CN116794807A - Optical imaging system - Google Patents
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- CN116794807A CN116794807A CN202311024479.8A CN202311024479A CN116794807A CN 116794807 A CN116794807 A CN 116794807A CN 202311024479 A CN202311024479 A CN 202311024479A CN 116794807 A CN116794807 A CN 116794807A
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- 238000012634 optical imaging Methods 0.000 title claims abstract description 144
- 230000008859 change Effects 0.000 claims abstract description 36
- 229920003023 plastic Polymers 0.000 claims description 29
- 239000004033 plastic Substances 0.000 claims description 29
- 239000011521 glass Substances 0.000 claims description 27
- 238000003384 imaging method Methods 0.000 description 31
- 230000004304 visual acuity Effects 0.000 description 15
- 230000004075 alteration Effects 0.000 description 14
- 230000003287 optical effect Effects 0.000 description 12
- 238000010586 diagram Methods 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 8
- 230000014509 gene expression Effects 0.000 description 7
- 238000000034 method Methods 0.000 description 4
- 230000008901 benefit Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
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- 238000012544 monitoring process Methods 0.000 description 1
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Classifications
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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
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
- G02B1/041—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
- G02B13/0015—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
- G02B13/18—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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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B29/00—Combinations of cameras, projectors or photographic printing apparatus with non-photographic non-optical apparatus, e.g. clocks or weapons; Cameras having the shape of other objects
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B30/00—Camera modules comprising integrated lens units and imaging units, specially adapted for being embedded in other devices, e.g. mobile phones or vehicles
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- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
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Abstract
An optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, which are disposed in order from an object side, and an image sensor for converting an incident image of an object into an electric signal; wherein the optical imaging system further comprises an aperture stop disposed between the second lens and the third lensAnd the third lens closest to the aperture stop has a positive refractive power, and wherein | Pnu | [10-6 ℃ -1mm-1 ]]And +.30, wherein PNU is ΣPnui, where i=1, 2, …, 7, pnui is 1/(vti·fi), vti is [ DTni/(ni-1) -CTEi] ‑1 Fi is the effective focal length of the ith lens, ni is the refractive index of the ith lens, DTni is the rate of change of refractive index of the ith lens according to temperature (dn 1/dT), and CTEi is the coefficient of thermal expansion of the ith lens.
Description
Cross Reference to Related Applications
The present application claims the benefit of priority from korean patent application No. 10-2021-0039790, filed on day 3 and 26 of 2021, the entire disclosure of which is incorporated herein by reference for all purposes.
Technical Field
The following description relates to an optical imaging system, and more particularly, to an optical imaging system applied to a camera mounted on a vehicle.
Background
As the number of vehicles equipped with image processing functions such as lane keeping or autonomous driving increases, the demand for monitoring cameras and sensing cameras that can support these functions also increases. As the number of required cameras increases, so does the need for cameras that can provide higher resolution for accurate image processing, and thus, the need to develop high-definition precision lenses suitable for mass production arises.
Taking a camera lens mounted on a vehicle as an example, a lens formed of glass is mainly used because resolution should be maintained even in a considerable temperature range. Glass lenses are relatively expensive and therefore disadvantageous in terms of mass production and economy. The use of plastic lenses is advantageous for mass production and can effectively reduce the cost of the lenses.
However, compared to glass, since plastics have the following properties: depending on the temperature variation, the refractive index or volume variation is relatively large, and thus it is difficult to provide an appropriate level of resolution in different environments. For example, according to a temperature change, plastic has a refractive index change about 100 times higher than that of glass and a thermal expansion coefficient about 10 times higher than that of glass, and thus, the defocus amount caused by the temperature change is large and it is difficult to maintain focus over a relatively wide temperature range.
Disclosure of Invention
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
Examples provide an optical imaging system having high quality resolution even over a relatively wide temperature range. In particular, examples provide an optical imaging system in which BFL variation is significantly lower even over a wide temperature range, and thus focal length can be maintained at a predetermined level.
In one general aspect, an optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens disposed in order from an object side. The optical imaging system satisfies | Pnu |is less than or equal to 30, wherein Pnu is Σpnui, wherein i=1, 2,..7, pnui is 1/(vti×fi), vti is [ DTni/(ni-1) -CTEi] -1 Fi is the effective focal length of the ith lens, ni is the refractive index of the ith lens, DTni is the rate of change of refractive index of the ith lens according to temperature (dni/dT), and CTEi is the coefficient of thermal expansion of the ith lens.
The optical imaging system may satisfy 0.4.ltoreq.f/f 3, where f is an effective focal length of the optical imaging system, and f3 is an effective focal length of the third lens.
The optical imaging system may include an aperture stop disposed between the second lens and the third lens.
The optical imaging system may satisfy | Pnu3/Pnu | <0.2.
The third lens may be composed of glass, and the second, fourth, fifth, sixth, and seventh lenses may be composed of plastic.
The optical imaging system can meet-2.0<∑1/(DTni·fi)[10 4 ℃mm -1 ]<20.0, wherein i=1, 2,..7.
The optical imaging system may satisfy 0.2< DTnF/DTnR <0.6, where DTnF is a sum Σdtni of DTn values of the first lens and the second lens (i=1, 2), and DTnR is a sum Σdtni of DTn values of the third lens to the seventh lens (i=3, 4,..7).
The optical imaging system can meet-620<DTnT[10 -6 ℃ -1 ]<-450, wherein DTnT is the sum Σdtni of the DTn values of the first to seventh lenses (i=1, 2..7).
The optical imaging system can meet 220<DTnF[10 -6 ℃ -1 ]<-100, wherein DTnF is the sum Σdtni of the DTn values of the first lens and the second lens (i=1, 2).
The optical imaging system can meet-400<DTnR[10 -6 ℃ -1 ]<-300, wherein DTnR is the sum Σdtni of the DTn values of the third to seventh lenses (i=3, 4..7).
The object-side surface of the seventh lens may be convex and the image-side surface of the seventh lens may be concave.
The first lens may have a negative refractive power, the third lens may have a positive refractive power, the fourth lens may have a positive refractive power, the fifth lens may have a negative refractive power, and the sixth lens may have a positive refractive power.
Other features and aspects will become apparent from the appended claims, the accompanying drawings, and the following detailed description.
