CN118393705B - Day and night confocal lens - Google Patents
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- CN118393705B CN118393705B CN202410845211.9A CN202410845211A CN118393705B CN 118393705 B CN118393705 B CN 118393705B CN 202410845211 A CN202410845211 A CN 202410845211A CN 118393705 B CN118393705 B CN 118393705B
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- 238000003384 imaging method Methods 0.000 claims abstract description 33
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- 239000006185 dispersion Substances 0.000 description 2
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/06—Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
- G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
- G02B13/0045—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having five or more lenses
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0055—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0055—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element
- G02B13/006—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element at least one element being a compound optical element, e.g. cemented elements
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/14—Optical objectives specially designed for the purposes specified below for use with infrared or ultraviolet radiation
- G02B13/146—Optical objectives specially designed for the purposes specified below for use with infrared or ultraviolet radiation with corrections for use in multiple wavelength bands, such as infrared and visible light, e.g. FLIR systems
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
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Abstract
The invention discloses a day and night confocal lens, which sequentially comprises the following components from an object side to an imaging surface along an optical axis: the first lens with negative focal power has a concave object side surface and a concave image side surface; a second lens with positive focal power, wherein the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface; a fourth lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a fifth lens with negative focal power, wherein the object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a concave surface; a sixth lens element with positive refractive power having a convex object-side surface and a convex image-side surface; the optical filter is a visible light optical filter or an infrared light optical filter; wherein at least one of the first lens to the sixth lens is a glass lens. The day-night confocal lens provided by the invention has one or more advantages of small volume, large wide angle, day-night confocal and high pixel.
Description
Technical Field
The invention relates to the technical field of imaging lenses, in particular to a day-night confocal lens.
Background
Along with the high-speed development of science and technology, the wide-angle lens has the advantages of large field angle and wide shooting scope, and is widely applied to the fields of security protection, vehicle-mounted, intelligent home and the like. However, due to the difference of application environments, the requirements of consumers on the performance of the lens are different, but the overall requirements are higher and higher. In some application scenes with complex environments, the lens is required to be not out of focus under the condition of large temperature difference between high temperature and low temperature, and shooting requirements can be met under the conditions of daytime and night. The traditional full-glass lens has large volume, low resolution of pixels and insufficient day-night confocal capability. For this reason, the current wide-angle lens is continuously moving towards the directions of higher definition image quality, small volume and day-night confocal, and the day-night confocal wide-angle lens with a corresponding new structure is the object to be developed.
Disclosure of Invention
The invention aims to provide a day-night confocal lens, which has at least one or more advantages of small volume, large wide angle, day-night confocal and high pixel.
Therefore, the invention provides a day-night confocal lens, which comprises six lenses in sequence from an object side to an imaging surface along an optical axis: a first lens with negative focal power, wherein the object side surface of the first lens is a concave surface, and the image side surface of the first lens is a concave surface; a second lens with positive focal power, wherein the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens with positive focal power, wherein the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface; a fourth lens element with positive refractive power, wherein the object-side surface of the fourth lens element is convex, and the image-side surface of the fourth lens element is convex; a fifth lens with negative focal power, wherein an object side surface of the fifth lens is a concave surface, and an image side surface of the fifth lens is a concave surface; a sixth lens element with positive refractive power having a convex object-side surface and a convex image-side surface; the optical filter is a visible light optical filter or an infrared light optical filter; wherein at least one of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens is a glass lens. In some embodiments, the fifth lens and the sixth lens form a cemented lens.
In some embodiments, the maximum field angle FOV of the day-night confocal lens satisfies: 110 ° < FOV <125 °.
In some embodiments, the effective focal length f of the day-night confocal lens satisfies: 3.0mm < f <4.0mm.
In some embodiments, the image height IH corresponding to the maximum field angle of the day-night confocal lens satisfies: 6.0mm < IH <8.0mm.
