1260441 九、發明說明： 【發明所屬之技術領域】 本發明是有關於一種拾像光學系統，特別是具有廣視 角的一種拾像鏡頭。 【先前技術】 廣視角的拾像光學系統應用產品愈來愈廣，例如監視 器、車載鏡頭及内視鏡。日本公開專利特開昭61-035, 414 揭露一種廣視角的内視鏡頭，該内視鏡頭具有四個光學元 件並且於鄰近成像端具有一新月型透鏡。 然而，特開昭61-035,414的内視鏡頭雖然可修正畸變 像差，但是卻無法將所有自物端入射該鏡頭的光線垂直入 射CCD，因此會產生陰影。 曰本公開專利特開平01-218, 286揭露改善上述缺點的 方法。於對物鏡與CCD之間***一場透鏡，使得光線可垂 直入射於CCD上。然而，卻使整個光學系統變得較為複雜 〇 曰本公開專利特開平05-107, 470揭露一種對物光學系 統，然而卻仍舊無法解決產生陰影的問題。 【發明内容】 因此，本發明之目的，即在提供一種拾像光學系統， 具有廣視角且解決影像產生陰影的問題。 根據上述目的，本發明之拾像光學系統，自物端至成 像端依序包括負屈光率的第一光學元件、正屈光率的第二 光學元件及負屈光率的第三光學元件；其中第二光學元件 1260441 滿足以下條件： 〇.7<|^-|<1.3 其中，fPi為第二光學元件的焦距，ft為拾像光學系統的焦 距。 如以上所述，本發明之拾像光學系統之第二及第三光 學元件為非球面透鏡，且分別具有至少一表面為非球面。 如以上所述，本發明之拾像光學系統之第二及第三光 學元件係以塑膠材料製造。 如以上所述’本發明之拾像光學系統可適用於各種溫 度與天候環境，其中第三光學元件滿足以下條件： 〇·5<|!ε!»|<1·5 其中，fpl為第二光學元件的焦距，fp2為第三光學元件的焦 距。 如以上所述，本發明之拾像光學系統之第一光學元件 為新月型負透鏡，其中朝向物端之表面為一凸面。較佳地 ，第一光學元件係以玻璃材料製造。 本發明之一優點在於，第一光學元件係用以消除畸變 像差及慧星像差’並獲得廣視角之功效。 本發明之另一優點在於，第二及第三光學元件係以塑 膠材料製作，可降低生產成本。 本發明之再一優點在於，第二及第三光學元件可用以 消除球面像差、像散像差及影像之陰影，並可適用於各種 1260441 溫度環境。 【實施方式】 有關本發明之前述及其他技術内容、特點與功效，在 以下配合參考圖式之一個較佳實施例的詳細說明中，將可 清楚的呈現。 本發明之拾像光學系統具有廣視角的優點，可應用於 内視鏡、監視器、車栽鏡頭等。該拾像光學系統自物端至 成像端依序包括具有負屈光率的第一光學元件、正屈光率 的第二光學元件及負屈光率的第三光學元件。其中，該拾 像光學系統之第二光學元件須滿足以下條件： 〇.7<|iL|<l.3......⑴BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pickup optical system, and more particularly to an image pickup lens having a wide viewing angle. [Prior Art] Wide-angle pickup optical system applications are becoming more and more popular, such as monitors, vehicle lenses, and endoscopes. Japanese Patent Laid-Open Publication No. SHO 61-035, No. 414 discloses a wide-view internal lens having four optical elements and having a crescent-shaped lens adjacent to the imaging end. However, although the internal lens of JP-A-61-035,414 can correct the distortion aberration, it is impossible to vertically inject all the light incident on the lens from the object end into the CCD, and thus a shadow is generated. A method for improving the above disadvantages is disclosed in Japanese Laid-Open Patent Publication No. Hei 01-218,286. A lens is inserted between the objective lens and the CCD so that the light can be incident perpendicularly on the CCD. However, the entire optical system has become complicated. 曰 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 。 SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a pickup optical system having a wide viewing angle and solving the problem of image generation of shadows. According to the above object, the pickup optical system of the present invention sequentially includes a first optical element of negative refractive power, a second optical element of positive refractive power, and a third optical element of negative refractive power from the object end to the imaging end. Wherein the second optical element 1680441 satisfies the following condition: 〇.7<|^-|<1.3 wherein fPi is the focal length of the second optical element, and ft is the focal length of the optical pickup system. As described above, the second and third optical elements of the pickup optical system of the present invention are aspherical lenses and each have at least one surface aspherical. As described above, the second and third optical elements of the pickup optical system of the present invention are made of a plastic material. As described above, the pickup optical system of the present invention can be applied to various temperature and weather environments, wherein the third optical component satisfies the following conditions: 〇·5<|!ε!»