Drawings
Fig. 1 is a diagram showing an optical imaging system according to a first example.
Fig. 2 is a graph showing aberrations of the optical imaging system according to the first example.
Fig. 3 is a graph showing the resolving power according to the field of view of the optical imaging system according to the first example.
Fig. 4 is a graph showing a change in BFL according to temperature in the optical imaging system according to the first example.
Fig. 5 is a diagram showing an optical imaging system according to a second example.
Fig. 6 is a graph showing aberrations of the optical imaging system according to the second example.
Fig. 7 is a graph showing the resolving power according to the field of view of the optical imaging system according to the second example.
Fig. 8 is a graph showing a change in BFL according to temperature in the optical imaging system according to the second example.
Fig. 9 is a diagram showing an optical imaging system according to a third example.
Fig. 10 is a graph showing aberrations of the optical imaging system according to the third example.
Fig. 11 is a graph showing the resolving power according to the field of view of the optical imaging system according to the third example.
Fig. 12 is a graph showing a change in BFL according to temperature in the optical imaging system according to the third example.
Fig. 13 is a diagram showing an optical imaging system according to a fourth example.
Fig. 14 is a graph showing aberrations of the optical imaging system according to the fourth example.
Fig. 15 is a graph showing the resolving power according to the field of view of the optical imaging system according to the fourth example.
Fig. 16 is a graph showing a change in BFL according to temperature in the optical imaging system according to the fourth example.
Fig. 17 is a diagram showing an optical imaging system according to a fifth example.
Fig. 18 is a graph showing aberrations of the optical imaging system according to the fifth example.
Fig. 19 is a graph showing the resolving power according to the field of view of the optical imaging system according to the fifth example.
Fig. 20 is a graph showing a change in BFL according to temperature in the optical imaging system according to the fifth example.
Fig. 21 is a diagram showing an optical imaging system according to a sixth example.
Fig. 22 is a graph showing aberrations of the optical imaging system according to the sixth example.
Fig. 23 is a graph showing an analytical force according to a field of view of an optical imaging system according to a sixth example.
Fig. 24 is a graph showing a change in BFL according to temperature in the optical imaging system according to the sixth example.
Fig. 25 is a diagram showing an optical imaging system according to a seventh example.
Fig. 26 is a graph showing aberrations of the optical imaging system according to the seventh example.
Fig. 27 is a graph showing an analytical force according to a field of view of an optical imaging system according to a seventh example.
Fig. 28 is a graph showing a change in BFL according to temperature in the optical imaging system according to the seventh example.
Like reference numerals refer to like elements throughout the drawings and detailed description. The figures may not be drawn to scale and the relative sizes, proportions, and depictions of elements in the figures may be exaggerated for clarity, illustration, and convenience.
Detailed Description
The following detailed description is provided to assist the reader in obtaining a thorough understanding of the methods, apparatus, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent to those of ordinary skill in the art. The order of the operations described herein is merely an example, except that the operations must occur in a particular order, and is not limited to the order set forth herein, but variations may be made that will be apparent to those of ordinary skill in the art. In addition, descriptions of functions and structures well known to those of ordinary skill in the art may be omitted for the sake of clarity and conciseness.
The features described herein may be embodied in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein have been provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
In this document, it should be noted that the use of the phrase "may" in connection with an embodiment or example (e.g., what may be included or implemented in connection with an embodiment or example) means that there is at least one embodiment or example in which such feature is included or implemented, and that all embodiments and examples are not limited thereto.
Throughout the specification, when an element such as a layer, region or substrate is described as being "on," connected to, "or" coupled to "another element, the element may be directly on," directly "connected to," or directly "coupled to" the other element, or there may be one or more other elements intervening elements between the element and the other element. In contrast, when an element is referred to as being "directly on," "directly connected to," or "directly coupled to" another element, there are no other elements intervening elements present.
As used herein, the term "and/or" includes any one of the listed items associated and any combination of any two or more.
Although terms such as "first," "second," and "third" may be used herein to describe various elements, components, regions, layers or sections, these elements, components, regions, layers or sections should not be limited by these terms. Rather, these terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first member, first component, first region, first layer, or first portion referred to in the examples may also be referred to as a second member, second component, second region, second layer, or second portion without departing from the teachings of the examples described herein.
Spatially relative terms such as "above," "upper," "lower," and "lower" may be used herein for convenience of description to describe one element's relationship to another element as illustrated in the figures. In addition to the orientations depicted in the drawings, these spatially relative terms are intended to encompass different orientations of the device in use or operation. For example, if the device in the figures is turned over, elements described as "above" or "upper" relative to another element would then be oriented "below" or "lower" relative to the other element. Thus, the term "above" encompasses both "above" and "below" orientations, depending on the spatial orientation of the device. The device may also be oriented in other ways (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing various examples only and is not intended to be limiting of the disclosure. The articles "a," "an," and "the" are intended to also include the plural forms unless the context clearly indicates otherwise. The words "comprise," "comprising," and "having" specify the presence of stated features, integers, operations, elements, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, operations, elements, and/or groups thereof.
The shapes of the illustrations as a result of manufacturing techniques and/or tolerances, are to be expected to vary. Accordingly, examples described herein are not limited to the particular shapes shown in the drawings, but include shape changes that occur during manufacturing.
The features of the examples described herein may be combined in various ways that will be apparent upon an understanding of the present disclosure. Furthermore, while the examples described herein have a variety of configurations, it will be apparent that other configurations are possible after an understanding of the present disclosure.
The figures may not be to scale and the relative sizes, proportions and descriptions of elements in the figures may be exaggerated for clarity, illustration and convenience.
In the following lens arrangement diagrams, the thickness, size, and shape of the lens are slightly exaggerated for description, and in particular, the shape of the spherical surface or the aspherical surface suggested in the lens arrangement diagrams is presented as an example, but is not limited thereto.
In this disclosure, the first lens refers to the lens closest to the object, and the last lens refers to the lens closest to the image sensor (or imaging surface).
Further, in each lens, the first surface refers to a surface (or object side) close to the object, and the second surface refers to a surface (or image side) close to the imaging surface. Further, in this specification, values of a radius of curvature, a thickness, a distance, and a focal length of a lens are all expressed in mm, and a unit of a field of view (FOV) is expressed in degrees.
