WO2019019496A1 - 鱼眼镜头装置 - Google Patents

鱼眼镜头装置 Download PDF

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Publication number
WO2019019496A1
WO2019019496A1 PCT/CN2017/112739 CN2017112739W WO2019019496A1 WO 2019019496 A1 WO2019019496 A1 WO 2019019496A1 CN 2017112739 W CN2017112739 W CN 2017112739W WO 2019019496 A1 WO2019019496 A1 WO 2019019496A1
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Prior art keywords
lens
fisheye
refractive power
lens device
image
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PCT/CN2017/112739
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English (en)
French (fr)
Inventor
毛庆
李顺楠
邓良君
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捷西迪（广州）光学科技有限公司
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Publication of WO2019019496A1 publication Critical patent/WO2019019496A1/zh

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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
    • 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

Definitions

  • the present specification relates to a fisheye lens device, and more particularly to a fisheye lens device for stereoscopic projection.
  • the fisheye lens adopts a specific projection method.
  • the projections below are well known.
  • f is the focal length of the fisheye lens device
  • ⁇ is the incident angle of the incident light incident on the fisheye lens device
  • y is the height (image height) of the image formed on the image plane.
  • Fig. 1 is an explanatory view showing a relationship between an incident angle and an image height according to a projection method.
  • the horizontal axis represents the incident angle ⁇ (radian), and the vertical axis represents the image height y (mm).
  • the curves C1 to C4 respectively indicate the image heights corresponding to the incident angles in the projection modes of (1) to (4), and these curves are hereinafter referred to as "image height curves".
  • the focal length F 1 mm is set.
  • the ratio ⁇ is the slope of the image height curve shown in Fig. 1.
  • the ratio ⁇ gradually decreases as the incident angle ⁇ increases. This means that the ratio of the amount of information of the peripheral portion is smaller than the amount of information of the central portion in the image.
  • the equidistant projection method curve C3
  • the ratio of the amount of information in the center portion of the image to the amount of information in the peripheral portion is substantially the same.
  • the ratio ⁇ gradually increases as the incident angle ⁇ increases. This means that the ratio of the amount of information in the peripheral portion is larger than the amount of information in the center portion in the image. Therefore, when it is necessary to have a large amount of information in the peripheral portion, it is preferable to use an equidistant projection method (curve C3) or a stereoscopic projection method (curve C4).
  • Patent Document 1 Japanese Patent Publication No. 2007-164079
  • the ratio ⁇ gradually increases as the incident angle ⁇ increases, so that it can be compared with the amount of information in the central portion of the image. Increase the proportion of information in the peripheral area.
  • the specification of the present application discloses a fisheye lens device which is small in size while increasing the amount of information in the peripheral portion.
  • the fisheye lens device disclosed in the present application is provided with a first lens having a negative refractive power, a second lens having a negative refractive power, a diaphragm, a third lens having a positive refractive power, and a positive refractive power in this order from the object side.
  • a fourth lens, a fifth lens having a positive refractive power, and a sixth lens having a positive refractive power wherein a focal length of the fisheye lens device is f, an incident angle of incident light of the fisheye lens device is ⁇ , and an image plane is formed
  • y 2 ⁇ f ⁇ tan( ⁇ /2) and ⁇ D/2y ⁇ 5.0.
  • the first lens, the second lens, and the third lens may each be composed of a material having a refractive power of 1.8 or more.
  • the fifth lens and the sixth lens described above may be formed by a cemented lens that is bonded (for example, bonded) to each other.
  • the aforementioned fourth lens may be composed of an aspherical lens.
  • the fisheye lens device disclosed in the present application since the stereoscopic projection method is adopted, a large amount of information can be obtained in the peripheral portion of the image. On the other hand, since ⁇ D/2y ⁇ 5.0, the fisheye lens device is miniaturized as compared with the image circle.
  • Figure 1 is an explanatory view showing the relationship between the incident angle and the image height
  • Fig. 2 is a view showing the structure of a fisheye lens device according to the first embodiment
  • Figure 3 is a light path diagram of the fisheye lens device of Figure 2;
  • Figure 4 is a view showing the structure of a fisheye lens device according to a second embodiment
  • Fig. 5 is an aberration diagram of the fisheye lens device according to the first embodiment
  • Figure 6 is a comparison of the fisheye lens device according to the first embodiment
  • Figure 7 is a diagram showing aberrations of the fisheye lens device according to the second embodiment.
  • Fig. 8 is a view showing the degree of contrast of the fisheye lens device according to the second embodiment.
  • FIG. 2 is a configuration diagram showing the configuration of the fisheye lens device 10.
  • FIG. 3 is an optical path diagram of the fisheye lens device 10.
  • the left side of the drawing is the object side
  • the right side of the drawing is the image side.
  • the fisheye lens device 10 disclosed in the present application can be applied to various image pickup apparatuses using image sensors such as CCD or CMOS.
  • the fisheye lens device 10 disclosed in the present application is particularly suitable for a case where a plurality of images are combined into a new image, or when it is desired to perform a wide-range shooting with a single camera.
