CN114415272A - Birefringent crystal lens and imaging device - Google Patents

Birefringent crystal lens and imaging device Download PDF

Info

Publication number
CN114415272A
CN114415272A CN202210135234.1A CN202210135234A CN114415272A CN 114415272 A CN114415272 A CN 114415272A CN 202210135234 A CN202210135234 A CN 202210135234A CN 114415272 A CN114415272 A CN 114415272A
Authority
CN
China
Prior art keywords
lens
sub
birefringent
crystal
splicing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202210135234.1A
Other languages
Chinese (zh)
Inventor
刘志强
王滨
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chengdu Yeta Technology Co ltd
Original Assignee
Chengdu Yeta Technology Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chengdu Yeta Technology Co ltd filed Critical Chengdu Yeta Technology Co ltd
Priority to CN202210135234.1A priority Critical patent/CN114415272A/en
Publication of CN114415272A publication Critical patent/CN114415272A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/0006—Arrays
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/0006—Arrays
    • G02B3/0037—Arrays characterized by the distribution or form of lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/02—Simple or compound lenses with non-spherical faces
    • G02B3/08—Simple or compound lenses with non-spherical faces with discontinuous faces, e.g. Fresnel lens
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3083—Birefringent or phase retarding elements

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lenses (AREA)

Abstract

The invention belongs to the technical field of birefringent lenses, and particularly relates to a birefringent crystal lens and an imaging device. The present invention provides a birefringent crystal lens, comprising: the first sub-lens is provided with a first splicing surface, and the normal directions of at least two parts of the first splicing surface are different; a second sub-lens having a second splicing surface, at least two portions of the second splicing surface having different normal directions; the first sub-lens is a crystal with ordinary light refractive index no1Extraordinary refractive index of ne1(ii) a The second sub-lens is amorphous and has a refractive index no2And n iso1＝no2(ii) a Or, the second sub-lens is a crystal with ordinary light refractive index no3Extraordinary refractive index of ne3The optical axis direction of the first sub-lens and the optical axis direction of the second sub-lens are perpendicular to each other, wherein no1＝no3And n iso1≠ne3Or no3≠ne1. The birefringent crystal lens has small volume and good imaging quality.