Further, in the description of the shape of the respective lenses, unless otherwise specified, the meaning of a convex shape on one surface means that the paraxial region portion of the surface is convex, and the meaning of a concave shape on one surface means that the paraxial region portion of the surface is concave. A surface being flat means that the paraxial region portion of the surface is flat. The paraxial region refers to a very narrow region near the optical axis.
Therefore, even when one surface of the lens is described as being convex, the edge portion of the lens may be concave. Similarly, even when one surface of the lens is described as having a concave shape, the edge portion of the lens may be convex. Further, even when one surface of the lens is described as flat, the edge portion of the lens may be convex or concave.
An optical imaging system according to an example includes at least 7 lenses.
For example, an optical imaging system according to an example includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens disposed in order from the object side. In an example, the first to seventh lenses are spaced apart from each other along the optical axis by a predetermined distance. In another example, adjacent lenses among the first to seventh lenses may be disposed in a combined state.
The optical imaging system according to an example may further comprise an image sensor for converting an incident image of the object into an electrical signal. In addition, the optical imaging system may further include an infrared cut filter IRCF (hereinafter referred to as "filter") for blocking infrared rays. The filter IRCF is arranged between the last lens and the image sensor.
The optical imaging system may further comprise an imaging plane IP. The imaging plane IP refers to a plane on which light refracted by the first to seventh lenses is imaged. For example, the imaging plane IP may indicate a surface on which an optical element (e.g., photodiode) is disposed in an image sensor.
In an example, the optical imaging system may further comprise an aperture stop AS for adjusting the amount of incident light. The aperture stop AS may be disposed between lenses constituting the optical imaging system. In an example, the aperture stop AS may be disposed on the object side of a lens having the highest refractive index among lenses constituting the optical imaging system. For example, the aperture stop AS may be disposed between the second lens and the third lens.
The lens constituting the optical imaging system according to the example may have an aspherical surface. For example, the object side surface and the image side surface of the second lens and the fourth lens to the seventh lens may have aspherical surfaces. In another example, the object-side and image-side surfaces of the first, second, and fourth to seventh lenses may have aspherical surfaces. The aspherical surface of the lens is represented by equation 1.
In equation 1, c is the curvature (inverse of the radius of curvature) of the lens, K is a conic constant, and Y is the distance from any point on the aspherical surface of the lens to the optical axis. Further, constants a to D refer to aspherical coefficients. Z represents the distance along the optical axis from any point on the aspherical surface of the lens to the vertex of the aspherical surface.
The first to seventh lenses of the optical imaging system may have negative refractive power/positive refractive power/negative refractive power in order from the object side. Alternatively, the first to seventh lenses of the optical imaging system may have negative refractive power/positive refractive power/negative refractive power/positive refractive power in order from the object side. Alternatively, the first to seventh lenses of the optical imaging system may have negative refractive power/positive refractive power/negative refractive power/positive refractive power in order from the object side.
The first lens may have a negative refractive power, an object side surface of the first lens may have a convex shape, and an image side surface of the first lens may have a concave shape.
In an example, the second lens may have a negative refractive power, an object side of the second lens may have a concave shape, and an image side of the second lens may have a convex shape.
In another example, the second lens may have a positive refractive power, an object side of the second lens may have a convex shape, and an image side of the second lens may have a concave shape.
The third lens may have a positive refractive power, an object side surface of the third lens may have a convex shape, and an image side surface of the third lens may have a convex shape.
The fourth lens may have a positive refractive power, and an image side surface of the fourth lens may have a convex shape.
In an example, the fifth lens may have a negative refractive power, an object side surface of the fifth lens may have a concave shape, and an image side surface of the fifth lens may have a concave shape.
In an example, the sixth lens may have a positive refractive power, an object side surface of the sixth lens may have a convex shape, and an image side surface of the sixth lens may have a convex shape. The sixth lens may have at least one inflection point on at least one of the object-side and image-side surfaces. For example, the object-side surface of the sixth lens may be convex in the paraxial region and concave in a region other than the paraxial region. The image side surface of the sixth lens may be convex in the paraxial region and concave in a region other than the paraxial region.
In an example, the object side of the seventh lens may have a convex shape and the image side of the seventh lens may have a concave shape. The seventh lens may have at least one inflection point on at least one of the object-side and image-side surfaces. For example, the object side surface of the seventh lens may be convex in the paraxial region and concave in a region other than the paraxial region. The image side surface of the seventh lens may be concave in the paraxial region and convex in a region other than the paraxial region.
The lenses constituting the optical imaging system according to the example may be formed of plastic or glass material. For example, the first lens and the third lens may be formed of glass, and the other lenses may be formed of plastic. In another example, the third lens may be formed of glass, and the other lenses may be formed of plastic.
Plastic lenses have the advantage of having a relatively high precision when manufactured in large quantities using molds. However, the plastic lens has a disadvantage in that the refractive index change or the degree of thermal expansion according to temperature is greater than that of the glass lens according to temperature. For example, the refractive index of a plastic lens varies by 50 to 100 times according to temperature more than that of a glass lens, and the linear expansion coefficient is about 10 times higher. Because of these drawbacks, application of plastic lenses to vehicle cameras has a limitation in that the operating temperature should be ensured from-40 degrees celsius (°c) to +80 degrees celsius (°c).
According to an example of the present disclosure, in an optical imaging system composed of a plurality of lenses, a glass lens and a plastic lens may be appropriately set in consideration of the influence of the refractive power of each lens on the focal length. Therefore, even in the case of a temperature change around the lens, the focus of the optical imaging system can be maintained.
The present disclosure provides an optical imaging system in which a change in back focal length (hereinafter referred to as "BFL") in a temperature range of-40 (°c) to 80 (°c) is within 10 μm. In this case, BFL refers to the distance between the image side of the lens closest to the imaging plane and the imaging plane.
In an example, a glass lens may be used in a portion having a larger optical refractive power, and a plastic lens may be provided in the remaining portion. For example, the third lens disposed near the aperture stop AS and having a relatively strong refractive power may be formed of glass, and the remaining lenses may be formed of plastic. In another example, the externally exposed first and third lenses may be formed of glass, and the other lenses may be formed of plastic.
