CN103257382A - Scattering method based on differences of refractive index in media and porous scattering material - Google Patents

Abstract

The invention relates to a scattering method based on differences of refractive index in media and a porous scattering material. According to the scattering method based on the differences of the refractive index in the media and the porous scattering material, the travelling direction of light is disturbed by using refraction or total reflection among the transparent media, and scattered light high in transmittance is obtained. The refraction or the total reflection among the transparent media is interfaces formed on the surface of a colorless and transparent scatterer which is scattered in the uniform and transparent media. Two sides of the interfaces have the different refractive index. The refractive index of the colorless and transparent scatterer is different from the refractive index of the uniform and transparent media. According to the scattering method based on the differences of the refractive index in the media and the porous scattering material, the colorless and transparent material is used, no transmission light barrier layer is arranged, a refraction angle or a reflection angle of the colorless and transparent scatterer is large, the linear degree of the light transmitting through the colorless and transparent scatterer is large, the number of the interfaces is few, so that the diffuseness effect is good, the linear degree and density of the scatterer can be selected and adjusted, luminous efficiency is high, and therefore the satisfactory scattering effect is obtained.

Description

Scattering Method and Porous Scattering Material Based on Difference of Refractive Index in Medium

technical field

The invention belongs to the field of illumination optics and relates to a scattering method and material, in particular to a scattering method and a porous scattering material based on the difference in refractive index in a medium.

Background technique

With the development of light source technology, the unit power density of the light source has been increasing, far exceeding the limit vision ability of human beings. The efficiency of lighting is not only related to the light source (lamp), but also related to the lamps. In the past, frosted glass and corrugated glass were used to reduce glare, and high brightness and point light sources were used as surface light sources. With the improvement of people's living standards, more and more attention is paid to the pursuit of the beauty of lamps and lanterns. Frosted glass has the advantage of high light transmittance, but low shading, and the blurred shape of the light source can still be seen through the frosted glass. In recent years, the trend of domestic lamps is that frosted glass lamps are hard to find. Instead, a thin layer of milky white paint is screen-printed on the surface of transparent glass. The fluorescent lamp or energy-saving lamp inside the lamp illuminates this layer of painted lamp glass. The whole body is bright, and it feels like frosted glass under the light, but the light effect is estimated to drop greatly. For example, the lighting effect of 3×55W tri-color energy-saving lamps is similar to the brightness of the original 40W fluorescent lamps to 55W energy-saving lamps using ground glass lamps. The only difference is that the lamps covered by paint cannot see the obvious energy-saving lamps The shape of the tube. Table 1 shows the transmittance coefficients of various glasses in a manual.

Table 1 Transmittance coefficient of several kinds of glass

It can be seen from Table 1 that the light transmission of milky white glass is extremely poor, which is consistent with the feeling in daily life. There is a great contrast between aesthetics and energy saving and environmental protection, which is incompatible with the world energy saving trend. How to change the light transmission efficiency of the diffuse light generating device while satisfying the shielding property. Analyze the white lampshade glass, or the white incandescent lamp bulb, all have a thin white layer. Titanium dioxide has the advantages of high whiteness and high reflectivity, but the diffused light produced by milky white glass on the light source is transmitted light, not reflected light, and titanium dioxide particles will block the light transmission. Although the reflectivity between particles is high, this many times Reflection severely attenuates the luminous flux, and this imperfect method of diffuse reflection greatly reduces lighting efficiency over time.

Contents of the invention

Aiming at the defects of the low transmittance of the existing diffuse light generating device itself and the high shading rate of the material itself selected for the device, the present invention analyzes the optical properties of transparent inorganic materials and transparent polymers through basic optical analysis, analysis and research of natural light phenomena, and Research has obtained the law of diffuse reflection suitable for engineering applications and the corresponding method of light scattering with high transmittance and the acquisition method of corresponding optical materials.