Description

Birefringent crystal lens and imaging device
Technical Field
The invention belongs to the technical field of birefringent lenses, and particularly relates to a birefringent crystal lens and an imaging device.
Background
With the development of portable devices, mechanical optical zoom systems are difficult to implement on portable devices, such as: cell phone cameras, webcams, micro projectors and endoscopes, and the like. Current optical zoom functions typically do so at the expense of digital scaling of the resolution of the image. Conventional optical zoom systems include many solid state lenses and utilize voice coil motors to control the movement of the lenses. The system comprises two lens groups, namely a focusing lens group and a zooming lens group. The focusing lens group is used for clear imaging, and the zooming lens group is used for changing the size of object imaging. The two lens groups are respectively controlled to achieve respective functions. However, for use on a portable device, the lens is fixed at the same position when zooming the image, and the electrically-controlled adjustable-focus lens replaces the traditional lens, so that the design with light weight and small volume is achieved. Common adjustable-focus lenses are liquid crystal lenses, liquid lenses, SLMs and the like respectively, wherein the liquid crystal lenses are light in weight and small in size, but the imaging quality and the response speed are low, and the liquid lenses and the SLMs are large in weight and not easy to carry.
Disclosure of Invention
In view of this, the present invention provides a birefringent crystal lens and an imaging device, so as to solve the technical problems of large quality and low imaging quality of an optical zoom system in the prior art.
The technical scheme adopted by the invention is as follows:
in a first aspect, the present invention provides a birefringent crystal lens comprising:
the first sub-lens is provided with a first splicing surface, and the normal directions of at least two parts of the first splicing surface are different;
a second sub-lens having a second splicing surface, at least two portions of the second splicing surface having different normal directions;
the first splicing surface of the first sub-lens and the second splicing surface of the second sub-lens are complementary in shape and spliced together; the first sub-lens is a crystal with ordinary light refractive index no1Extraordinary refractive index of ne1；
The second sub-lens is amorphousHaving a refractive index no2And n iso1＝no2；
Or, the second sub-lens is a crystal with ordinary light refractive index no3Extraordinary refractive index of ne3The optical axis direction of the first sub-lens and the optical axis direction of the second sub-lens are perpendicular to each other, wherein no1＝no3And n iso1≠ne3Or no3≠ne1。
Preferably, the first sub-lens is a crystal, the first sub-lens includes a first plane, the first splicing surface is an inwardly concave arc surface, the second sub-lens is a crystal, the second sub-lens includes a second plane, two ends of the second plane are connected to two ends of the second splicing surface, the second splicing surface is an outwardly convex arc surface, and the first plane and the second plane are parallel to each other.
Preferably, the first sub-lens is a crystal, the second sub-lens includes a fifth plane and a sixth plane that are parallel to each other, and the first splicing surface is enclosed in the second splicing surface.
Preferably, the first sub-lens is a crystal, the first sub-lens includes a third plane, the first splicing surface is an inwardly concave arc surface, the second sub-lens is an amorphous body, the second sub-lens includes a fourth plane, two ends of the fourth plane are connected to two ends of the second splicing surface, the second splicing surface is an outwardly convex arc surface, and the third plane and the fourth plane are parallel to each other.
Preferably, the first splicing surface and the second splicing surface have fresnel lens optical structures.
Preferably, the first splicing surface comprises a plurality of first splicing surface units arranged in an array, each first splicing surface unit comprises at least two parts, the normal directions of the parts are different, the second splicing surfaces comprise second splicing surface units corresponding to the first splicing surface units one by one, and the second splicing surface units are spliced together with the corresponding first splicing surface units.
In a second aspect, the present invention provides an imaging device comprising the birefringent crystal lens of the first aspect.
Preferably, the liquid crystal display further comprises a polarizing element and an optical rotation device, wherein the polarizing element, the optical rotation device and the birefringent crystal lens are sequentially arranged along the incident direction of the light ray.
Preferably, the imaging apparatus further includes a first lens between the optical rotation device and the birefringent crystal lens in a light incident direction, a second lens between the birefringent lens and the image sensor, and an image sensor.
In a third aspect, the present invention provides an imaging apparatus, including a polarizing element, an optical rotation device, a first lens, a first birefringent lens, a second birefringent lens, and an image sensor, which are sequentially arranged along an incident direction of a light ray, wherein the first birefringent lens is a negative lens, the second birefringent lens is a positive lens, and the first birefringent lens and the second birefringent lens are the birefringent crystal lens according to the first aspect.
Has the advantages that: the birefringent crystal lens is formed by splicing two sub-lenses, the second sub-lens of the two sub-lenses is a crystal lens, the refractive index of the first sub-lens is the same as the ordinary refractive index of the second sub-lens when the first sub-lens is an amorphous lens, and the ordinary refractive index of the first sub-lens is the same as that of the second sub-lens when the first sub-lens is a crystal lens. By adopting the structure, the birefringent crystal lens has a switching function, can refract polarized light in a certain specific polarization direction, and enables the polarized light in the certain specific polarization direction to be incident in parallel and then to be emitted out in parallel, so that an image is selectively zoomed in an imaging system. The second sub-lens is made of crystal materials, so that the size is small, the response is fast, and the imaging quality is high.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below, and for those skilled in the art, without any creative effort, other drawings may be obtained according to the drawings, and these drawings are all within the protection scope of the present invention.
FIG. 1 is a schematic diagram of a first birefringent crystal lens of the present invention;
FIG. 2 is a schematic diagram of a second birefringent crystal lens according to the present invention;
FIG. 3 is a schematic diagram of a third birefringent crystal lens according to the present invention;
FIG. 4 is a schematic diagram of a fourth birefringent crystal lens according to the present invention;
