CN102854551B - Method for manufacturing broad-spectrum strong-focusing Fresnel lens - Google Patents

Abstract

The invention provides a method for manufacturing a broad-spectrum strong-focusing Fresnel lens, belonging to the optics field. The method is used to solve the problems that a Fresnel lens imaging through a traditional concentration system has a poor effect of converging sunlight and is difficult to obtain higher conversion efficiency. A realization process of the method comprises the following steps: firstly, obtaining a iteration relation between dip angle ThetaBL of a ring zonal gear of a Fresnel lens and ring height HGR of the Fresnel lens by computation after a divergence angle Thetas of incident sunlight is introduced; adopting a prediction-correction algorithm to obtain an dip angle ThetaBL and ring height HGR of each ring, and using a Monte Carlo radiosity algorithm to obtain a power density Psi of the sunlight received by a fixed area in a focal plane; obtaining a power density limit value Psilim based on an imaging concentration principle; and calculating a spectrum range of a to-be-manufactured Fresnel lens : absolute value of (Psilim-Psi) is less than or equal to Epsilon, and manufacturing a die according to final parameters of the Fresnel lens obtained by simulation so as to obtain a lens entity. The methodprovided byf the invention is used for manufacturing the broad-spectrum strong-focusing Fresnel lens.

Description

A kind of method for making of wide spectrum strong focusing Fresnel Lenses

Technical field

The present invention relates to a kind of Fresnel optical collector method for designing for the strong focusing of solar spectrum, belong to optical field.

Background technology

Along with exhausting fast and the demand of sustainable development of fossil fuel, the mankind are in the urgent need to searching out a kind of clean energy resource.But due to the restriction of technical bottleneck, as the annual actual utilization Zhi Zhan world of the sun power of all clean energy resource first-selections 0.1% of the electric weight that always generates electricity, be equivalent to the solar radiation energy (4.3 × 1020J) that in a hour, ground receives.Visible, be very huge to expanding space of sun power utilization.

Because magnesium element content in the earth's crust accounts for the 8th, at the earth's surface in seawater MgO to enrich very much concentration be 1.3g/l, constituent content is the 2nd, therefore can by the sunshine of broad band be converted to laser decompose in the earth's crust with seawater in the MgO form that obtains Mg or hydrogen stored.Traditional condenser system (parabola+composite parabolic) volume greatly all the time, heavier, difficult processing, cost be high, cause commercialization low, although also can improve the utilization ratio to sunshine, but the poor effect of the Fresnel Lenses converge sunlight of imaging is difficult to obtain higher conversion efficiency.

Summary of the invention

The object of the invention is the weak effect of the Fresnel Lenses converge sunlight in order to solve traditional condenser system imaging, be difficult to obtain the problem of higher conversion efficiency, a kind of method for making of wide spectrum strong focusing Fresnel Lenses is provided.

A method for making for wide spectrum strong focusing Fresnel Lenses, the implementation procedure of the method is:

Step 1, inclination angle and this ring of setting the ring of Fresnel Lenses to be produced apart from the iterative relation formula of the distance in this lens center of circle are:

$H_{\mathrm{GR}}=H_{\mathrm{GR}-1}+\frac{d_{\mathrm{BL}}/2}{\tan \left({\mathrm{\θ}}_{\mathrm{BL}}\right)}+\frac{d_{\mathrm{BL}}/2}{\tan \left({\mathrm{\θ}}_{\mathrm{BL}-1}\right)}---\left(3\right)$

$\tan \left({\sin }^{-1}\right[n_R\sin {\mathrm{\θ}}_{\mathrm{BL}}]-{\mathrm{\θ}}_{\mathrm{BL}})=\frac{{2H}_{\mathrm{GR}}}{{\mathrm{\Σ}}_{\mathrm{LC}}}-\tan \left({\sin }^{-1}\right[n_B\sin {\mathrm{\θ}}_{\mathrm{BL}}]-{\mathrm{\θ}}_{\mathrm{BL}})---\left(4\right)$

