CN102944934A - Multilayer curve compound eye type imaging system with large visual field of 180 DEG - Google Patents

Abstract

The invention discloses a multilayer curve compound eye type imaging system with a large visual field of 180 DEG. The system comprises a first layer of lens array, a second layer of lens array, a third layer of lens array, a fourth layer of lens array and an image sensor array arranged in sequence; all layers of lens arrays are arranged on the same spherical substrate, a spherical peak is used as a center, a micro lens is placed as a central lens, the optical axis of the micro lens passes through the spherical peak and a spherical center, six micro lenses are arranged outside the micro lens by using hexagonal structures, and the included angles between the optical axes of the six micro lenses and the optical axis of the central lens are all equal to theta; and all the lens arrays and the image sensor array are arranged in the same way. The design concept of a multilayer compound eye structure is adopted, and incident light from different visual fields is received in a way of multi-path CCD (Charge Coupled Detector) combination, so that the lens can obtain an image with higher quality while ensuring the characteristics of compound eye and large visual field; and in addition, the multilayer curve compound eye type imaging system is small and compact in whole structure and convenient to apply.

Description

The large view field imaging of 180 ° of multilayer curved compound eye formulas system

Technical field

The present invention relates to the bionic compound eyes imaging field, specifically large view field imaging system.

Background technology

In recent years, the bionic compound eyes imaging system has caused researchist's extensive concern, and its unique visual field is large, volume is little, to the characteristics such as sensitivity height of moving object, makes its application in fields such as medical treatment, industry, national defence have very large potentiality.Compound eye is a kind of small and exquisite and accurate optical texture that is present in occurring in nature.Be different from our known single aperture imaging system, compound eye is comprised of many hexagonal son eye unit, and these hexagonal son eyes are arranged on the curved surface closely.Every height eye is made of corneal lens, crystalline cone, rhabdom and photosensory cell.Because size is less, every height eye can only be to a certain field of view imaging in space, during all son eye collaborative works, can carry out target detection to large view field space.

Biological compound eye is present in the middle of the insect more, so the compound eye overall dimensions is less, and the size of every height eye does not wait from several microns to tens microns, and the number of the contained son eye of compound eye also extremely several ten thousand does not wait from hundreds of.The visual field of Compound Eye of Insects is very open, and some insect horizontal field of view scope can reach 240 °, and the vertical visual field scope can reach 360 °.Yet the resolution of Compound Eye of Insects is very low, usually only has about 1 meter, even the strongest honeybee of eyesight, its eyesight also only has one of percentage of human eye.If in the faint place of light, their eyesight is also poorer.But Compound Eye of Insects is very high to the sensitivity of moving object, such as honeybee reaction time of emergent object is only needed 0.01 second, and human eye needs 0.05 second.In addition, because the field angle of each height eye is less, therefore to the incident light of all directions in the space, all can be similar to and be considered as paraxial light, the relatively conventional wide angle imaging system of image deformation and aberration has clear superiority.

According to some good characteristics that biological compound eye shows, the structure of copying biological compound eye, people have proposed the multi-form artificial compound eye system of many kinds.The research initial stage, bionic compound eyes mostly adopts the form of planar lens array, comprise individual layer and sandwich construction, the field angle that this compound eye structural can reach is less, and because it is less to consist of the lenslet dimension of compound eye, processing technology is difficult to guarantee lenticular shape parameter, so that the image quality of this compound eye is relatively poor, seldom be applied in the middle of the image device, major applications obtains uniform light at lighting field.Along with the development of Ultraprecision Machining, manufacturing capacity improves constantly, and dimensional uniformity and machining precision are high, and surfaceness is little, controllability is strong, can be used to realize high-precision curved bionics optics compound eye.At present, in order to realize large view field imaging system, related scientific research both domestic and external mechanism has worked out some curved compound eye structures, and main thought is to connect airtight the distribution microlens array in the curved surface substrate, each height eye lenticule all adopts the hexagon aspheric surface, and its focal length is according to the present position and difference.The field angle of the type compound eye increases than planar structure, but in order to adapt to CCD size commonly used, the type compound eye device size is less, so that the logical light quantity of each son eye passage is lower, only can be responsive to high intensity object or close-range target, and picture element is relatively poor, and similar with real Compound Eye of Insects.Analyze its reason, mainly contain two aspects: be because the lens arra that the curved compound eye of present stage also just is comprised of simple lens on the one hand, the design freedom of this structure is less as can be known according to Aberration Theory, be difficult to the various aberrations of correct influences image quality, therefore each lenticular areas imaging is limited, and image quality is not high, in order to obtain larger field angle, just need at the more son eye lenticule of curved surface substrate distribution, so bring very large difficulty to processing again.On the other hand, because the imageing sensor of present stage all is planar structures, this structure is so that each lenticular optical axis has an angle with it, and this angle brings out of focus inevitably for the picture point of visual field, lenticule edge, and this is unacceptable to imaging system.