FIG. 5 is a schematic diagram of a fifth birefringent crystal lens according to the present invention;
FIG. 6 is a schematic structural view of a sixth birefringent crystal lens according to the present invention;
FIG. 7 is a schematic diagram of a birefringent crystal lens according to the present invention employing a Fresnel lens optical structure;
FIG. 8 is a schematic diagram of a birefringent crystal lens in the form of an array according to the present invention;
fig. 9 is a schematic view of a structure when an optical rotatory device does not operate in an image forming apparatus according to embodiment 8 of the present invention;
fig. 10 is a schematic view of the structure of an optical rotatory device in an image forming apparatus according to embodiment 8 of the present invention in operation;
fig. 11 is a schematic structural view of an image forming apparatus in embodiment 9 of the invention;
fig. 12 is an image scaling schematic diagram of an imaging apparatus in embodiment 9 of the present invention;
fig. 13 is an image scaling schematic diagram of an imaging apparatus in embodiment 10 of the present invention;
fig. 14 is a schematic structural view of an image forming apparatus in embodiment 11 of the invention;
fig. 15 is an image scaling schematic diagram of an imaging apparatus in embodiment 11 of the present invention.
Description of reference numerals:
the image sensor comprises a first sub-lens 10, a first splicing surface 11, a second sub-lens 20, a second splicing surface 21, a first plane 31, a second plane 32, a third plane 33, a fourth plane 34, a fifth plane 35, a sixth plane 36, a seventh plane 37, an eighth plane 38, a first splicing surface unit 111, a second splicing surface unit 211, a polarizing element 40, an optical rotation device 50, a first lens 60, a second lens 70, an image sensor 80, a birefringent crystal lens 90, an axicon lens 100, a first birefringent lens 110, a second birefringent lens 120, a first intermediate image 702, a partial image 703 and a second intermediate image 704.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element. In case of conflict, the embodiments of the present invention and the various features of the embodiments may be combined with each other within the scope of the present invention.
Example 1
As shown in fig. 1 and 4, the present embodiment provides a birefringent crystal lens including a first sub-lens and a second sub-lens:
the first sub-lens is provided with a first splicing surface, and the normal directions of at least two parts of the first splicing surface are different;
the first splicing surface can be an arc surface, a curved surface, a plane or an inclined plane with different angles, or a combination of surfaces with different shapes, and requirements can be met as long as the first splicing surface has two parts with different normal directions. Wherein the normal direction of a portion of the first splicing face is the direction perpendicular to the tangent plane of the portion.
The second sub-lens is provided with a second splicing surface, and the normal directions of at least two parts of the second splicing surface are different;
the second splicing surface can be an arc surface, a curved surface, a plane or an inclined plane with different angles, or a combination of surfaces with different shapes, and requirements can be met as long as the first splicing surface has two parts with different normal directions. Wherein the normal direction of a portion of the second splicing face is the direction perpendicular to the tangent plane of the portion.
The first splicing surface of the first sub-lens and the second splicing surface of the second sub-lens are complementary in shape and spliced together; the first sub-lens is a crystal with ordinary light refractive index no1；
The birefringent crystal lens of the embodiment is formed by splicing a first sub-lens and a second sub-lens, and the surfaces spliced by the first sub-lens and the second sub-lens, namely the first splicing surface and the second splicing surface, have complementary shapes, so that the first sub-lens and the second sub-lens can be spliced together more closely. In this embodiment, the first lens is made of a crystalline material.
Wherein the crystal is a homogeneous, transparent, but anisotropic medium. One incident light wave is decomposed into two light waves with mutually perpendicular polarization directions and different refraction angles in the crystal. One light obeys the ordinary law of refraction, called ordinary light (o light); the other light does not obey the ordinary law of refraction and is called extraordinary or extraordinary (e-rays).
In this embodiment, the second sub-lens may be made of an amorphous material or a crystalline material, and when the second sub-lens is made of an amorphous material, the refractive index of the second lens is no2And n iso1＝no2；
In the present embodiment, when the polarization direction of the incident light is perpendicular to the optical axis direction of the first sub-lens, the incident light is ordinary light (o light). The refractive index of the first sub-lens for the polarized light is the refractive index n of the ordinary lighto1Since the second sub-lens is made of amorphous material, the refractive index thereof is n regardless of the polarization direction of the polarized lighto2Due to no1＝no2Therefore, when the polarization direction of the incident light is perpendicular to the optical axis direction of the first sub-lens, the light passing through the birefringent crystal lens is not refracted.
When the polarization direction of the incident light is parallel to the optical axis direction of the first sub-lens, the incident light is extraordinary light (e-light). The refractive index of the first sub-lens for the polarized light is the refractive index n of the ordinary lighte1Since the second sub-lens is made of amorphous material, the refractive index thereof is n regardless of the polarization direction of the polarized lighto2Due to ne≠no1＝no2Therefore, when the polarization direction of the incident light is parallel to the optical axis direction of the first sub-lens, the light passing through the birefringent crystal lens will be refracted.
When the second sub-lens is a crystal, the ordinary light refractive index is no3An optical axis direction of the first sub-lens and an optical axis direction of the second sub-lens are perpendicular to each other, and no1＝no3。
In the present embodiment, when the polarization direction of the incident light is perpendicular to the optical axis direction of the first sub-lens and perpendicular to the optical axis direction of the second sub-lens, the incident light is ordinary light (o light) for both the first sub-lens and the second sub-lens. Refractive index of the first sub-lens for the polarized lightRefractive index n for ordinary rayso1The refractive indexes of the second sub-lenses are all no3Due to no1＝no3Therefore, when the polarization direction of the incident light is perpendicular to the optical axis direction of the first sub-lens, the light passing through the birefringent crystal lens is not refracted.