The optical imaging system according to the example may be configured by appropriately combining a plastic lens and a glass lens, and thus, the BFL variation amount in a wide operating temperature range of-40 degrees celsius (°c) to 80 degrees celsius (°c) may be limited to within 10 μm.
In an example, the optical imaging system may include an imaging plane IP (or image sensor) having a diagonal length of about 6 mm. In an example, the optical imaging system may be configured to have a total length of 15mm or less.
In an example, the optical imaging system may be characterized in that a lens that can generate an image with a resolving power of 80lp/mm or more may be used such that the length of the entire optical imaging system is shortened to 15mm or less. Therefore, the optical imaging system can be easily installed in a mobile device or the like. When a pattern corresponding to a spatial frequency of 80lp/mm is properly imaged on the imaging plane, it can be seen that a resolution of 1/960 of the diagonal length of the 6mm sensor is ensured. Thus, when the camera system is configured with a total field of view of 120 degrees, an angular resolution of 0.125 degrees can be ensured, thereby ensuring an resolving power that can distinguish objects about 20cm apart at a distance of 10 m.
The optical imaging system according to the example includes a total of 7 lenses composed of plastic lenses and glass lenses, and can obtain a sufficient level of resolving power required at a wide operating temperature of-40 degrees celsius (°c) to +80 degrees celsius (°c) by suppressing BFL variation.
The optical imaging system may satisfy one or more of the following conditional expressions.
In an example, there is provided a hybrid optical imaging system in which a glass lens and a plastic lens are used together, and which controls the change in BFL according to temperature in such a manner that the refractive power of each lens is optimized so as to satisfy conditional expression (1).
|Pnu|[10-6℃ -1 mm -1 ]≤30(1)
Pnu is an index representing the change in refractive power of the entire optical imaging system according to temperature, and is defined as the sum of Pnu values of lenses constituting the optical imaging system (i.e., pnu = Σpnui, i=1, 2..7). The Pnu value (i.e., pnui) of the i-th lens from the object side is defined as 1/(vti×fi). For example, the Pnu value of the entire optical imaging system is calculated as Σ1/(vti·fi) (i=1, 2, …, 7).
vti is [ DTni/(ni-1) -CTEi] -1 (°c), fi is the effective focal length of the ith lens, ni is the refractive index of the ith lens, and DTni is the rate of change of refractive index of the ith lens as a function of temperature (dni/dT), and CTEi is the coefficient of thermal expansion of the ith lens.
In an example, the third lens closest to the aperture stop AS is formed of glass, and the optical imaging system may satisfy conditional expression (2). For example, the effective focal length of the third lens may be 0.4 times or more the effective focal length of the entire optical imaging system.
f/f3≥0.4(2)
In the above conditional expression, f is an effective focal length of the entire optical imaging system, and f3 may be an effective focal length of the third lens.
In an example, the optical imaging system may satisfy conditional expression (3). In an example, the optical imaging system is configured such that a change in refractive power of the third lens as a function of temperature (Pnu 3) is substantially less than a change in refractive power of the entire optical imaging system as a function of temperature (Pnu). Therefore, BFL changes in a relatively wide temperature range may be suppressed to 10 μm or less.
|Pnu3/Pnu|<0.2(3)
In an example, the optical imaging system may additionally satisfy one or more of the following conditional expressions (4) to (8).
-2.0<∑1/(DTni·fi)[10 4 ℃mm -1 ]<20.0(i=1,2,…,7)(4)
0.2<DTnF/DTnR<0.6(5)
0.3-620<DTnT[10 -6 ℃ -1 ]<-450(6)
-220<DTnF[10 -6 ℃ -1 ]<-100(7)
-400<DTnR[10 -6 ℃ -1 ]<-300(8)
DTnT is the sum of the DTn values of the first to seventh lenses (i.e., Σdtni (i=1, 2,..7)), DTnF is the sum of the DTn values of the first and second lenses (i.e., Σdtni (i=1, 2)), DTnR is the sum of the DTn values of the third to seventh lenses (i.e., Σdtni (i=3, 4,..7)), and IMG HT is half the diagonal length of the imaging plane IP.
Hereinafter, examples will be described in detail with reference to the accompanying drawings.
Fig. 1 shows an optical imaging system 100 according to a first example. Fig. 2 is a graph showing aberrations of the optical imaging system 100. Fig. 3 is a graph showing the resolving power according to the field of view of the optical imaging system 100. Fig. 4 is a graph showing a change in BFL according to temperature in the optical imaging system 100.
The optical imaging system 100 includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixth lens 160, and a seventh lens 170, and may further include an aperture stop AS, a filter IRCF, and an imaging plane IP. A separate filter F may be additionally provided on the imaging plane IP. The filter F may be used to protect the imaging plane IP. In an example, the aperture stop AS is located between the second lens 120 and the third lens 130.
In an example, the first lens 110 and the third lens 130 are formed of glass, and the other lenses are formed of plastic.
Table 1 shows the characteristics (radius of curvature, thickness of lenses or distance between lenses, refractive index and abbe number) of the respective lenses. Table 1 also shows the refractive index change rate (DTn), coefficient of Thermal Expansion (CTE), and vt values of each lens according to temperature.
TABLE 1
The first lens 110 has a negative refractive power, the object side of the first lens 110 is convex, and the image side of the first lens 110 is concave.
The second lens 120 has a negative refractive power, the object side of the second lens 120 is concave, and the image side of the second lens 120 is convex.
The third lens 130 has a positive refractive power, the object side of the third lens 130 is convex, and the image side of the third lens 130 is convex.
The fourth lens 140 has a positive refractive power, the object side of the fourth lens 140 is convex, and the image side of the fourth lens 140 is convex.
The fifth lens 150 has a negative refractive power, the object side of the fifth lens 150 is concave, and the image side of the fifth lens 150 is concave.
The sixth lens 160 has a positive refractive power, the object side of the sixth lens 160 is convex, and the image side of the sixth lens 160 is convex.
The seventh lens 170 has a negative refractive power, the object side of the seventh lens 170 is convex, and the image side of the seventh lens 170 is concave. The seventh lens 170 may have at least one inflection point on at least one of the object-side and image-side surfaces. For example, the object-side surface of the seventh lens 170 may be convex in the paraxial region and concave in a region other than the paraxial region. The image side of the seventh lens 170 may be concave in the paraxial region and convex in regions other than the paraxial region.