  • a new image is synthesized from a plurality of images, for example, a surround view system mounted on a vehicle or a case where an image is captured for 3D photography.
  • the camera and the in-vehicle camera (camera) mounted on the vehicle to detect a pedestrian or an obstacle are monitored.
  • An image sensor 100 composed of a CCD, CMOS, or the like is disposed at an imaging surface of the fisheye lens device 10.
  • the image sensor 100 outputs an image pickup signal corresponding to the optical image formed by the fisheye lens device 10.
  • the fisheye lens device 10 includes six lenses arranged along the optical axis Z1.
  • the lenses constituting the fisheye lens device 10 are referred to as a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6 in order from the object side.
  • the fisheye lens device 10 is provided with an aperture stop 12 between the third lens L3 and the fourth lens L4. Further, between the sixth lens L6 and the image sensor 100, the fisheye lens device 10 can arrange various optical members 14 in accordance with the configuration of the image pickup apparatus to which it is mounted.
  • the optical member 14 includes, for example, a flat optical member such as a cover glass and an infrared cut filter for protecting the surface of the image sensor.
  • the fifth lens L5 and the sixth lens L6 may be coated with a film or the like without using the optical member 14, so as to achieve the same effect as the optical member 14. According to this, the number of parts can be reduced and the total length can be shortened.
  • the first lens (first lens L1) from the object side is a glass lens having a negative refractive power; the second lens (second lens L2) has a negative optical focus.
  • Degree of glass lens More specifically, the first lens L1 is a meniscus-shaped negative lens having a surface S1 on the convex object side (that is, a convex surface toward the object side) and a surface S2 on the concave image side in this order from the object side. Both the face S1 and the face S2 are spherical.
  • the second lens L2 is a meniscus-shaped negative lens having a surface S3 on the convex object side and a surface S4 on the image side in the order from the object side. Both the face S3 and the face S4 are spherical.
  • the third lens (third lens L3) from the object side is a glass lens having positive refractive power. More specifically, the third lens L3 is a meniscus-shaped positive lens having a surface S5 on the concave object side and a surface S6 on the convex image side in this order from the object side. Face S5 And the surface S6 is spherical.
  • the first lens L1, the second lens L2, and the third lens L3 are each composed of glass having a refractive power of 1.8 or more.
  • the total optical length ⁇ D can be shortened while maintaining the viewing angle 2 ⁇ .
  • the total optical length ⁇ D refers to the distance from the end surface of the object side of the first lens L1 to the optical axis between the image planes of the image sensor 100. Further, according to such a configuration, the chromatic aberration of the entire fisheye lens device 10 can be reduced.
  • the fourth lens L4 located behind the image aperture 12 (image side) is a glass lens having positive power. More specifically, the fourth lens L4 is a biconvex positive lens having a surface S8 on the convex object side and a surface S9 on the convex image side in this order from the object side. Both the face S8 and the face S9 are aspherical.
  • the fourth lens L4 is aspherical in order to improve the quality of the peripheral portion (peripheral image) of the image obtained in the final image plane, which will be described later.
  • the fifth lens L5 and the sixth lens L6 constitute a cemented lens (double cemented lens) that are joined to each other.
  • the fisheye lens device 10 disclosed in the present specification is composed of six five sets of structures.
  • the fifth lens L5 is a glass lens having positive refractive power. More specifically, the fifth lens L5 is a double convex positive lens having a surface S10 convex toward the object side and a surface S11 convex toward the image side in this order from the object side. Both the face S10 and the face S11 are spherical.
  • the sixth lens L6 is a glass lens having a negative refractive power.
  • the sixth lens L6 is a meniscus-shaped negative lens having a surface S11 on the concave object side and a surface S12 concave on the image side in order from the object side.
  • This face S12 is a spherical surface.
  • y is the height of the image formed on the image plane
  • f is the focal length of the fisheye lens device 10
  • ⁇ is the incident angle of the incident light of the fisheye lens device 10.
  • the closer to the periphery, the larger the ratio ⁇ ⁇ y / ⁇ of the increase amount ⁇ y of the image height y of the increase amount ⁇ of the incident angle ⁇ .
  • the ratio ⁇ 85-90 at 85° ⁇ ⁇ ⁇ 90° of the peripheral portion of the image is approximately twice the ratio ⁇ 0-5 at 0° ⁇ ⁇ ⁇ 5° of the central portion of the image.
  • the stereoscopic projection is similar to human vision, and the closer the sun and the moon are to the horizon, the larger the psychological space looks the same.
  • the amount of increase ⁇ y of the image height y increases as the peripheral portion approaches.
  • a large amount of information is required as the peripheral portion, for example, a plurality of images are combined. More specifically, for example, in a surround view system and 3D photography mounted on a vehicle, a plurality of cameras are used to combine a plurality of images into one composite image. At this time, in order to improve the accuracy of the synthesis, it is desirable that the image obtained from each camera is an image having a relatively large amount of information in the peripheral portion. Therefore, the stereoscopic projection method is a particularly useful projection method in the case of a surround view system that combines a plurality of images and 3D photography.