In some embodiments, the aperture value FNO of the day-night confocal lens satisfies: FNO <1.7.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 4< TTL/f <6,2.8< TTL/BFL <4; wherein TTL represents the optical total length of the day-night confocal lens, f represents the effective focal length of the day-night confocal lens, and BFL represents the optical back focal length of the day-night confocal lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: -1.1< f1/f < -0.8, -0.2< f1/f2< -0.05; wherein f1 represents an effective focal length of the first lens, and f2 represents an effective focal length of the second lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 5< f2/f <12,0.8< R3/R4<1; wherein f2 represents an effective focal length of the second lens, R3 represents a radius of curvature of an object side surface of the second lens, and R4 represents a radius of curvature of an image side surface of the second lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 2.5< f3/f <25,1< R5/R6<4; wherein f3 represents an effective focal length of the third lens, R5 represents a radius of curvature of an object side surface of the third lens, and R6 represents a radius of curvature of an image side surface of the third lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 1< f4/f <3, -0.8< R7/R8< -0.05; wherein f4 represents an effective focal length of the fourth lens, R7 represents a radius of curvature of an object side surface of the fourth lens, and R8 represents a radius of curvature of an image side surface of the fourth lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: -1.8< f5/f < -1.1,0.9< f6/f <1.3; where f5 represents an effective focal length of the fifth lens, and f6 represents an effective focal length of the sixth lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: -100< R1/R2< -8, -60< R1/f < -8; wherein R1 represents a radius of curvature of an object side surface of the first lens, and R2 represents a radius of curvature of an image side surface of the first lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: -1< f1/f6< -0.6; wherein f1 represents an effective focal length of the first lens, and f6 represents an effective focal length of the sixth lens.
In some embodiments, the fifth lens and the sixth lens form a cemented lens, and the day-night confocal lens satisfies the conditional expression: -1.5< f5/f6< -1.1,2< f56/f <4; where f5 denotes an effective focal length of the fifth lens, f6 denotes an effective focal length of the sixth lens, and f56 denotes a combined focal length of the fifth lens and the sixth lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: -60< R1/f < -8,1< (R3+CT2)/R4 <1.3; wherein R1 represents a radius of curvature of an object side surface of the first lens, R3 represents a radius of curvature of an object side surface of the second lens, R4 represents a radius of curvature of an image side surface of the second lens, and CT2 represents a center thickness of the second lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: -0.35< SAG11/SAG12< -0.01,1.2< SAG21/SAG22<1.8; wherein SAG11 represents the sagittal height of the object side surface of the first lens at the maximum aperture, SAG12 represents the sagittal height of the image side surface of the first lens at the maximum aperture, SAG21 represents the sagittal height of the object side surface of the second lens at the maximum aperture, and SAG22 represents the sagittal height of the image side surface of the second lens at the maximum aperture.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 50 ° < f×fov/IH <65 °, wherein FOV represents the maximum field angle of the day-night confocal lens, and IH represents the image height corresponding to the maximum field angle of the day-night confocal lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: and (3) IH/f <2.2, wherein IH represents the image height corresponding to the maximum field angle of the day and night confocal lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: and 4.0mm < IH/FNo <4.8mm, wherein IH represents the image height corresponding to the maximum field angle of the day-night confocal lens, and FNo represents the aperture value of the day-night confocal lens.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 1.3< BFL/f <1.8.
In some embodiments, a stop is disposed between the third lens and the fourth lens.
In some embodiments, a filter and a cover glass are disposed between the sixth lens and the imaging surface.
In some embodiments, the first lens and the fourth lens are glass lenses.
In some implementations, the second lens, the third lens, the fifth lens, and the sixth lens are plastic lenses.
In some implementations, at least one of the second lens, the third lens, the fifth lens, and the sixth lens is an aspherical lens.
Compared with the prior art, the day-night confocal lens provided by the invention adopts a six-piece glass-plastic mixed lens structure, and different optical filters are switched according to different visible or infrared light sources through specific surface shape collocation and reasonable optical power distribution, so that high-definition imaging of the lens with small day-night confocal can be well realized.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
fig. 1 is a schematic diagram of a day-night confocal lens according to a first embodiment of the invention.
Fig. 2 is a graph showing distortion curves of a day-night confocal lens according to a first embodiment of the invention.
Fig. 3 is a graph showing a field curve of a day-night confocal lens according to a first embodiment of the invention.
Fig. 4 is a graph showing a vertical axis chromatic aberration curve of a day-night confocal lens according to a first embodiment of the invention.
Fig. 5 is a schematic diagram of a day-night confocal lens according to a second embodiment of the invention.
Fig. 6 is a graph showing distortion curves of a day-night confocal lens according to a second embodiment of the invention.
Fig. 7 is a graph showing a field curve of a day-night confocal lens according to a second embodiment of the invention.