The respective surfaces of the second lens 120 and the fourth lens 140 to the seventh lens 170 have aspherical coefficients as shown in table 2.
TABLE 2
Referring to fig. 4, in the optical imaging system 100, the BFL variation is maintained at a level of 9 μm over a temperature range of-40 degrees celsius (°c) to 80 degrees celsius (°c).
Fig. 5 shows an optical imaging system 200 according to a second example. Fig. 6 is a graph showing aberrations of the optical imaging system 200. Fig. 7 is a graph showing the resolving power according to the field of view of the optical imaging system 200. Fig. 8 is a graph showing a change in BFL according to temperature in the optical imaging system 200.
The optical imaging system 200 includes a first lens 210, a second lens 220, a third lens 230, a fourth lens 240, a fifth lens 250, a sixth lens 260, and a seventh lens 270, and may further include an aperture stop AS, an optical filter IRCF, and an imaging plane IP. A separate filter F may be additionally provided on the imaging plane IP. The filter F may be used to protect the imaging plane IP. In an example, the aperture stop AS is located between the second lens 220 and the third lens 230.
In an example, the first lens 210 and the third lens 230 are formed of glass, and the other lenses are formed of plastic.
Table 3 shows the characteristics (radius of curvature, thickness of lenses or distance between lenses, refractive index and abbe number) of the respective lenses. Table 3 also shows the refractive index change rate (DTn), coefficient of Thermal Expansion (CTE), and vt values of each lens according to temperature.
TABLE 3
The first lens 210 has a negative refractive power, the object side of the first lens 210 is convex, and the image side of the first lens 210 is concave.
The second lens 220 has a positive refractive power, the object side of the second lens 220 is concave, and the image side of the second lens 220 is convex.
The third lens 230 has a positive refractive power, the object side of the third lens 230 is convex, and the image side of the third lens 230 is convex.
The fourth lens 240 has a positive refractive power, the object side of the fourth lens 240 is concave, and the image side of the fourth lens 240 is convex.
The fifth lens 250 has a negative refractive power, the object side of the fifth lens 250 is concave, and the image side of the fifth lens 250 is concave.
The sixth lens 260 has a positive refractive power, the object side of the sixth lens 260 is convex, and the image side of the sixth lens 260 is convex. The sixth lens 260 may have at least one inflection point on at least one of the object-side and image-side surfaces. For example, the object-side surface of the sixth lens 260 may be convex in the paraxial region and concave in a region other than the paraxial region. The image side surface of the sixth lens 260 may be convex in the paraxial region and concave in a region other than the paraxial region.
The seventh lens 270 has a positive refractive power, the object side of the seventh lens 270 is convex, and the image side of the seventh lens 270 is concave. The seventh lens 270 may have at least one inflection point on at least one of the object-side and image-side surfaces. For example, the object-side surface of the seventh lens 270 may be convex in the paraxial region and concave in a region other than the paraxial region. The image side of the seventh lens 270 may be concave in the paraxial region and convex in regions other than the paraxial region.
The respective surfaces of the second lens 220 and the fourth lens 240 to the seventh lens 270 have aspherical surface coefficients as shown in table 4.
TABLE 4
Face numbering | K | A | B | C |
3 | -1.9178E+00 | -6.8773E-03 | -4.8305E-05 | -1.7677E-05 |
4 | 9.2986E-01 | -4.3618E-03 | 1.2975E-04 | 6.0999E-05 |
8 | -5.4817E+01 | -1.1096E-02 | 1.1958E-03 | 7.1589E-05 |
9 | 2.2549E+01 | -1.5180E-02 | 2.4476E-03 | 9.4191E-05 |
10 | 6.9512E+00 | -7.2864E-03 | 1.2951E-03 | 0.0 |
11 | -2.5817E+01 | -8.0063E-04 | 2.7939E-04 | -1.2485E-04 |
12 | -8.6693E+00 | -4.5403E-03 | 1.0275E-03 | -1.7864E-04 |
13 | 0.0 | -1.2453E-03 | 4.1014E-04 | -4.3439E-05 |
14 | 0.0 | -1.4026E-02 | 8.8105E-05 | -6.5722E-05 |
15 | 0.0 | -1.3579E-02 | -1.9796E-04 | -1.6600E-05 |
Referring to fig. 8, in the optical imaging system 200, the BFL variation is maintained at a level of 2 μm over a temperature range of-40 degrees celsius (°c) to 80 degrees celsius (°c).
Fig. 9 shows an optical imaging system 300 according to a third example. Fig. 10 is a graph showing aberrations of the optical imaging system 300. Fig. 11 is a graph showing the resolving power according to the field of view of the optical imaging system 300. Fig. 12 is a graph showing a change in BFL according to temperature in the optical imaging system 300.
The optical imaging system 300 includes a first lens 310, a second lens 320, a third lens 330, a fourth lens 340, a fifth lens 350, a sixth lens 360, and a seventh lens 370, and may further include an aperture stop AS, an optical filter IRCF, and an imaging plane IP. A separate filter F may be additionally provided on the imaging plane IP. The filter F may be used to protect the imaging plane IP. In an example, the aperture stop AS is located between the second lens 320 and the third lens 330.
In an example, the first lens 310 and the third lens 330 are formed of glass, and the other lenses are formed of plastic.
Table 5 shows the characteristics (radius of curvature, thickness of lenses or distance between lenses, refractive index, and abbe number) of each lens. Table 5 also shows the refractive index change rate (DTn), coefficient of Thermal Expansion (CTE), and vt values of each lens according to temperature.
TABLE 5
The first lens 310 has a negative refractive power, an object side of the first lens 310 is convex, and an image side of the first lens 310 is concave.
The second lens 320 has a negative refractive power, the object side of the second lens 320 is concave, and the image side of the second lens 320 is convex.
The third lens 330 has a positive refractive power, the object side of the third lens 330 is convex, and the image side of the third lens 330 is convex.
The fourth lens 340 has a positive refractive power, the object side of the fourth lens 340 is convex, and the image side of the fourth lens 340 is convex.
The fifth lens 350 has a negative refractive power, the object side of the fifth lens 350 is concave, and the image side of the fifth lens 350 is concave.
The sixth lens 360 has positive refractive power, the object side of the sixth lens 360 is convex, and the image side of the sixth lens 360 is convex.