In sum, owing to being subject to the restriction of the factors such as present stage processing technology, image quality, realize not yet that at present field angle reaches 180 ° of scopes, and compact overall structure, compound eye system that picture element is higher.

Summary of the invention

In order to overcome the deficiencies in the prior art, the purpose of this invention is to provide a kind of monoblock type bionic compound eyes vision system of realizing the large view field imaging of 180 ° of scopes, high picture element, miniaturization, curved surface.

For achieving the above object, technical scheme of the present invention is as follows: the large view field imaging of 180 ° of a kind of multilayer curved compound eye formulas system comprises ground floor lens arra, second layer lens arra, the 3rd layer of lens arra, the 4th layer of lens arra and image sensor array of being arranged in order.In order to reduce the son eye number difficulty that too much processing brings to compound eye, adopt 7 son eye passages to consist of compound eye imaging system and realize 180 ° of imagings.In order to be reduced to the problem of picture blind area and imaging Duplication as far as possible, and make whole compound eye system can realize imaging in 180 ° of scopes, the structure of every one deck toroidal lens array as shown in Figure 3, on a spherical substrate, centered by the sphere summit, place a lenticule as center lens, its optical axis is crossed sphere summit and the centre of sphere, with hexagonal structure six lenticules of arranging, the optical axis included angle of these six lenticular optical axises and center lens is θ outside it.

Fig. 4 is the schematic diagram of curved compound eye structure object space imaging blind area and overlay region, shown in Fig. 4 a, and the true field zero lap, the blind area mainly is divided into two parts.Blind area between middle center eye visual field and the son eye visual field, two edges is called blind area I, and the blind area between son eye visual field, two edges and the 180 ° of visual field border is called blind area II.Namely there is not the son eye passage can be to this regional imaging.This moment, outer circle eye axle and middle center eye axle angle theta and son eye field angle 2 α should satisfy θ=2 α.The existence of blind area will produce considerable influence to Effect on Detecting, for this reason, need to increase son eye passage field angle, or will reduce θ, make θ＜2 α, thereby eliminate this blind area.Shown in Fig. 4 b, when θ and 2 α reached a certain value, blind area I just disappeared, and can obtain the following relational expression about θ and 2 α this moment

$\sin \frac{\mathrm{\α}}{2}=\frac{\sqrt{2-\sqrt{3}\sin \mathrm{\θ}\sin \mathrm{\α}-2\cos \mathrm{\θ}\cos \mathrm{\α}}}{2}---\left(\text{1}\right)$

Wherein θ is outer circle eye axle and middle center eye axle clamp angle, and 2 α are the field angle of every height eye, just can obtain in the situation that the blind area minimum according to following formula, and the angle of half field-of view of son eye passage is

$\mathrm{\α}=\arctan \frac{2(1-\cos \mathrm{\θ})}{\sqrt{3}\sin \mathrm{\θ}}---\left(2\right)$

Because son eye number is less, in order to realize 180 ° of imagings in the field range, certain relation need to be satisfied in θ angle and α angle, concerns and can obtain according to arranging of each height eye passage

$\mathrm{\θ}+\mathrm{\α}=\frac{\mathrm{\π}}{2}---\left(3\right)$

At this moment, the field angle of whole compound eye system can reach the imaging of 180 ° of visual fields.