When the polarization direction of the incident light is perpendicular to one optical axis direction of the first sub-lens and the second sub-lens and parallel to the other optical axis direction, the light passing through the birefringent crystal lens is refracted. The incident light is ordinary light (o light) for the sub-lens whose optical axis direction is perpendicular to its polarization direction, and is extraordinary light (e light) for the sub-lens whose optical axis direction is parallel to its polarization direction. Since the extraordinary refraction of one of the two sub-lenses is different from the ordinary refraction of the other sub-lens, the incident light rays are refracted when passing through the birefringent crystal lens.
From the above analysis, it is seen that, with the birefringent crystal lens in this embodiment, by changing the relationship between the vibration direction of the polarized light and the direction of the optical axis of the sub-lens made of the crystal material, it is possible to switch between two modes, i.e., refraction and non-refraction of the incident light. When the birefringent crystal lens is in a mode in which incident light can be refracted, an image modulated thereby can be scaled, and when the birefringent crystal lens is in a mode in which incident light is not refracted, the size of the image modulated thereby can be kept constant.
In this embodiment, the first sub-lens and the second sub-lens are spliced to form a lens with the light incident surface and the light emitting surface parallel to each other. Thus, when the birefringent lens is in a mode that does not refract incident light, the passage of light through the birefringent crystal lens is equivalent to the passage through a flat glass plate, which allows the production of an original image in an imaging system without scaling.
In this embodiment, the cross section of the birefringent crystal lens formed by splicing the first sub-lens and the second sub-lens is rectangular. The birefringent crystal lens adopting the structure is small in size and convenient to be matched with other components.
Example 2
In this embodiment, a further improvement is made on the basis of embodiment 1, in this embodiment, the first sub-lens is a crystal, the first sub-lens includes a first plane, the first splicing surface is an inwardly concave arc surface, the second sub-lens is a crystal, the second sub-lens includes a second plane, two ends of the second plane are connected to two ends of the second splicing surface, the second splicing surface is an outwardly convex arc surface, and the first plane and the second plane are parallel to each other.
The first splicing surface and the second splicing surface can be arc surfaces, elliptic arc surfaces or arc surfaces with other shapes. As a preferred embodiment, the first splicing surface and the second splicing surface are semi-circular arc surfaces. As another embodiment, the first splicing surface and the second splicing surface are semi-elliptical arc surfaces. As one of the preferred embodiments, the first sub-lens and the second sub-lens may be a positive uniaxial crystal or a negative uniaxial crystal.
As shown in fig. 1, the first sub-lens is a positive uniaxial crystal lens made of a crystal material, the optical axis direction of the first sub-lens is a vertical direction in the figure, the second sub-lens is a positive uniaxial crystal lens made of a crystal material, and the optical axis direction of the second sub-lens is a horizontal direction in the figure.
When the vibration direction is vertical to the optical axis direction of the second sub-lens and a beam of light parallel to the optical axis direction of the first sub-lens enters the first sub-lens after being normally incident to the second sub-lens and finally is refracted when being emitted from the first sub-lens, the birefringent crystal lens is a negative lens. The case when the first sub-lens and the second sub-lens employ negative uniaxial crystals is opposite to that of positive uniaxial crystals.
As shown in fig. 1, the first sub-lens is a positive uniaxial crystal lens made of a crystal material, the optical axis direction of the first sub-lens is the horizontal direction in the figure, the second sub-lens is a positive uniaxial crystal lens made of a crystal material, and the optical axis direction of the second sub-lens is the vertical direction in the figure.
When the vibration direction is parallel to the optical axis direction of the second sub-lens, and a beam of light perpendicular to the optical axis direction of the first sub-lens enters the second sub-lens, enters the first sub-lens again and finally is refracted when being emitted from the first sub-lens, the birefringent crystal lens is a negative lens. The case when the first sub-lens and the second sub-lens employ negative uniaxial crystals is opposite to that of positive uniaxial crystals.
It is to be understood that the directions of the first sub-lens and the second sub-lens are not limited to the directions in the foregoing drawings, as long as the optical axis directions of the first sub-lens and the second sub-lens are perpendicular to each other.
Example 3
In this embodiment, a further improvement is made on the basis of embodiment 1, in the birefringent crystal lens of this embodiment, the first sub-lens is a crystal, the second sub-lens includes a fifth plane and a sixth plane that are parallel to each other, and the first splicing surface is enclosed in the second splicing surface. Wherein the first sub-lens and the second sub-lens may be a positive uniaxial crystal or a negative uniaxial crystal.
As shown in fig. 3, the first sub-lens is a positive uniaxial crystal lens made of a crystal material, the optical axis direction of the first sub-lens is a vertical direction in the figure, the second sub-lens is a positive uniaxial crystal lens made of a crystal material, and the optical axis direction of the second sub-lens is a horizontal direction in the figure.
When the vibration direction is vertical to the optical axis direction of the second sub-lens, and a beam of light parallel to the optical axis direction of the first sub-lens enters the second sub-lens after being normally incident on the second sub-lens, then enters the second sub-lens from the first sub-lens, and finally is refracted twice when being emitted from the second sub-lens, and the birefringent crystal lens is a positive lens. The case when the first sub-lens and the second sub-lens employ negative uniaxial crystals is opposite to that of positive uniaxial crystals.
As shown in fig. 4, the first sub-lens is a positive uniaxial crystal lens made of a crystal material, the optical axis direction of the first sub-lens is the horizontal direction in the figure, the second sub-lens is a positive uniaxial crystal lens made of a crystal material, and the optical axis direction of the second sub-lens is the vertical direction in the figure.
When the vibration direction is parallel to the optical axis direction of the second sub-lens, and a beam of light perpendicular to the optical axis direction of the first sub-lens enters the second sub-lens, enters the first sub-lens, enters the second sub-lens from the first sub-lens, and finally is refracted twice when being emitted from the second sub-lens, and the birefringent crystal lens is a negative lens. The case when the first sub-lens and the second sub-lens employ negative uniaxial crystals is opposite to that of positive uniaxial crystals.
