with the horizontal range of concentrating refractive face, bottom refraction point, n is Refractive Index of Material; N is a natural number, and the xsect by whole curved surface is divided into N decile, and d is the ratio of light geometric ratio compression, numerically equals formula 1 can be tried to achieve by the top flank of tooth, and formula 2 is substituted into formula 3, tries to achieve y' in conjunction with formula 1 _n, by y' _nsubstitute into formula 6 and try to achieve β _n, by y' _nsubstitute into formula 2 and try to achieve △ x', △ x' is substituted into formula 5 and tries to achieve x' _n, so just obtain each point coordinate (y' in lower teeth face _n, x' _n), namely obtain the curve of the bottom flank of tooth;

Wherein, the upper and lower flank of tooth of corresponding upper and lower teeth groove is equivalent to formation one independently lens, assuming that the radius of whole Fresnel Lenses is R, i.e. X ₀=R, can try to achieve upper and lower two continuous curves by above-mentioned equation, blocks continuous curve at rational height and position H place, and the X value of disconnect position is X ₁, intercepting face width of tooth is W ₁, then X ₁=R-W ₁, in this, as the initial calculation point of the next flank of tooth, when next flank of tooth height is close to H, block curve; By that analogy, until X _nwhen=0, whole Fresnel Lenses calculates complete.

2. two-sided Fresnel Lenses according to claim 1, it is characterized in that: the teeth groove on the described plane of incidence and the teeth groove on exit facet respectively with the axle center of lens for symcenter rotational symmetry arrange, the teeth groove number on the described plane of incidence is equal with the teeth groove number on exit facet.