Fig. 8 is a graph showing a vertical axis chromatic aberration curve of a day-night confocal lens according to a second embodiment of the invention.
Fig. 9 is a schematic diagram of a day-night confocal lens according to a third embodiment of the invention.
Fig. 10 is a distortion graph of a day-night confocal lens according to a third embodiment of the invention.
FIG. 11 is a graph showing a field curve of a day-night confocal lens according to a third embodiment of the invention.
Fig. 12 is a graph showing a vertical axis chromatic aberration curve of a day-night confocal lens according to a third embodiment of the invention.
Detailed Description
In order that the objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Several embodiments of the invention are presented in the figures. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Like reference numerals refer to like elements throughout the specification.
It should be noted that in the present specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the feature. Accordingly, a first lens discussed below may also be referred to as a second lens or a third lens without departing from the teachings of the present invention.
In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for convenience of explanation. In particular, the spherical or aspherical shape shown in the drawings is shown by way of example. That is, the shape of the spherical or aspherical surface is not limited to the shape of the spherical or aspherical surface shown in the drawings. The figures are merely examples and are not drawn to scale.
Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, then the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is referred to as the object side of the lens, and the surface of each lens closest to the imaging plane is referred to as the image side of the lens.
It will be further understood that the terms "comprises," "comprising," "includes," "including," "having," "containing," and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Furthermore, when a statement such as "at least one of the following" appears after a list of features that are listed, the entire listed feature is modified instead of modifying a separate element in the list. Furthermore, when describing embodiments of the application, use of "may" means "one or more embodiments of the application. Also, the term "exemplary" is intended to refer to an example or illustration.
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.
The embodiment of the invention provides a day-night confocal lens, which sequentially comprises the following components from an object side to an imaging surface along an optical axis: the optical centers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the optical filter and the protective glass are positioned on the same straight line.
In some embodiments, the first lens is configured to have negative focal power, and the object side surface of the first lens is a concave surface, and the image side surface of the first lens is a concave surface, so that as much as possible of the collected light rays with a large field of view enter the rear optical system, the light rays with a large angle passing through the first lens can be rapidly dispersed, and meanwhile aberration correction of the light rays with a large angle by the rear optical system is facilitated, and imaging quality of the lens is improved.
In some embodiments, the second lens has positive focal power, and the object side surface is convex, and the image side surface is concave, so that light rays emitted from the first lens can be converged and adjusted, and the height of the light rays entering the subsequent optical system can be reduced, so that the light rays can be more stable in trend, a part of aberration and distortion can be corrected, and the resolving power of the lens can be improved.
In some embodiments, the third lens is configured to have positive focal power, the object side surface is a concave surface, the image side surface is a convex surface, so that light rays can be further converged, the trend of the light rays in the central view field and the edge view field can be adjusted to make the transition gentle, various aberrations generated by the front end lens are balanced, and the imaging quality of the lens is improved.
In some embodiments, the fourth lens element has positive optical power, and has a convex object-side surface and a convex image-side surface, so that light passing through the front-end lens assembly can be converged and adjusted, distortion of an edge field angle can be corrected, and imaging quality of the lens assembly can be improved.
In some embodiments, the fifth lens and the sixth lens form a cemented lens, which can effectively balance the chromatic aberration of each pupil, effectively reduce the offset of infrared light back focus and achieve day-night confocal effect. Meanwhile, the fifth lens is arranged to have negative focal power, the sixth lens is arranged to have positive focal power, the object side surface of the fifth lens is concave, and the image side surface of the sixth lens is convex, so that specular reflection ghost images of the fifth lens and the sixth lens can be effectively eliminated, and imaging quality is improved.
In some embodiments, the diaphragm is arranged between the third lens and the fourth lens, so that light entering the optical system can be effectively converged, the focal power distribution and aberration of the lens groups before and after the diaphragm can be balanced, the uniformity of the incident angle of the light of the front lens and the rear lens is ensured, the caliber of the lens at the rear end of the optical system is reduced, the sensitivity of the lens is reduced, and the stability of the day-night confocal lens is improved.
In some embodiments, the day-night confocal lens in the embodiment of the invention can select one of the visible light filter or the infrared light filter according to different matched light sources, so that a good imaging effect under a visible light or infrared light working state is realized. Specifically, when the day-night confocal lens is in a visible light source, a visible light filter is selected, and the day-night confocal lens is in a working state of visible light; when the day and night confocal lens is in the infrared light source, an infrared light filter is selected, and the day and night confocal lens is in the working state of infrared light. The focal point of the day-night confocal lens basically does not deviate no matter in a visible light state or an infrared light state, and the day-night confocal effect can be well realized.