  • the angle of view 2 ⁇ is larger than 180°. Therefore, the fisheye lens device 10 of the present application is an ideal camera for large-scale photography, and is also applicable to, for example, a surveillance camera and an in-vehicle camera or the like mounted on a vehicle for detecting a pedestrian/obstacle or the like.
  • the fifth lens L5 and the sixth lens L6 in the present application are cemented lenses.
  • the distortion of the fisheye lens device 10 is obtained. It is corrected to a state close to (Y-Y') / Y' ⁇ 100.
  • the fourth lens L4 close to the image side is used as an aspherical lens than the cemented lens (the fifth lens L5 and the sixth lens L6).
  • This fourth lens L4 solves the problem of the angle between the chief ray and the optical axis, and the obtained aspherical shape improves the relationship between the fourth lens L4 and the fifth lens L5, improving the quality of the peripheral image.
  • the present application is composed of a glass lens having a high refractive power (refractive force N 1.8 or more) of three lenses (L1, L2, L3) close to the image side.
  • the ratio of the optical total length ⁇ D to the image circle 2y can be reduced, that is, ⁇ D/2y.
  • ⁇ D/2y is set to 5.0 or less.
  • the total length of the fisheye lens device 10 can be reduced. Therefore, the fisheye lens device 10 of the present application is a lens device which is particularly suitable for a camera (camera) having a limited space such as an in-vehicle camera.
  • all of the six lenses constituting the fisheye lens device 10 are glass lenses.
  • Glass has a lower coefficient of thermal expansion (temperature dependence) than plastic. Therefore, all of the first to sixth lenses L1 to L6 are glass lenses, and variations in lens characteristics (such as focal length) that change with temperature can be reduced. As a result, a stable quality image can be obtained even in an environment where the temperature changes greatly.
  • the configuration of the fisheye lens device 10 of the first embodiment is as shown in FIG. 2.
  • the fisheye lens device 10 of the first embodiment is provided with a glass lens first lens L1 having a negative refractive power and a glass lens second lens L2 having a negative refractive power, and a glass lens having a positive refractive power, in order from the object side.
  • the first lens L1, the second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 are all spherical lenses, and the fourth lens L4 is an aspherical lens.
  • the fisheye lens device 10 has a focal length EFFL of 1.41 mm, an F/No (F-number) of 2.0, and a viewing angle 2 ⁇ of 190°. Further, the total optical length ⁇ D of the fisheye lens device 10 is 16.048 mm, the circle 2y is about 5.35 mm, and the ⁇ D/2y is about 3. Tables 1 to 3 show specific lens data of the fisheye lens device 10 according to the first embodiment. Among them, OBJ is the object surface, STO is the light surface, and IMA is the image surface.
  • the "face #” column indicates that the number of the face Si is represented by i.
  • the column “R” in Table 1 indicates the value of the radius of curvature in the vicinity of the optical axis of each surface Si (mm); the column “D” indicates the distance between the faces on the optical axis between the surface Si and the surface Si+1 (mm)
  • the column “N” indicates the refractive indices of the lenses L1 to L5 and the optical member 14, and the column “V” indicates the Abbe number of each of the lenses L1 to L5 and the optical member 14.
  • the shape of the surface convex toward the object side is positive, and the shape of the surface convex toward the image side is negative.
  • the surface number of the surface shape is accompanied by an * symbol.
  • Table 2 shows the focal length and refractive power of each of the lenses L1 to L5.
  • Table 3 shows aspherical data in the lens device of the first embodiment.
  • the symbol “E” indicates that 10 is the bottom “index” of its continuation value, and the value represented by 10 as the lowest index function is multiplied by the value before "E".
  • "1.0E-02" means "1.0 x 10-2”.
  • the aspherical surface data describes the values of the respective coefficients An, K in the formula of the representative aspherical shape according to the following formula 1.
  • Z in Formula 1 represents the length (mm) of a perpendicular line from a point on a certain aspheric surface at a position h from the optical axis height to a tangent plane (a plane perpendicular to the optical axis) of the aspherical apex.
  • FIG. 4 is a cross-sectional view of the lens device 10 associated with the second embodiment.
  • the lens device 10 according to the second embodiment is provided in this order from the object side, a glass lens first lens L1 having a negative refractive power, a glass lens second lens L2 having a negative refractive power, and a glass lens having a positive refractive power.
  • the first, second, third, fifth, and sixth lenses L1, L2, L3, L5, and L6 are all spherical lenses, and the fourth lens L4 is an aspherical lens.
  • the fisheye lens device 10 has a focal length EFFL of 0.958 mm, an F/No. of 2.0, and a viewing angle 2 ⁇ of 190°. Further, in the fisheye lens device 10, the ⁇ D is 16.052 mm, the image circle 2y is about 3.57 mm, and the ⁇ D/2y is about 4.5. Tables 4 to 6 show specific lens data of the fisheye lens device 10 according to the second embodiment.