The birefringent crystal lens of the structure can obtain a larger refraction angle because the light rays are refracted twice in the birefringent crystal lens.
It is to be understood that the directions of the first sub-lens and the second sub-lens are not limited to the directions in the foregoing drawings, as long as the optical axis directions of the first sub-lens and the second sub-lens are perpendicular to each other.
Example 4
In this embodiment, the first sub-lens is a crystal, the first sub-lens includes a third plane, the first splicing surface is an inwardly concave arc surface, the second sub-lens is an amorphous body, the second sub-lens includes a fourth plane, two ends of the fourth plane are connected to two ends of the second splicing surface, the second splicing surface is an outwardly convex arc surface, and the third plane and the fourth plane are parallel to each other.
The first splicing surface and the second splicing surface can be arc surfaces, elliptic arc surfaces or arc surfaces with other shapes. As a preferred embodiment, the first splicing surface and the second splicing surface are semi-circular arc surfaces. As another embodiment, the first splicing surface and the second splicing surface are semi-elliptical arc surfaces. As one of the preferred embodiments, the first sub-lens may be a positive uniaxial crystal or a negative uniaxial crystal.
As shown in fig. 5, the first sub-lens is a positive uniaxial crystalline lens made of a crystalline material, the optical axis direction of the first sub-lens is the vertical direction in the figure, and the second sub-lens is made of an amorphous material and has an isotropic refractive index.
When a beam of light with the vibration direction parallel to the optical axis direction of the first sub-lens enters the second sub-lens and then enters the first sub-lens, and finally is emitted from the first sub-lens, refraction occurs, and the birefringent crystal lens is a negative lens. The case when the first sub-lens employs a negative uniaxial crystal is opposite to that of a positive uniaxial crystal.
Example 5
In this embodiment, the first sub-lens is a crystal, the first sub-lens includes a seventh plane, the first splicing surface is an inward-outward convex arc surface, two ends of the seventh plane are connected to two ends of the first splicing surface, the second sub-lens is an amorphous body, the second sub-lens includes an eighth plane, the second splicing surface is an inward concave arc surface, and the seventh plane and the eighth plane are parallel to each other.
The first splicing surface and the second splicing surface can be arc surfaces, elliptic arc surfaces or arc surfaces with other shapes. As a preferred embodiment, the first splicing surface and the second splicing surface are semi-circular arc surfaces. As another embodiment, the first splicing surface and the second splicing surface are semi-elliptical arc surfaces. As one of the preferred embodiments, the first sub-lens may be a positive uniaxial crystal or a negative uniaxial crystal.
As shown in fig. 6, the first sub-lens is a positive uniaxial crystalline lens made of a crystalline material, the optical axis direction of the first sub-lens is a vertical direction in the drawing, and the second sub-lens is made of an amorphous material and has an isotropic refractive index.
When a beam of light with the vibration direction parallel to the optical axis direction of the first sub-lens enters the second sub-lens after being normally incident to the first sub-lens and finally exits from the second sub-lens, refraction occurs, and the birefringent crystal lens is a positive lens. The case when the first sub-lens employs a negative uniaxial crystal is opposite to that of a positive uniaxial crystal.
Example 6
In this embodiment, a further improvement is made on the basis of embodiment 1, and in the birefringent crystal lens of this embodiment, the first splicing surface and the second splicing surface of the first splicing surface and the second splicing surface have a fresnel lens optical structure.
The Fresnel lens (Fresnel lens) is also called screw lens, one surface of the transparent lens is a smooth surface, and the other surface is recorded with an optical annular zone from small to large, and the texture of the Fresnel lens is designed according to the requirements of light interference and interference, relative sensitivity and receiving angle. The Fresnel lens converts spherical and aspherical lenses into light and thin planar lenses to achieve the same optical effect. The surface of the Fresnel lens is the surface with the same shape as the surface of the Fresnel lens with the optical ring zone. The Fresnel lens optical structure is the same structure with the Fresnel lens surface structure with the same optical effect. In this embodiment, the surfaces of the first splicing surface and the second splicing surface are set as the fresnel lens optical structure, so that the birefringent lens with a large aperture, a small focal length and a light weight can be obtained.
As shown in fig. 7, the first sub-lens and the second sub-lens both employ positive uniaxial crystal lenses. When a beam of light is incident normally and the vibration direction of the light is vertical to the optical axes of the first sub-lens and the second sub-lens, the focal length of the lens is infinite, when the vibration direction of the light is parallel to the first sub-lens and vertical to the second sub-lens, the lens is a positive lens, and when the vibration direction of the light is vertical to the first sub-lens and parallel to the second sub-lens, the lens is a negative lens. Negative uniaxial crystals are the opposite of positive uniaxial crystals.
Example 7
As shown in fig. 8, this embodiment is a further improvement on the basis of embodiment 1, and this embodiment provides a birefringent crystal lens, where the first splicing surface includes a plurality of first splicing surface units arranged in an array, the second splicing surface includes second splicing surface units corresponding to the first splicing surface units one to one, and the second splicing surface units are spliced together with the corresponding first splicing surface units. The birefringent crystal lens with the structure is equivalent to a birefringent crystal lens obtained by arraying the birefringent crystal lenses of any one of the embodiments 1 to 5 in an array form, wherein each lens unit formed by splicing the first splicing surface unit and the second splicing surface unit is equivalent to the birefringent crystal lens of any one of the embodiments 1 to 5.
Example 8
This embodiment provides an imaging device comprising the birefringent crystal lens of any one of the preceding embodiments.
In this embodiment, the imaging apparatus further includes a polarizing element and an optical rotation device, and the polarizing element, the optical rotation device, and the birefringent crystal lens are arranged in this order along the incident direction of the light.
