CN101126818A - Square aperture self-focusing lens array and its manufacture method - Google Patents

Abstract

The utility model relates to a square aperture self-focusing lens array and the manufacture method of the square aperture self-focusing lens array, which is characterized in that a plurality of square self-focusing lens arranged in the array according to the rule and fixed adhesively with each other by the glue are positioned in a U-shape frame and a safety glass substrate is adhesively connected on the surface of the U-shape frame. The manufacture method of the utility model is characterized in the following steps: the manufacture of the square glass silk, the manufacture of the square aperture self-focusing lens and the manufacture of the square aperture self-focusing lens array. After the aberration correction, the manufactured square self-focusing lens has the advantages of almost ideal distribution of the index of refraction and good imaging performance. According to the theoretical and experience proof that the distribution of the index of refraction of the square self-focusing lens is relevant not only to the radial coordinate r but also to the angle coordinate Theta; as long as the geometric dimension precision of a single square self-focusing lens is high, the filling coefficient of the micro-lens array manufactured can be very high, which is up to 95%.

Description

Square aperture self-focusing lens array and preparation method thereof

Technical field

The present invention relates to micro-optics element and preparation method thereof, be specifically related to square aperture self-focusing lens array and preparation method thereof.

Background technology

Along with the microminiaturization of optical element, discrete component is developed to array element.But mostly the lens cells of the microlens array of making is cylindrical or semisphere at present, and index distribution has radial symmetry or rotation symmetry, is widely used in optical information processing.The typical arrangement mode that the spherical lens cells of cylindrical or semicircle constitutes microlens array has two kinds: a kind of is square arrangement.The greatest problem that this arrangement mode exists is that activity coefficient (being defined as the ratio of effective light-receiving area and the lenticule total area) is little, and theoretical boundary is 78.8%, has the optical information more than 21% to be fallen by the air gap leakage between lens cells.Another kind is that hexagonal is closely arranged.This arrangement mode increases activity coefficient, and theoretical boundary is 90.7%, and the optical information transmission is sewed to some extent and reduced, but still has 9.3% optical information leakage.In a word, these two kinds of arrangement modes, though manufacture craft is simple, because of the space between can not fine elimination lens cells to the sewing of optical information, improve activity coefficient, reduce the optical information leakage problem thereby can not fundamentally solve.In focusing, the shaping of optical information, be of coupled connections, interconnection, imaging and require to realize that high fill-factor just becomes the gordian technique that microlens array must solve under the leak free situation of optical information unit, also be one of key of the novel photonic device of development.

Since the end of the eighties in last century, many scholars are doing some explorations aspect the activity coefficient that improves microlens array.But up to the present, the lens cells of microlens array all is spheroidal usually.The manufacture craft of special-shaped lens unit and array thereof still is in research, exploratory stage, but also has the big difficulty of aberration.Therefore, further investigation improves the method for microlens array activity coefficient, and producing adaptable abnormity (hexagon, rectangle, square etc.) lenticule and special-shaped aperture microlens array is the vital task that current scientific and technological circle face.

Summary of the invention

The purpose of this invention is to provide a kind of square aperture self-focusing lens array and preparation method thereof.The activity coefficient height of this array, optical information is sewed little, and the distortion of transmission optical information is little; A kind of method of making square aperture self-focusing lens array is provided simultaneously.

Theoretical analysis and experiment showed, square thallium glass silk KNO at a certain temperature ₃In the fused salt, through after the ion-exchange of certain hour, because the T1 in the glass ⁺With the K in the dissolved salt ⁺Exchange the T1 that forms in the glass ⁺Common diffusion equation is obeyed in the distribution of ion concentration.Under the boundary condition of square-section and certain starting condition, T1 in the glass ⁺The CONCENTRATION DISTRIBUTION c of ion (r, θ) satisfy following relation:

$C(r,\mathrm{\&theta;})=a_0+a_1{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20061009502600111.png"\; state="\{\{state\}\}">r</figure-callout>}}^{\frac{1}{2}}\cos \frac{\mathrm{\&theta;}}{2}+a_{2}r\cos \mathrm{\&theta;}+r^{\frac{3}{2}}(a_2\cos \frac{3\mathrm{\&theta;}}{2}-a_3)+\mathrm{\&Lambda;}$