  • 5 to 8 show the lens characteristics of the fisheye lens device 10 according to the first embodiment and the second embodiment.
  • 5 and 7 are aberration diagrams of the fisheye lens device 10 according to the first embodiment and the second embodiment, respectively.
  • the distortion map, the field curvature map, and the spherical aberration diagram (axial aberration) are shown in order from top to bottom.
  • the distortion map the horizontal axis is represented by the image height distortion (%), and the vertical axis is represented by the image height y.
  • the distortion is such that the actual image height is represented by y and the ideal image height is represented by y', and the value represented by (y-y') / y' ⁇ 100.
  • the horizontal axis represents the position where the light and the optical axis intersect, and the vertical axis represents the image height y.
  • the curve with the symbol S represents the sagittal image point
  • the curve with the symbol T represents the tangential image point.
  • the horizontal axis represents the distance (mm) to the image plane on the optical axis
  • the vertical axis represents the incident height of the light incident on the fisheye lens device 10.
  • FIGS. 6 and 8 show the degree of contrast of the fisheye lens device 10 according to the first embodiment and the second embodiment.
  • the horizontal axis represents the angle and the vertical axis represents the relative illuminance.
  • the fisheye lens device 10 according to the first embodiment and the second embodiment is reduced in distortion to the stereoscopic projection 2f ⁇ tan ( ⁇ /2) by 15% or less.
  • the fisheye lens device 10 according to the first embodiment ⁇ D/2y ⁇ 4.5; the fisheye lens device 10 according to the second embodiment, ⁇ D/2y ⁇ 3. Therefore, both the first embodiment and the second embodiment satisfy the condition ⁇ D/2y ⁇ 5. Therefore, the condition of ⁇ D/2y ⁇ 5 is satisfied, and the fisheye lens device 10 can be miniaturized.
  • the refractive indices of the first lens L1, the second lens L2, and the third lens L3 of the fisheye lens device 10 according to the first embodiment are 1.950, 18.80, and 1.945, respectively.