In some embodiments, the aperture value FNO of the day-night confocal lens satisfies: FNO <1.7. The above range is satisfied, so that the day-night confocal lens has the characteristic of a large aperture, particularly, when the day-night confocal lens images in a darker environment such as an infrared light source state, the noise influence caused by too weak light can be reduced, thereby improving the imaging quality, and the day-night confocal lens can meet the imaging requirements under different luminous fluxes.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 4< TTL/f <6; wherein TTL represents the optical total length of the day-night confocal lens, and f represents the effective focal length of the day-night confocal lens. The optical lens has the advantages that the ratio of the total optical length to the effective focal length of the optical lens is reasonably set, so that the length of the lens can be effectively limited, the miniaturization of the optical lens is realized, light rays are better converged on an imaging surface, and the imaging quality of the lens is improved.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 2.8< TTL/BFL <4; wherein TTL represents the total optical length of the day-night confocal lens, and BFL represents the optical back focal length of the day-night confocal lens. The optical back Jiao Jiaochang of the lens can be convenient for the optical filter switching device to switch the visible light filter and the infrared optical filter, and the high-definition imaging of the optical lens under day and night confocal is facilitated.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: -1.1< f1/f < -0.8; wherein f1 represents an effective focal length of the first lens. The first lens element with high negative refractive power can converge the divergence angle of incident light rays, optimize system aberration in a large field angle, and improve overall imaging quality.
In some embodiments, the refractive index Nd1 of the first lens satisfies: nd1 is more than 1.7; the day and night confocal lens meets the following conditions: -100< R1/R2< -8, -60< R1/f < -8; wherein R1 represents a radius of curvature of an object side surface of the first lens, and R2 represents a radius of curvature of an image side surface of the first lens. The first lens is made of high-hardness glass, the conditions are met, the curvature radius of the object side surface of the first lens is larger and is close to a flat plate state, the first lens is exposed outside the monitoring machine and is not easy to scratch, the use of protective glass at the end of the machine can be reduced, and the cost of the machine is reduced.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 5< f2/f <12,0.8< R3/R4<1; wherein f2 represents an effective focal length of the second lens, R3 represents a radius of curvature of an object side surface of the second lens, and R4 represents a radius of curvature of an image side surface of the second lens. The second lens element with proper positive refractive power can be controlled to converge light rays, so that the aberration caused by the negative refractive power of the first lens element can be effectively balanced, and the imaging resolution can be improved.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 2.5< f3/f <25,1< R5/R6<4; wherein f3 represents an effective focal length of the third lens, R5 represents a radius of curvature of an object side surface of the third lens, and R6 represents a radius of curvature of an image side surface of the third lens. The lens meets the conditions, is favorable for smooth transition of light, reduces the correction difficulty of edge aberration and distortion, and has small distortion while realizing a large angle of view.
In some embodiments, the abbe number Vd4 of the fourth lens satisfies: vd4 > 58; and the day and night confocal lens meets the following conditions: 1< f4/f <3, -0.8< R7/R8< -0.05; wherein f4 represents an effective focal length of the fourth lens, R7 represents a radius of curvature of an object side surface of the fourth lens, and R8 represents a radius of curvature of an image side surface of the fourth lens. The fourth lens is made of ultra-low dispersion glass, so that chromatic aberration can be effectively reduced, light rays with various wavelengths are ensured to be actually focused on the same plane, near infrared is not defocused, and high-definition imaging is achieved all day long at daytime and night.
In some embodiments, the fifth lens and the sixth lens adopt a cemented structure, and the day-night confocal lens satisfies the following conditional expression: -1.8< f5/f < -1.1,0.9< f6/f <1.3; where f5 represents an effective focal length of the fifth lens, and f6 represents an effective focal length of the sixth lens. The above conditions are met, and the fifth lens and the sixth lens adopt a gluing structure, so that on one hand, chromatic aberration of the system can be effectively eliminated, and on the other hand, specular reflection ghost images between the fifth lens and the sixth lens can be effectively eliminated, and imaging quality is improved.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: -0.2< f1/f2< -0.05; wherein f1 represents an effective focal length of the first lens, and f2 represents an effective focal length of the second lens. The focal length relation of the first lens and the second lens is reasonably set, so that as much large-view-field light rays can be collected as possible to enter the optical system, and the performance of large view fields and large apertures of day and night confocal lenses can be realized.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: -1< f1/f6< -0.6; wherein f1 represents an effective focal length of the first lens, and f6 represents an effective focal length of the sixth lens. The above conditions are met, and the focal length relation of the head lens and the tail lens is reasonably set, so that the pupil chromatic aberration can be effectively balanced, the infrared light back focal offset can be reduced, and day-night confocal imaging of the lens can be well realized.