Because son eye number is less, in order to reach the imaging in 180 ° of scopes of field angle, the θ angle can not be too small.Because the field angle that the too small meeting of θ is born every height eye is very large, the complexity of sub-ocular structure can be increased like this, picture can't be embodied as for a simple lens, for this reason, select the multilayer lens arrangement to increase the design freedom of sub-eye system, the imaging performance of son eye is improved.

The complex imaging system that every height eye passage all is comprised of the multi-disc lens, the aperture that can add therein in case of necessity one or more circles limits the light beam that enters imaging system.Therefore be provided with the aperture array between ground floor lens arra and second layer lens arra, the arrangement mode of the arrangement mode of aperture array and all lens arras and image sensor array is identical.

Lens shape on above-mentioned all lens arras can be plano-concave lens, biconvex lens, positive meniscus shaped lens, biconcave lens, plano-concave lens or negative meniscus lens.The various combination of these several lens can make its field angle can reach between 60 ° ~ 70 °, and image quality is superior.The complex imaging system has lens surface face type (radius-of-curvature) parameter, lens thickness, and the design parameter such as interval and different materials refractive index between lens, the exact position institute Construction designing degree of freedom that adds aperture diaphragm can well be controlled desired focal length, the design objectives such as F number and field angle.

In the present invention, the reduction of image fault (aberration that distortion brings) is mainly by using a rotational symmetric aspheric surface to realize, according to designing requirement and aberration correction principle, described Design of Aspherical Lenses becomes a biconcave lens, and designed non-spherical lens is positioned at the last lens that close on imageing sensor in whole systems, namely be positioned at the front (the 4th layer of lens arra) of imageing sensor, aspheric surface face type equation is

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="cr"\; filenames="HDA00002571344200011.png"\; state="\{\{state\}\}">cr</figure-callout>}}^2}{1+\sqrt{1-(1+k)c^2{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="HDA00002571344200011.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}+{\mathrm{\&alpha;}}_4{r}^4+{\mathrm{\&alpha;}}_6{\mathrm{<figure-callout\; id="6"\; label="r"\; filenames="HDA00002571344200011.png"\; state="\{\{state\}\}">r</figure-callout>}}^6+{\mathrm{\&alpha;}}_8{r}^8+\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;---\left(\text{4}\right)$

Wherein establishing the z axle is optical axis, and r is that any point is remembered r to the distance of optical axis on the aspheric surface ²=x ²+ y ², c is the curvature (being the inverse of radius) at place, aspheric surface summit, α ₄, α ₆, α ₈Deng being coefficient repeatedly.Wherein k is the quadric surface coefficient, and k=0 represents sphere, and k=-1 represents parabola ,-1＜k＜0 expression ellipsoid, k＜-1 expression hyperboloid, the k＞flat ellipsoid of 0 expression.

Except the 4th layer of lens arra, aperture preferable shape on lens on all the other lens arras and the aperture array is as follows: the lens on the ground floor lens arra are plano-concave lens, lens on the second layer lens arra are biconvex lens, lens on the 3rd layer of lens arra are positive meniscus shaped lens, and the aperture on the aperture array is a manhole.

Whole compound eyes need 7 son eye passages as can be known according to the above description, because sub-eye system belongs to the poly-lens system, so need every chip-lens array in will every individual sub-eye system above the substrate, 7 such lenslets are arranged in each substrate, arrangement has just obtained multilayer curved compound eye structure proposed by the invention as shown in Figure 1 as shown in Figure 2.The optical axis of the lens in each passage is coaxial and add the aperture array and make the separately imaging and be not subject to the impact of other passages of every height eye passage.