The seventh lens 370 has a positive refractive power, the object side of the seventh lens 370 is convex, and the image side of the seventh lens 370 is concave. The seventh lens 370 may have at least one inflection point on the image side.
The respective surfaces of the second lens 320 and the fourth lens 340 to the seventh lens 370 have aspherical surface coefficients as shown in table 6.
TABLE 6
The lens shape having both concave and convex shapes on one surface may be advantageous in making the entire optical imaging system 300 small and correcting image-side curvature of field, but has a disadvantage of being difficult to manufacture. In the third example, the seventh lens 370 has a relatively simple shape, which may be advantageous in ensuring mass production.
Referring to fig. 12, in the optical imaging system 300, the BFL variation is maintained at a level of 6 μm over a temperature range of-40 degrees celsius (°c) to 80 degrees celsius (°c).
Fig. 13 is a diagram showing an optical imaging system 400 according to a fourth example. Fig. 14 is a graph showing aberrations of the optical imaging system 400. Fig. 15 is a graph showing the resolving power according to the field of view of the optical imaging system 400. Fig. 16 is a graph showing a change in BFL according to temperature in the optical imaging system 400.
The optical imaging system 400 includes a first lens 410, a second lens 420, a third lens 430, a fourth lens 440, a fifth lens 450, and sixth and seventh lenses 460 and 470, and may further include an aperture stop AS, an optical filter IRCF, and an imaging plane IP. A separate filter F may be additionally provided on the imaging plane IP. The filter F may be used to protect the imaging plane IP. In an example, the aperture stop AS is located between the second lens 420 and the third lens 430.
In an example, the first lens 410 and the third lens 430 are formed of glass, and the other lenses are formed of plastic.
Table 7 shows the characteristics (radius of curvature, thickness of lenses or distance between lenses, refractive index, and abbe number) of each lens. Table 7 also shows refractive index change rate (DTn), coefficient of Thermal Expansion (CTE), and vt values according to temperature for each lens.
TABLE 7
The first lens 410 has a negative refractive power, the object side of the first lens 410 is convex, and the image side of the first lens 410 is concave.
The second lens 420 has a positive refractive power, the object side of the second lens 420 is convex, and the image side of the second lens 420 is concave.
The third lens 430 has a positive refractive power, an object side of the third lens 430 is convex, and an image side of the third lens 430 is convex.
The fourth lens 440 has a positive refractive power, the object side of the fourth lens 440 is concave, and the image side of the fourth lens 440 is convex.
The fifth lens 450 has a negative refractive power, the object side of the fifth lens 450 is concave, and the image side of the fifth lens 450 is concave.
The sixth lens 460 has positive refractive power, the object side of the sixth lens 460 is convex, and the image side of the sixth lens 460 is convex. The sixth lens 460 may have at least one inflection point on the image side.
The seventh lens 470 has a positive refractive power, an object side of the seventh lens 470 is convex, and an image side of the seventh lens 470 is concave. The seventh lens 470 may have at least one inflection point on the image side.
The respective surfaces of the second lens 420 and the fourth lens 440 to seventh lens 470 have aspherical surface coefficients as shown in table 8.
TABLE 8
Face numbering | K | A | B | C |
3 | -1.9178E+00 | 1.6847E-03 | 7.9798E-05 | 9.3773E-05 |
4 | 9.2986E-01 | -3.0996E-03 | 3.1458E-04 | 2.6065E-04 |
8 | -5.4817E+01 | -1.8991E-02 | 7.7995E-04 | 1.8995E-04 |
9 | 2.2549E+01 | -3.5607E-02 | 5.3216E-03 | -4.2579E-04 |
10 | 6.9512E+00 | 2.8062E-03 | -1.1297E-03 | 0.0 |
11 | -2.5817E+01 | 1.3599E-02 | -3.5750E-03 | 2.8194E-04 |
12 | -8.6693E+00 | -1.3414E-02 | 2.3052E-03 | -2.5433E-05 |
13 | 0.0 | 2.5580E-03 | -1.3568E-04 | 1.6813E-04 |
14 | 0.0 | -1.8436E-02 | 2.2527E-03 | -1.5342E-04 |
15 | 0.0 | -2.5029E-02 | 2.5506E-03 | -1.5835E-04 |
In a fourth example, the object side of the second lens 420 has a convex meniscus shape. If the object-side surface of the second lens 420 is concave, there may be a disadvantage in that the incident angle of the lower light ray of the field of view having a large field angle increases, so that the entire optical imaging system 400 becomes sensitive. In a fourth example, the above-described drawbacks may be compensated for.
Referring to fig. 16, in the optical imaging system 400, the BFL variation is maintained at a level of 5 μm over a temperature range of-40 degrees celsius (°c) to 80 degrees celsius (°c).
Fig. 17 shows an optical imaging system 500 according to a fifth example. Fig. 18 is a graph showing aberrations of the optical imaging system 500. Fig. 19 is a graph showing the resolving power according to the field of view of the optical imaging system 500. Fig. 20 is a graph showing a change in BFL according to temperature in the optical imaging system 500.
The optical imaging system 500 includes a first lens 510, a second lens 520, a third lens 530, a fourth lens 540, a fifth lens 550, a sixth lens 560, and a seventh lens 570, and may further include an aperture stop AS, an optical filter IRCF, and an imaging plane IP. A separate filter F may be additionally provided on the imaging plane IP. The filter F may be used to protect the imaging plane IP. In an example, the aperture stop AS is located between the second lens 520 and the third lens 530.
In an example, the third lens 530 is formed of glass, and the other lenses are formed of plastic. In contrast to the other examples discussed above, in the fifth example, the first lens 510 is formed of plastic. In the case where the indoor camera is not externally exposed, the optical imaging system can withstand external impact even when the first lens 510 is formed of plastic. Since the first lens 510 is formed of plastic, the manufacturing cost and weight of the optical imaging system can be reduced.
Table 9 shows the characteristics (radius of curvature, thickness of lenses or distance between lenses, refractive index, and abbe number) of each lens. Table 9 also shows the refractive index change rate (DTn), coefficient of Thermal Expansion (CTE), and vt values of each lens according to temperature.
TABLE 9
The first lens 510 has a negative refractive power, the object side of the first lens 510 is convex, and the image side of the first lens 510 is concave.