In some embodiments, the fifth lens and the sixth lens form a cemented lens, and the day-night confocal lens satisfies the conditional expression: -1.5< f5/f6< -1.1,2< f56/f <4; where f5 denotes an effective focal length of the fifth lens, f6 denotes an effective focal length of the sixth lens, and f56 denotes a combined focal length of the fifth lens and the sixth lens. The focal length ratio of the fifth lens and the sixth lens in the cemented lens is reasonably configured to meet the above conditions, so that chromatic aberration of the day-night confocal lens can be effectively eliminated on one hand, specular reflection ghost images between the fifth lens and the sixth lens can be effectively eliminated on the other hand, and imaging quality of the day-night confocal lens is improved.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 1< (R3+CT2)/R4 <1.3; wherein R3 represents a radius of curvature of an object side surface of the second lens, R4 represents a radius of curvature of an image side surface of the second lens, and CT2 represents a center thickness of the second lens. The second lens adopts meniscus matching close to concentric circles, so that the optical path difference between the center and the periphery of the lens can be reduced, the distortion of the lens can be corrected, and high-quality imaging of the lens can be realized.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: -0.35< SAG11/SAG12< -0.01,1.2< SAG21/SAG22<1.8; wherein SAG11 represents the sagittal height of the object side surface of the first lens at the maximum aperture, SAG12 represents the sagittal height of the image side surface of the first lens at the maximum aperture, SAG21 represents the sagittal height of the object side surface of the second lens at the maximum aperture, and SAG22 represents the sagittal height of the image side surface of the second lens at the maximum aperture. The lens has the advantages that the conditions are met, the edge sagittal height of the first lens and the edge sagittal height of the second lens are reasonably set, as much light as possible can be collected to enter the system, the large aperture performance of the lens is better realized, the lens also has better imaging effect in a darker environment, and the confocal imaging requirement of the lens in a day and night environment is met.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 50 ° < f×fov/IH <65 °, wherein FOV represents the maximum field angle of the day-night confocal lens, and IH represents the image height corresponding to the maximum field angle of the day-night confocal lens. The conditions are met, so that reasonable balance between large-field-angle imaging and high-quality imaging of the day-night confocal lens is facilitated, and suitability of the day-night confocal lens is improved.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: and (3) IH/f <2.2, wherein IH represents the image height corresponding to the maximum field angle of the day and night confocal lens. The conditions are met, the wide-angle characteristic can be achieved through reasonably controlling the ratio of the image height and the focal length of the day-night confocal lens, so that the requirement of large wide-angle shooting is met, the large image surface characteristic can be achieved, and the imaging quality of the day-night confocal lens is improved. More preferably, the above condition is satisfied to better realize that the maximum field angle FOV of the day and night confocal lens satisfies 110 ° < FOV <125 °, and the image height IH corresponding to the maximum field angle of the day and night confocal lens satisfies 6.0mm < IH <8.0mm.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: and 4.0mm < IH/FNo <4.8mm, wherein IH represents the image height corresponding to the maximum field angle of the day-night confocal lens, and FNo represents the aperture value of the day-night confocal lens. The method meets the conditions and is favorable for realizing reasonable balance of the large image plane and the large aperture.
In some embodiments, the day-night confocal lens satisfies the following conditional expression: 1.3< BFL/f <1.8. The optical lens has the advantages that the optical lens has larger optical back focal length by setting day and night confocal lenses, interference between the lenses and an imaging chip is reduced, interference does not occur when the optical filter switching device is placed, day and night confocal seamless switching is further better achieved, and day and night confocal imaging performance of the lens is ensured.