Usually, the refractive index of glass and thallium ion concentration have linear relationship.Therefore, after the ion-exchange, the index distribution of square glass stick can be write as:

$n(r,\mathrm{\&theta;})=a_0+a_1{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20061009502600111.png"\; state="\{\{state\}\}">r</figure-callout>}}^{\frac{1}{2}}\cos \frac{\mathrm{\&theta;}}{2}+a_{2}r\cos \mathrm{\&theta;}+r^{\frac{3}{2}}(a_2\cos \frac{3\mathrm{\&theta;}}{2}-a_3)\mathrm{\&Lambda;\&Lambda;\&Lambda;\&Lambda;\&Lambda;\&Lambda;}---\left[1\right]$

Following formula shows, the index distribution n of square self-focusing lens (r, θ) not only relevant with radial coordinate r, but also relevant with azimuthal coordinate θ.Coefficient a in the formula ₀, a ₁, a ₂And a ₃Be four undetermined constants, can be determined by experiment.(see Han Yan tinkling of pieces of jade Master's thesis: the theoretical analysis of square self-focusing lens and array and manufacture craft.Chongqing, Southwestern University, 2006) have the medium of index distribution [1], have focusing, imaging function.But because of symmetry is lower than plain cylindrical form GRIN Lens, aberration is bigger.Therefore, in application, must adopt the aberration correction technology to improve aberration, improve image quality.

Square aperture self-focusing lens array of the present invention; it is characterized in that: in " ㄩ " shape frame (1); be provided with many by the square self-focusing lens that is regularly arranged into array (2); stick with glue between the square self-focusing lens and connect fixingly, be bonded with a block protection glass substrate (3) above " ㄩ " shape frame.

Above-mentioned square aperture self-focusing lens array is characterized in that: the size heterogeneity degree of each square self-focusing lens and optical property heterogeneity degree are all less than 1%, and activity coefficient is greater than 95%.Sewing of optical information is very little.

The method for making of square aperture self-focusing lens array of the present invention comprises three steps;

(1) making of square glass stick

The circular glass silk that will have diameter and be 0.5～3mm is cut into the short silk of glass of 5～15mm with cutting machine, again with the short silk of several glass with propolis abreast on the conglutinate glass substrate, through grinding, polishing, the short silk of glass is side by side ground a plane; Then, heated substrate glass takes off the short silk of glass on a plane, oppositely planar section is bonded on the glass substrate, with second plane of the short silk of same processes glass, reprocesses the 3rd and the 4th plane, just makes the short silk of square cylinder glass;

Because the dimensional accuracy of the short silk of square cylinder glass and the activity coefficient of lens arra have much relations, therefore, the geometric accuracy of square shaped requires very high, and the precision that four length of side errors are less than 1%, four angle will reach 90 °+0.1 °;

(2) making of square self-focusing lens

At first, carry out ion-exchange treatment, make uniform refractive index become refractive index heterogeneous processing the short silk of qualified square glass; Ion-exchange treatment is highly stable in furnace temperature, and temperature fluctuation≤0.5 degree and temperature are carried out in the uniform ion stove of exchanging very much, and dissolved salt adopts KNO ₃, 530 ℃ ± 15 ℃ of exchange temperature, 100～120 hours swap times;

Secondly, the method that adopts us to propose (sees that Liu Desen writes: " medium of varying refractive index theory and engineering practice thereof " by oneself, publishing house of Southwestern Normal University, 2005.11 first published), " cycle data " of the exchange silk that measurement ion-exchange obtains, adopt glass-cutting, grinding technics again, will exchange the square self-focusing lens that silk is processed into four/one-period length; The parameter of the square self-focusing lens of making is the length of side: 1.30mm focuses on constant: 0.376mm ^-1, length: 10.21mm;

The 3rd, refractive Index Distribution Measurement, the square self-focusing lens sample is inlayed in organic glass, through accurate attrition process, make the interference piece that thickness is 0.19mm～0.25mm, adopt the Jamin interference technique (to see that Liu Desen writes: " medium of varying refractive index theory and engineering practice thereof ", publishing house of Southwestern Normal University, 2005.11 first published), draw the interference fringe image of square self-focusing lens. by test striped radius length not at the same level time, thereby and then obtain the value of refractive index on different radii. can obtain the refractive index at different r values place.