In formula, θ _bLthe inclination angle of the ring obtaining for this iteration, H _gRthe ring obtaining for this iteration is apart from the distance in this lens center of circle, H _gR-1the ring obtaining for front iteration is apart from the distance in the Fresnel Lenses center of circle; θ _bL-1the inclination angle of the Fresnel Lenses ring obtaining for front iteration; d _bLfor the ring of Fresnel Lenses high; n _bfor short wavelength's light is in the refractive index of Fresnel Lenses inside to be produced; n _rfor long wavelength's light is in the refractive index of Fresnel Lenses inside to be produced; ∑ _lCfor the focal length of Fresnel Lenses to be produced;

By the angle of divergence θ of incident sunshine _sintroducing formula (4) obtains:

$\frac{H_{\mathrm{GR}}(\tan {\mathrm{\θ}}_{\mathrm{BL}}+\cot {\mathrm{\θ}}_{r1})-(h+d_{\mathrm{BL}}/2)}{\tan {\mathrm{\θ}}_{\mathrm{BL}}+\cot {\mathrm{\θ}}_{r1}}+\frac{H_{\mathrm{GR}}(\tan {\mathrm{\θ}}_{\mathrm{BL}}-\cot {\mathrm{\θ}}_{r2})-(h+d_{\mathrm{BL}}/2)}{\tan {\mathrm{\θ}}_{\mathrm{BL}}-\cot {\mathrm{\θ}}_{r2}}$

$={\mathrm{\Σ}}_{\mathrm{LC}}\left(\begin{array}{c}\tan \left[{\sin }^{-1}\right[n_R\sin ({\mathrm{\θ}}_{\mathrm{BL}}-{\sin }^{-1}\left(\frac{1}{n_R}\sin {\mathrm{\θ}}_s\right))]-{\mathrm{\θ}}_{\mathrm{BL}}]+\\ \tan \left[{\sin }^{-1}\right[n_B\sin ({\mathrm{\θ}}_{\mathrm{BL}}+{\sin }^{-1}\left(\frac{1}{n_R}\sin {\mathrm{\θ}}_s\right))]-{\mathrm{\θ}}_{\mathrm{BL}}]\end{array}\right)---\left(5\right)$

In formula, θ _r2with θ _r1be respectively short wavelength's incident ray and the refraction angle of long wavelength's incident ray in ring corresponding with this iteration; H is the substrate thickness of Fresnel Lenses;

Step 3, adopt Predictor-Correcting Algorithm to adopt iterative to go out inclination angle that Fresnel Lenses to be produced respectively encircles and the corresponding each ring distance apart from this lens center of circle to formula (3) and formula (5);

Step 4, use Monte Carlo ray tracing algorithm be the distance H apart from this lens center of circle to each ring of the each inclination angle of encircling of the Fresnel Lenses to be produced of step 3 gained and correspondence _gRemulation obtains corresponding Fresnel Lenses, and the Fresnel Lenses of emulation acquisition is focused on to emulation, obtains the sunshine power density ψ receiving in its focused spot size;

Step 5, according to imaging optically focused principle, the parameter of Fresnel Lenses to be produced obtaining according to step 3 draws the sunshine power density ultimate value ψ that this Fresnel Lenses ideally receives in its focused spot size _lim:

${\mathrm{\ψ}}_{\lim }=C_{\mathrm{sun}}{\left(\frac{D}{2{\mathrm{\Σ}}_{\mathrm{Lc}}{\mathrm{\θ}}_s}\right)}^2---\left(7\right)$

In formula, C _sunfor ground surface solar constant; D is Fresnel Lenses diameter to be produced;

Step 6, according to set criterion ε, calculate and approach power density ultimate value ψ most _limdesign spectral range:

|ψ _lim-ψ|≤ε (8)

In formula, ε≤1; Export if this inequality is set up the Fresnel Lenses final argument to be produced that step 3 obtains, make mould according to these parameters, and adopt this mould manufacture to obtain Fresnel Lenses entity;

If | ψ _lim-ψ | > ε, returns to step 1 and recalculates the parameter of Fresnel Lenses to be produced.