As an implementation mode, six lenses in the day-night confocal lens can all adopt plastic lenses or all adopt glass lenses, also can adopt glass-plastic mixed material collocation structure, specifically, the day-night confocal lens adopts the glass-plastic mixed collocation structure of two glass spherical lenses and four plastic aspherical lenses, through the face and focal power of reasonable constraint each lens, can realize big angle of view, long back focus, big light ring, day-night confocal and the characteristics that thermal stability is good. The first lens and the fourth lens are glass spherical lenses, and the geometrical chromatic aberration of the optical system is effectively corrected through the characteristic of low chromatic dispersion of glass; the second lens, the third lens, the fifth lens and the sixth lens adopt plastic aspheric lenses, and the fifth lens and the sixth lens form a cemented lens, so that the cost can be effectively reduced, the aberration can be corrected, and an optical performance product with higher cost performance can be provided.
The invention is further illustrated in the following examples. In each embodiment, the thickness, radius of curvature and material selection of each lens in the day-night confocal lens are different, and the specific differences can be seen in the parameter table of each embodiment. The following examples are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following examples, and any other changes, substitutions, combinations or simplifications that do not depart from the gist of the present invention are intended to be equivalent substitutes within the scope of the present invention.
In various embodiments of the present invention, when the lens in the day-night confocal lens is an aspherical lens, the aspherical surface type of the lens satisfies the following equation:
；
Where z is the distance sagittal height from the aspherical surface vertex when the aspherical surface is at a position of height h in the optical axis direction, c is the paraxial curvature of the surface, k is a quadric surface coefficient, and a 2i is an aspherical surface type coefficient of 2 i-th order.
First embodiment
Referring to fig. 1, a schematic diagram of a day-night confocal lens 100 according to a first embodiment of the present invention is shown, where the day-night confocal lens 100 includes, in order from an object side to an imaging surface S16 along an optical axis: the optical lens comprises a first lens L1, a second lens L2, a third lens L3, a diaphragm ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, an optical filter G1 and a protective glass G2.
The first lens element L1 has a negative refractive power, wherein an object-side surface S1 of the first lens element is a concave surface, and an image-side surface S2 of the first lens element is a concave surface; the second lens element L2 has positive refractive power, wherein an object-side surface S3 of the second lens element is convex, and an image-side surface S4 of the second lens element is concave; the third lens element L3 with positive refractive power has a concave object-side surface S5 and a convex image-side surface S6; the fourth lens element L4 has positive refractive power, wherein an object-side surface S7 of the fourth lens element is convex, and an image-side surface S8 of the fourth lens element is convex; the fifth lens element L5 with negative focal power has a concave object-side surface S9 and a concave image-side surface; the sixth lens L6 has positive focal power, the object side surface of the sixth lens is a convex surface, the image side surface S10 of the sixth lens is a convex surface, the fifth lens L5 and the sixth lens L6 form a bonding lens, and the bonding surface is S10; the object side surface S12 and the image side surface S13 of the optical filter G1 are planes; the object side surface S14 and the image side surface S15 of the cover glass G2 are both planar.
In order to better realize small volume of the lens and reduce cost, the first lens L1 and the fourth lens L4 adopt glass spherical lenses, and the second lens L2, the third lens L3, the fifth lens L5 and the sixth lens L6 all adopt plastic aspherical lenses.
The optical filter G1 is a visible light optical filter or an infrared light optical filter, specifically, the day-night confocal lens 100 in the embodiment of the invention adapts to different light sources according to the change of the current working environment (day/night), and selects one of the visible light optical filter or the infrared light optical filter according to the light sources, thereby realizing a good imaging effect under the working state of visible light or infrared light. When the day-night confocal lens 100 is in a visible light source (in daytime), a visible light filter is selected, and the day-night confocal lens 100 is in a visible light working state; when the day-night confocal lens 100 is in the infrared light source (in the dark), an infrared light filter is selected, and the day-night confocal lens is in the working state of infrared light. The focal point of the day-night confocal lens 100 is not substantially shifted in the visible light state or the infrared light state, and the day-night confocal effect can be well achieved.
Specifically, the design parameters of each lens of the day-night confocal lens 100 provided in this embodiment are shown in table 1.
TABLE 1
In this embodiment, the aspherical surface profile coefficients of the respective lenses in the day-night confocal lens 100 are shown in table 2.