Test result shows, although the same refractive index difference of radius on the different directions angle illustrates that the index distribution of square self-focusing lens is all relevant with radius and deflection.In conjunction with experimental data, obtain reflecting four constants in the distribution and expression formula [1], so the mathematic(al) representation of square self-focusing lens index distribution can be write as:

$n(r,\mathrm{\&theta;})=1.617-0.010{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20061009502600111.png"\; state="\{\{state\}\}">r</figure-callout>}}^{\frac{1}{2}}\mathrm{<figure-callout\; id="1"\; label="cos"\; filenames="A20061009502600111.png"\; state="\{\{state\}\}">cos</figure-callout>}\frac{1}{2}\mathrm{\&theta;}-0.031\left(r\cos \mathrm{\&theta;}{+r}^{\frac{3}{2}}\cos \frac{3}{2}\mathrm{\&theta;}\right)+0.021r^{\frac{3}{2}}\mathrm{\&Lambda;\&Lambda;\&Lambda;\&Lambda;\&Lambda;}---\left[2\right]$

Square self-focusing lens also can be made like this.At first, adopt (2) same process in ion exchanging furnace, to carry out ion-exchange, after obtaining variable refractivity and distributing, secondly, adopt the technology identical that cylindrical GRIN Lens is made into square self-focusing lens with the front to cylinder thallium glass silk.

The 4th, aberration correction, there is bigger aberration in the square self-focusing lens that said method is made.In order to improve the aberration characteristic of square self-focusing lens, will improve the index distribution of primary ions exchange back glass fiber.Can adopt for this reason the secondary ion exchange process (see the gloomy patent of invention of Liu De: improve the new method of GRIN Lens aberration characteristic, CN1790062A, 2006.6.21).Be exactly the square glass stick that ion-exchange is good, put into 5-10%NaNO ₃And 90-95%KNO ₃Salt-mixture in. ion-exchange temperature is 525 ℃ ± 5 ℃, and the time of secondary ion exchange is 25～40 minutes.The time of secondary ion exchange is to determine according to the requirement of only revising the index distribution of lens limit portion.Experiment showed, the amount of distortion of the square self-focusing lens after primary ions exchange and the secondary ion exchange is measured, is 11.2% before the correction, is 2.95% after the correction.Correction is the result show, after the secondary ion exchange, the aberration of square self-focusing lens has had tangible improvement.

(3) making of square aperture self-focusing lens array

Because square aperture self-focusing lens array is to be made of a plurality of square self-focusing lenses by arranging technology, in order to ensure the image quality of array, single square self-focusing lens will satisfy following requirement: size dimension heterogeneity and optical property heterogeneity are all less than 1%.Aligning method is: in " ㄩ " of glass that performs in advance or metal shape frame, edgewise wire closely is arranged in a row (as about 5) with optical cement, on single, coats very thin one deck optical cement equably, adopt same quadrat method again, ranked second a layer edgewise wire, after having arranged required layer, sticking more above lastblock glass substrate, just make a microlens array blank, at last, blank is carried out attrition process handle, just can obtain well behaved square self-focusing lens array.

Beneficial technical effects of the present invention is: the square self-focusing lens of making, and through behind the aberration correction, index distribution is near perfect condition, and imaging performance is good.Theoretical not only relevant with radial coordinate r with the index distribution that experiment showed, square self-focusing lens, and relevant with angular coordinate theta.As long as the geometric accuracy height of single square self-focusing lens, the microlens array of producing just has very high activity coefficient, reaches more than 95%.

Description of drawings

Fig. 1 is the structural representation of square aperture self-focusing lens array.

The interferogram of the square self-focusing lens that Fig. 2 makes.