|<1·5 wherein fpl is The focal length of the two optical elements, fp2 is the focal length of the third optical element. As described above, the first optical element of the pickup optical system of the present invention is a crescent-type negative lens in which the surface facing the object end is a convex surface. Preferably, the first optical element is made of a glass material. An advantage of the present invention is that the first optical element is used to eliminate distortion aberrations and comet aberrations' and to obtain a wide viewing angle. Another advantage of the present invention is that the second and third optical components are fabricated from a plastic material to reduce production costs. Still another advantage of the present invention is that the second and third optical components can be used to eliminate spherical aberration, astigmatic aberrations, and shadows of images, and can be applied to various 1260441 temperature environments. The above and other technical contents, features, and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments. The pickup optical system of the present invention has the advantages of a wide viewing angle and can be applied to an endoscope, a monitor, a vehicle lens, and the like. The pickup optical system sequentially includes a first optical element having a negative refractive power, a second optical element having a positive refractive power, and a third optical element having a negative refractive power from the object end to the imaging end. Wherein, the second optical component of the optical pickup system must satisfy the following conditions: 〇.7<|iL|<l.3...(1)
It 其中’ fpl為第二光學元件的焦距，ft為拾像光學系統的焦 ° 本發明之拾像光學系統中，第一光學元件為新月型負 透鏡，且朝向物端之表面為凸面。孔徑光闌設置於第一光 學元件與第二光學元件之間，藉此可有效地將遠離光轴外 的光線以較大的入射角進入該系統中，進而獲得廣視角之 優點。 本發明之拾像光學系統中，第二光學元件為正透鏡以 及第三光學元件為負透鏡，且第二、第三光學元件皆具有 至少一非球面表面。較佳地，第二及第三光學元件係以塑 踢材料形成之。 本發明之拾像光學系統中，第三光學元件滿足以下條 1260441 件： 0·5<|於丨<ι 5......(2) ΓΡ2 ’ 其中，為第二光學元件的焦距，fp2為第三光學元件的隹 距。 當丨大於條件（1)的上限值時，會造成拾像光學系統 的球面像差趨於明顯而無法被修正。當|fpi/ft!小於條件⑴的 下限值時拾像光學系統的像散像差趨於明顯而無法被修 正。 當丨fPl/fP2丨大於條件（2)的上限時，拾像光學系統於高溫 環境或低溫環境的解像能力（MTF)快速變差。當丨丨小於 條件（2)的下限時，拾像光學系統的後焦過長，使得拾像光 學系統的總光程（total track)將會過長。 本發明之拾像光學系統之第二、第三光學元件皆為非 球面塑膠鏡片，但仍可於溫度範圍-川它至6〇t之間保持良 好的攝像品質。 〈發明詳細說明〉 參閱圖1，本發明之拾像光學系統之實施例，拾像光學 系統自物端至成像端依序包含負屈光率的第一透鏡（1〇)、正 屈光率的第二透鏡（20)及負屈光率的第三透鏡（3〇);以及， 該拾像光學系統的系統焦距為ft=l.〇 mm，數值孔徑 Fno.sZ.e ’且全視角南達162度。 第一透鏡（10)為新月型負透鏡，朝向物端之表面為凸面 且朝向成像端的表面為凹面。第一透鏡係以玻璃材料製作 8 1260441 ，具有抗刮、耐磨及不吸水的特性；使得拾像光學系統適 合戶外或潮濕環境使用。凸面朝向物端係用以修正畸變像 差。 第二透鏡（20)為雙凸正透鏡，且至少一表面為非球面並 採用塑膠材料製作。孔徑光闌位於第一透鏡（10)與第二透鏡 (20)之間，且鄰近第二透鏡設置；藉此，當偏離光轴且以大 角度入射第一透鏡的光線將可以較小的角度通過孔徑光闌 入射第二透鏡。於本實施例中，第二透鏡之焦距為fpi==0.94 mm ° 第三透鏡（30)為雙凹負透鏡，且至少一表面為非球面並 採用塑膠材料製作。於本實施例中，第三透鏡之焦距為 fp2 = -〇-95 mm 〇 於本發明之實施例中，拾像光學系統的第一透鏡（10)、 第二透鏡（20)及第三透鏡（30)的各項參數依序列於表1中： 表1 系統焦距長度ft=l.〇 mm ; Fno.=2.8 表面序號 曲率半徑 (mm) 厚度（mm) 折射率 (Nd) 阿貝係數 (Vd) R1 11.428 0.62 1.58913 61.2 R2 1.382 3.89 1.00000 STO. Infinity 0.00 1.00000 R3 1.165 1.24 1.52471 56.21 R4 ' -0.536 0.04 1.00000 R5 -1.323 0.39 1.60727 26.65 R6 1.128 0.20 1.00000 R7 Infinity 0.695 1.51633 64.15 IMA. Infinity 0.656 1.00000 此外，於本發明之實施例中，第二透鏡之表面序號R3 1260441 、R4及第二透鏡之透鏡表面序號R5、R6為非球面，其非 球面之相關數值依序列於表2 : 表2 表面序號 K A B C D R3 -9.303731 0.57434098 -1.06587400 0 0 R4 -4.537273 -0.56658212 -0.0041955651 0 0 R5 -30.082221 -0.80405480 -0.77832456 0 0 R6 -14.735885 -0.39857821 0.12753988 0 0 該等係數滿足以下非球面公式： z = -：--37+ Ah 4 + Bh 6 + Ch 8 + Dh 10 。