  • the first lens L1, the second lens L2, and the third lens L3 of the fisheye lens device 10 according to the second embodiment have refractive indices of 2.001, 1.911, and 1.946, respectively. Therefore, both the first embodiment and the second embodiment can satisfy the condition that the first lens L1, the second lens L2, and the third lens L3 are materials having a refractive index of 1.8 or more. Thereby, the optical total length ⁇ D is shortened while ensuring a large viewing angle.

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Abstract

一种鱼眼镜头装置，能使周边部信息量多的同时实现小型化。鱼眼镜头装置10从物侧开始依次为具有负折射力的第一透镜（L1）、具有负折射力的第二透镜（L2）、具有正折射力的第三透镜（L3）、光阑（12）、具有正折射力的第四透镜（L4）、具有正折射力的第五透镜（L5）和具有负折射力的第六透镜（L6）；鱼眼镜头装置的焦距为f、鱼眼镜头装置的入射光的入射角为θ、像面中形成的像高为y、光学总长为ΣD情况下，满足y＝2•f•tan(θ/2)以及ΣD/2y≦5.0。

Description

鱼眼镜头装置 技术领域
本说明书涉及鱼眼镜头装置，特别涉及立体投影的鱼眼镜头装置。
背景技术
以往的包含多个镜头构成的鱼眼镜头装置已为公众所知。使用鱼眼镜头装置，仅用一个相机就能进行大范围空间的拍摄，因此鱼眼镜头装置被广泛运用于监视摄像机等。
这里，鱼眼镜头采用特定的投影方式。例如，下文的投影方式就广为人知。另外，在下文中，f为鱼眼镜头装置的焦距，θ为入射到鱼眼镜头装置的入射光的入射角，y为在像面形成的像的高度(像高)。
(1)正投影方式…y＝f·sinθ
(2)等立体角投影方式…y＝2·f·sin(θ/2)
(3)等距离投影方式…y＝f·θ
(4)立体投影方式…y＝2·f·tan(θ/2)
图1是表示依据投影方式的入射角和像高的关系说明图。横轴表示入射角θ(弧度)，纵轴表示像高y(mm)。曲线C1～C4分别表示在(1)～(4)的投影方式中对应入射角的像高，以下称这些曲线为“像高曲线”。另外，图1中，为方便起见，设定为焦距F＝1mm。
这里，入射角θ＝90度附近，考虑对应入射角θ的增加量Δθ，像高y的增加量Δy的比例α＝Δy/Δθ。比例α是图1中表示的像高曲线的斜率。由图1明显可知，正投影方式(曲线C1)和等立体角投影方式(曲线C2)中，随着入射角θ的增大，比例α逐渐下降。这意味着，与像内的中心部的信息量相比周边部信息量的比例较小。另一方面，等距离投影方式(曲线C3)中，即使入射角θ变化，比例α基本不变。这意味着，像内的中心部的信息量和周边部信息量的比例基本相同。并且，立体投影方式(曲线C4)中，比例α随着入射角θ增大而逐渐增加。这意味着，与像内的中心部的信息量相比，周边部信息量的比例较大。因此，需要周边部的信息量多的情况下，理想的是采用等距离投影方式(曲线C3)或立体投影方式(曲线C4)。
但是，以往的技术在采用等距离投影方式(曲线C3)或立体投影方式(曲线C4)的情况下，构成鱼眼镜头装置的透镜枚数需要10枚左右，滋生了成本增加、大型化等问题。
在先技术文献
专利文献
专利文献1：日本特许公开2007-164079号公报
发明内容
发明要解决的问题
专利文献1公开了投影方式为y＝3·f·tan(θ/3)的鱼眼镜头装置，该鱼眼镜头装置由6枚至7枚透镜构成。图1中的曲线CA表示在y＝3·f·tan(θ/3)的投影方式中对应入射角的像高。由图1明显可知，根据y＝3·f·tan(θ/3)的投影方式，比例α随着入射角θ增大而逐渐增加，所以与像内的中心部的信息量相比，可以提高周边部信息量的比例。
但是，专利文献1中揭示的鱼眼镜头装置存在对应像圆(Image Circle)直径＝2y的光学总长ΣD偏大的问题。具体来说，专利文献1中采用y＝3·f·tan(θ/3)的投影方式的鱼眼镜头装置的ΣD/2y的值很大，为7.57和7.89。为此，专利文献1中的鱼眼镜头装置，难以应用于车载相机(摄像头)等设置空间受限的相机中。
于是，本申请说明书中公开了增大周边部信息量的同时，又实现小型化的鱼眼镜头装置。
解决问题的手段
本申请揭示的鱼眼镜头装置，从物侧开始依次配备具有负折射力的第一透镜、具有负折射力的第二透镜、光阑、具有正折射力的第三透镜、具有正折射力的第四透镜、具有正折射力的第五透镜和具有正折射力的第六透镜，前述鱼眼镜头装置的焦距为f、前述鱼眼镜头装置的入射光的入射角为θ、像面中形成的像高为y、光学总长为ΣD情况下，具有能满足y＝2·f·tan(θ/2)以及ΣD/2y≦5.0。
前述第一透镜、第二透镜和第三透镜都可以用折射力在1.8以上的材料组成。
另外，前述第五透镜和前述第六透镜可以用相互接合(例如粘合)的接合透镜构成。
再有，前述第四透镜可以用非球面透镜组成。
发明的效果
根据本申请揭示的鱼眼镜头装置，因为采用立体投影方式，所以像的周边部可以得到很多的信息量。另一方面，由于ΣD/2y≦5.0，所以与像圆相比，鱼眼镜头装置实现了小型化。
附图说明
图1表示入射角和像高关系的说明图；
图2表示第一实施形态涉及的鱼眼镜头装置结构的图；
图3为图2的鱼眼镜头装置的光路图；
图4表示第二实施形态涉及的鱼眼镜头装置结构的图；
图5为第一实施形态涉及的鱼眼镜头装置的像差图；
图6为第一实施形态涉及的鱼眼镜头装置的相对照度；
图7为第二实施形态涉及的鱼眼镜头装置的像差图；
图8为第二实施形态涉及的鱼眼镜头装置的相对照度。
具体实施方式
以下将参照附图，说明本申请揭示的鱼眼镜头装置10附图。图2是表示鱼眼镜头装置10的结构的结构图。另外，图3是该鱼眼镜头装置10的光路图。此外，图2-图4中，附图左侧为物侧、附图右侧为像侧。本申请揭示的鱼眼镜头装置10可应用于采用了CCD或CMOS等图像传感器的各种摄像设备中。本申请揭示的鱼眼镜头装置10特别适用于将多个图像合成新的图像的场合，或者想要用单台相机进行大范围摄影的场合等。作为由多个图像合成新的图像的场合，例如，搭载在车辆上的环视系统或为了3D摄影而拍摄图像的场合等。再者，作为想要进行大范围摄影的场合，监视摄像头和为了检测步行者/障碍物而搭载在车辆上的车载相机(摄像机)等。
以下，参考图2和图3对本申请揭示的鱼眼镜头装置10进行说明。鱼眼镜头装置10的成像面处配置由CCD或CMOS等组成的图像传感器100。图像传感器100输出对应鱼眼镜头装置10形成的光学像的摄像信号。
鱼眼镜头装置10包括沿着光轴Z1配置的6枚透镜。以下，将构成鱼眼镜头装置10的透镜按照从物侧开始依次称为第一透镜L1，第二透镜L2、第三透镜L3、第四透镜L4、第五透镜L5和第六透镜L6。
并且，鱼眼镜头装置10在第三透镜L3和第四透镜L4之间设有孔径光阑12。另外，第六透镜L6和图像传感器100之间，鱼眼镜头装置10根据其被装载的摄像设备的结构，可配置各种各样的光学部件14。作为光学部件14，举例包括用于保护图像传感器表面的保护玻璃和红外线截止滤光片等平板状的光学部件等。此外，也可以不采用光学部件14，对第五透镜L5和第六透镜L6实施镀膜等，使其达到与光学部件14同等的效果。据此，可以削减部件数量和缩短总长。
本申请揭示的鱼眼镜头装置10中，从物侧数第1个透镜(第一透镜L1)是具有负光焦度的玻璃透镜；第2个透镜(第二透镜L2)是具有负光焦度的玻璃透镜。更详细地说明，第一透镜L1是，从物侧开始依次具有凸向物侧的面S1(即凸面朝向被摄物体一侧)和凹向像侧的面S2的弯月形的负透镜。该面S1以及面S2都是球面。其次，第二透镜L2是，从物侧开始依次具有凸向物侧的面S3，凹向像侧的面S4的弯月形的负透镜。面S3以及面S4都是球面。
从物侧数第3个透镜(第三透镜L3)是具有正光焦度的玻璃透镜。更详细地说明，第三透镜L3是从物侧开始依次具有凹向物侧的面S5和凸向像侧的面S6的弯月形的正透镜。面S5 以及面S6都是球面。
该第一透镜L1、第二透镜L2、第三透镜L3都是由折射力1.8以上的玻璃组成。像这样在物侧配置有高折射力材料组成的3枚透镜L1～L3，可以保持视角2ω大的同时，缩短光学总长ΣD。此外，光学总长ΣD指的是从第一透镜L1的物侧的端面开始，到图像传感器100的像面之间的光轴上的距离。另外，根据这样的构成，能降低鱼眼镜头装置10全体的色差。
位于孔径光阑12后方(像侧)的第四透镜L4是具有正光焦度的玻璃透镜。更详细地说明，第四透镜L4是从物侧开始依次具有凸向物侧的面S8和凸向像侧的面S9的双凸形的正透镜。该面S8以及面S9都是非球面。这里，把第四透镜L4设为非球面是为了提高在最终的像面里得到的像的周边部分(周边像)的质量，对此，后续会有讲述。
第五透镜L5及第六透镜L6构成相互接合的接合透镜(双胶合透镜)。换而言之，本说明书中揭示的鱼眼镜头装置10是由6枚5组的结构。第五透镜L5是具有正光焦度的玻璃透镜。更详细地说明，第五透镜L5是，从物侧开始依次具有凸向于物侧的面S10和凸向于像侧的面S11的双凸形的正透镜。该面S10以及面S11都是球面。另外，第六透镜L6是具有负光焦度的玻璃透镜。更详细地说明，第六透镜L6是从物侧开始依次具有凹向物侧的面S11和凹向于像侧的面S12的弯月形的负透镜。该面S12是球面。
以上的鱼眼镜头装置10采用满足y＝2·F·tan(θ/2)的立体投影方式。在这里，y为像面上形成的像的高度，f为鱼眼镜头装置10的焦点距离，θ为鱼眼镜头装置10入射光的入射角。另外，鱼眼镜头装置10的视角2ω大于180度，例如，2ω＝190°。
立体投影方式中，越接近周边，对于入射角θ的增加量Δθ的像高y的增加量Δy的比例α＝Δy/Δθ越大。例如，立体投影方式中，像的周边部的85°<θ<90°处的比例α85-90约为像的中心部的0°<θ<5°处的比例α0-5的2倍。该立体投影方式与人类的视觉相似，与太阳和月亮越接近地平线看起来越大这种心理的空间像是一样的。
另外，立体投影方式下，随着接近周边部，像高y的增加量Δy不断增加。换而言之，越接近周边部，像具有的信息量也增加，立体投影方式可以说对周边部需要较多信息量的场合有用。作为周边部需要较多信息量的场合，例如，将多个图像合成的场合。更具体，例如，在装载在车辆上的环视系统和3D摄影中，使用多个相机将取得多个图像合成为一个合成图像。这时，为了提高合成精度，希望从各个相机得到的图像是周边部信息量比较多的图像。因此，立体投影方式，在合成多个图像的环视系统和3D摄影等场合中，是特别有用的投影方式。
如上所述，本申请揭示的鱼眼镜头装置10是立体投影方式，即满足y＝2·F·tan(θ/2)的镜头装置。因此，本申请揭示的鱼眼镜头装置10，在例如，在环视系统和3D摄影等合成多个图像的情况下，可以说是特别有用的镜头装置。
另外，本申请揭示的鱼眼镜头装置10中，视角2ω大于180°。因此，本申请的鱼眼镜头装置10是大范围摄影的理想相机，例如，还适用于监视摄像机和为了检测步行者/障碍物等装载在车辆上的车载摄像头等。
在此，如前文所述，在本申请中的第五透镜L5和第六透镜L6为接合透镜。这样，把最靠近像面的两个透镜作为接合透镜，是为了补正对于y＝2·F·tan(θ/2)的畸变，并且可减少色差。即，本申请的鱼眼镜头装置10中，在设为Y＝2·F·tan(θ/2)，Y’＝f·tan(θ)”的情况下，该鱼眼镜头装置10的畸变被补正到接近(Y-Y’)/Y’×100的状态。
但是，补正对于y＝2·f·tan(θ/2)的畸变像差的情况下，增大从第四透镜L4出射的主光线和光轴之间的角度，会使得周边像恶化。为了解决此问题，本申请中，比起接合透镜(第五透镜L5、第六透镜L6)，把靠近像侧的第四透镜L4作为非球面透镜。此第四透镜L4解决了主光线和光轴的角度问题，得到的非球面形状改善了第四透镜L4和第五透镜L5的关系，改善了周边像的质量。
另外，如上所示，本申请由靠近像侧的3个透镜(L1,L2，L3)高折射力(折射力N 1.8以上)的玻璃透镜构成。根据此结构，能减小对于像圆2y的光学总长ΣD的比例，即ΣD/2y。具体而言，在本申请中，将ΣD/2y设为5.0以下。而根据此结构，可以减少鱼眼镜头装置10的总长。因此，本申请的鱼眼镜头装置10是特别适用于车载相机等设置空间受限的相机(摄像机)的镜头装置。
而且，构成鱼眼镜头装置10的6枚透镜均是玻璃透镜。玻璃与塑胶相比热膨胀系数(温度依存性)低。因此，第一透镜～第六透镜L1～L6全部采用玻璃透镜，能减少随着温度变化的镜头特性(比如焦距等)的变动。其结果是，即使在温度变化大的环境中，也能得到稳定质量的像。
接下来，对以上构成的鱼眼镜头装置10的实施例进行说明。首先说明第一实施例。第一实施例鱼眼镜头装置10的构成如图2所示。第一实施例的鱼眼镜头装置10配备从物侧开始依次为具有负折射力的玻璃透镜第一透镜L1、具有负折射力的玻璃透镜第二透镜L2、具有正折射力的玻璃透镜第三透镜L3、具有正折射力的玻璃透镜第四透镜L4、具有正折射力的玻璃透镜第五透镜L5和具有负折射力的玻璃透镜第六透镜L6。第一透镜L1、第二透镜L2、第三透镜L3、第五透镜L5以及第六透镜L6都是球面透镜，第四透镜L4是非球面透镜。
此鱼眼镜头装置10的焦距EFFL为1.41mm，F/No(F-number)为2.0，视角2ω为190°。另外，此鱼眼镜头装置10中的光学总长ΣD为16.048mm，像圆2y约为5.35mm，ΣD/2y约为3。表1～表3表示第一实施例涉及的鱼眼镜头装置10的具体镜头数据。其中OBJ为物面，STO为光阑面，IMA为像面。
【表1】
第一实施例
Figure PCTCN2017112739-appb-000001
【表2】
第一实施例
透镜 焦距 光焦度
101 -6.40 -0.1563
102 -4.10 -0.2439
103 9.70 0.1031
104 3.80 0.2632
105 20.70 0.0483
106 -13.90 -0.0700
【表3】
第一实施例
  8面 9面
K 56.6 0.188
A2 0.0000E+00 0.0000E+00
A4 -1.6000E-02 1.0000E-02
A6 -1.6000E-02 -4.6250E-03
A8 2.3100E-02 2.4084E-03
A10 -1.4000E-02 -5.1600E-04
A12 2.7300E-03 4.6528E-05
A14 -1.1800E-04 0.0000E+00
A16 0.0000E+00 0.0000E+00
表1中，「面#」栏表示面Si的编号用i表示。另外，表1中「R」栏表示各面Si的光轴附近的曲率半径的值(mm)；「D」栏表示面Si和面Si+1之间的光轴上的面间距离(mm)；「N」栏表示各透镜L1～L5以及光学部件14的折射率；「V」栏表示各透镜L1～L5以及光学部件14阿贝数。且有，关于曲率半径的符号，凸向于物侧的面形状为正，凸向于像侧的面形状为负。另外，表1的基本镜头数据中，面形状的面编号附有＊符号。
表2表示各透镜L1～L5的焦距和折射力。表3表示第一实施状态的镜头装置中的非球面数据。非球面数据显示的数值中，记号“E”表示，把10作为其接续数值的最底“指数”，将10作为最底的指数函数表示的该数值乘以“E”前面的数值。例如，「1.0E-02」表示「1.0×10-2」。
非球面数据根据以下公式1，记述代表的非球面形状的公式中的各系数An，K的值。
公式1中的Z表示从距离光轴高度为h的位置的某个非球面上的点，到非球面的顶点的切面(垂直于光轴的平面)的垂线的长度(mm)。另外，公式1中的C是近轴曲率半径R的倒数(即C＝1/R)。