Refractive index distribution curve on the square self-focusing lens different directions that Fig. 3 makes.

Distortion photo before the square self-focusing lens that Fig. 4 makes is proofreaied and correct.

Distortion photo after the square self-focusing lens that Fig. 5 makes is proofreaied and correct.

Embodiment

Embodiment 1:

At first, with diameter 1.86mm to contain the thallium glass silk clean with alcohol wash, be processed into the short silk that length is 10mm with grinding wheel.Get 10 and be arranged in a row, entirely be bonded on the good glass substrate of prior mill with honeybee is cured.In order to obtain square column,, adopt glass grinding technology will grind off the high circular arc of 0.27mm according to theoretical analysis.With the glass substrate heating, take off glass fiber, the one side that glass fiber is flat is bonded on the glass substrate with honeybee is cured, adopts and grinds second plane with sampling technology.Then, adopt same process to grind third and fourth plane again, just obtained square thallium glass silk.It should be noted that to add to require man-hour length of side error foursquare four right angles that the angle must be a standard less than 1%.

Secondly, square thallium glass silk put into homemade ion exchanging furnace carry out, require furnace temperature stable, evenly.Its temperature fluctuation is less than ± 0.5 °, and exchange is 120-130 hour under 530 ± 5 ℃ of temperature, and the exchange dissolved salt is KNO ₃.

Three, because the aberration of square self-focusing lens is bigger, we adopt the secondary ion exchange process to carry out aberration correction in homemade ion exchanging furnace.With the square glass stick after the ion-exchange, put into 5-10%NaNO ₃And 90-95%KNO ₃Salt-mixture in. ion-exchange temperature is 525 ℃ ± 5 ℃, and the time of secondary ion exchange is 25～40 minutes.The secondary ion exchange process can improve the aberration of square self-focusing lens significantly.Experiment showed, the amount of distortion of the square self-focusing lens after primary ions exchange and the secondary ion exchange is measured.Being 11.2% before the correction, is 2.95% after the correction.Referring to Fig. 4, Fig. 5.

Four, the thallium glass silk to exchanging, first sampling and measuring goes out to have related parameter: Cycle Length 16.7mm focuses on constant 0.376mm ^-1, length of side 1.3mm. is processed into square self-focusing lens by definite size with square glass stick then.

Five, square aperture self-focusing lens array is made.Five square self-focusing lenses 2 to making referring to Fig. 1 are arranged in a row in " ㄩ " shape groove 1, fix with optical cement.On first row, ranked second layer again, ranked third layer, the 4th layer and layer 5 again after fixing with optical cement, at last with glass sheet 3 because of above fixing on.Must make closely contact between adjacent lens during arrayed, to improve the activity coefficient of array.

Six, interfere sample making.The GRIN Lens sample is embedded in the organic glass, through Precision Machining, make the interference piece that thickness is 0.19mm～0.25mm, the method of utilizing Jamin to interfere, draw the interference fringe image of square self-focusing lens, referring to Fig. 2. by test inferior striped radius length not at the same level, just can obtain refractive index, referring to Fig. 3 at different r values place.Test result shows, although the same refractive index difference of radius on the different directions angle illustrates that the index distribution of square self-focusing lens is all relevant with radius and deflection.In conjunction with experimental data, derive the mathematic(al) representation of square self-focusing lens index distribution theoretically.That is:

$n(r,\mathrm{\&theta;})=1.617-0.010{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20061009502600111.png"\; state="\{\{state\}\}">r</figure-callout>}}^{\frac{1}{2}}\mathrm{<figure-callout\; id="1"\; label="cos"\; filenames="A20061009502600111.png"\; state="\{\{state\}\}">cos</figure-callout>}\frac{1}{2}\mathrm{\&theta;}-0.031(r\cos \mathrm{\&theta;}+r^{\frac{3}{2}}\cos \frac{3}{2}\mathrm{\&theta;})+0.021r^{\frac{3}{2}}\mathrm{}$

Seven, square aperture self-focusing lens array performance measurement.Utilize the main optical characteristics of our breadboard testing tool square shaped GRIN Lens and square aperture self-focusing lens array to measure.

Embodiment 2:

At first, the circular glass silk is carried out ion-exchange.In homemade ion exchanging furnace, carry out, require furnace temperature stable, even.Its temperature fluctuation is less than ± 0.5 °, and exchange is 120-130 hour under 530 ± 15 ℃ of temperature, and the exchange dissolved salt is KNO ₃.

Secondly, adopt embodiment 1 method to grind to form square exchange silk circle exchange silk, the 3rd, to improve aberration, remake the squarely GRIN Lens, the 4th by the secondary ion exchange process, in " ㄩ " shape groove, the saturating lens arrangement of square self-focusing is become array, fix with glue again, last, adopt attrition process squarely aperture selfoc lens array.

Claims (3)

1. square aperture self-focusing lens array; it is characterized in that: in " ㄩ " shape frame (1); be provided with a plurality of by the square self-focusing lens that is regularly arranged into array (2); stick with glue between the square self-focusing lens and connect fixingly, be bonded with a block protection glass substrate (3) above " ㄩ " shape frame.

2. square aperture self-focusing lens array according to claim 1 is characterized in that: the mutual size heterogeneity degree of square self-focusing lens (2) is less than 1%, and the optical heterogeneity degree is less than 1%.Activity coefficient is greater than 95%.

3., the method for making of square aperture self-focusing lens array as claimed in claim 1 may further comprise the steps:

(1) making of square glass stick

The circular glass silk that will have diameter and be 0.5～3mm is cut into the short silk of glass of 5～15mm with cutting machine, again with the short silk of several glass with propolis abreast on the conglutinate glass substrate, through grinding, polishing, the short silk of glass is side by side ground a plane; Then, heated substrate glass takes off the short silk of glass on a plane, oppositely planar section is bonded on the glass substrate, with second plane of the short silk of same processes glass, reprocesses the 3rd and the 4th plane, just makes the short silk of square cylinder glass; The precision that the geometric accuracy requirement of square shaped glass fiber, four length of side errors are less than 1%, four angle will reach 90 °+0.1 °;

(2) making of square self-focusing lens

At first, carry out ion-exchange treatment, make uniform refractive index become refractive index heterogeneous processing the short silk of qualified square glass; Ion-exchange treatment is highly stable in furnace temperature, and temperature fluctuation≤0.5 degree and temperature are carried out in the uniform ion stove of exchanging very much, and dissolved salt adopts KNO ₃, 530 ℃ ± 15 ℃ of exchange temperature, 100～120 hours swap times;

Secondly, " cycle data " of the exchange silk that measurement ion-exchange obtains adopts glass-cutting, grinding technics again, will exchange the square self-focusing lens that silk is processed into four/one-period length; The parameter of the square self-focusing lens of making is the length of side: 1.30mm focuses on constant: 0.376mm ^-1, length: 10.21mm;

The 3rd, refractive Index Distribution Measurement, the square self-focusing lens sample is inlayed in organic glass, through accurate attrition process, make the interference piece that thickness is 0.19mm～0.25mm, adopt the Jamin interference technique, draw the interference fringe image of square self-focusing lens. by test inferior striped radius length not at the same level, and then obtain the value of refractive index on different radii, thereby can obtain the refractive index at different r values place;

The 4th, aberration correction adopts the secondary ion exchange process, and the square glass stick that ion-exchange is good is put into 5-10%NaNO ₃And 90-95%KNO ₃Salt-mixture in. ion-exchange temperature is 525 ℃ ± 5 ℃, and the time of secondary ion exchange is 25～40 minutes;

(3) making of making square aperture self-focusing lens array

Aligning method is: in " ㄩ " of glass that performs in advance or metal shape frame, with optical cement edgewise wire closely is arranged in a row, on single, coats very thin one deck optical cement equably, adopt same quadrat method again, ranked second a layer edgewise wire, after having arranged required layer, sticking more above lastblock glass substrate, just make a microlens array blank, at last, blank is carried out attrition process handle, just can obtain well behaved square self-focusing lens array.

Images