The basic working principle is based on the relationship between light reflectance R and transmittance T of transparent media. Calculation formula of reflectivity R on the surface of transparent medium

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

For example, when the refractive index of glass n'=1.5, and the refractive index of air n=1.0, the calculated result is R=0.04, that is, the reflectivity of each surface of the glass plate is about 4%, and the transmittance of the colorless and transparent white glass plate The rate T is only 92.16%, so the total reflectance of the colorless white glass plate Rt _{white glass plate} =1－T=1－92.16%=7.84%. The transmittance of the N-layer colorless white glass plate is only ^TN .

The present invention utilizes the refraction or total reflection between transparent media to disturb the traveling direction of light to obtain scattered light with high transmittance. The refraction or total reflection between transparent media is colorless and transparent light distributed in uniform transparent media. The interface formed on the surface of the scatterer has different refractive indices on both sides of the interface; the refractive index n' of a colorless and transparent scatterer is different from that of a homogeneous transparent material, and the difference between the two can be positive or negative. The scatterers are spheres or irregular bodies.

It is preferred that the refractive index n' of the colorless and transparent scatterer is lower than that of the homogeneous material, and the scatterer has a concave lens effect, which causes a large area of total reflection in the scatterer, increases the divergence angle of a single scatterer, and reduces the internal Retroreflection reduces light loss; the size of the diffuser is sub-millimeter level to 1 mm,

The size of the scatterer is sub-millimeter level to 1 mm. The distribution of the scatterer in the uniform transparent medium is along the direction of light travel, that is, the thickness direction of the uniform transparent medium. The density value is 2 to 6, not more than 12. The optimal density Between 2 and 4, the scattering effect can be adjusted by controlling the size and density of the scattering body.

The colorless and transparent scattering (sphere) body of the present invention is formed by crystallization or foaming, which can limit the difference in refractive index between the uniform transparent medium and the colorless and transparent scattering body in a small range, and weaken the interface between two different media. Reflectivity, improve the light output rate of scattered light.

The colorless and transparent scatterer of the present invention is formed by crystallization or foaming; the crystal grain size in the transparent and uniform medium can be controlled by raw material selection, raw material temperature, and mold holding time to form inorganic glass-ceramic or polycrystalline high Molecular materials;

The colorless and transparent scatterer of the present invention is formed by crystallization or foaming; gas is mixed in a colorless and transparent inorganic substance or a colorless and transparent polymer material in a molten state to form bubbles wrapped in a transparent medium and evenly distributed in the medium.

The carrier of the present invention can be a hard transparent material, such as colorless glass, a polymer material with high light transmittance, such as plexiglass (polymethyl methacrylate, PMMA), polybutyl methacrylate (PBA), Polystyrene (PS), polycarbonate (PC), polyvinylidene fluoride (PVDF), polyester (PET), can also be a flexible polymer material film, through the form of a film on a transparent hard inorganic or polymer Lighting fixtures for materials or where diffused light needs to be produced.

The material used in the present invention is colorless and transparent, has no transmitted light blocking layer, the refraction or reflection angle of the colorless and transparent scatterer is large, the linearity of the colorless and transparent scatterer experienced by the light is large, the number of interfaces is small, and the diffusion is good. The size and density of the scatterer can be selected and adjusted, so that the light extraction efficiency is high to obtain a satisfactory scattering effect, and the implementation methods are diversified, the manufacturing process is mature, and the cost is low.

Description of drawings

Accompanying drawing 1 is the present invention about medium reflectance curve.

Accompanying drawing 2 is the ray trace diagram in the transparent medium plate G1 of the present invention.

Figure 3(a) is a schematic diagram of the main transmitted light of the multi-layer transparent medium plate of the present invention.

Figure 3(b) is a schematic diagram of the influence of the retroreflected light on the outgoing light of the multi-layer transparent medium plate of the present invention.

Accompanying drawing 4 is a schematic diagram of the influence of the transparent medium sphere with convex lens effect on the refraction direction of light in the present invention.

Accompanying drawing 5 is the structural diagram of the optical scattering plate with different refractive index transparent medium sphere groups of the present invention.