Figure PCTCN2017112739-appb-000002
其次，对于第二实施例进行说明。图4是第二实施例关联的镜头装置10的横截面图。第二实施例涉及的镜头装置10，从物侧开始依次配备，具有负折射力的玻璃透镜第一透镜L1、具有负折射力的玻璃透镜第二透镜L2、具有正折射力的玻璃透镜第三透镜L3、具有正折射力的玻璃透镜第四透镜L4、具有正折射力的玻璃透镜第五透镜L5和具有负折射力的玻璃透镜第六透镜L6。第1、第2、第3、第5、第六透镜L1，L2，L3，L5，L6都是球面透镜，第四透镜L4是非球面透镜。
此鱼眼镜头装置10的焦距EFFL为0.958mm，F/No.为2.0，视角2ω为190°。另外，此鱼眼镜头装置10中的ΣD为16.052mm、像圆2y约为3.57mm、ΣD/2y约为4.5。表4-表6表示，第二实施例涉及的鱼眼镜头装置10的具体的镜头数据。
【表4】
第二实施例
Figure PCTCN2017112739-appb-000003
Figure PCTCN2017112739-appb-000004
【表5】
第二实施例
透镜 焦距 光焦度
101 -5.570 -0.180
102 -3.536 -0.283
103 9.590 0.104
104 2.674 0.374
105 2.464 0.406
106 -1.862 -0.537
【表6】
第二实施例
  8面 9面
K -12.362 -0.722
A2 0.0000E+00 0.0000E+00
A4 -3.4900E-02 1.6290E-03
A6 3.1130E-02 -6.9560E-03
A8 -3.4970E-02 3.0872E-03
A10 9.2092E-03 -9.7610E-04
A12 3.6818E-03 9.8738E-05
A14 4.7813E-05 1.5156E-06
A16 0.0000E+00 0.0000E+00
图5～图8表示，这些第一实施例和第二实施例涉及的鱼眼镜头装置10的镜头特性。图5、图7分别是，第一实施例和第二实施例涉及的鱼眼镜头装置10的像差图。图5、图7中从上而下依次表示，畸变图、场曲图、球差图(轴向色差)。畸变图中，横轴用像高的失真(％)表示，纵轴用像高y表示。这里，众所周知，畸变为，实际的像高用y表示、理想像高用y’表示的情况下，(y-y’)/y’×100所表示的值。图5、图7是，理想像高为y’，运用了2f·tan(θ/2)。场曲图中，横轴是光线和光轴相交的位置，纵轴表示像高y。场曲图中，带有符号S的曲线表示弧矢像点，带有符号T的曲线表示切向像点。球差图中，横轴表示到光轴上的像面的距离(mm)，纵轴表示入射到鱼眼镜头装置10的光的入射高度。
图6、图8表示，第一实施例和第二实施例涉及的鱼眼镜头装置10的相对照度。图6、图8中，横轴表示角度，纵轴表示相对照度。
从图5、图7明显可知，第一实施例和第二实施例涉及的鱼眼镜头装置10、对于立体投影2f·tan(θ/2)的畸变被减少到15％以下。另外，如上所述，第一实施例涉及的鱼眼镜头装置10，ΣD/2y≒4.5；第二实施例涉及的鱼眼镜头装置10，ΣD/2y≒3。因此，第一实施例、2都能满足条件ΣD/2y<5。所以满足了ΣD/2y<5的条件，能把鱼眼镜头装置10做到小型化。
另外，从表2明显可知，第一实施例涉及的鱼眼镜头装置10的第一透镜L1、第二透镜L2和第三透镜L3的折射率分别为1.950，18.80，1.945。第二实施例涉及的鱼眼镜头装置10的第一透镜L1、第二透镜L2和第三透镜L3的折射率分别为2.001，1.911，1.946。因此，第一实施例和第二实施例都能满足第一透镜L1、第二透镜L2和第三透镜L3为折射率在1.8以上的材料的条件。由此，保证大视角的同时缩短了光学总长ΣD。
附图标记的说明：
10    鱼眼镜头装置
12    孔径光阑
14    光学部件
100   图像传感器
L1    第一透镜
L2    第二透镜
L3    第三透镜
L4    第四透镜
L5    第五透镜
L6    第六透镜。

Claims (5)

  1. 鱼眼镜头装置，其特征在于：
    包括从物侧开始依次具有负折射力的第一透镜、具有负折射力的第二透镜、光阑、具有正折射力的第三透镜、具有正折射力的第四透镜、具有正折射力的第五透镜和具有正折射力的第六透镜，
    在所述鱼眼镜头装置的焦距为f，入射所述鱼眼镜头装置的光的入射角为θ、像面中形成的像高为y、光学总长为ΣD情况下，满足y＝2·f·tan(θ/2)且ΣD/2y≦5.0。
  2. 如权利要求1所述的鱼眼镜头装置，其特征在于：
    所述第一透镜、第二透镜和第三透镜都由折射力为1.8以上的材料构成。
  3. 如权利要求1或2所述的鱼眼镜头装置，其特征在于：
    所述第五透镜和所述第六透镜为相互接合的接合透镜构成的特征的鱼眼镜头装置。
  4. 如权利要求1或2所述的鱼眼镜头装置，其特征在于：
    所述第四透镜为非球面透镜。
  5. 如权利要求3所述的鱼眼镜头装置，其特征在于：
    所述第四透镜为非球面透镜。
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