It where 'fpl is the focal length of the second optical element, and ft is the focal point of the optical pickup system. In the optical pickup system of the present invention, the first optical element is a crescent-shaped negative lens, and the surface toward the object end is convex. The aperture stop is disposed between the first optical element and the second optical element, thereby effectively entering light outside the optical axis into the system at a large angle of incidence, thereby obtaining the advantage of a wide viewing angle. In the pickup optical system of the present invention, the second optical element is a positive lens and the third optical element is a negative lens, and the second and third optical elements each have at least one aspherical surface. Preferably, the second and third optical elements are formed from a plastic kick material. In the pickup optical system of the present invention, the third optical element satisfies the following item 1640441: 0·5<|在丨<ι 5...(2) ΓΡ2 ' where the focal length of the second optical element , fp2 is the lay length of the third optical component. When 丨 is larger than the upper limit of the condition (1), the spherical aberration of the optical pickup system tends to be conspicuous and cannot be corrected. When |fpi/ft! is smaller than the lower limit value of the condition (1), the astigmatic aberration of the optical pickup system tends to be conspicuous and cannot be corrected. When 丨fPl/fP2丨 is larger than the upper limit of the condition (2), the resolution (MTF) of the pickup optical system in a high-temperature environment or a low-temperature environment is rapidly deteriorated. When 丨丨 is less than the lower limit of the condition (2), the back focus of the pickup optical system is too long, so that the total track of the optical system of the optical pickup will be too long. The second and third optical elements of the optical pickup system of the present invention are all aspherical plastic lenses, but still maintain good image quality in the temperature range from -1 to 6 〇t. DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, in an embodiment of the optical pickup system of the present invention, the optical lens of the optical pickup system includes a first lens (1〇) having a negative refractive power and a positive refractive power from the object end to the imaging end. a second lens (20) and a third lens of negative refractive power (3〇); and, the focal length of the optical system of the optical pickup system is ft=l.〇mm, numerical aperture Fno.sZ.e' and full viewing angle South 162 degrees. The first lens (10) is a crescent-shaped negative lens having a convex surface toward the object end and a concave surface toward the imaging end. The first lens is made of glass material 8 1260441, which is scratch-resistant, wear-resistant and non-absorbent; it makes the pickup optical system suitable for outdoor or wet environments. The convex surface is oriented toward the object end to correct the distortion aberration. The second lens (20) is a double convex positive lens, and at least one surface is aspherical and made of a plastic material. The aperture stop is located between the first lens (10) and the second lens (20) and disposed adjacent to the second lens; thereby, the light that is incident on the first lens from the optical axis and at a large angle may be at a smaller angle The second lens is incident through the aperture stop. In this embodiment, the focal length of the second lens is fpi==0.94 mm°. The third lens (30) is a double concave negative lens, and at least one surface is aspherical and made of a plastic material. In this embodiment, the focal length of the third lens is fp2 = -〇-95 mm. In the embodiment of the present invention, the first lens (10), the second lens (20), and the third lens of the optical pickup system The parameters of (30) are listed in Table 1: Table 1 System focal length ft=l.