Fig. 6 is a schematic diagram of projected cross-sectional area ratio of total reflection at the interface between the uniform transparent medium and the air bubble of the present invention.

Detailed ways

The present invention is described below in conjunction with accompanying drawing.

Computing theory and derivation thereof on the basis of the present invention:

Accompanying drawing 1 is the reflectance curve of the medium on which the present invention is based, and the materials are taken from Figures 12-13 of "Optics" edited by mother Guoguang and Zhan Yuanling (People's Education Publishing House, 1978.9 first edition). Curve Ⅰ, curve Ⅱ, and curve Ⅲ in the figure respectively correspond to: the reflectivity Rp of vibration parallel to the incident surface (polarized light), the reflectivity Rs of vibration perpendicular to the incident surface (polarized light), and the reflectivity R of natural light. The axis represents the reflectivity R, and the horizontal axis is the angle of incidence i. Usual unpolarized light (natural light) corresponds to curve III. It can be seen from Figure 1 that the reflectivity R of the incident angle i within 40° is almost unchanged, and the reflectivity depends on the formula:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; no</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In formula (1), n’ and n are the refractive indices of different media on both sides of the interface, respectively. Generally, the refractive index of glass is n'=1.5, while that of air is n=1.0. The calculated refractive index is R=0.0400 (4.00%).

1. Derivation of reflectivity and transmittance of a single transparent medium plate:

Figure 2 shows a beam of light irradiating the transparent medium plate G1 at a small incident angle. The first incident light E1 is irradiated on the upper surface Su of the transparent medium plate G1, and the reflection produces the first reflected light R1 and the refraction produces the first round-trip light D1. The first round-trip light D1 propagates to the lower surface Sd of the transparent medium plate G1, and is reflected by the interface to generate the second round-trip light D2. The reflectivity conforms to formula (1), and is refracted by the lower surface Sd to generate the first outgoing light O1; Intensity: the first incident light E1=100%, the first reflected light R1=[(n'-n)/(n'+n)] ² (%)=R (according to formula (1)), the first round-trip light D1 =1-R1=1-R (%), the second round-trip light D2=RD1=R(1-R) (%), the first outgoing light O1=D1 ² =(1-R) ² (%).

Continue to trace the whereabouts and intensity of light rays in the transparent medium plate G1, the second round-trip light D2 is reflected on the upper surface Su of the transparent medium plate G1 to generate the third round-trip light D3, and the second reflected light R2 is generated through refraction; its relative intensity: The third round-trip light D3=RD2=R ² D1=R ² (1-R) (%), the second reflected light R2=(1-R)D2=(1-R)RD1=R(1-R) ² (%).

The third round-trip light D3 propagates to the lower surface Sd of the transparent medium plate G1, and is reflected to generate the fourth round-trip light D4. The reflectivity conforms to formula (1), and is refracted by the lower surface Sd to generate the second outgoing light O2; the relative intensity of each light : The fourth round-trip light D4=RD3=R ² D2=R ³ D1=R ³ (1-R) (%), the second outgoing light O2=(1-R)D3=(1-R)RD2=(1 -R)R ² D1=R ² (1-R) ² .

The fourth round-trip light D4 is reflected on the upper surface Su of the transparent medium plate G1 to generate the fifth round-trip light D5, and the third reflected light R3 is generated through refraction; the relative intensity of each light: the fifth round-trip light D5=R ⁴ (1- R) (%), the third reflected light R3=R ³ (1−R) ² (%).

The fifth round-trip light D5 propagates to the lower surface Sd of the transparent medium plate G1, and is reflected to generate the sixth round-trip light D6. The reflectivity conforms to formula (1), and is refracted by the lower surface Sd to generate the third outgoing light O3; the relative intensity of each light : The sixth round-trip light D6=R ⁵ (1-R) (%), the third outgoing light O3=R ⁴ (1-R) ² (%).