When both the first sub-lens and the second sub-lens adopt positive uniaxial crystals, as shown in fig. 9, the parallel light becomes linearly polarized light through the polarizing element, when the optical rotation device does not work, the polarization direction of the linearly polarized light is perpendicular to the optical axes of the first sub-lens and the second sub-lens of the birefringent lens, and the light is not deflected when the birefringent lens propagates through the birefringent lens, and the focal length of the birefringent lens is infinite at this time, as shown in fig. 10. When the optical rotation device works, the polarization direction of linearly polarized light passing through the polarization element is rotated by 90 degrees, the polarization direction of the linearly polarized light is parallel to the optical axis of one sub-lens of the birefringent lens and is perpendicular to the optical axis of the other sub-lens, and the birefringent lens is a positive lens.
Example 9
As shown in fig. 11, this embodiment is further improved on the basis of embodiment 8, in this embodiment, the imaging apparatus further includes a first lens, a second lens and an image sensor, the first lens is located between the optical rotation device and the birefringent crystal lens along the incident direction of the light, and the second lens is located between the birefringent lens and the image sensor.
The present embodiment provides an imaging apparatus having an area zoom function. In this embodiment, when the optical rotation device is not in operation, the focal length of the birefringent lens is infinite, and the light beam emitted from the object is imaged on the image sensor through the first lens and the second lens. When the optical rotation device shown in fig. 12 is operated, the light beam emitted from the object is formed into an intermediate image by the first lens, the birefringent crystal lens is positioned behind the intermediate image and partially modulates the intermediate image, the unmodulated part and the modulated part reach the final image surface by the relay system, and the first lens is moved in a plane perpendicular to the incident light to observe the local zooming condition. As shown in fig. 11, when the birefringent crystal lens is in the lens state, the partial image modulated by it is in the zoom state.
The principle of partial zooming is explained below, as shown in fig. 12, wherein the first intermediate image is an image formed by the optical system before the birefringent crystal lens, the partial image is a portion of the first intermediate image, and the second intermediate image is an image formed by the second intermediate image after passing through the birefringent crystal lens. Assuming that the first intermediate image, the partial image, and the second intermediate image have heights Y, Y ', a partial enlargement is achieved because Y' > Y. The magnification of partial magnification is beta, assuming that F ' is the focal length of the birefringent lens, F and F ' are the object space and image space focal points of the birefringence, x is the object distance, x ' is the image distance, and the magnification is according to the Gaussian formula
Figure BDA0003504334460000141
The magnification here has to satisfy the Nyquist criterion, i.e. the diameter of the image spot is smaller than the pixel size of the detection device. Assume that the amplification of the relay system 64 is β1The focal length f of the focusing system 62, the focal length f of the entire partial magnification systemmWherein f ism＝ββ1f; according to the formula of the transverse direction lambda/4,
Figure BDA0003504334460000142
where λ is the wavelength of the incident light wave, D is the diameter of the entrance pupil, DpixieTo detect the pixel size of the device. The maximum magnification can thus be obtained as:
Figure BDA0003504334460000143
example 10
As shown in fig. 13, this embodiment is further improved from embodiment 8, in which the imaging device further includes an axicon lens, and the axicon lens is located between the birefringent crystal lens and the second lens along the incident direction of the light ray.
Lens depth of field is the ability of a lens to maintain a desired image quality (at a specified spatial frequency of contrast degradation) without having to refocus when the object is positioned closer to and farther from the best focus. The simplest method of increasing the system is to reduce the aperture stop of the system, which results in a square-power attenuation of the output image of the system, although the imaging intensity can be guaranteed by increasing the illumination intensity. But reducing the aperture stop also results in a reduction in imaging resolution and signal-to-noise ratio.
A conventional imaging process can be seen as a process of image degradation, the degradation function of which is an optical transfer function that depends on the object distance. For the degraded image, the image quality obtained by the image system can be improved to the maximum extent through a graph restoration operation, and the selection of the image restoration function is based on a degradation concave function. The optical transfer functions of the conventional optical imaging system are different at different object distances, which causes the following problems: for imaging objects with different object distances within the depth of field, different image restoration functions are required, and in general, the size of the actual object distance is not known, so that the image restoration work cannot effectively improve the images corresponding to all object distances within the depth of field.
If a specially designed phase template is added in the traditional optical imaging system, so that the image degradation process is consistent or approximately consistent in the depth of field range, a single image restoration function can be used for carrying out effective image restoration operation on all corresponding images in the depth of field range, and the optical-digital processing hybrid imaging system becomes possible. The optical imaging system with large depth of field obtained by combining optics and image processing needs to have the following characteristics: the optical imaging system loaded with the phase template has defocus invariance. Namely, the following mathematical expression is satisfied:
Figure BDA0003504334460000151
wherein H (f)x,fy；W20) Representing the optical transfer function of the system at different defocus conditions. Wherein f isxDenotes the focal length of the x-axis, fyIndicating the focal length of the y-axis. W20Indicating the defocus of the system.
In the imaging device of the embodiment, the axicon is placed in the incoherent illumination light path, and the light reflected from the spatial object passes through the axicon and then forms an image which is insensitive to defocusing on the image sensor. In embodiment 8, we obtain an optical imaging system with a partial area enlarged after being modulated by a birefringent lens by using the depth of field of the optical system, but the magnification is limited by the depth of field of the system, so this embodiment obtains an optical system with a large depth of field and a larger magnification by using the characteristics of an aspheric surface.