TABLE 2
Fig. 2 shows an optical distortion graph of the day-night confocal lens 100 in this embodiment, which shows distortion of different field angles on the imaging surface, the horizontal axis shows distortion values (unit:%) and the vertical axis shows field angles (unit: °). As can be seen from the figure, the optical distortion value is controlled within-45%, which indicates that the day and night confocal lens 100 can better correct distortion.
Fig. 3 shows a field curve diagram of the day-night confocal lens 100 in this embodiment, which indicates the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, the horizontal axis indicates the amount of shift (unit: mm), and the vertical axis indicates the angle of view (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within ±0.2mm, which means that the day-night confocal lens 100 can better correct the field curvature.
Fig. 4 shows a graph of vertical axis chromatic aberration of the day-night confocal lens 100 in this embodiment, which represents chromatic aberration at different image heights on the imaging plane for each wavelength with respect to the center wavelength (0.555 μm), the horizontal axis represents vertical axis chromatic aberration value (unit: μm) for each wavelength with respect to the center wavelength, and the vertical axis represents normalized field angle. As can be seen from the figure, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±4 μm, indicating that the day-night confocal lens 100 can correct chromatic aberration of the fringe field of view well.
Second embodiment
Referring to fig. 5, a schematic diagram of a day-night confocal lens 200 according to a second embodiment of the invention is shown, and the day-night confocal lens 200 of the present embodiment is substantially the same as the first embodiment, and the main differences are that: the lens surfaces have different radii of curvature, aspherical coefficients, and thicknesses.
Specifically, the design parameters of each lens of the day-night confocal lens 200 provided in this embodiment are shown in table 3.
TABLE 3 Table 3
In this embodiment, the aspherical surface profile coefficients of the respective lenses in the day-night confocal lens 200 are shown in table 4.
TABLE 4 Table 4
Referring to fig. 6, 7 and 8, an optical distortion curve, a field curvature curve and a vertical axis chromatic aberration curve of the day-night confocal lens 200 are shown. As can be seen from fig. 6, the optical distortion of the day-night confocal lens 200 is controlled within-40%, which indicates that the day-night confocal lens 200 can better correct the distortion; as can be seen from fig. 7, the offset of the curvature of field is controlled within ±0.15mm, which indicates that the day-night confocal lens 200 can better correct curvature of field; as can be seen from fig. 8, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±4 μm, which indicates that the day-night confocal lens 200 can correct chromatic aberration of the fringe field of view well.
Third embodiment
Referring to fig. 9, a schematic diagram of a day-night confocal lens 300 according to a third embodiment of the invention is shown, and the day-night confocal lens 300 of the present embodiment is substantially the same as the first embodiment, and the main differences are that: the radius of curvature, aspherical coefficient, and thickness of each lens surface also vary.
Specifically, the design parameters of each lens of the day-night confocal lens 300 provided in this embodiment are shown in table 5.
TABLE 5
In this example, the aspherical surface profile coefficients of each lens in the day-night confocal lens 300 are shown in table 6.
TABLE 6
Referring to fig. 10, 11 and 12, optical distortion curves, field curvature curves and vertical axis chromatic aberration curves of the day-night confocal lens 300 are shown. As can be seen from fig. 10, the optical distortion of the day-night confocal lens 300 is controlled within-45%, which indicates that the day-night confocal lens 300 can better correct the distortion; as can be seen from fig. 11, the offset of the curvature of field is controlled within ±0.2mm, which indicates that the day-night confocal lens 300 can better correct curvature of field; as can be seen from fig. 12, the vertical chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±3 μm, indicating that the day-night confocal lens 300 can correct chromatic aberration of the fringe field of view well.
Referring to table 7, the optical characteristics of the day-night confocal lens provided in the above three embodiments are shown, and include the total optical length TTL, the effective focal length f, the maximum field angle FOV, the image height IH corresponding to the maximum field angle, the aperture value Fno, and the correlation value corresponding to each of the above conditions.