Advantage of the present invention is:

The Fresnel Lenses of a kind of strong focusing that the present invention proposes is than the Fresnel Lenses of imaging, and it improves approximately 18.8% on the sunshine power focusing on, and has improved like this conversion efficiency of sunshine to laser, can accelerate the process of sunshine pump laser commercialization;

Than existing imaging Fresnel Lenses, the beneficial effect of strong focusing Fresnel Lenses method for designing of the present invention is mainly manifested in:

(1) provide a kind of strong focusing Fresnel Lenses method for designing, thereby realized the strong convergence in the fixed area of focal plane to wide spectrum sunshine;

(2) pump light of the high power density that the wide spectrum Fresnel Lenses design of strong focusing focusing sunlight obtains is conducive to pumped solid-state laser medium and obtains high efficiency Laser output, reduces the threshold pump power of Laser output.

(3) set up model according to the laser medium size of required pumping, carry out ray tracing algorithm it is calculated, improved design efficiency, reduced design cost.

Brief description of the drawings

Fig. 1 is the structural representation of Fresnel Lenses to be produced; In figure, the A-A sectional view that left side is Fresnel Lenses, the front elevation that right side is Fresnel Lenses; W _gRfor the ring width of Fresnel Lenses to be produced; θ _bLfor the inclination angle of Fresnel Lenses ring to be produced; d _bLfor the ring of Fresnel Lenses high; D is the diameter of Fresnel Lenses to be produced;

Fig. 2 is how much refraction route maps that incident ray sees through Fresnel Lenses; In figure, h _spotfor the radius of the focal beam spot after focusing on, ∑ _lCfor the focal length of Fresnel Lenses to be produced;

Fig. 3 is the angle of divergence θ that has considered sunshine _safter incident ray see through how much refraction route maps of Fresnel Lenses; In figure, l ₁with l ₂two light that have the angle of divergence.

Embodiment

Embodiment one: below in conjunction with Fig. 1 to Fig. 3, present embodiment is described, the method for making of a kind of wide spectrum strong focusing Fresnel Lenses described in present embodiment, the implementation procedure of the method is:

Step 1, inclination angle and this ring of setting the ring of Fresnel Lenses to be produced apart from the iterative relation formula of the distance in this lens center of circle are:

$H_{\mathrm{GR}}=H_{\mathrm{GR}-1}+\frac{d_{\mathrm{BL}}/2}{\tan \left({\mathrm{\θ}}_{\mathrm{BL}}\right)}+\frac{d_{\mathrm{BL}}/2}{\tan \left({\mathrm{\θ}}_{\mathrm{BL}-1}\right)}---\left(3\right)$

$\tan \left({\sin }^{-1}\right[n_R\sin {\mathrm{\θ}}_{\mathrm{BL}}]-{\mathrm{\θ}}_{\mathrm{BL}})=\frac{{2H}_{\mathrm{GR}}}{{\mathrm{\Σ}}_{\mathrm{LC}}}-\tan \left({\sin }^{-1}\right[n_B\sin {\mathrm{\θ}}_{\mathrm{BL}}]-{\mathrm{\θ}}_{\mathrm{BL}})---\left(4\right)$

In formula, θ _bLthe inclination angle of the ring obtaining for this iteration, H _gRthe ring obtaining for this iteration is apart from the distance in this lens center of circle, H _gR-1the ring obtaining for front iteration is apart from the distance in the Fresnel Lenses center of circle; θ _bL-1the inclination angle of the Fresnel Lenses ring obtaining for front iteration; d _bLfor the ring of Fresnel Lenses high; n _bfor short wavelength's light is in the refractive index of Fresnel Lenses inside to be produced; n _rfor long wavelength's light is in the refractive index of Fresnel Lenses inside to be produced; ∑ _lCfor the focal length of Fresnel Lenses to be produced;

By the angle of divergence θ of incident sunshine _sintroducing formula (4) obtains:

$\frac{H_{\mathrm{GR}}(\tan {\mathrm{\θ}}_{\mathrm{BL}}+\cot {\mathrm{\θ}}_{r1})-(h+d_{\mathrm{BL}}/2)}{\tan {\mathrm{\θ}}_{\mathrm{BL}}+\cot {\mathrm{\θ}}_{r1}}+\frac{H_{\mathrm{GR}}(\tan {\mathrm{\θ}}_{\mathrm{BL}}-\cot {\mathrm{\θ}}_{r2})-(h+d_{\mathrm{BL}}/2)}{\tan {\mathrm{\θ}}_{\mathrm{BL}}-\cot {\mathrm{\θ}}_{r2}}$

$={\mathrm{\Σ}}_{\mathrm{LC}}\left(\begin{array}{c}\tan \left[{\sin }^{-1}\right[n_R\sin ({\mathrm{\θ}}_{\mathrm{BL}}-{\sin }^{-1}\left(\frac{1}{n_R}\sin {\mathrm{\θ}}_s\right))]-{\mathrm{\θ}}_{\mathrm{BL}}]+\\ \tan \left[{\sin }^{-1}\right[n_B\sin ({\mathrm{\θ}}_{\mathrm{BL}}+{\sin }^{-1}\left(\frac{1}{n_R}\sin {\mathrm{\θ}}_s\right))]-{\mathrm{\θ}}_{\mathrm{BL}}]\end{array}\right)---\left(5\right)$

In formula, θ _r2with θ _r1be respectively short wavelength's incident ray and the refraction angle of long wavelength's incident ray in ring corresponding with this iteration; H is the substrate thickness of Fresnel Lenses;

Step 3, adopt Predictor-Correcting Algorithm to adopt iterative to go out inclination angle that Fresnel Lenses to be produced respectively encircles and the corresponding each ring distance apart from this lens center of circle to formula (3) and formula (5);

Step 4, use Monte Carlo ray tracing algorithm be the distance H apart from this lens center of circle to each ring of the each inclination angle of encircling of the Fresnel Lenses to be produced of step 3 gained and correspondence _gRemulation obtains corresponding Fresnel Lenses, and the Fresnel Lenses of emulation acquisition is focused on to emulation, obtains the sunshine power density ψ receiving in its focused spot size;

Step 5, according to imaging optically focused principle, the parameter of Fresnel Lenses to be produced obtaining according to step 3 draws the sunshine power density ultimate value ψ that this Fresnel Lenses ideally receives in its focused spot size _lim:

${\mathrm{\ψ}}_{\lim }=C_{\mathrm{sun}}{\left(\frac{D}{2{\mathrm{\Σ}}_{\mathrm{Lc}}{\mathrm{\θ}}_s}\right)}^2---\left(7\right)$

In formula, C _sunfor ground surface solar constant; D is Fresnel Lenses diameter to be produced;

Step 6, according to set criterion ε, calculate and approach power density ultimate value ψ most _limdesign spectral range:

|ψ _lim-ψ|≤ε (8)

In formula, ε≤1; Export if this inequality is set up the Fresnel Lenses final argument to be produced that step 3 obtains, make mould according to these parameters, and adopt this mould manufacture to obtain Fresnel Lenses entity;

If | ψ _lim-ψ | > ε, returns to step 1 and recalculates the parameter of Fresnel Lenses to be produced.

Embodiment two: below in conjunction with Fig. 1 to Fig. 3, present embodiment is described, present embodiment is for to obtain θ to embodiment one _bLwith H _gRthe further illustrating of iterative relation formula, step 3 described in present embodiment, adopt Predictor-Correcting Algorithm to adopt iterative to go out θ to formula (3) and formula (5) _bLwith H _gRmethod be: according to W _gR, H _gRwith θ _bLdirectly relational expression:

$\tan \left({\sin }^{-1}\right[n_R\sin {\mathrm{\θ}}_{\mathrm{BL}}]-{\mathrm{\θ}}_{\mathrm{BL}})=\frac{{2H}_{\mathrm{GR}}}{{\mathrm{\Σ}}_{\mathrm{LC}}}-\tan \left({\sin }^{-1}\right[n_B\sin {\mathrm{\θ}}_{\mathrm{BL}}]-{\mathrm{\θ}}_{\mathrm{BL}});---\left(1\right)$

W _GR＝d _BL/tan(θ _BL)； (2)

Obtain; In formula, W _gRfor the ring width between each ring of Fresnel Lenses to be produced.

Embodiment three: present embodiment is described below in conjunction with Fig. 1 to Fig. 3, present embodiment is to adopting further illustrating of Predictor-Correcting Algorithm in embodiment one and embodiment two, and the employing Predictor-Correcting Algorithm described in present embodiment solves the inclination angle theta of each ring to formula (3) and formula (5) _bLwith the high H of ring _gRpredictor and the corrector of middle Predictor-Correcting Algorithm are respectively:

$\left\{\begin{array}{c}{y}_{n+1}^{*}=y_{n-q}+h\underset{j=0}{\overset{s}{\mathrm{\Σ}}}{\mathrm{\α}}_{j}f(x_{n-j},y_{n-j})\\ y_{n+1}=y_{n-p}+h\underset{j=1}{\overset{t}{\mathrm{\Σ}}}{\mathrm{\β}}_{j}f(x_{n+1-j},y_{n+1-j})+{\mathrm{h\β}}_{0}f(x_{n+1},y_{n+1}^{*})\end{array}\right..---\left(6\right)$

Embodiment four: present embodiment is described below in conjunction with Fig. 1 to Fig. 3, present embodiment is to the further illustrating of Fresnel Lenses diameter D to be produced in embodiment one, and the scope of the Fresnel Lenses diameter D to be produced described in present embodiment is 300mm～1200mm.

Embodiment five: below in conjunction with Fig. 1 to Fig. 3, present embodiment is described, present embodiment is the focal length ∑ to Fresnel Lenses to be produced in embodiment one _lCfurther illustrate, the focal length ∑ of the Fresnel Lenses to be produced described in present embodiment _lCscope be the Fresnel Lenses diameter D to be produced of 1～1.5 times.

The present invention is not limited to above-mentioned embodiment, can also be the reasonable combination of technical characterictic described in the respective embodiments described above.

Claims (4)

1. a method for making for wide spectrum strong focusing Fresnel Lenses, is characterized in that: the implementation procedure of the method is:

Step 1, inclination angle and this ring of setting the ring of Fresnel Lenses to be produced apart from the iterative relation formula of the distance in this lens center of circle are:

$H_{\mathrm{GR}}=H_{\mathrm{GR}-1}+\frac{d_{\mathrm{BL}}/2}{\tan \left({\mathrm{\θ}}_{\mathrm{BL}}\right)}+\frac{d_{\mathrm{BL}}/2}{\tan \left({\mathrm{\θ}}_{\mathrm{BL}-1}\right)}---\left(3\right)$

$\tan \left({\sin }^{-1}\right[n_R\sin {\mathrm{\θ}}_{\mathrm{BL}}]-{\mathrm{\θ}}_{\mathrm{BL}})=\frac{{2H}_{\mathrm{GR}}}{{\mathrm{\Σ}}_{\mathrm{LC}}}-\tan \left({\sin }^{-1}\right[n_B\sin {\mathrm{\θ}}_{\mathrm{BL}}]-{\mathrm{\θ}}_{\mathrm{BL}})---\left(4\right)$

In formula, θ _bLthe inclination angle of the ring obtaining for this iteration, H _gRthe ring obtaining for this iteration is apart from the distance in this lens center of circle, H _gR-1the ring obtaining for front iteration is apart from the distance in the Fresnel Lenses center of circle; θ _bL-1the inclination angle of the Fresnel Lenses ring obtaining for front iteration; d _bLfor the ring of Fresnel Lenses high; n _bfor short wavelength's light is in the refractive index of Fresnel Lenses inside to be produced; n _rfor long wavelength's light is in the refractive index of Fresnel Lenses inside to be produced; ∑ _lCfor the focal length of Fresnel Lenses to be produced;

By the angle of divergence θ of incident sunshine _sintroducing formula (4) obtains:

$\begin{array}{c}\frac{H_{\mathrm{GR}}(\tan {\mathrm{\θ}}_{\mathrm{BL}}+\cot {\mathrm{\θ}}_{r1})-(h+d_{\mathrm{BL}}/2)}{\tan {\mathrm{\θ}}_{\mathrm{BL}}+\cot {\mathrm{\θ}}_{r1}}+\frac{H_{\mathrm{GR}}({\mathrm{\θ}}_{\mathrm{BL}}-\cot {\mathrm{\θ}}_{r2})-(h+d_{\mathrm{BL}}/2)}{\tan {\mathrm{\θ}}_{\mathrm{BL}}-\cot {\mathrm{\θ}}_{r2}}\\ ={\mathrm{\Σ}}_{\mathrm{LC}}\left(\begin{array}{c}\tan \left[{\sin }^{-1}\right[n_R\sin ({\mathrm{\θ}}_{\mathrm{BL}}-{\sin }^{-1}\left(\frac{1}{n_R}\sin {\mathrm{\θ}}_s\right))]-{\mathrm{\θ}}_{\mathrm{BL}}]+\\ \tan \left[{\sin }^{-1}\right[n_B\sin ({\mathrm{\θ}}_{\mathrm{BL}}+{\sin }^{-1}\left(\frac{1}{n_R}\sin {\mathrm{\θ}}_s\right))]-{\mathrm{\θ}}_{\mathrm{BL}}]\end{array}\right)\end{array}---\left(5\right)$

In formula, θ _r2with θ _r1be respectively short wavelength's incident ray and the refraction angle of long wavelength's incident ray in ring corresponding with this iteration; H is the substrate thickness of Fresnel Lenses;

Step 3, adopt Predictor-Correcting Algorithm to carry out iterative to formula (3) and formula (5) to go out inclination angle that Fresnel Lenses to be produced respectively encircles and the corresponding each ring distance apart from this lens center of circle;

Step 4, use Monte Carlo ray tracing algorithm be the distance H apart from this lens center of circle to each ring of the each inclination angle of encircling of the Fresnel Lenses to be produced of step 3 gained and correspondence _gRemulation obtains corresponding Fresnel Lenses, and the Fresnel Lenses of emulation acquisition is focused on to emulation, obtains the sunshine power density ψ receiving in its focused spot size;

Step 5, according to imaging optically focused principle, the parameter of Fresnel Lenses to be produced obtaining according to step 3 draws the sunshine power density ultimate value ψ that this Fresnel Lenses ideally receives in its focused spot size _lim:

${\mathrm{\ψ}}_{\lim }=C_{\mathrm{sum}}{\left(\frac{D}{2{\mathrm{\Σ}}_{\mathrm{Lc}}{\mathrm{\θ}}_s}\right)}^2---\left(7\right)$

In formula, C _sunfor ground surface solar constant; D is Fresnel Lenses diameter to be produced;

Step 6, according to set criterion ε, calculate and approach power density ultimate value ψ most _limdesign spectral range:

|ψ _lim-ψ|≤ε (8)

In formula, ε≤1; Export if this inequality is set up the Fresnel Lenses final argument to be produced that step 3 obtains, make mould according to these parameters, and adopt this mould manufacture to obtain Fresnel Lenses entity;

If | ψ _lim-ψ | > ε, returns to step 1 and recalculates the parameter of Fresnel Lenses to be produced.

2. the method for making of a kind of wide spectrum strong focusing Fresnel Lenses according to claim 1, is characterized in that: step 3, adopt Predictor-Correcting Algorithm to carry out iterative to formula (3) and formula (5) to go out θ _bLwith H _gRmethod be: according to W _gR, H _gRwith θ _bLdirectly relational expression:

$\tan \left({\sin }^{-1}\right[n_R\sin {\mathrm{\θ}}_{\mathrm{BL}}]-{\mathrm{\θ}}_{\mathrm{BL}})=\frac{{2H}_{\mathrm{GR}}}{{\mathrm{\Σ}}_{\mathrm{LC}}}-\tan \left({\sin }^{-1}\right[n_B\sin {\mathrm{\θ}}_{\mathrm{BL}}]-{\mathrm{\θ}}_{\mathrm{BL}});---\left(1\right)$

W _GR＝d _BL/tan(θ _BL)； (2)

Obtain; The ring width of each ring of Fresnel Lenses to be produced is W _gR.

3. the method for making of a kind of wide spectrum strong focusing Fresnel Lenses according to claim 1, is characterized in that: the scope of Fresnel Lenses diameter D to be produced is 300mm～1200mm.

4. the method for making of a kind of wide spectrum strong focusing Fresnel Lenses according to claim 1, is characterized in that: the focal length ∑ of Fresnel Lenses to be produced _lCscope be the Fresnel Lenses diameter D to be produced of 1～1.5 times.