The second lens 520 has a negative refractive power, the object side of the second lens 520 is concave, and the image side of the second lens 520 is convex.
The third lens 530 has a positive refractive power, the object side of the third lens 530 is convex, and the image side of the third lens 530 is convex.
The fourth lens 540 has a positive refractive power, the object side of the fourth lens 540 is convex, and the image side of the fourth lens 540 is convex.
The fifth lens 550 has a negative refractive power, the object side of the fifth lens 550 is concave, and the image side of the fifth lens 550 is concave.
The sixth lens 560 has positive refractive power, the object side of the sixth lens 560 is convex, and the image side of the sixth lens 560 is convex. The sixth lens 560 can have at least one inflection point on the image side. For example, the image side surface of the sixth lens 560 may be convex in the paraxial region and concave in a region other than the paraxial region.
The seventh lens 570 has a negative refractive power, an object side of the seventh lens 570 is convex, and an image side of the seventh lens 570 is concave. The seventh lens 570 may have at least one inflection point on at least one of an object side and an image side. For example, the object-side surface of the seventh lens 570 may be convex in the paraxial region and concave in regions other than the paraxial region. The image side of the seventh lens 570 may be concave in the paraxial region and convex in regions other than the paraxial region.
The respective surfaces of the first lens 510, the second lens 520, and the fourth lens 540 to the seventh lens 570 have aspherical surface coefficients as shown in table 10.
TABLE 10
Referring to fig. 20, in the optical imaging system 500, the BFL variation is maintained at a level of 5 μm.
Fig. 21 shows an optical imaging system 600 according to a sixth example. Fig. 22 is a graph showing aberrations of the optical imaging system 600. Fig. 23 is a graph showing the resolving power according to the field of view of the optical imaging system 600. Fig. 24 is a graph showing a change in BFL according to temperature in the optical imaging system 600.
The optical imaging system 600 includes a first lens 610, a second lens 620, a third lens 630, a fourth lens 640, a fifth lens 650, a sixth lens 660, and a seventh lens 670, and may further include an aperture stop AS, an optical filter IRCF, and an imaging plane IP. A separate filter F may be additionally provided on the imaging plane IP. The filter F may be used to protect the imaging plane IP. In an example, the aperture stop AS is located between the second lens 620 and the third lens 630.
In an example, the first lens 610 and the third lens 630 are formed of glass, and the other lenses are formed of plastic.
Table 11 shows the characteristics (radius of curvature, thickness of lenses or distance between lenses, refractive index, and abbe number) of each lens. Table 11 also shows refractive index change rate (DTn), coefficient of Thermal Expansion (CTE), and vt values according to temperature for each lens.
TABLE 11
The first lens 610 has a negative refractive power, an object side of the first lens 610 is convex, and an image side of the first lens 610 is concave.
The second lens 620 has a negative refractive power, the object side of the second lens 620 is concave, and the image side of the second lens 620 is convex.
The third lens 630 has a positive refractive power, the object side of the third lens 630 is convex, and the image side of the third lens 630 is convex.
The fourth lens 640 has a positive refractive power, an object side of the fourth lens 640 is convex, and an image side of the fourth lens 640 is convex.
The fifth lens 650 has a negative refractive power, an object side of the fifth lens 650 is concave, and an image side of the fifth lens 650 is concave.
The sixth lens 660 has a positive refractive power, an object side surface of the sixth lens 660 is convex, and an image side surface of the sixth lens 660 is convex. The sixth lens 660 may have at least one inflection point on at least one of the object-side and image-side surfaces. For example, the object-side surface of the sixth lens 660 may be convex in the paraxial region and concave in a region other than the paraxial region. The image side surface of the sixth lens 660 may be convex in the paraxial region and concave in a region other than the paraxial region.
The seventh lens 670 has a negative refractive power, the object side of the seventh lens 670 is convex, and the image side of the seventh lens 670 is concave. The seventh lens 670 may have at least one inflection point on at least one of the object-side surface and the image-side surface. For example, the object-side surface of the seventh lens 670 may be convex in the paraxial region and concave in a region other than the paraxial region. The image side surface of the seventh lens 670 may be concave in the paraxial region and convex in a region other than the paraxial region.
The respective surfaces of the second lens 620 to the seventh lens 670 have aspherical coefficients as shown in table 12.
TABLE 12
Referring to fig. 24, in the optical imaging system 600, the BFL variation is maintained at a level of 3 μm.
Fig. 25 shows an optical imaging system 700 according to a seventh example. Fig. 26 is a graph showing aberrations of the optical imaging system 700. Fig. 27 is a graph showing the resolving power according to the field of view of the optical imaging system 700. Fig. 28 is a graph showing a change in BFL according to temperature in the optical imaging system 700.
The optical imaging system 700 includes a first lens 710, a second lens 720, a third lens 730, a fourth lens 740, a fifth lens 750, a sixth lens 760, and a seventh lens 770, and may further include an aperture stop AS, an optical filter IRCF, and an imaging plane IP. A separate filter F may be additionally provided on the imaging plane IP. The filter F may be used to protect the imaging plane IP. In an example, the aperture stop AS is located between the second lens 720 and the third lens 730.
In an example, the first lens 710 and the third lens 730 are formed of glass, and the other lenses are formed of plastic.
Table 13 shows the characteristics (radius of curvature, thickness of lenses or distance between lenses, refractive index, and abbe number) of each lens. Table 13 also shows the refractive index change rate (DTn), coefficient of Thermal Expansion (CTE), and vt values of each lens according to temperature.
TABLE 13
The first lens 710 has a negative refractive power, an object side of the first lens 710 is convex, and an image side of the first lens 710 is concave.
The second lens 720 has a negative refractive power, the object side of the second lens 720 is concave, and the image side of the second lens 720 is convex.
The third lens 730 has a positive refractive power, the object side of the third lens 730 is convex, and the image side of the third lens 730 is convex.
The fourth lens 740 has a positive refractive power, the object side of the fourth lens 740 is convex, and the image side of the fourth lens 740 is convex.
The fifth lens 750 has a negative refractive power, the object side of the fifth lens 750 is concave, and the image side of the fifth lens 750 is concave.