Beneficial effect: the present invention in view of individual layer compound eye device in the limitation aspect the aberration correction, adopt multilayer compound eye structural design philosophy, mode by the combination of multichannel ccd detector, reception is from the incident light of different visual fields, thereby make these lens when guaranteeing the large field-of-view characteristics of compound eye, can obtain the imaging of higher picture element, one-piece construction is small and exquisite, compact, is convenient to use.When realizing 180 ° of field angle of whole compound eye systems, can obtain preferably image quality, satisfy the application of catching picture rich in detail on a large scale.

Description of drawings

The overall schematic of Fig. 1 multilayer compound eye structural;

Fig. 2 be single son eye passage along the longitudinal sectional drawing of optical axis direction, and the optical path-tracing figure under the different field angle; Shown index path is that half field-of-view α/2 are with interior viewing angle;

Fig. 3 is the front elevation of ground floor toroidal lens array;

Fig. 4 a is the schematic diagram that curved compound eye structure object space areas imaging only has the blind area;

Fig. 4 b is the schematic diagram that curved compound eye structure object space areas imaging only has the overlay region.

Embodiment

Below in conjunction with the drawings and specific embodiments, further illustrate the present invention, the present embodiment is implemented under take technical solution of the present invention as prerequisite, should understand these embodiment and only be used for explanation the present invention and be not used in and limit the scope of the invention.

Fig. 1 is the described multilayer curved compound eye of the present embodiment lens, comprises the ground floor lens arra 1 that is arranged in order, aperture array 2, second layer lens arra 3, the 3rd layer of lens arra 4, the 4th layer of lens arra 5 and image sensor array 6; Every one deck lens arra is on a spherical substrate, centered by the sphere summit, place a lenticule as center lens, its optical axis is crossed sphere summit and the centre of sphere, with hexagonal structure six lenticules of arranging, the optical axis included angle of these six lenticular optical axises and center lens is θ outside it; The arrangement mode of above-mentioned all lens arras and aperture array 2 and image sensor array 6 is identical.

As shown in the figure, 1-1,3-1,4-1,5-1 are respectively a lenticule on ground floor lens arra 1, second layer lens arra 3, the 3rd layer of lens arra 4 and the 4th layer of lens arra 5, corresponding 2-1 is an aperture on the aperture array, and 6-1 is a slice imageing sensor of imageing sensor layer.The first lenticule 1-1, the second lenticule 3-1, the 3rd lenticule 4-1, the 4th lenticule 5-1 and aperture 2-1, imageing sensor 6-1 have formed a son eye passage of compound eye system.Similarly, other lenticules on the curved compound eye lens are other 6 son eye passages of consisting of of corresponding aperture and imageing sensor with it, all the compound eye system is comprised of 7 son eye passages, according to the described arrangement form of summary of the invention and about the statement of blind area and overlapping region, can obtain θ=57.6 ° according to formula (2) and formula (3), in the time of 2 α=64.8 °, the imaging blind area is minimum, and the field angle of whole system reaches 180 °.

Fig. 2 be among the present invention single son eye passage along the longitudinal sectional drawing of optical axis direction and the optical path-tracing figure under the different field angle.Every height eye passage all is comprised of the aperture of 4 lens and a circle, and aperture 2-1 is between the first lenticule 1-1 and the second lenticule 3-1.The field angle of whole sub-eye systems can reach 64.8 °, and maximum image height y '=2.4mm, system's focal length are 3.42mm, the overall length 22.88mm of system.Among the embodiment, the first lenticule 1-1 is a plano-concave lens, and namely the first surface of lens is a plane, and second is a concave surface, and its surperficial radius-of-curvature is respectively by R ₁₁And R ₁₂Expression.The second lenticule 3-1 is a biconvex lens, and namely two of lens surfaces are convex surface entirely, and its surperficial radius-of-curvature is respectively by R ₃₁And R ₃₂Expression.The 3rd lenticule 4-1 is a positive meniscus shaped lens, and the first surface of lens is convex surface, and second is concave surface, and its surperficial radius-of-curvature difference is R again ₄₁And R ₄₂Expression.The 4th lenticule 5-1 is a biconcave lens, and two surfaces of lens are concave surface entirely, and the radius-of-curvature on surface is by R ₅₁And R ₅₂Expression.The second lens 3-1 has the first surface radius of curvature R of 5.22mm ₃₁And-the second surface radius of curvature R of 17.69mm ₃₂, the R here ₃₂For negative value does not have practical significance, just according to the optical mask rule, for just, the left side is for bearing on the right side on curved surface summit in the curved surface center of circle.Aperture is that a diameter is 0.6mm, and thickness is the manhole of 0.7mm.Each structural parameters of other of lens are as shown in table 1, comprise the thickness of lens, diameter, material, the clearance between refractive index and the lens.