Total transmitted light T1=O1+O2+O3+……=(1+R ² +R ⁴ +…)(1－R) ² (%)(2)

Total reflected light Rt1=R1+R2+R3+...=R+R(1－R) ² +R ³ (1－R) ² +...（%）(3)

Among them, the reflectivity R is determined by formula (1), and finally depends on the refractive indices n' and n of the two media. When n'=1.5, n=1.0, interface reflectivity R=0.04 (4%), R ⁴ is on the order of 10 ^-6 , R ⁵ is on the order of 10 ^-7 , so O4 and R4 can be ignored as infinitesimal quantities,

The total transmitted light T1 corresponding to the transparent medium plate G1=0.923077.

The total reflected light Rt1=1-T1=0.076923 corresponding to the transparent medium plate G1.

The above calculations assume that the absorption rate of the transparent medium plate G1 is 0.

2. The transmittance derivation of the parallel overlapping of multiple layers of the same transparent medium plate:

Attached Figure 3 (a) is the direct transmitted light under the parallel overlapping of multiple layers of the same transparent medium plates G1~G3 (regardless of the reflection of the transparent medium plate Gi, which is reflected by the upper layer of transparent medium plates G _i-1 , G _i-2 The contribution of reflection again), the total transmitted light T1 of the transparent medium plate G1 is equal to the incident light E2 of the transparent medium plate G2, the total transmitted light T2 of the transparent medium plate G2 is equal to the total incident light E3 of the transparent medium plate G3, and the transparent medium plate G3’s The total transmitted light T3 is equal to the total incident light E4 of the transparent medium plate G4, and so on. Under the premise of ignoring the contribution of reflected light and the absence of medium absorption, the total transmitted light of the transparent medium plate G3 is T3=E4=T1 ³ =0.786527 (the reflectivity R is taken as 0.04).

Because the reflected light Ii of the lower transparent medium plate Gi reversely travels, the upper transparent medium plate G _i-1 and the upper layer transparent medium plate G _i-2 are illuminated, and the transparent medium plate G _i-1 and the transparent medium plate G The light reflected again _{by i-2} will finally irradiate the upper surface of the transparent medium plate Gi itself. Due to the reversibility of the optical path, the calculation formula (2) and formula (3) can be applied, and the final result can be calculated as long as the number of reflection or refraction of the optical path structure is counted. E1-E2-E3-E4 of accompanying drawing 3(b) is the same as that of accompanying drawing 3(a), which are directly transmitted light. E4' is the (reverse) reflected light of the transparent medium plate G2, which is reflected from the lower surface of the transparent medium plate G1, and then transmitted through the transparent medium plate G2 and the transparent medium plate G3, and contributes to the outgoing light T3 of the transparent medium plate G3 ;

E4" is the (reverse) reflected light of the transparent medium plate G3, and then reflected from the lower surface of the transparent medium plate G2, and re-enters the contribution of the transparent medium plate G3 to the outgoing light T3;

E4"' is the (reverse) reflected light of the transparent medium plate G3, after being transmitted by the transparent medium plate G2, it shines on the lower surface of the transparent medium plate G1, and is reflected by the transparent medium plate G1 from the lower surface, and then passes through the transparent medium plate The transmission of G2 and the transparent medium plate G3, the contribution to the outgoing light T3 of the transparent medium plate G3;

E4' has twice more reflections of transparent medium plates G1 and G2 than E4, so the intensity of E4' is: T1 ³ Rt1 ² =0.005917T1 ³ =0.005917·E4.

E4" has two more reflections of transparent medium plates G3 and G2 than E4, so the intensity of E4" is the same as that of E4': T1 ³ Rt1 ² =0.005917T1 ³ =0.005917·E4.

Compared with E4, E4"' has twice more reflections from the transparent medium plates G3 and G1, and two more (forward and reverse) transmissions through the transparent medium plate G2, so the intensity of E4"': T1 ⁵ Rt1 ² =0.005917T1 ⁵ =0.005917·T1 ² E4=0.852071×0.005917·E4.