The sixth lens 760 has a positive refractive power, the object-side surface of the sixth lens 760 is convex, and the image-side surface of the sixth lens 760 is convex. The sixth lens 760 may have at least one inflection point on at least one of the object-side and image-side surfaces. For example, the object-side surface of the sixth lens 760 may be convex in the paraxial region and concave in a region other than the paraxial region. The image side surface of the sixth lens 760 may be convex in the paraxial region and concave in a region other than the paraxial region.
The seventh lens 770 has negative refractive power, the object side of the seventh lens 770 is convex, and the image side of the seventh lens 770 is concave. The seventh lens 770 can have at least one inflection point on at least one of the object side and the image side. For example, the object side surface of the seventh lens 770 may be convex in the paraxial region and concave in regions other than the paraxial region. The image side of the seventh lens 770 may be concave in the paraxial region and convex in regions other than the paraxial region.
The respective surfaces of the first lens 710, the second lens 720, and the fourth lens 740 to seventh lens 770 have aspherical surface coefficients as shown in table 14.
TABLE 14
Face numbering | K | A | B | C | D |
1 | 0.0 | -2.3483E-03 | 1.8531E-05 | 0.0 | 0.0 |
2 | 0.0 | -2.7242E-03 | -4.6246E-04 | 0.0 | 0.0 |
3 | 0.0 | 1.5923E-03 | 1.3811E-03 | 0.0 | 0.0 |
4 | 0.0 | 2.3964E-03 | 5.2067E-04 | 0.0 | 0.0 |
8 | 0.0 | 2.0679E-03 | 1.5744E-04 | 5.2633E-05 | -2.5139E-05 |
9 | 0.0 | -5.5756E-03 | -4.8888E-04 | 3.6114E-04 | -3.8940E-05 |
10 | 0.0 | -1.2112E-02 | 3.1724E-04 | 6.9229E-04 | -6.3864E-05 |
11 | 0.0 | -1.3503E-02 | 3.0251E-03 | -5.5277E-04 | 6.6208E-05 |
12 | 0.0 | -1.0109E-03 | 5.0109E-04 | -1.7585E-04 | 1.4231E-05 |
13 | 0.0 | 7.7453E-03 | 1.0580E-03 | 5.5385E-05 | -4.7434E-06 |
14 | 0.0 | -3.1178E-02 | 8.1158E-04 | -4.3599E-05 | 1.5809E-05 |
15 | 0.0 | -4.0082E-02 | 1.8155E-03 | -7.9485E-05 | -2.3984E-06 |
Referring to fig. 28, in the optical imaging system 700, the amount of BFL change is maintained at a level of 7 μm.
Table 15 shows values of conditional expressions of the optical imaging systems according to the respective examples.
TABLE 15
As described above, the optical imaging system according to various examples can provide relatively high quality resolution even over a wide temperature range. Furthermore, the optical imaging system may be configured such that BFL variation is significantly small even over a wide temperature range, and thus, focal length may be maintained at a particular level.
While this disclosure includes particular examples, it will be apparent to those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the claims and their equivalents. The examples described herein should be construed in a descriptive sense only and not for purposes of limitation. The descriptions of features or aspects in each example should be considered applicable to similar features or aspects in other examples. Suitable results may also be obtained if the described techniques are performed in a different order and/or if components in the described systems, architectures, devices or circuits are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Thus, the scope of the present disclosure is defined not by the detailed description but by the claims and their equivalents, and all modifications within the scope of the claims and their equivalents are to be construed as being included in the present disclosure.
Claims (11)
1. An optical imaging system, comprising:
a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens disposed in order from the object side, and an image sensor for converting an incident image of the object into an electrical signal;
Wherein the optical imaging system further includes an aperture stop disposed between the second lens and the third lens, and the third lens closest to the aperture stop has positive refractive power, and
wherein, pnu is 10-6-1 mm-1]And +.30, wherein PNU is ΣPnui, where i=1, 2, …, 7, pnui is 1/(vti·fi), vti is [ DTni/(ni-1) -CTEi] -1 Fi is the effective focal length of the ith lens, ni is the refractive index of the ith lens, DTni is the rate of change of refractive index of the ith lens as a function of temperature (dni/dT), and CTEi is the coefficient of thermal expansion of the ith lens.
2. The optical imaging system of claim 1, wherein,
0.4.ltoreq.f/f 3, where f is the effective focal length of the optical imaging system, and f3 is the effective focal length of the third lens.
3. The optical imaging system of claim 1, wherein i Pnu3/Pnu i <0.2.
4. The optical imaging system of claim 1, wherein the third lens is comprised of glass and the second, fourth, fifth, sixth, and seventh lenses are comprised of plastic.
5. The optical imaging system of claim 1, wherein-2.0 <∑1/(DTni·fi)[10 4 ℃ mm -1 ]<20.0, wherein i=1, 2, …, 7.
6. The optical imaging system of claim 1, wherein 0.2< DTnF/DTnR <0.6, wherein DTnF is a sum of DTn values of the first and second lenses Σdtni (i=1, 2), and DTnR is a sum of DTn values of the third to seventh lenses Σdtni (i=3, 4, …, 7).
7. The optical imaging system of claim 1, wherein-620<DTnT[10 -6 ℃ -1 ]<-450, wherein DTnT is the sum Σdtni of the DTn values of the first to seventh lenses (i=1, 2, …, 7).
8. The optical imaging system of claim 1, wherein-220<DTnF[10 -6 ℃ -1 ]<-100, wherein DTnF is the sum Σdtni of the DTnF values of the first and second lenses (i=1, 2).
9. The optical imaging system of claim 1, wherein-400<DTnR[10 -6 ℃ -1 ]<-300, wherein DTnR is the sum Σdtni of the DTn values of the third to seventh lenses (i=3, 4, …, 7).
10. The optical imaging system of claim 1, wherein an object side of the seventh lens is convex and an image side of the seventh lens is concave.
11. The optical imaging system of claim 1, wherein the first lens has a negative refractive power, the fourth lens has a positive refractive power, the fifth lens has a negative refractive power, and the sixth lens has a positive refractive power.
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CN111830679A (en) * | 2020-07-22 | 2020-10-27 | 天津欧菲光电有限公司 | Optical imaging system, image capturing module, terminal and automobile |
KR102642903B1 (en) * | 2021-03-26 | 2024-03-04 | 삼성전기주식회사 | Optical Imaging System |
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