For the impact of removal of images distortion on compound eye system imaging quality, with second face R of the 4th lens 5-1 ₅₂Be set to rotational symmetric aspheric surface.Its asphericity coefficient and quadric surface coefficient are as shown in table 2.

Table 1

Table 2

。

Claims (5)

1. the large view field imaging of 180 ° of multilayer curved compound eye formulas system is characterized in that: comprise the ground floor lens arra (1), second layer lens arra (3), the 3rd layer of lens arra (4), the 4th layer of lens arra (5) and the image sensor array (6) that are arranged in order; Every one deck lens arra is on a spherical substrate, centered by the sphere summit, place a lenticule as center lens, its optical axis is crossed sphere summit and the centre of sphere, with hexagonal structure six lenticules of arranging, the optical axis included angle of these six lenticular optical axises and center lens is θ outside it; The arrangement mode of above-mentioned all lens arras and image sensor array (6) is identical.

2. the large view field imaging of 180 ° of described multilayer curved compound eye formulas system according to claim 1, it is characterized in that: be provided with aperture array (2) between ground floor lens arra (1) and second layer lens arra (3), the arrangement mode of the arrangement mode of aperture array (2) and all lens arras and image sensor array (6) is identical.

3. the large view field imaging of 180 ° of described multilayer curved compound eye formulas system according to claim 2, it is characterized in that: the lens shape on described ground floor lens arra (1), second layer lens arra (3), the 3rd layer of lens arra (4) and the 4th layer of lens arra (5) is plano-concave lens, biconvex lens, positive meniscus shaped lens, biconcave lens, plano-concave lens or negative meniscus lens.

4. the large view field imaging of 180 ° of described multilayer curved compound eye formulas system according to claim 1, it is characterized in that: the lens on described the 4th layer of lens arra (5) are biconcave lens, and its second face is rotational symmetric aspheric surface, and aspheric surface face type equation is

$z=\frac{{\mathrm{cr}}^2}{1+\sqrt{1-(1+k)c^2{r}^2}}+{\mathrm{\&alpha;}}_4{r}^4+{\mathrm{\&alpha;}}_6{r}^6+{\mathrm{\&alpha;}}_8{r}^8+\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;$

Wherein establishing the z axle is optical axis, and r is that any point is remembered r to the distance of optical axis on the aspheric surface ²=x ²+ y ², c is the curvature (being the inverse of radius) at place, aspheric surface summit, α ₄, α ₆, α ₈Deng being coefficient repeatedly.Wherein k is the quadric surface coefficient, and k=0 represents sphere, and k=-1 represents parabola ,-1＜k＜0 expression ellipsoid, k＜-1 expression hyperboloid, the k＞flat ellipsoid of 0 expression.

5. the large view field imaging of 180 ° of described multilayer curved compound eye formulas system according to claim 2, it is characterized in that: the lens on the described ground floor lens arra (1) are that the lens on plano-concave lens, the second layer lens arra (3) are that lens on biconvex lens, the 3rd layer of lens arra (4) are positive meniscus shaped lens, and the aperture on the aperture array (2) is a manhole.

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