〇mm; Fno.=2.8 Surface number radius of curvature (mm) Thickness (mm) Refractive index (Nd) Abbe's coefficient ( Vd) R1 11.428 0.62 1.58913 61.2 R2 1.382 3.89 1.00000 STO. Infinity 0.00 1.00000 R3 1.165 1.24 1.52471 56.21 R4 ' -0.536 0.04 1.00000 R5 -1.323 0.39 1.60727 26.65 R6 1.128 0.20 1.00000 R7 Infinity 0.695 1.51633 64.15 IMA. Infinity 0.656 1.00000 In addition, In the embodiment of the present invention, the surface numbers R3 1260441 and R4 of the second lens and the lens surface numbers R5 and R6 of the second lens are aspherical, and the relative values of the aspheric surfaces are listed in Table 2: Table 2 Surface number KABCD R3 -9.303731 0.57434098 -1.06587400 0 0 R4 -4.537273 -0.56658212 -0.0041955651 0 0 R5 -30.082221 -0.80405480 -0.77832456 0 0 R6 -14.735885 -0.39857821 0.12753988 0 0 These coefficients are satisfied The following aspheric formula: z = -:--37+ Ah 4 + Bh 6 + Ch 8 + Dh 10 .
i+E-〇 + i>2a2J 於本發明之實施例中，拾像光學系統之各項數值皆符 合條件（1)及（2)。該拾像光學系統之成像端設置一影像感測 單元，例如CCD或CMOS ;此外，可於拾像光學系統與成 像端之間設置濾光片（40)，以濾除紅外光。 圖2顯示本發明之實施例之拾像光學系統，於溫度環 境為25°C之球面像差（spherical aberration)。根據圖2所示 ，該拾像光學系統於像高1Y範圍内的球面像差皆小於〇·〇1 mm範圍内。 圖3顯示本發明之實施例之拾像光學系統，於溫度環 境為25°C之場曲像差（field curvature)。根據圖3所示，該 拾像光學系統之弧矢光束（sagittal beam)與切向光束 (tangential beam)於最大像場高度1Y範圍内分離的程度皆小 於0.03 mm範圍内，因此顯示該拾像光學系統之像散像差 極小。 圖4顯示本發明之實施例之拾像光學系統，於溫度環 10 1260441 境為25°C之畸變像差（distortion)。根據圖4所示，該拾像 光學系統於像高1Y範圍内的畸變像差大於-60%。 圖5顯示本發明之實施例之拾像光學系統，於溫度環 境為25°C之馨星像差（coma aberration)。根據圖5所示，該 拾像光學系統於〇·7倍物高處，其產生的彗星像差圖案均方 根半徑（RMS Radius)小於 2·892 //m。 圖6顯示本發明之實施例之拾像光學系統，於溫度環 境為 25°C 之調變轉換函數值（Modulation Transfer Function) 。根據圖6所示，該拾像光學系統之弧矢光束與切向光束 於0.7倍物高處，焦點偏移量不大於0.02 mm。 為檢視本發明實施例提供之拾像光學系統確實可適用 於各種氣候環境，針對-10°c、25°c、60°c量測後焦的偏移 量。於溫度為-l〇°C時，該拾像光學系統之後焦值較25°C時 的後焦時增加〇·〇19 mm;於溫度為60°C時，該拾像光學系 統之後焦值較25°C時的後焦時短少0.018 mm。由以上可知 ，本發明之實施例的拾像光學系統具有極佳的成像品質； 雖然第二透鏡與第三透鏡皆使用塑膠射出成型的非球面透 鏡，但不受溫度變化而使成像品質惡化。 總的來說，本發明提供一種拾像光學系統，該系統的 孔徑光闌位於第一負透鏡與第二正透鏡之間且鄰近第二正 透鏡設置，使得該系統的全視角範圍高達162度；改變該 孔徑光闌與第二正透鏡之間的距離可改變全視角的範圍。 此外，第二及第三鏡片使用塑膠鏡片可有效降低該系統的 成本。 11 1260441 惟以上所述者，僅為本發明之具體實施例而已，當不 能以此限定本發明實施之範圍，即大凡依本發明申請專利 範圍及發明說明内容所作之簡單的等效變化與修飾，皆仍 屬本發明專利涵蓋之範圍内。 【圖式簡單說明】 圖1是本發明實施例之拾像光學系統之光線追跡圖； 圖2顯示本發明之實施例之拾像光學系統，於溫度環 境為25°C之球面像差； 圖3顯示本發明之實施例之拾像光學系統，於溫度環 境為25°C之場曲像差； 圖4顯示本發明之實施例之拾像光學系統，於溫度環 境為25°C之畸變像差； 圖5顯示本發明之實施例之拾像光學系統，於溫度環 境為25°C之彗星像差圖案；及 圖6顯示本發明之實施例之拾像光學系統，於溫度環 境為25°C之調變轉換函數值。 【主要元件符號說明】 10 * • ·第一光學元件 40 * * 濾光片 20 * ·第二光學元件 IMA * 成像面 30 · • ·第三光學元件 STO . ♦ 孔鏡光闌 12i + E - 〇 + i > 2a2J In the embodiment of the present invention, the values of the optical pickup system are in compliance with the conditions (1) and (2). An image sensing unit such as a CCD or a CMOS is disposed at the imaging end of the optical pickup system. Further, a filter (40) may be disposed between the optical pickup system and the imaging end to filter out the infrared light. Fig. 2 shows a pickup optical system of an embodiment of the present invention having a spherical aberration of 25 ° C in a temperature environment. According to Fig. 2, the spherical aberration of the pickup optical system in the range of image height 1Y is smaller than 〇·〇1 mm. Fig. 3 shows a pickup optical system of an embodiment of the present invention having a field curvature of 25 ° C in a temperature environment. According to FIG. 3, the sagittal beam and the tangential beam of the optical pickup system are separated by less than 0.03 mm in the range of the maximum image field height 1Y, so that the image is displayed. The astigmatic aberration of the optical system is extremely small. Fig. 4 shows a pickup optical system of an embodiment of the present invention having a distortion of 25 ° C in the temperature loop 10 1260441. According to Fig. 4, the image pickup optical system has a distortion aberration in the range of image height 1Y of more than -60%. Fig. 5 shows a pickup optical system of an embodiment of the present invention having a coma aberration of 25 ° C in a temperature environment. According to Fig. 5, the pickup optical system has a RMS Radius of less than 2·892 //m at a height of 7·7 times. Fig. 6 is a view showing a modulation optical system of a pickup optical system of an embodiment of the present invention having a temperature modulation environment of 25 °C. According to Fig. 6, the focus beam and the tangential beam of the pickup optical system are at a height of 0.7 times, and the focus shift is not more than 0.02 mm. The optical pickup system provided for inspecting the embodiments of the present invention is indeed applicable to various climatic environments, and the offset of the back focus is measured for -10 ° C, 25 ° C, and 60 ° c. When the temperature is -10 °C, the focal value of the pickup optical system is increased by 〇·〇19 mm from the back focus at 25 °C; after the temperature is 60 °C, the focal value of the pickup optical system is It is 0.018 mm shorter than the back focus at 25 °C. As apparent from the above, the pickup optical system of the embodiment of the present invention has excellent image quality; although both the second lens and the third lens use a plastic injection molded aspherical lens, the image quality is deteriorated without being subjected to temperature change. In general, the present invention provides a pickup optical system having an aperture stop between a first negative lens and a second positive lens and adjacent to a second positive lens such that the system has a full viewing angle range of up to 162 degrees. Changing the distance between the aperture stop and the second positive lens changes the range of the full viewing angle. In addition, the use of plastic lenses for the second and third lenses can effectively reduce the cost of the system. 11 1260441 The above is only the specific embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent change and modification according to the scope of the invention and the description of the invention. All remain within the scope of the invention patent. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a ray tracing diagram of a pickup optical system according to an embodiment of the present invention; FIG. 2 is a view showing a spherical aberration of a pickup optical system according to an embodiment of the present invention at a temperature of 25 ° C; 3 shows a field optical aberration of a pickup optical system according to an embodiment of the present invention at a temperature of 25 ° C; FIG. 4 shows a distortion optical image of a pickup optical system of an embodiment of the present invention at a temperature of 25 ° C. FIG. 5 shows a pickup optical system of an embodiment of the present invention, a coma aberration pattern at 25 ° C in a temperature environment; and FIG. 6 shows a pickup optical system of an embodiment of the present invention at a temperature environment of 25°. The modulation conversion function value of C. [Main component symbol description] 10 * • · First optical component 40 * * Filter 20 * · Second optical component IMA * Imaging surface 30 · • · Third optical component STO . ♦ Hole mirror aperture 12