The light spot at a position within the focal line due to the axicon is generated by a ring of light rays incident at different positions of the axicon. The present embodiment utilizes this characteristic from another aspect, and assumes that the leftmost side is the image plane, and the light from a point on the image plane passes through the axicon and the lens to form a focal line object, and at this time, the object plane is not on a point but on a line, so as to achieve the purpose of increasing the depth of field.
Example 11
As shown in fig. 14, in the present embodiment, the imaging device includes a polarizing element, an optical rotation device, a first lens, a first birefringent lens, a second birefringent lens, and an image sensor, which are sequentially arranged in the incident direction of light, wherein the first birefringent lens is a negative lens, and the second birefringent lens is a positive lens.
When the optical rotation device does not work, light rays reflected from a space object form an image on the image sensor after passing through the first lens, the first birefringent lens and the second birefringent lens, and at the moment, the focal length of the birefringent lens is infinite without zone scaling. When the optical rotation device is operated, the whole optical system has independently zoomed regions.
Next, a zoom of the imaging device will be described, where as shown in fig. 15, P is a position of an object, a distance from the object to the first lens is D, Q is a position of an image, distances from the image to the second lens are S2, f1 and f2 are focal lengths of two lenses, and a distance from the first lens to the second lens is D.
According to the Gaussian formula, the single lens imaging formula is
Figure BDA0003504334460000161
Where s is the object distance, s' is the image distance, f is the focal length of the einzel lens, and M represents the lateral magnification, where
Figure BDA0003504334460000162
The object distance of the first lens in the magnification system is s1 ═ D, so the image distance is:
Figure BDA0003504334460000163
the lateral magnification of the first lens is
Figure BDA0003504334460000164
The second lens has an object distance s2＝d-s1', the image distance of the second lens is:
Figure BDA0003504334460000171
will s1' come to
Figure BDA0003504334460000172
When the system is at a distance s2' when held constant, the magnification of the system is
Figure BDA0003504334460000173
In the imaging device of the embodiment, when the optical rotation device is not in operation, light in the space is reflected by an object and then imaged on the image sensor through the first lens, and when the birefringent lens is in operation, a partial image on the sensing surface of the image sensor is modulated through the first birefringent lens and the second birefringent lens, so that the partial image can be zoomed under the condition that the image surface is not changed.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A birefringent crystal lens, comprising:
the first sub-lens is provided with a first splicing surface, and the normal directions of at least two parts of the first splicing surface are different;
a second sub-lens having a second splicing surface, at least two portions of the second splicing surface having different normal directions;
the first splicing surface of the first sub-lens and the second splicing surface of the second sub-lens are complementary in shape and spliced together; the first sub-lens is a crystal with ordinary light refractive index no1Extraordinary refractive index of ne1；
The second sub-lens is amorphous and has a refractive index no2And 0.5no1≤no2≤1.5no1；
Or, the second sub-lens is a crystal with ordinary light refractive index no3Extraordinary refractive index of ne3The optical axis direction of the first sub-lens and the optical axis direction of the second sub-lens are perpendicular to each other, wherein no1＝no3And n iso1≠ne3Or no3≠ne1。
2. The birefringent crystal lens of claim 1, wherein the first sub-lens is a crystal, the first sub-lens comprises a first plane, the first splicing surface is an inwardly concave arc surface, the second sub-lens is a crystal, the second sub-lens comprises a second plane, two ends of the second plane are connected to two ends of a second splicing surface, the second splicing surface is an outwardly convex arc surface, and the first plane and the second plane are parallel to each other.
3. A birefringent crystal lens according to claim 1, wherein the first sub-lens is a crystal and the second sub-lens is a crystal, the second sub-lens comprising fifth and sixth planes parallel to each other, the first splicing face being enclosed within the second splicing face.
4. The birefringent crystal lens of claim 1, wherein the first sub-lens is a crystal, the first sub-lens comprises a third plane, the first splicing face is an inwardly concave curved surface, the second sub-lens is an amorphous body, the second sub-lens comprises a fourth plane, two ends of the fourth plane are connected to two ends of a second splicing face, the second splicing face is an outwardly convex curved surface, and the third plane and the fourth plane are parallel to each other.
5. A birefringent crystal lens according to claim 1, wherein the first and second splicing surfaces have a fresnel lens optical structure.
6. A birefringent crystal lens according to claim 1, wherein said first splicing face comprises a plurality of first splicing face units arranged in an array, each first splicing face unit comprising at least two portions with different normal directions and said second splicing face comprises second splicing face units corresponding to said first splicing face units one to one, said second splicing face units being spliced together with their corresponding first splicing face units.
7. An imaging device comprising the birefringent crystal lens of any one of claims 1 to 6.
8. The imaging apparatus according to claim 7, further comprising a polarizing element and a rotation rotator, the polarizing element, the rotation rotator, and the birefringent crystal lens being arranged in order along an incident direction of light.
9. The imaging apparatus according to claim 8, further comprising a first lens between the optical rotation device and the birefringent crystal lens in a light incident direction, a second lens between the birefringent lens and the image sensor, and an image sensor.
10. An imaging apparatus comprising a polarizing element, an optical rotation device, a first lens, a first birefringent lens, a second birefringent lens, and an image sensor arranged in this order along an incident direction of a light ray, wherein the first birefringent lens is a negative lens, the second birefringent lens is a positive lens, and the first birefringent lens and the second birefringent lens are the birefringent crystal lens of any one of claims 1 to 6.
CN202210135234.1A 2022-02-14 2022-02-14 Birefringent crystal lens and imaging device Pending CN114415272A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210135234.1A CN114415272A (en) 2022-02-14 2022-02-14 Birefringent crystal lens and imaging device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210135234.1A CN114415272A (en) 2022-02-14 2022-02-14 Birefringent crystal lens and imaging device