TABLE 7
In summary, the day-night confocal lens provided by the invention adopts a glass-plastic mixed collocation structure of two glass spherical lenses and four plastic aspherical lenses, and different optical filters are switched according to different visible light or infrared light sources through specific surface shape collocation and reasonable optical power distribution, so that good day-night confocal effect is realized, and meanwhile, the day-night confocal lens has the characteristics of large field angle (FOV reaches 117.2 degrees), large aperture (FNo is 1.6), long back focus, good thermal stability and low cost.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (11)
1. The day and night confocal lens is composed of six lenses, and is characterized by comprising, in order from an object side to an imaging surface along an optical axis:
a first lens with negative focal power, wherein the object side surface of the first lens is a concave surface, and the image side surface of the first lens is a concave surface;
A second lens with positive focal power, wherein the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;
A third lens with positive focal power, wherein the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface;
A fourth lens element with positive refractive power, wherein the object-side surface of the fourth lens element is convex, and the image-side surface of the fourth lens element is convex;
A fifth lens with negative focal power, wherein an object side surface of the fifth lens is a concave surface, and an image side surface of the fifth lens is a concave surface;
a sixth lens element with positive refractive power having a convex object-side surface and a convex image-side surface;
the optical filter is a visible light optical filter or an infrared light optical filter;
wherein at least one of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens is a glass lens;
the day and night confocal lens meets the following conditions: 4< TTL/f <6,2.8< TTL/BFL <4; wherein TTL represents the optical total length of the day-night confocal lens, f represents the effective focal length of the day-night confocal lens, and BFL represents the optical back focal length of the day-night confocal lens.
2. The day-night confocal lens according to claim 1, wherein the day-night confocal lens satisfies the following formula: -1.1< f1/f < -0.8, -0.2< f1/f2< -0.05; wherein f1 represents an effective focal length of the first lens, and f2 represents an effective focal length of the second lens.
3. The day-night confocal lens according to claim 1, wherein the day-night confocal lens satisfies the following formula: 5< f2/f <12,0.8< R3/R4<1; wherein f2 represents an effective focal length of the second lens, R3 represents a radius of curvature of an object side surface of the second lens, and R4 represents a radius of curvature of an image side surface of the second lens.
4. The day-night confocal lens according to claim 1, wherein the day-night confocal lens satisfies the following formula: 2.5< f3/f <25,1< R5/R6<4; wherein f3 represents an effective focal length of the third lens, R5 represents a radius of curvature of an object side surface of the third lens, and R6 represents a radius of curvature of an image side surface of the third lens.
5. The day-night confocal lens according to claim 1, wherein the day-night confocal lens satisfies the following formula: 1< f4/f <3, -0.8< R7/R8< -0.05; wherein f4 represents an effective focal length of the fourth lens, R7 represents a radius of curvature of an object side surface of the fourth lens, and R8 represents a radius of curvature of an image side surface of the fourth lens.
6. The day-night confocal lens according to claim 1, wherein the day-night confocal lens satisfies the following formula: -1.8< f5/f < -1.1,0.9< f6/f <1.3; where f5 represents an effective focal length of the fifth lens, and f6 represents an effective focal length of the sixth lens.
7. The day-night confocal lens according to claim 1, wherein the day-night confocal lens satisfies the following formula: -100< R1/R2< -8, -60< R1/f < -8; wherein R1 represents a radius of curvature of an object side surface of the first lens, and R2 represents a radius of curvature of an image side surface of the first lens.
8. The day-night confocal lens according to claim 1, wherein the day-night confocal lens satisfies the following formula: -1< f1/f6< -0.6; wherein f1 represents an effective focal length of the first lens, and f6 represents an effective focal length of the sixth lens.
9. The day-night confocal lens according to claim 1, wherein the fifth lens and the sixth lens constitute a cemented lens, and the day-night confocal lens satisfies a conditional expression: -1.5< f5/f6< -1.1,2< f56/f <4; where f5 denotes an effective focal length of the fifth lens, f6 denotes an effective focal length of the sixth lens, and f56 denotes a combined focal length of the fifth lens and the sixth lens.
10. The day-night confocal lens according to claim 1, wherein the day-night confocal lens satisfies the following formula: 1< (R3+CT2)/R4 <1.3; wherein R3 represents a radius of curvature of an object side surface of the second lens, R4 represents a radius of curvature of an image side surface of the second lens, and CT2 represents a center thickness of the second lens.
11. The day-night confocal lens according to claim 1, wherein the day-night confocal lens satisfies the following formula: -0.35< SAG11/SAG12< -0.01,1.2< SAG21/SAG22<1.8; wherein SAG11 represents the sagittal height of the object side surface of the first lens at the maximum aperture, SAG12 represents the sagittal height of the image side surface of the first lens at the maximum aperture, SAG21 represents the sagittal height of the object side surface of the second lens at the maximum aperture, and SAG22 represents the sagittal height of the image side surface of the second lens at the maximum aperture.
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