The contribution of the retroreflection of the transparent medium plate G _i－1 and G _i－2 to the light extraction rate of the three-layer laminated transparent medium plate Gi: E'+E”+E”’=0.016876·E4; the three-layer colorless transparent medium plate G The total light output rate=1.016876·E4=80.0%. Among them, E4 is the direct transmitted light (%) of the transparent medium plates G1-G3.

By analogy, when the transparent medium plate G has 5 layers, the intensity of the transmitted light emitted directly from the transparent medium plate G5 is T5=T1 ⁵ =0.670177, and the reflected light generated by each layer, except the transparent medium plate G1, has Contributed reflections are available in 10 permutations.

The retroreflected light of the transparent medium plate G2 contributes to the emission of the transparent medium plate G5: T1 ⁵ Rt1 ² ;

The retroreflected light of the transparent medium plate G3 has two ways of contribution to the output of the transparent medium plate G5:

T1 ⁵ Rt1 ² +T1 ⁵ T1 ² Rt1 ²

The retroreflected light of the transparent medium plate G4 contributes three ways to the output contribution of the transparent medium plate G5:

T1 ⁵ Rt1 ² +T1 ⁵ T1 ² Rt1 ² +T1 ⁵ T1 ⁴ Rt1 ²

The retroreflected light of the transparent medium plate G5 is divided into 4 ways to the outgoing contribution of the transparent medium plate G5:

T1 ⁵ Rt1 ² +T1 ⁵ T1 ² Rt1 ² +T1 ⁵ T1 ⁴ Rt1 ² +T1 ⁵ T1 ⁶ Rt1 ²

The percentage of retroreflected light to direct outgoing light is:

Rt1 ² (4+3T1 ² +2T1 ⁴ +T1 ⁶ )=8.626888Rt1 ² =0.051046

The overall light transmittance of the 5-layer colorless transparent medium plate G is 70.4%.

3. Medium scattering model with transparent medium spheres with different refractive indices

Attached Figure 4 shows a transparent medium sphere model irradiated by parallel light. According to the law of refraction n’sin i’=nsin i, the side with a large refractive index has a small incident angle or a small exit angle, and the outgoing light travels in all directions. In the figure, the refractive index of the sphere n' > the refractive index n of the medium outside the sphere, the sphere presents a convex lens effect, and the light rays converge inside the sphere. According to Figure 1, the reflectivity R of the edge of the sphere is extremely high at low grazing angles. When The incident angle is between 80° and 90°, and the reflectivity R is between 0.55 and 1.0; if the refractive index n' of the sphere is less than the refractive index n of the medium outside the sphere, based on existing knowledge and experimental verification, the following inferences can be obtained: ① sphere It presents a concave lens effect. ②The light entering the sphere diverges, and the outgoing light includes a wider angle, and the scattering effect is stronger. ③The external light irradiates on the edge of the sphere and undergoes total reflection, which makes the outgoing light more efficient.

4. Methods to improve the transmittance of transparent media

According to the derivation and calculation results of the transmissivity of the aforementioned transparent medium plates G1~Gi after multi-layer stacking, every time a colorless and transparent medium plate Gi with a refractive index n'=1.5 passes through, the transmittance Ti of each transparent medium plate Gi=92.3 %, reflectance Ri=1-Ti, the more transparent medium plate G experienced, the lower the total transmittance and the higher the total reflectance. According to formula (1), the following inference can be obtained: when the values of n’ and n are closer, the reflectivity R is smaller, that is, the transmittance T=1-R of the transparent medium plate Gi is higher. Therefore, if the refractive index n' of medium 1 is closer to the refractive index n of medium 2, the total transmittance of the same multi-layer transparent medium plate Gj must be greater than that of the transparent medium plate Gi with a large difference in refractive index between the two media.

5. Scattering model and scattering material of transparent medium sphere group with different refractive index

When the transparent medium plate G is changed to an irregular sphere, the incident light irradiates the sphere and scatters to the surroundings, and the ratio of light traveling in the opposite direction is small, which greatly reduces the light attenuation of forward propagation and improves the scattering efficiency. Because the irregular transparent medium spheres are not only scattered in the plane perpendicular to the traveling path of the irradiating light, but also have a certain thickness distribution along the traveling path of the irradiating light. The near-parallel irradiating light is affected by the irregular first transparent medium sphere, such as the irregular transparent medium sphere in Figure 4, forming scattering, propagating in different directions, and the light energy begins to disperse. After traveling a short distance, it meets again The second irregular transparent medium sphere, due to the dispersion of the direction of the light incident on the second irregular transparent medium sphere, after the refraction or total reflection of the second irregular transparent medium sphere, the outgoing light has a wider distribution in the direction, and then may encounter The third irregular transparent medium sphere, the fourth irregular transparent medium sphere, after several times of refraction or total reflection of the irregular transparent medium sphere, can well convert the directional light into scattered light, and obtain an angular range of ±90° Diffuse light with good uniformity of internal illumination.

穿透5层无色透明介质平板G1～G5的透光率为70.4%，过多、过密的透明介质球体群对器材的透射率构成了影响和挑战，需要在散射效果和透光率之间找到平衡点。Accompanying drawing 5 is the sheet material that contains the transparent medium sphere of different refractive index in the transparent homogeneous medium, wherein the transparent medium sphere of different refractive index is randomly distributed in space, macroscopic statistics is uniform distribution; The wavelength λ of red light. The density of the transparent medium spheres in the plate is preferably 2 to 10 transparent medium spheres in the thickness direction of the plate. According to the analysis of the model in Figure 3(b), when Δn=0.5,

The light transmittance of G1-G5 penetrating through 5 layers of colorless transparent medium plates is 70.4%. Too many and too dense transparent medium spheres pose an impact and challenge on the transmittance of the equipment. It is necessary to balance the scattering effect and light transmittance. Find a balance between.

According to the aforementioned analysis and discussion, the method for improving the scattering efficiency and transmittance of the transparent medium sphere in the present invention can be summarized as follows:

① Improve the scattering efficiency of a single transparent medium sphere—expand the scattering angle and distribution; ② Reduce the number of transparent medium spheres passing through the scattering path; ③ Reduce the reflected energy between different medium interfaces; ④ Create a total reflection environment.

① To improve the scattering efficiency of a single transparent medium sphere, it is required that the angular distribution of the light emitted from a single transparent medium sphere is large, so that only a small amount of transparent medium spheres need to penetrate to meet the scattering requirements. The field angle of the lens composed of convex lens group is small. The first lens of super wide-angle lens and fisheye lens adopts concave lens. The telescope composed of convex lens and concave lens reverses the optical path and looks in from the objective lens end (convex lens end). The field of view seen is much larger than the field of view seen in the eyepiece (concave lens end) when the telescope is used. Analyzing the optical path of the concave lens, when the parallel light irradiates the concave lens, the light that diverges outward is obtained. If you change the way of thinking from another angle, add a transparent medium sphere with a refractive index n'<the refractive index of the transparent uniform medium to the transparent uniform medium, and the light passes through the transparent uniform medium with a refractive index n and enters a transparent medium with a smaller refractive index n' A sphere, at this time, a transparent medium sphere with a smaller refractive index n' becomes a concave lens. According to the characteristics of the concave lens, the light entering it will be refracted into a wider spatial range.

②Reducing the number of transparent medium spheres passing through the scattering path can reduce the number of interface mutations, that is, reduce the number of reflections. It is known that the reflectivity R of each time is constant (in the range of angle 0°-40°), and the total transmission The rate is related to (1-R) ^k , and the total reflectance is 1-(1-R) ^k , where k is the number of reflections; in addition, the linearity of the transparent medium sphere is large, and each bundle of refracted light rays in the sphere The traveling distance is long, the distance between the refracted beams is large, and the scattering characteristics are good, so the number of transparent medium spheres that need to meet the same scattering index is small.

③Reduce the reflected energy between different medium interfaces. According to formula (1), reflectivity R∝Δn ² , such as n'=1.5 glass and n=1.0 air, Δn=0.5, according to formula (1) R=0.04, and if use n'=1.33 water For the interface formed with air, the reflectivity R=(0.33/2.33) ² =0.02006, which is almost half of the reflectivity of the interface between glass and air. Therefore, reducing the difference in the refractive index of the two media can reduce the reflected energy of the light passing through the interface each time and increase the intensity of the transmitted light.

④ Create a total reflection environment. When light passes from an optically denser medium to an optically rarer medium, the light whose incident angle exceeds the critical angle undergoes total reflection. For example, according to the law of refraction, the critical angle of total reflection from water (n'=1.33) to air i'=48.7535°, the critical angle of total reflection from glass with n'=1.5 to air i'=41.81°, air is wrapped in a transparent medium After bubbles, total reflection occurs at the part exceeding the critical angle under the irradiation of parallel light. Figure 6 shows the relative area projection relationship of total reflection. The air bubble Air in the figure, the critical angle i' of total reflection and its corresponding projection area FR of total reflection . The air bubble (sphere) produces a total reflection projection area FR (the top is regarded as a ring), and its relative cross-sectional area

S=1－sin ² i'(4)

Wherein i' is the critical incident angle of the optically dense medium, which is deduced with reference to the geometric relationship of accompanying drawing 6. For air bubbles and water, the relative cross-sectional area of total reflection S=43.46%, for the medium and air bubbles with n’=1.5, the relative cross-sectional area of total reflection S=55.55%.

The present invention adopts the transparent medium spheres distributed in the transparent uniform medium in the form of Fig. 5. When the light passes through the transparent uniform medium, it will encounter transparent medium spheres with different refractive indices from the transparent uniform medium many times, and will present scattered light after refraction. In the present invention, the refractive index of the transparent medium sphere n' > the refractive index of the transparent uniform medium n, or the refractive index of the transparent medium sphere n' < the refractive index of the transparent uniform medium n, but the divergence angle of the refracted outgoing light in the latter case is larger , the scattering effect is better, and the forward light loss is less.

The preparation method of the different refractive index transparent medium sphere group of the present invention

Optical glass glasses and optical lens glass are transparent, but after more than 10 years or decades of storage, crystals will precipitate inside the lens glass, causing the lens glass to become cloudy; the light transmission of glass-ceramics is not as good as that of glass-like materials, and the reasons are analyzed. The refractive index of the fine crystal is different from that of the surrounding medium, causing light disturbance. The light transmittance of some engineering plastics has a great relationship with the processing technology, such as polypropylene (PP) plastic, the plastic body of direct mold injection molding is milky white and turbid; biaxially oriented polypropylene (BOPP) film is transparent, and it is different from injection molding The appearance of polypropylene is essentially different; the appearance of injection molding of polypropylene raw materials with microcrystallization treatment agent is much higher than that of untreated polypropylene raw materials; analysis of the reasons shows that polypropylene has strong crystallinity, and polycrystals are formed after molding, and the crystal diameter Small but extremely numerous, resulting in too many transmission-reflection times between crystal particles, and the light transmission is naturally poor. The biaxially oriented polypropylene (BOPP) film cools quickly, the grains are too late to grow, and the natural light transmission is excellent. Polystyrene (PS) has excellent light transmission. The commonly used shock-absorbing material expanded polystyrene is milky white, with high reflectivity and low light transmittance, which is far from the almost colorless and transparent natural color of polystyrene.

The light-transmitting scattering material of the present invention can be obtained in two ways:

①Recrystallization of transparent material plates to obtain transparent medium sphere groups with different refractive indices in a homogeneous medium, control the size and quantity of crystals, and obtain a balance point between scattering and light transmittance; industrially select raw materials and their temperatures, initiators, and molds Temperature and clamping time to control the scattering effect.

②The air bubbles are filled before the transparent material is solidified, and the formed miniature air bubbles are evenly suspended in the transparent medium. It can be seen that the light beam passing through the diffuser plate should not be refracted or reflected too many times, so as to improve the light transmittance. Bubbles or transparent (spherical) bodies have a linear dimension of submillimeter order to 1 mm, and their density in the transparent medium is that the average value of light scattering (spherical) bodies along the direction of travel (plate thickness direction) is 2 to 6, not exceeding 12 The optimal density is between 2 and 4.

The concrete implementation method of the present invention is as follows:

The colorless and transparent scattering (sphere) body of the present invention is formed by crystallization or foaming; the crystal grain size in the transparent and uniform medium can be controlled by raw material selection, raw material temperature, and mold holding time to form inorganic glass-ceramic or polycrystalline Crystalline polymer material; when colorless and transparent inorganic substances or colorless and transparent polymer materials are melted, gas is added to form bubbles wrapped in a transparent medium and evenly distributed in the medium. The carrier of the present invention can be a hard transparent material, such as glass with uniform bubbles, a foam plastic layer, colorless glass, high light-transmitting polymer materials, such as plexiglass (polymethyl methacrylate, PMMA), Polybutylmethacrylate (PBA), polystyrene (PS), polycarbonate (PC), polyvinylidene fluoride (PVDF), can also be a flexible polymer material film, through the form of a film on a transparent hard Lamps with inorganic or polymer materials or where diffuse light is required. The linear dimension of the foaming volume is submillimeter level to 1 mm, 2 to 6 cells along the thickness direction, generally no more than 10 cells, and the optimal density is between 2 to 4 cells.

Claims (6)

1. Scattering method based on the difference in refractive index in the medium, characterized in that the method uses refraction or total reflection between transparent media to disturb the direction of travel of light to obtain scattered light with high transmittance; The refraction or total reflection between the transparent media is an interface formed by the surface of a colorless and transparent scatterer scattered in a uniform transparent medium, and the two sides of the interface have different refractive indices; the colorless and transparent scatterer has a refractive index n 'is different from the refractive index n of a homogeneous transparent medium, and the value of n'-n can be positive or negative; the scatterer is a sphere or an irregular body. 2. The scattering method according to claim 1, characterized in that: The refractive index n' of the colorless and transparent scatterer is lower than that of the homogeneous material, and the scatterer has a concave lens effect, which causes a large area of total reflection in the scatterer, increases the divergence angle of a single scatterer, and reduces internal retroreflection. Reduce light loss; the scatterer line is sub-millimeter level to 1 mm, and the distribution of scatterers in the uniform transparent medium is along the direction of light travel, that is, the thickness direction of the uniform transparent medium, and its density value is 2 to 6, not more than 12 , to control the size and density of the scatterer, and adjust the scattering effect. 3. The scattering method according to claim 2, characterized in that: the density value of the scatterers in the uniform transparent medium is 2-4. 4. The porous scattering material manufactured by the scattering method according to claim 1 is characterized in that: the porous scattering material is formed by crystallization or foaming, and can limit the difference between the refractive index of a uniform transparent medium and a colorless and transparent scatterer. The difference is between 0.1-0.4, which weakens the reflectivity between two different medium interfaces and improves the light output rate of scattered light. 5. The porous scattering material manufactured by the scattering method according to claim 1, characterized in that: the porous scattering material is formed by crystallization or foaming, and is controlled by raw material selection, raw material temperature, and holding time of the mold in a transparent and uniform medium. The grain size can form inorganic glass-ceramics or polycrystalline polymer materials. 6. The porous scattering material produced by the scattering method according to claim 1, characterized in that: the porous scattering material is formed by crystallization or foaming, and is in a molten state of a colorless and transparent inorganic substance or a colorless and transparent polymer material The gas is added to form bubbles wrapped in a transparent medium and evenly distributed in the medium.

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