Publications (1)

Publication Number Publication Date
CN114415272A true CN114415272A (en) 2022-04-29

Family

ID=81262424

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210135234.1A Pending CN114415272A (en) 2022-02-14 2022-02-14 Birefringent crystal lens and imaging device

Country Status (1)

Country Link
CN (1) CN114415272A (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5867315A (en) * 1995-07-31 1999-02-02 Pioneer Electronic Corporation Crystal optic lens and an optical system for an optical pickup device
CN101738734A (en) * 2010-01-14 2010-06-16 友达光电股份有限公司 Switchable 2D/3D liquid crystal display panel
US20150022705A1 (en) * 2013-03-11 2015-01-22 Tera Xtal Technology Corporation Camera device and projector device having protective lens
US20190324271A1 (en) * 2018-04-24 2019-10-24 Samsung Electronics Co., Ltd. See-through type display apparatus
WO2021044659A1 (en) * 2019-09-04 2021-03-11 株式会社村田製作所 Lens unit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5867315A (en) * 1995-07-31 1999-02-02 Pioneer Electronic Corporation Crystal optic lens and an optical system for an optical pickup device
CN101738734A (en) * 2010-01-14 2010-06-16 友达光电股份有限公司 Switchable 2D/3D liquid crystal display panel
US20150022705A1 (en) * 2013-03-11 2015-01-22 Tera Xtal Technology Corporation Camera device and projector device having protective lens
US20190324271A1 (en) * 2018-04-24 2019-10-24 Samsung Electronics Co., Ltd. See-through type display apparatus
WO2021044659A1 (en) * 2019-09-04 2021-03-11 株式会社村田製作所 Lens unit

Similar Documents

Publication Publication Date Title
US11681126B2 (en) Optical imaging system and portable electronic device including the same
US11231560B2 (en) Optical imaging system
US11231565B2 (en) Optical lens comprising eight lenses of −−++−++− refractive powers
US20230418028A1 (en) Optical imaging system
KR20060129323A (en) Variable lens system
KR20150084631A (en) Dual focus lens and image pickup apparatus including the same
TWI420140B (en) Zoom camera module
CN107436482B (en) Turning type telescopic fixed-focus lens and camera device
US11796760B2 (en) Optical imaging system
CN113302536B (en) Image capturing apparatus
JP2581767B2 (en) Variable focus lens system
US20240085672A1 (en) Optical imaging system
KR100351216B1 (en) Wide angle objective system
CN114415272A (en) Birefringent crystal lens and imaging device
US20220252847A1 (en) Optical imaging system
US11796764B2 (en) Camera module with telephoto imaging including three lenses of +-+, four lenses of +--+, or five lenses of +-+-+ or +--+- refractive powers
TW202316161A (en) Optical imaging system
US20220099949A1 (en) Optical system, optical apparatus, imaging apparatus, and method for manufacturing optical system and imaging apparatus
CN112005151B (en) Camera module and optical device
KR20220008573A (en) Lens optical system and camera module having thereof
CN113302535A (en) Image capturing apparatus
KR20150070876A (en) Inner-focus type compact lens system and imaging apparatus employing the same
KR100773837B1 (en) Adjustable optical system, and method for using and manufacturing such
CN214586220U (en) Periscopic lens assembly
CN218298623U (en) Visual field expanding type infrared double-visual field optical system

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination