Optical lens system for photographing, image capture unit and electronic device

Abstract

An optical lens system for photographing, comprising four lens elements (E1, E2, E3, and E4), the four lens elements (E1, E2, E3, and E4) being, in order from an object side to an image side along an optical path, a first lens element (E1), a second lens element (E2), a third lens element (E3), and a fourth lens element (E4), each of the four lens elements (E1, E2, E3, and E4) having an object side surface facing the object side and an image side surface facing the image side; wherein the first lens element (E1) has a positive refractive index, the object side surface of the first lens element (E1) being convex in a paraxial region thereof, the second lens element (E2) having a positive refractive index, the object side surface of the second lens element (E2) being convex in a paraxial region thereof, the third lens element (E3) having a negative refractive index, the image side surface of the third lens element (E3) being concave in a paraxial region thereof, the image side surface of the fourth lens element (E4) being convex in a paraxial region thereof, and at least one surface of at least one lens element in the optical lens system for photographing has at least one inversion point (P); wherein an axial distance between the object side surface of the first lens element (E1) and the image side surface of the fourth lens element (E4) is TD, wherein an axial distance between the image side surface of the fourth lens element (E4) and an image surface (IMG) is BL, wherein a focal length of the second lens element (E2) is f2, wherein a focal length of the fourth lens element (E4) is f4, wherein a central thickness of the first lens element (E1) is CT1, wherein a central thickness of the second lens element (E2) is CT2, wherein a central thickness of the third lens element (E3) is CT3, wherein a radius of curvature of the object side surface of the first lens element (E1) is R1, wherein a radius of curvature of the object side surface of the third lens element (E3) is R5, and wherein the following conditions are met: 0.05 < TD / BL < 0.60 ; 0.05 < | f 2 / f 4 | < 1.50 ; 0.10 < ( CT 2 + CT 3 ) / CT 1 < 1.00 ; and − 4.50 < (R 1 − R 5 ) / (R 1 + R 5 ) < 0.25.

Description

BACKGROUNDTechnical field

[0001] The present disclosure relates to an optical lens system for photographing, an image capturing unit and an electronic device, particularly to an optical lens system for photographing and an image capturing unit which can be used in an electronic device. Description of the technical environment

[0002] With the development of semiconductor manufacturing technology, the performance of image sensors has increased and their pixel size has decreased. Therefore, high image quality is one of the essential features of an optical system today.

[0003] Furthermore, due to rapid technological changes, electronic devices incorporating optical systems are becoming increasingly multifunctional for various applications, increasing the requirements for the functionality of optical systems. However, in a conventional optical system, it is difficult to achieve a balance between requirements such as high image quality, low sensitivity, a suitable aperture size, miniaturization, and a desired field of view. SUMMARY

[0004] According to one aspect of the present disclosure, an optical lens system for photographing includes four lens elements. The four lens elements are a first lens element, a second lens element, a third lens element, and a fourth lens element, which are arranged in order from an object side to an image side along an optical path. Each of the four lens elements has an object side surface facing the object side and an image side surface facing the image side.

[0005] Preferably, the first lens element has a positive refractive index. Preferably, the object side surface of the first lens element is convex in a paraxial region thereof. Preferably, the second lens element has a positive refractive index. Preferably, the object side surface of the second lens element is convex in a paraxial region thereof. Preferably, the third lens element has a negative refractive index. Preferably, the image side surface of the third lens element is concave in a paraxial region thereof. Preferably, the image side surface of the fourth lens element is convex in a paraxial region thereof. Preferably, at least one surface of at least one lens element in the optical lens system for photographing has at least one point of inflection.

[0006] When an axial distance between the object side surface of the first lens element and the image side surface of the fourth lens element is TD, an axial distance between the image side surface of the fourth lens element and an image surface is BL, a focal length of the second lens element is f2, a focal length of the fourth lens element is f4, a central thickness of the first lens element is CT1, a central thickness of the second lens element is CT2, a central thickness of the third lens element is CT3, a radius of curvature of the object side surface of the first lens element is R1, and a radius of curvature of the object side surface of the third lens element is R5, the following conditions are preferably met: 0.05 <TD / BL<0,60; 0.05<|f2 / f4|<1.50; 0.10<(CT2+CT3) / CT1<1.00; and −4.50<(R1−R5) / (R1+R5)<0.25.

[0007] According to another aspect of the present disclosure, an optical lens system for photographing includes four lens elements. The four lens elements are a first lens element, a second lens element, a third lens element, and a fourth lens element, which are arranged in order from an object side to an image side along an optical path. Each of the four lens elements has an object side surface facing the object side and an image side surface facing the image side.

[0008] Preferably, the first lens element has a positive refractive index. Preferably, the object-side surface of the first lens element is convex in a paraxial region thereof. Preferably, the second lens element has a positive refractive index. Preferably, the third lens element has a negative refractive index. Preferably, the image-side surface of the third lens element is concave in a paraxial region thereof. Preferably, at least one surface of at least one lens element in the optical lens system for photographing has at least one reversal point.

[0009] When an axial distance between the object side surface of the first lens element and the image side surface of the fourth lens element is TD, an axial distance between the image side surface of the fourth lens element and an image surface is BL, wherein a refractive index of the first lens element is N1, wherein an Abbe number of the second lens element is V2, wherein a central thickness of the second lens element is CT2, and wherein an axial distance between the third lens element and the fourth lens element is T34, the following conditions are preferably satisfied: 0.05 <RD / BL<0,60; 1,650 <N1<2,200; 10.0 <V2<45,0; und 0.05 <CT2 / T34<1,00.

[0010] According to another aspect of the present disclosure, an image capturing unit comprises one of the aforementioned photographing optical lens systems and an image sensor, wherein the image sensor is arranged on the image surface of the photographing optical lens system.

[0011] According to another aspect of the present disclosure, an electronic device comprises the aforementioned image capture unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The disclosure can be better understood by reading the following detailed description of the embodiments with reference to the accompanying drawings: Fig. 1 is a schematic view of an image acquisition unit according to the first embodiment of the present disclosure; Fig. 2 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image sensing unit according to the first embodiment; Fig. 3 is a schematic view of an image acquisition unit according to the second embodiment of the present disclosure; Fig. 4 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image acquisition unit according to the second embodiment; Fig. 5 is a schematic view of an image acquisition unit according to the third embodiment of the present disclosure; Fig. 6 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image sensing unit according to the third embodiment; Fig. 7 is a schematic view of an image acquisition unit according to the fourth embodiment of the present disclosure; Fig. 8 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image sensing unit according to the fourth embodiment; Fig. 9 is a schematic view of an image acquisition unit according to the fifth embodiment of the present disclosure; Fig. 10 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image sensing unit according to the fifth embodiment; Fig. 11 is a schematic view of an image acquisition unit according to the sixth embodiment of the present disclosure; Fig. 12 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image sensing unit according to the sixth embodiment; Fig. 13 is a schematic view of an image acquisition unit according to the seventh embodiment of the present disclosure; Fig. 14 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image sensing unit according to the 7th embodiment; Fig. 15 is a schematic view of an image acquisition unit according to the 8th embodiment of the present disclosure; Fig. 16 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image sensing unit according to the 8th embodiment; Fig. 17 is a schematic view of an image acquisition unit according to the 9th embodiment of the present disclosure; Fig. 18 shows spherical aberration curves, astigmatic field curves and a distortion curve of the image sensing unit according to the 9th embodiment; Fig. 19 is a perspective view of an image acquisition unit according to the 10th embodiment of the present disclosure; Fig. 20 is a perspective view of an electronic device according to the 11th embodiment of the present disclosure; Fig. 21 is another perspective view of the electronic device in Fig. 20; Fig. 22 is a block diagram of the electronic device in Fig. 20; Fig. 23 is a schematic view of an electronic device according to the 12th embodiment of the present disclosure; Fig. 24 is another schematic view of the electronic device in Fig. 23; Fig. 25 is a perspective view of an electronic device according to the 13th embodiment of the present disclosure; Fig. 26 shows a schematic view of reversal points and critical points on lens surfaces according to the first embodiment of the present disclosure; Fig. 27 shows a schematic view of Sag3R1, ET2 and ET3 according to the first embodiment of the present disclosure; Fig. 28 shows a schematic view of a shape of an aperture stop according to the present disclosure; Fig. 29 shows a schematic view of another shape of an aperture stop according to the present disclosure; Fig. 30 to Fig. 32 each shows a schematic view of a configuration of a reflective element in an optical lens system for photographing according to an embodiment of the present disclosure; Fig. 33 and Fig. 34 each shows a schematic view of a configuration of two reflective elements in an optical lens system for photographing according to an embodiment of the present disclosure; Fig. 35 is a schematic view showing a configuration of a double reflective element in an optical lens system for photographing according to an embodiment of the present disclosure; Fig. 36 is a schematic view showing a configuration of a tri-reflective element in an optical lens system for photographing according to an embodiment of the present disclosure; Fig. 37 is a schematic view showing a configuration of a quadruple reflective element in an optical lens system for photographing according to an embodiment of the present disclosure; Fig. 38 is a schematic view showing a configuration of a five-fold reflective element in an optical lens system for photographing according to an embodiment of the present disclosure; Fig. 39 is a schematic view showing a configuration of a reflective element in an optical lens system for photographing according to an embodiment of the present disclosure; Fig. 40 is a schematic view showing a configuration of another reflective element in an optical lens system for photographing according to an embodiment of the present disclosure; Fig. 41 is a schematic view showing a configuration of a reflective element and its associated optical path deflection in the image sensing unit according to the first embodiment; Fig. 42 is a schematic view showing a configuration of another reflecting element and its associated optical path deflection in the image capturing unit according to the first embodiment; Fig. 43 is a schematic view showing a configuration of another reflecting element and its associated optical path deflection in the image capturing unit according to the first embodiment; Fig. 44 shows a schematic view of a configuration of another reflective element and its associated optical path deflection in the image acquisition unit according to the first embodiment; Fig. 45 is a schematic view showing a configuration of another reflecting element and its associated optical path deflection in the image capturing unit according to the first embodiment; Fig. 46 is a schematic view showing a configuration of another reflecting element and its associated optical path deflection in the image capturing unit according to the first embodiment; Fig. 47 is a schematic view showing a configuration of another reflecting element and its associated optical path deflection in the image capturing unit according to the first embodiment; Fig. 48 is a schematic view showing a configuration of another reflecting element and its associated optical path deflection in the image sensing unit according to the ninth embodiment; Fig. 49 is a schematic view showing a configuration of a reflecting element in the optical lens system for photographing the image sensing unit according to the first embodiment; Fig. 50 shows a perspective view of the reflective element of Fig. 49 before forming shortened edges and a recess; and Fig. 51 shows a perspective view of the reflective element of Fig. 49 after forming shortened edges and a recess. DETAILED DESCRIPTION

[0013] An optical lens system for photography includes four lens elements. The four lens elements are a first lens element, a second lens element, a third lens element, and a fourth lens element, which are arranged in order from an object side to an image side along an optical path. Each of the four lens elements of the optical lens system for photography has an object-side surface facing the object side and an image-side surface facing the image side.

[0014] The first lens element has a positive refractive index. This is advantageous for reducing the size while controlling the shooting angle and increasing the amount of incident light. The object-side surface of the first lens element is convex in a paraxial region thereof. This is advantageous for adjusting the surface shape of the first lens element to reduce the outer diameter on the object side of the optical lens system for photography.

[0015] The second lens element has a positive refractive index. This is advantageous for converging light, controlling the light path, and correcting spherical aberration in the optical lens system for photographing. The object-side surface of the second lens element may be convex in a paraxial region thereof. This is advantageous for providing the object-side surface of the second lens element with the property of converging light, thereby achieving downsizing.

[0016] The third lens element has a negative refractive index. This is beneficial for balancing the refractive index of the first lens element, preventing excessive refraction angles of light and thus reducing aberrations. The image side surface of the third lens element is concave in a paraxial region thereof. This is beneficial for balancing the back focal point of the optical lens system for photography and correcting off-axis aberrations.

[0017] The fourth lens element may have a positive refractive index. This is advantageous for smoothing the light path and correcting spherical aberrations in the optical lens system for photographing, thereby maintaining a suitable back focal length. The image side surface of the fourth lens element may be convex in a paraxial region thereof. This is advantageous for adjusting the refraction direction of light in the fourth lens element, thereby enlarging the image area.

[0018] According to the present disclosure, at least one surface of at least one lens element in the optical lens system for photographing has at least one inversion point. Specifically, among the first lens element to the fourth lens element in the optical lens system for photographing, one or more lens elements each have at least one inversion point, and the lens element having at least one inversion point refers to a lens element in which at least one of the object side surface and the image side surface has at least one inversion point. This is advantageous for increasing optical design flexibility for astigmatism correction. Furthermore, at least one of the object side surface and the image side surface of the fourth lens element may have at least one inversion point.This is beneficial for adjusting the angle of incidence of light on the image surface and for controlling the angle of peripheral light to reduce distortion. It is used on . Fig. 26, which shows a schematic view of the reversal points P on the lens surfaces according to the first embodiment of the present disclosure. In Fig. 26, the object side surface of the second lens element E2, the image side surface of the third lens element E3 and the image side surface of the fourth lens element E4 each have a reversal point P, and the image side surface of the second lens element E2 and the object side surface of the fourth lens element E4 each have two reversal points P. The in Fig. The first embodiment of the present disclosure shown in Figure 26 is merely exemplary. Each of the lens elements in various embodiments of the present disclosure may have one or more reversal points.

[0019] The object side surface of the fourth lens element may have at least one critical point in a deviating axial region. This is advantageous for improving the ability of the fourth lens element to correct aberrations in peripheral images. Fig. 26, which shows a schematic view of the critical points C on the lens surfaces according to the first embodiment of the present disclosure. In Fig. 26, the object side surface of the second lens element E2 and the object side surface and the image side surface of the fourth lens element E4 each have a critical point C in an off-axis region thereof. Fig. The first embodiment of the present disclosure shown in Figure 26 is merely exemplary. Each of the lens elements in various embodiments of the present disclosure may have one or more critical points in a different axial region.

[0020] The first lens element may be made of glass material. Using glass material for the first lens element can reduce the sensitivity of the first lens element to environmental influences, thereby providing high stability in various environments. Additionally, using glass material near the object side of the optical lens system for photography is advantageous in protecting against moisture and preventing surface scratches, thereby improving the service life of electronic products.

[0021] According to the present disclosure, the photographing optical lens system may further include at least one reflective element, and the at least one reflective element may be disposed between the fourth lens element and an image surface along a moving direction of the optical path. This is advantageous for providing different optical path directions for the photographing optical lens system, thereby making the configuration of the lens space more flexible to reduce mechanical constraints and facilitate downsizing of the lens. Furthermore, the reflective element may have at least two reflective surfaces. Therefore, by multiple reflecting light rays within the reflective element and forming images, it is advantageous for reducing the overall size of the image capturing unit.In addition, the reflective element may also have at least three reflective surfaces.

[0022] According to the present disclosure, the optical lens system for photographing may further include an aperture stop. This is advantageous for ensuring that the optical lens system for photographing has a suitable entrance pupil and the field of view is controlled to achieve a telephotography effect. Furthermore, the aperture stop may have a major axis direction and a minor axis direction that are perpendicular to an optical axis and different from each other, and wherein an effective radius of the aperture stop in the major axis direction is different from an effective radius of the aperture stop in the minor axis direction. This is advantageous for adjusting the geometry of the aperture stop so as to reduce stray light. Fig. 28 and Fig. 29, which show schematic views of non-circular aperture stops according to the present disclosure, wherein Fig. 28 shows a schematic view of a geometry of an aperture stop according to the present disclosure and Fig. 29 shows a schematic view of another geometry of an aperture stop according to the present disclosure. As in Fig. 28, in some embodiments of the present disclosure, a geometry of an aperture stop ST is elliptical, and wherein the aperture stop ST has a major axis direction LX and a minor axis direction SY perpendicular to an optical axis OA. The major axis direction LX and the minor axis direction SY are two different directions, and wherein an effective radius Ra of the aperture stop ST in the major axis direction LX is greater than an effective radius Rb of the aperture stop ST in the minor axis direction SY. As shown in Fig. 29, in some embodiments of the present disclosure, an aperture stop ST is configured to have truncated edges on an outer periphery thereof, and wherein the aperture stop ST has a major axis direction LX and a minor axis direction SY perpendicular to an optical axis OA. The major axis direction LX and the minor axis direction SY are two different directions, and wherein an effective radius Ra of the aperture stop ST in the major axis direction LX is larger than an effective radius Rb of the aperture stop ST in the minor axis direction SY.

[0023] When an axial distance between the object side surface of the first lens element and the image side surface of the fourth lens element is TD, and an axial distance between the image side surface of the fourth lens element and the image surface is BL, the following condition is satisfied: 0.05 < TD / BL < 0.60. This is beneficial for setting the back focal length to an appropriate length, thereby facilitating light path folding. In addition, the following condition may also be satisfied: 0.10 < TD / BL < 0.45. In addition, the following condition may also be satisfied: 0.12 < TD / BL < 0.35. In addition, the following condition may also be satisfied: 0.19 ≤ TD / BL ≤ 0.31.

[0024] When a focal length of the second lens element is f2 and a focal length of the fourth lens element is f4, the following condition may be satisfied: 0.05 < |f2 / f4| < 1.50. This is beneficial for balancing the refractive index of the second lens element and the fourth lens element, thereby balancing light convergence or divergence and improving the overall focusing quality across the entire field of view. Furthermore, the following condition may also be satisfied: 0.15 < |f2 / f4| < 1.25. Furthermore, the following condition may also be satisfied: 0.20 ≤ |f2 / f4| ≤ 1.14.

[0025] When a central thickness of the first lens element is CT1, a central thickness of the second lens element is CT2, and a central thickness of the third lens element is CT3, the following condition can be satisfied: 0.10 < (CT2 + CT3) / CT1 < 1.00. This is advantageous for equalizing the spatial distribution of the central thicknesses of the first lens element, the second lens element, and the third lens element to take into account the manufacturing constraints of the first lens element. In addition, by adjusting the central thicknesses of the second lens element and the third lens element, the size of the optical lens system for photographing can be reduced. In addition, the following condition can also be satisfied: 0.30 < (CT2 + CT3) / CT1 < 0.85. In addition, the following condition can also be satisfied: 0.35 < (CT2 + CT3) / CT1 < 0.95. In addition, the following condition can also be met: 0.48 ≤ (CT2+CT3) / CT1 ≤ 0.91.

[0026] When a radius of curvature of the object side surface of the first lens element is R1 and a radius of curvature of the object side surface of the third lens element is R5, the following condition may be satisfied: -5.00 < (R1-R5) / (R1+R5) < 0.50. This is beneficial to equalize the radii of curvature of the object side surface of the first lens element and the object side surface of the third lens element, thereby improving the central focusing effect of imaging. In addition, the following condition may also be satisfied: -4.50 < (R1-R5) / (R1+R5) < 0.25. Furthermore, the following condition may also be satisfied: -3.50 < (R1-R5) / (R1+R5) < -0.30. In addition, the following condition may also be satisfied: -3.00 < (R1-R5) / (R1+R5) < -0.60. In addition, the following condition can also be met: -2.88 ≤ (R1-R5) / (R1+R5) ≤ - 0.19.

[0027] When the refractive index of the first lens element is N1, the following condition can be satisfied: 1.650 < N1 < 2.200. This is beneficial for adjusting the refractive index of the first lens element, thereby improving the peripheral light convergence ability and thereby improving imaging contrast and focusing quality. Furthermore, the following condition can also be satisfied: 1.750 < N1 < 2.100. Furthermore, the following condition can also be satisfied: 1.850 < N1 < 2.000. Furthermore, the following condition can also be satisfied: 1.544 ≤ N1 ≤ 1.954.

[0028] When the Abbe number of the second lens element is V2, the following condition can be satisfied: 10.0 < V2 < 45.0. This is beneficial for adjusting the material composition of the second lens element to balance the convergence ability of light across different wavelengths. Furthermore, the following condition can also be satisfied: 15.0 < V2 < 40.0. Furthermore, the following condition can also be satisfied: 20.0 < V2 < 30.0. Furthermore, the following condition can also be satisfied: 22.5 ≤ V2 ≤ 56.0.

[0029] When the central thickness of the second lens element is CT2 and an axial distance between the third lens element and the fourth lens element is T34, the following condition can be satisfied: 0.05 < CT2 / T34 < 1.00. This is advantageous for balancing the central thickness of the second lens element and the distance between the third lens element and the fourth lens element, thereby increasing design flexibility and reducing manufacturing tolerances, thus meeting the requirement of a thinner optical lens system for photographing. In addition, the following condition can also be satisfied: 0.20 < CT2 / T34 < 0.80. Furthermore, the following condition can also be satisfied: 0.39 ≤ CT2 / T34 ≤ 0.90.

[0030] When the focal length of the optical lens system for photography is f and the focal length of the third lens element is f3, the following condition can be met: -5.00 < f / f3 < -1.80. This is beneficial for balancing the light path of the first lens element and correcting systematic spherical aberration to maintain a suitable back focal length. Furthermore, the following condition can also be met: -4.00 < f / f3 < -2.00.

[0031] When the focal length of the optical lens system for photographing is f, the radius of curvature of the image side surface of the second lens element is R4, and the radius of curvature of the object side surface of the third lens element is R5, the following condition can be satisfied: 0.05 < |f / R4|+|f / R5| < 2.80. This is advantageous for adjusting the total focal length and the radii of curvature of the image side surface of the second lens element and the object side surface of the third lens element to correct off-axis aberrations and maintain a suitable focal length within a limited space. In addition, the following condition can also be satisfied: 0.30 < |f / R4|+|f / R5| < 2.60.

[0032] When the radius of curvature of the image side surface of the second lens element is R4 and the radius of curvature of the image side surface of the third lens element is R6, the following condition can be satisfied: 0.20 < (R4+R6) / (R4-R6) < 1.80. This is beneficial for balancing the radii of curvature of the image side surface of the second lens element and the image side surface of the third lens element, adjusting the direction of peripheral light, correcting astigmatism, and reducing stray light within the optical lens system for photographing. Furthermore, the following condition can also be satisfied: 0.60 < (R4+R6) / (R4-R6) < 1.50.

[0033] When the aperture of the optical lens system for photography is Fno, the following condition can be satisfied: 1.50 < Fno < 2.50. This is beneficial for achieving a balance between illuminance and depth of field and improving light penetration to enhance image quality. Furthermore, the following condition can also be satisfied: 1.80 < Fno < 2.40. Furthermore, the following condition can also be satisfied: 2.00 < Fno < 2.35.

[0034] When half of the maximum field of view of the optical lens system for photography is HFOV, the following condition can be met: 5.0 degrees < HFOV < 20.0 degrees. This is advantageous, so that the optical lens system for photography has a field of view suitable for telephoto applications. In addition, the following condition can also be met: 8.0 degrees < HFOV < 17.0 degrees. In addition, the following condition can also be met: 10.0 degrees < HFOV < 15.0 degrees.

[0035] When an axial distance between the aperture stop and the image side surface of the fourth lens element is SD and the axial distance between the object side surface of the first lens element and the image side surface of the fourth lens element is TD, the following condition can be satisfied: 0.05 < SD / TD < 0.90. This is advantageous for making the position of the aperture stop and the axial distance between the aperture stop and the image side surface of the fourth lens element smaller than the axial distance from the object side surface of the first lens element to the image side surface of the fourth lens element in order to increase the relative illuminance of the peripheral field of view. In addition, the following condition can also be satisfied: 0.10 < SD / TD < 0.88. Furthermore, the following condition can also be satisfied: 0.30 < SD / TD < 0.65.

[0036] When the Abbe number of the third lens element is V3 and the Abbe number of the fourth lens element is V4, the following condition can be satisfied: 0.10 < V3 / V4 < 0.85. This is beneficial for adjusting the distribution of lens materials to correct chromatic aberration. Furthermore, the following condition can also be satisfied: 0.20 < V3 / V4 < 0.50.

[0037] When a displacement parallel to the optical axis from an axial vertex of the object side surface of the third lens element to a position of the maximum effective radius of the object side surface of the third lens element is Sag3R1 and the central thickness of the third lens element is CT3, the following condition can be satisfied: -0.10 < Sag3R1 / CT3 < 0.80. This is advantageous for the third lens element to have the property of controlling the direction of the light beam at its edge, regulating the angle of incidence of the light entering the image surface, and preventing stray light from being generated after passing through light folding elements (e.g., reflective elements). In addition, the following condition can also be satisfied: 0 < Sag3R1 / CT3 < 0.75. It is Fig. 27, which shows a schematic view of Sag3R1 according to the first embodiment of the present disclosure. When the direction from the axial vertex of a surface to the position of the maximum effective radius of the same surface faces the image side of the photographing optical lens system, the amount of shift is positive. When the direction from the axial vertex of the surface to the position of the maximum effective radius of the same surface faces the object side of the photographing optical lens system, the amount of shift is negative.

[0038] When a distance parallel to the optical axis between a position of the maximum effective radius of the object side surface of the second lens element and a position of the maximum effective radius of the image side surface of the second lens element is ET2 and the central thickness of the second lens element is CT2, the following condition can be satisfied: 0.50 < ET2 / CT2 < 1.50. This is advantageous for determining the ratio of the edge thickness to the central thickness of the second lens element so as to maintain a suitable edge thickness, thereby improving ease of assembly. In addition, the following condition can also be satisfied: 0.60 < ET2 / CT2 < 1.00. Fig. 27, which shows a schematic view of ET2 according to the first embodiment of the present disclosure.

[0039] When the Abbe number of the first lens element is V1 and the Abbe number of the second lens element is V2, the following condition can be satisfied: 0.80 < V1 / V2 < 2.00. This is beneficial for matching the material composition of the first lens element and the second lens element, thereby reducing chromatic aberration and improving the condition of violet fringing in peripheral images. Furthermore, the following condition can also be satisfied: 0.90 < V1 / V2 < 1.80. Furthermore, the following condition can also be satisfied: 1.00 < V1 / V2 < 1.50.

[0040] When the radius of curvature of the object side surface of the first lens element is R1 and the radius of curvature of the image side surface of the second lens element is R4, the following condition can be satisfied: -3.00 < (R1+R4) / (R1-R4) < 0. This is beneficial for equalizing the radii of curvature of the object side surface of the first lens element and the image side surface of the second lens element, thereby improving the focusing quality of the imaging light, improving the field curvature, and reducing spherical aberration. Furthermore, the following condition can also be satisfied: -2.50 < (R1+R4) / (R1-R4) < -0.20.

[0041] When the axial distance between the object side surface of the first lens element and the image side surface of the fourth lens element is TD, the central thickness of the second lens element is CT2, and an axial distance between the second lens element and the third lens element is T23, the following condition can be satisfied: 4.50 < TD / (CT2+T23) < 8.00. This is advantageous for adjusting the lens element distribution and balancing the thickness of the second lens element with the distance between the second lens element and the third lens element to increase space utilization efficiency. In addition, the following condition can also be satisfied: 4.70 < TD / (CT2+T23) < 7.00.

[0042] When the complemented focal length of the first lens element and the second lens element is f12 and the focal length of the fourth lens element is f4, the following condition can be satisfied: 0.01 < |f12 / f4| < 0.27. This is beneficial for balancing the ratio of the complemented focal length of the first lens element and the second lens element to the focal length of the fourth lens element, thereby increasing systematic symmetry and reducing the spot size in the central field of view. Furthermore, the following condition can also be satisfied: 0.05 < |f12 / f4| < 0.26.

[0043] When an axial distance between the object side surface of the first lens element and the image surface is TL and a maximum image height of the photographing optical lens system (which may be half a diagonal of an effective photosensitive area of an image sensor) is ImgH, the following condition can be satisfied: 5.50 < TL / lmgH < 7.00. This is beneficial for balancing the total length of the guide of the photographing optical lens system with the image height, reducing the size of the lens elements, and forming a telephoto lens structure. In addition, the following condition can also be satisfied: 5.60 < TL / lmgH < 6.80. In addition, the following condition can also be satisfied: 5.70 < TL / lmgH < 6.50.

[0044] When the distance parallel to the optical axis between the position of the maximum effective radius of the object side surface of the second lens element and the position of the maximum effective radius of the image side surface of the second lens element is ET2, and a distance parallel to the optical axis between the position of the maximum effective radius of the object side surface of the third lens element and a position of the maximum effective radius of the image side surface of the third lens element is ET3, the following condition can be satisfied: 0.10 < ET2 / ET3 < 0.85. This is advantageous for balancing the edge thickness of the second lens element with the edge thickness of the third lens element, thereby controlling the direction of peripheral light to achieve focusing, thereby improving peripheral image quality. In addition, the following condition can also be satisfied: 0.20 < ET2 / ET3 < 0.80. It is noted that Fig. 27, which shows a schematic view of ET2 and ET3 according to the first embodiment of the present disclosure.

[0045] According to the present disclosure, the above features and conditions can be used in numerous combinations to achieve corresponding effects.

[0046] According to the present disclosure, the lens elements of the photographing optical lens system can be made of either glass or plastic material. When the lens elements are made of glass material, the refractive power distribution of the photographing optical lens system can be more flexible, and the influence on imaging caused by changes in ambient temperature can be reduced. The glass lens element can be manufactured by either grinding or casting. When the lens elements are made of plastic material, the manufacturing cost can be effectively reduced. Furthermore, the surfaces of each lens element can be designed to be spherical or aspherical. Spherical lens elements are easy to manufacture.The design of aspherical lens elements allows for more control variables to eliminate aberrations and reduce the required number of lens elements, effectively shortening the overall length of the optical lens system for photography. Additionally, the aspherical surfaces can be manufactured using plastic injection molding or glass molding.

[0047] According to the present disclosure, an aspheric lens surface means that the lens surface has an aspherical shape in its entire optically effective area or in one or more parts thereof.

[0048] According to the present disclosure, the material of one or more lens elements may optionally include an additive that creates light absorption and interference effects and modifies the transmittance of the lens elements in a specific wavelength range to reduce unwanted stray light or color variations. For example, the additive may optionally filter out light in the wavelength range of 600 nm to 800 nm to reduce excessive red light and / or near-infrared light, or optionally filter out light in the wavelength range of 350 nm to 450 nm to prevent excessive blue light and / or near-ultraviolet light from interfering with the final image. The additive may be homogeneously blended with a plastic material used to manufacture a blended-material lens element by injection molding. Furthermore, the additive may be applied to the lens surfaces to achieve the above-mentioned effects.

[0049] According to the present disclosure, each of an object side surface and an image side surface has a paraxial region and an off-axis region. The paraxial region refers to the region of the surface where light rays travel close to the optical axis, and the off-axis region refers to the region of the surface far from the paraxial region. Specifically, unless otherwise stated, when the lens element has a convex surface, it means that the surface is convex in the paraxial region thereof. When the lens element has a concave surface, it means that the surface is concave in the paraxial region thereof. When a portion of the refractive index or focal point of a lens element is undefined, it means that the portion of the refractive index or focal point of the lens element lies in its paraxial region.

[0050] According to the present disclosure, an inflection point is a point on the surface of the lens element where the surface changes from concave to convex, or vice versa. A critical point is an off-axis point on the lens surface where its tangent is perpendicular to the optical axis.

[0051] According to the present disclosure, the image surface of the photographing optical lens system may be flat or curved based on the corresponding image sensor, and in particular, a curved surface is concavely facing the object side of the photographing optical lens system.

[0052] According to the present disclosure, an image correction unit, such as a field flattener, may optionally be arranged between the lens element located along the optical path closest to the image side of the photographing optical lens system and the image surface to correct aberrations such as field curvature. The optical properties of the image correction unit, such as curvature, thickness, refractive index, position, and surface shape (convex or concave surface with spherical, aspherical, diffractive, or Fresnel types), can be adjusted according to the design of the image sensing unit. In general, a preferred image correction unit is, for example, a thin transparent element having a concave object side surface and a planar image side surface, and the thin transparent element is arranged near the image surface.

[0053] According to the present disclosure, at least one reflective element such as a prism or a reflective mirror may be optionally provided, and the surface of the prism or the reflective mirror may be planar, spherical, aspherical, or free-form, so that the optical lens system for photographing can be more flexible in spatial arrangement. The reflective element may be arranged between an imaged object and the image surface to reduce the size of the optical lens system for photographing. The optical path may be deflected at least once by the reflective element. An angle between the optical axis and a normal direction of a reflective surface of the reflective element is not limited to 45 degrees, but may also be other angles depending on the spatial arrangement.The optical path along an optical axis on the object side can be redirected by the reflective element to an optical axis on the image side. An angle between a vector of the optical axis on the object side and that on the image side can be any angle, not limited to 0, 90, or 180 degrees. Furthermore, in order to reduce the size of the optical lens system for photographing, the length and width of the reflective mirror can be different from each other, and the length, width, and height of the prism can be different from each other. The surface of the reflective element (e.g., the surface of the prism or the reflective mirror) can be planar, spherical, aspherical, or a freeform shape according to optical design requirements, but the present disclosure is not limited thereto.The reflective element may consist of more than one prism depending on the design requirements. The prism may be made of glass or plastic depending on the design requirements. Furthermore, the optical path folding prism is not one of the lens elements, meaning that the optical path folding prism is not included in the four lens elements of the optical lens system for photography.

[0054] Furthermore, the Fig. 30 to Fig. 32, each showing a schematic view of a configuration of a reflective element in an optical lens system for photographing according to an embodiment of the present disclosure. As shown in Fig. 30 to Fig. 32, the optical lens system for photographing may include, in order from an imaged object (not shown in the figures) to an image surface IMG along a propagation direction of a light path, a reflecting element LF, a lens group LG, a filter FT, and the image surface IMG.

[0055] In Fig. 30, the reflective element LF is a prism and has, in a propagation sequence of the light on the beam path, a first light-transmitting surface LP1, a reflective surface RF1, and a second light-transmitting surface LP2. The beam path enters the reflective element LF through the first light-transmitting surface LP1 and reaches the reflective surface RF1 along a first optical axis OA1. The reflective surface RF1 deflects the beam path from the first optical axis OA1 to a second optical axis OA2, and the beam path then passes the second light-transmitting surface LP2, passes through the lens group LG and the filter FT, and finally reaches the image surface IMG along the second optical axis OA2. As in Fig. 30, both the first light-transmitting surface LP1 and the second light-transmitting surface LP2 of the reflective element LF may be planar.

[0056] In Fig. 31, the reflective element LF is a flat reflecting mirror with a reflecting surface RF1. The beam path reaches the reflecting surface RF1 along a first optical axis OA1. The reflecting surface RF1 deflects the beam path from the first optical axis OA1 to a second optical axis OA2. The beam path then passes through the lens group LG and the filter FT and finally reaches the image surface IMG along the second optical axis OA2.

[0057] In Fig. 32, the reflective element LF is a prism and has, in the direction of propagation of the light on the beam path, a first light-transmitting surface LP1, a reflective surface RF1, and a second light-transmitting surface LP2. The beam path enters the reflective element LF through the first light-transmitting surface LP1 and reaches the reflective surface RF1 along a first optical axis OA1. The reflective surface RF1 deflects the beam path from the first optical axis OA1 to a second optical axis OA2, whereupon the beam path passes through the second light-transmitting surface LP2, passes through the lens group LG and the filter FT, and finally strikes the image surface IMG along the second optical axis OA2. As in Fig. 32, both the first light-transmitting surface LP1 and the second light-transmitting surface LP2 of the reflective element LF may be curved.

[0058] It will also be Fig. 33 and Fig. 34, each showing a schematic view of a configuration of two reflective elements in an optical lens system for photographing according to an embodiment of the present disclosure. As shown in Fig. 33 and Fig. 34, the optical lens system for photographing may include, in order from an imaged object (not shown in the figures) to an image surface IMG along a propagation direction of a light path, a first reflecting element LF1, a lens group LG, a filter FT, a second reflecting element LF2, and the image surface IMG. The light path enters the first reflecting element LF1 and reaches the first reflecting surface RF1 along a first optical axis OA1, and the first reflecting surface RF1 deflects the light path from the first optical axis OA1 to a second optical axis OA2. The light path passes through the lens group LG and the filter FT along the second optical axis OA2.The beam then enters the second reflective element LF2 and reaches the second reflective surface RF2 along the second optical axis OA2. The second reflective surface RF2 deflects the beam from the second optical axis OA2 to a third optical axis OA3. The beam finally reaches the image surface IMG along the third optical axis OA3. Fig. 33, both the first reflecting element LF1 and the second reflecting element LF2 can be a prism. In Fig. 34, the first reflecting element LF1 and the second reflecting element LF2 may be a prism and a flat reflecting mirror, respectively.

[0059] It will be Fig. 35 to Fig. 38. Fig. 35 is a schematic view showing a configuration of a double reflective element in an optical lens system for photographing according to an embodiment of the present disclosure; Fig. 36 is a schematic view showing a configuration of a triple reflective element in an optical lens system for photographing according to an embodiment of the present disclosure; Fig. 37 is a schematic view showing a configuration of a quadruple reflecting element in an optical lens system for photographing according to an embodiment of the present disclosure, and Fig. 38 is a schematic view showing a configuration of a five-fold reflective element in an optical lens system for photographing according to an embodiment of the present disclosure.

[0060] As in Fig. 35, the optical lens system for photographing may include, in order from an imaged object (not shown in the figures) to an image surface IMG along a propagation direction of a light path, a lens group LG, a filter FT, a reflective element LF, and the image surface IMG. The reflective element LF may be a prism and has, in sequence along a propagation direction of light on the light path, a first light-transmitting surface LP1, a first reflective surface RF1, a second reflective surface RF2, and a second light-transmitting surface LP2. The light path passes through the lens group LG and the filter FT, enters the reflective element LF through the first light-transmitting surface LP1, and reaches the first reflective surface RF1 along a first optical axis OA1.The first reflecting surface RF1 deflects the optical path from the first optical axis OA1 to a second optical axis OA2, the second reflecting surface RF2 deflects the optical path from the second optical axis OA2 to a third optical axis OA3, and then the optical path passes through the second light-transmitting surface LP2 and finally arrives at the image surface IMG along the third optical axis OA3.

[0061] As in Fig. 36, the optical lens system for photographing in a sequence from an imaged object (not shown in the figures) to an image surface IMG along a propagation direction of a light path may include a lens group LG, a filter FT, a reflective element LF, and the image surface IMG. The reflective element LF may be a prism and has, in sequence, in the propagation direction of the light on the light path, a first light-transmitting surface LP1, a first reflective surface RF1, a second reflective surface RF2, a third reflective surface RF3, and a second light-transmitting surface LP2. The light path passes through the lens group LG and the filter FT, enters the reflective element LF through the first light-transmitting surface LP1, and reaches the first reflective surface RF1 along a first optical axis OA1.The first reflective surface RF1 deflects the optical path from the first optical axis OA1 to a second optical axis OA2, the second reflective surface RF2 deflects the optical path from the second optical axis OA2 to a third optical axis OA3, the third reflective surface RF3 deflects the optical path from the third optical axis OA3 to a fourth optical axis OA4, and the optical path then passes through the second translucent surface LP2 and finally reaches the image surface IMG along the fourth optical axis OA4. Furthermore, the first translucent surface LP1 and the second reflective surface RF2 can be coplanar.

[0062] As in Fig. 37, the optical lens system for photographing may include, in a sequence from an imaged object (not shown in the figures) to an image surface IMG along a propagation direction of a light path, a lens group LG, a reflective element LF, a filter FT, and the image surface IMG. The reflective element LF may be a prism and has, in sequence, in the propagation direction of light on the light path, a first light-transmitting surface LP1, a first reflection surface RF1, a second reflection surface RF2, a third reflection surface RF3, a fourth reflection surface RF4, and a second light-transmitting surface LP2. The light path passes through the lens group LG, enters the reflective element LF through the first light-transmitting surface LP1, and reaches the first reflection surface RF1 along a first optical axis OA1.The first reflective surface RF1 directs the beam path from the first optical axis OA1 to a second optical axis OA2, the second reflective surface RF2 directs the beam path from the second optical axis OA2 to a third optical axis OA3, the third reflective surface RF3 directs the beam path from the third optical axis OA3 to a fourth optical axis OA4, and the fourth reflective surface RF4 directs the beam path from the fourth optical axis OA4 to a fifth optical axis OA5. The beam path then passes through the second translucent surface LP2, traverses the filter FT, and finally arrives at the image surface IMG along the fifth optical axis OA5. Furthermore, the first translucent surface LP1 and the second reflective surface RF2 can be coplanar.

[0063] As in Fig. 38, the optical lens system for photographing may include, in order from an imaged object (not shown in the figures) to an image surface IMG along a propagation direction of a light path, a lens group LG, a reflective element LF, a filter FT, and an image surface IMG. The reflective element LF may be a prism and has, in sequence, in the propagation direction of light on the light path, a first light-transmitting surface LP1, a first reflective surface RF1, a second reflective surface RF2, a third reflective surface RF3, a fourth reflective surface RF4, a fifth reflective surface RF5, and a second light-transmitting surface LP2.The beam path passes through the lens group LG, enters the reflective element LF through the first light-transmitting surface LP1 and reaches the first reflective surface RF1 along a first optical axis OA1. The first reflective surface RF1 deflects the beam path from the first optical axis OA1 to a second optical axis OA2, the second reflective surface RF2 deflects the beam path from the second optical axis OA2 to a third optical axis OA3, the third reflective surface RF3 deflects the beam path from the third optical axis OA3 to a fourth optical axis OA4, the fourth reflective surface RF4 deflects the beam path from the fourth optical axis OA4 to a fifth optical axis OA5 and the fifth reflective surface RF5 deflects the beam path from the fifth optical axis OA5 to a sixth optical axis OA6.The optical path then passes through the second translucent surface LP2, passes through the filter FT, and finally reaches the image surface IMG along the sixth optical axis OA6. Furthermore, the first translucent surface LP1 and the second reflective surface RF2 may be coplanar.

[0064] It will also be Fig. 39 and Fig. 40. Fig. 39 is a schematic view showing a configuration of a reflective element in an optical lens system for photographing according to an embodiment of the present disclosure, and Fig. 40 shows a schematic view of a configuration of another reflective element in an optical lens system for photographing according to an embodiment of the present disclosure. As in Fig. 39 and Fig. 40, the optical lens system for photographing may include, in the order from an imaged object (not shown in the figures) to an image surface IMG along a propagation direction of a light path, a lens group LG, a reflective element LF, a filter FT, and the image surface IMG. The reflective element LF may be a pentaprism and has, in a propagation sequence of the light on the light path, a first light-transmitting surface LP1, a first reflective surface RF1, a second reflective surface RF2, and a second light-transmitting surface LP2. The light path enters the reflective element LF through the first light-transmitting surface LP1 and reaches the first reflective surface RF1 along a first optical axis OA1.The first reflecting surface RF1 directs the optical path from the first optical axis OA1 to a second optical axis OA2, and the second reflecting surface RF2 directs the optical path from the second optical axis OA2 to a third optical axis OA3. The optical path then passes through the second translucent surface LP2, then passes through the filter FT, and finally reaches the image surface IMG along the third optical axis OA3. In . Fig. 39, both the first translucent surface LP1 and the second translucent surface LP2 may be planar. In Fig. 40, both the first translucent surface LP1 and the second translucent surface LP2 may be curved. Furthermore, as shown in Fig. 39 and Fig. 40, the first optical axis OA1 and the third optical axis OA3 are intersecting and perpendicular to each other.

[0065] Furthermore, in order to reduce the size of the optical lens system for photography, the length and width of the reflecting mirror may be different from each other, and the length, width, and height of the prism may also be different from each other. The prism may have at least one shortened edge or at least one recess at its optically ineffective portion to reduce its weight and size and be designed in accordance with other components in the electronic device. In addition, a light-absorbing layer may be applied to the surface in the recess to prevent light reflections and block stray light. Fig. 49 to Fig. 51, where Fig. 49 is a schematic view showing a configuration of a reflective element in the optical lens system for photographing the image sensing unit according to the first embodiment, wherein Fig. 50 a perspective view of the reflective element of Fig. 49 before forming shortened edges and a recess, and where Fig. 51 a perspective view of the reflective element of Fig. 49 after forming curved edges and a recess. As in Fig. 49 and Fig. 50, the reflective element E5 has optically ineffective regions NPR, ie, imaging light does not penetrate the optically ineffective regions NPR in the reflective element E5. Therefore, in the construction, the parts of the reflective element E5 that are provided with the optically ineffective regions NPR according to Fig. 49 and Fig. 50, can be omitted, and thus the reflective element E5 with shortened edges CP and a recess RP (according to Fig. 51) are trained.

[0066] The optical lens system for photographing may optionally be provided with three or more reflective elements, and the present disclosure is not limited to the type, number, and position of the reflective elements of the embodiments disclosed in the above-mentioned figures.

[0067] According to the present disclosure, the optical lens system for photographing may include at least one diaphragm, such as an aperture diaphragm, a diaphragm stop, or a field diaphragm stop. The diaphragm stop or the field diaphragm is used to eliminate stray light and thereby improve the image quality thereof.

[0068] According to the present disclosure, an aperture stop may be configured as a front stop or a center stop. A front stop disposed between an imaged object and the first lens element can provide a larger distance between an exit pupil of the photographing optical lens system and the image surface to create a telecentric effect, thereby improving the image perception efficiency of an image sensor (e.g., CCD or CMOS). A center stop disposed between the first lens element and the image surface is advantageous for increasing the viewing angle of the photographing optical lens system, thereby providing a wider field of view therefor.

[0069] According to the present disclosure, the optical lens system for photographing may include an aperture control unit. The aperture control unit may be a mechanical component or a light modulator that can control the size and shape of the aperture through electricity or electrical signals. The mechanical component may include a movable element such as a blade array or a light-shielding film. The light modulator may include a shielding element such as a filter, an electrochromic material, or a liquid crystal layer. The aperture control unit controls the amount of incident light or the exposure time to improve the image quality adjustment property. Furthermore, the aperture control unit may be the aperture stop of the present disclosure, which changes the F-number to achieve different image effects such as depth of field or light intensity.

[0070] According to the present disclosure, the photographing optical lens system may include one or more optical elements for limiting the shape of light passing through the photographing optical lens system. Each optical element may be, but is not limited to, a filter, a polarizer, etc., and each optical element may be, but is not limited to, a single-piece element, a composite component, a thin film, etc. The optical element may be located on the object side or the image side of the photographing optical lens system, or between two adjacent lens elements to transmit light in a specific shape and thereby meet application requirements.

[0071] According to the present disclosure, the optical lens system for photographing may include at least one optical lens element, an optical element, or a substrate having at least one surface with a low-reflection layer. The low-reflection layer can effectively reduce stray light generated due to light reflection at the interface. The low-reflection layer may be disposed in an optically ineffective region of an object side surface or an image side surface of the optical lens element, or a connecting surface between the object side surface and the image side surface. The optical element may be a light-impermeable element, an annular spacer, a mount element, a cover glass, a blue glass, a filter, a color filter, an optical path folding element (e.g., a reflective element), a prism, a mirror, etc.The carrier may be a base for holding a lens assembly, a microlens disposed on an image sensor, a substrate surrounding the image sensor, a glass plate for protecting the image sensor, etc.

[0072] According to the present disclosure, the object side and the image side are defined according to the direction of the optical axis, and the axial optical information is calculated along the optical axis. Furthermore, when the optical axis is deflected by a light folding element, the axial optical information is also calculated along the deflected optical axis.

[0073] In accordance with the above description of the present disclosure, the following specific embodiments are provided for further explanation. 1. Embodiment

[0074] Fig. 1 is a schematic view of an image acquisition unit according to the first embodiment of the present disclosure. Fig. Figure 2 shows, in order from left to right, spherical aberration curves, astigmatic field curves, and a distortion curve of the image acquisition unit according to the first embodiment. Fig. 1, the image sensing unit 1 includes the photographing optical lens system (the reference numeral of which is omitted) of the present disclosure and an image sensor IS. The photographing optical lens system includes, in order from the object side to the image side along an optical path, a stop S1, a first lens element E1, a second lens element E2, an aperture stop ST, a third lens element E3, a fourth lens element E4, a diaphragm S2, a reflecting element E5, a filter E6, and an image surface IMG. The photographing optical lens system includes four lens elements (E1, E2, E3, and E4), and no additional lens element is disposed between each of the adjacent four lens elements.

[0075] The first lens element E1 with a positive refractive index has an object side surface that is convex in a paraxial region and an image side surface that is convex in a paraxial region. The first lens element E1 is made of glass material and has both the object side surface and the image side surface, which are each spherical.

[0076] The second lens element E2 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic and has both the object side surface and the image side surface, each of which is aspherical. The object side surface of the second lens element E2 has two reversal points. The image side surface of the second lens element E2 has two reversal points. The object side surface of the second lens element E2 has a concave critical point in an off-axis region.

[0077] The third lens element E3 with a negative refractive index has an object side that is convex in a paraxial region and an image side that is concave in a paraxial region. The third lens element E3 is made of plastic and has both the object and image sides aspherical. The image side surface of the third lens element E3 has a reversal point.

[0078] The fourth lens element E4 with a positive refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The fourth lens element E4 is made of plastic and has the object side surface and the image side surface, both of which are aspherical. The object side surface of the fourth lens element E4 has two reversal points. The image side surface of the fourth lens element E4 has one reversal point. The object side surface of the fourth lens element E4 has a convex critical point in a deviated axial region therefrom. The image side surface of the fourth lens element E4 has a concave critical point in a deviated axial region therefrom.

[0079] The reflective element E5 is made of glass material and is located between the fourth lens element E4 and the image surface IMG along the optical axis without affecting the focal length of the optical lens system for photographing. The reflective element E5 is a prism configured with a function for deflecting the light path. For ease of illustration, Fig. 1, the deflection of the beam path caused by the reflective element E5 is not shown. However, the reflective element E5 can have different configurations depending on the actual design requirements, causing different deflection effects on the beam path. It is shown on Fig. 41 to Fig. 47, each showing a schematic view of a configuration of a reflective element and the associated optical path deflection in the image acquisition unit according to the first embodiment.

[0080] In Fig. 41 to Fig. 43, the reflective element E5 has, in a sequence along a propagation direction of the light on the beam path, a first light-transmitting surface LP1, a first reflective surface RF1, a second reflective surface RF2, and a second light-transmitting surface LP2. The first reflective surface RF1 deflects the beam path from a first optical axis OA1 to a second optical axis OA2, the second reflective surface RF2 deflects the beam path from the second optical axis OA2 to a third optical axis OA3, and then the beam path reaches the image surface IMG along the third optical axis OA3. Fig. 41 to Fig. 43, the reflecting element E5 deflects the beam path twice. Furthermore, Fig. 41 a configuration in which the first light-transmitting surface LP1 and the second light-transmitting surface LP2 are coplanar, wherein a normal direction of the first reflecting surface RF1 may be at an angle of 45.0 degrees to both the first optical axis OA1 and the second optical axis OA2, and wherein a normal direction of the second reflecting surface RF2 may be at an angle of 45.0 degrees to both the second optical axis OA2 and the third optical axis OA3, so that an angle between a vector of the optical axis on the object side (e.g., the first optical axis OA1) and a vector of the optical axis on the image side (e.g., the third optical axis OA3) may be 180 degrees. Fig. 42 shows a configuration in which the first light-transmitting surface LP1 and the second light-transmitting surface LP2 are parallel to each other and not coplanar, wherein a normal direction of the first reflecting surface RF1 may be at an angle of 42.0 degrees to both the first optical axis OA1 and the second optical axis OA2, and wherein a normal direction of the second reflecting surface RF2 may be at an angle of 48.0 degrees to both the first optical axis OA1 and the second optical axis OA2, so that an angle between a vector of the optical axis on the object side (e.g., the first optical axis OA1) and a vector of the optical axis on the image side (e.g., the third optical axis OA3) may be 180 degrees. Fig. 43 shows a configuration in which the first light-transmitting surface LP1 and the second light-transmitting surface LP2 are not parallel to each other and not coplanar, wherein a normal direction of the first reflecting surface RF1 may be at an angle of 47.0 degrees to both the first optical axis OA1 and the second optical axis OA2, and wherein a normal direction of the second reflecting surface RF2 may be at an angle of 55.6 degrees to both the second optical axis OA2 and the third optical axis OA3, so that an angle between a vector of the optical axis on the object side (e.g., the first optical axis OA1) and a vector of the optical axis on the image side (e.g., the third optical axis OA3) may be an obtuse angle.

[0081] In Fig. 44, the reflective element E5 is a pentaprism and has, in the direction of propagation of the light on the beam path, a first light-transmitting surface LP1, a first reflective surface RF1, a second reflective surface RF2, and a second light-transmitting surface LP2. The first reflective surface RF1 deflects the beam path from a first optical axis OA1 to a second optical axis OA2, with the second reflective surface RF2 deflecting the beam path from the second optical axis OA2 to a third optical axis OA3, and the beam path then reaches the image surface IMG along the third optical axis OA3. Fig. 44, the reflective element E5 deflects the beam path twice, wherein a normal direction of the first reflective surface RF1 can be at an angle of 23.5 degrees to both the first optical axis OA1 and the second optical axis OA2, and wherein a normal direction of the second reflective surface RF2 can be at an angle of 21.5 degrees to both the second optical axis OA2 and the third optical axis OA3, so that an angle between a vector of the optical axis on the object side (e.g., the first optical axis OA1) and a vector of the optical axis on the image side (e.g., the third optical axis OA3) can be 90 degrees. of the second reflective surface can be 5 degrees to both the second optical axis OA2 and the third optical axis OA3, so that an angle between a vector of the optical axis on the object side (e.g., the first optical axis OA1) and a vector of the optical axis on the image side (e.g.,the third optical axis OA3) can be 90 degrees.

[0082] In Fig. 45 and Fig. 46, the reflective element E5 has, in a sequence along a propagation direction of the light on the beam path, a first light-transmitting surface LP1, a first reflective surface RF1, a second reflective surface RF2, a third reflective surface RF3, and a second light-transmitting surface LP2. The first reflective surface RF1 directs the beam path from a first optical axis OA1 to a second optical axis OA2, the second reflective surface RF2 directs the beam path from the second optical axis OA2 to a third optical axis OA3, the third reflective surface RF3 directs the beam path from the third optical axis OA3 to a fourth optical axis OA4, and the beam path then reaches the image surface IMG along the fourth optical axis OA4. In Fig. 45 and Fig. 46, the reflective element E5 deflects the beam path three times. In addition, Fig. 45 an equipment in which the first light-transmitting surface LP1, the second reflective surface RF2 and the second light-transmitting surface LP2 are coplanar, wherein a normal direction of the first reflective surface RF1 can be at an angle of 30.0 degrees to both the first optical axis OA1 and the second optical axis OA2, wherein a normal direction of the second reflective surface RF2 can be at an angle of 60.0 degrees to both the second optical axis OA2 and the third optical axis OA3, and wherein a normal direction of the third reflective surface RF3 can be at an angle of 30.0 degrees to the third optical axis OA3 and the fourth optical axis OA4, so that an angle between a vector of the optical axis on the object side (e.g., the first optical axis OA1) and a vector of the optical axis on the image side (e.g., the fourth optical axis OA4) can be 180 degrees. Fig. 46 shows a configuration in which the first light-transmitting surface LP1 and the second light-transmitting surface LP2 are not parallel to each other and not coplanar, wherein a normal direction of the first reflecting surface RF1 may be at an angle of 40.0 degrees to both the first optical axis OA1 and the second optical axis OA2, wherein a normal direction of the second reflecting surface RF2 may be at an angle of 55.0 degrees to both the second optical axis OA2 and the third optical axis OA3, and wherein a normal direction of the third reflecting surface RF3 may be at an angle of 27.5 degrees to both the third optical axis OA3 and the fourth optical axis OA4, so that an angle between a vector of the optical axis on the object side (e.g., the first optical axis OA1) and a vector of the optical axis on the image side (e.g.,the fourth optical axis OA4) can be an obtuse angle.

[0083] In Fig. 47, the reflective element E5 has, in a sequence along a propagation direction of the light on the beam path, a first light-transmitting surface LP1, a first reflective surface RF1, a second reflective surface RF2, a third reflective surface RF3, a fourth reflective surface RF4 and a second light-transmitting surface LP2.The first reflective surface RF1 directs the beam path from a first optical axis OA1 to a second optical axis OA2, the second reflective surface RF2 directs the beam path from the second optical axis OA2 to a third optical axis OA3, the third reflective surface RF3 directs the beam path from the third optical axis OA3 to a fourth optical axis OA4, the fourth reflective surface RF4 directs the beam path from the fourth optical axis OA4 to a fifth optical axis OA5, and the beam path reaches the image area IMG along the fifth optical axis OA5. In . Fig. 47, the reflective element E5 deflects the beam path four times. A normal direction of the first reflective surface RF1 can be at an angle of 28.0 degrees to both the first optical axis OA1 and the second optical axis OA2, wherein a normal direction of the second reflective surface RF2 can be at an angle of 56.0 degrees to both the second optical axis OA2 and the third optical axis OA3, wherein a normal direction of the third reflective surface RF3 can be at an angle of 56.0 degrees to both the third optical axis OA3 and the fourth optical axis OA4, and wherein a normal direction of the fourth reflective surface RF4 can be at an angle of 28.0 degrees to both the fourth optical axis OA4 and the fifth optical axis OA5, so that an angle between a vector of the optical axis on the object side (e.g.the first optical axis OA1) and a vector of the optical axis on the image side (e.g., the fifth optical axis OA5) may be 0 degrees. Furthermore, the reflective element E5 in the first embodiment may have a configuration similar to that in FIG. Fig. 38, which deflects the beam path five times. Further details are given in the description with Fig. 38 and are not repeated here.

[0084] The E6 filter is made of glass and is located between the reflective element E5 and the image surface IMG, without affecting the focal length of the optical lens system for photography. The IS image sensor is located on or near the image surface IMG of the optical lens system for photography.

[0085] The equation of the aspherical surface profiles of the above-mentioned lens elements of the first embodiment is as follows: X(Y)=(Y2 / R) / (1+sqrt(1−(1+k)×(Y / R)2))+∑i(Ai)×(Yi) , where X is the displacement parallel to an optical axis from an axial vertex on the aspherical surface to a point at a distance Y from the optical axis on the aspherical surface. Y is the vertical distance from the point on the aspherical surface to the optical axis; R is the radius of curvature; k is the conicity coefficient; and Ai is the i-th aspherical coefficient, and in the embodiments, i may be 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26 and 28, but is not limited thereto.

[0086] In the photographing optical lens system of the image sensing unit 1 according to the first embodiment, when a focal length of the photographing optical lens system is f, an F-number of the photographing optical lens system is Fno, and half of a maximum field of view of the photographing optical lens system is HFOV, these parameters have the following values: f = 14.7 millimeters (mm), Fno = 2.28, and HFOV = 13.6 degrees (degrees). 74 millimeters (mm), Fno = 2.28, and HFOV = 13.6 degrees (degrees).

[0087] When an axial distance between the object side surface of the first lens element E1 and the image surface IMG is TL and a maximum image height of the optical lens system for photographing is ImgH, the following condition is satisfied: TL / lmgH = 5.92.

[0088] When an axial distance between the object side surface of the first lens element E1 and the image side surface of the fourth lens element E4 is TD and an axial distance between the image side surface of the fourth lens element E4 and the image surface IMG is BL, the following condition is satisfied: TD / BL = 0.25.

[0089] When an axial distance between the aperture stop ST and the image side surface of the fourth lens element E4 is SD and the axial distance between the object side surface of the first lens element E1 and the image side surface of the fourth lens element E4 is TD, the following condition is satisfied: SD / TD = 0.39.

[0090] When the focal length of the optical lens system for photographing is f and a focal length of the third lens element E3 is f3, the following condition is satisfied: f / f3 = -2.26.

[0091] When a focal length of the second lens element E2 is f2 and a focal length of the fourth lens element E4 is f4, the following condition is satisfied: |f2 / f4| = 0.43.

[0092] When a combined focal length of the first lens element E1 and the second lens element E2 is f12 and the focal length of the fourth lens element E4 is f4, the following condition is satisfied: |f12 / f4| = 0.10.

[0093] When the focal length of the optical lens system for photographing is f, a radius of curvature of the image side surface of the second lens element E2 is R4, and a radius of curvature of the object side surface of the third lens element E3 is R5, the following condition is satisfied: |f / R4|+|f / R5| = 1.60.

[0094] When a radius of curvature of the object side surface of the first lens element E1 is R1 and the radius of curvature of the image side surface of the second lens element E2 is R4, the following condition is satisfied: (R1+R4) / (R1-R4) = -2.06.

[0095] When the radius of curvature of the object side surface of the first lens element E1 is R1 and the radius of curvature of the object side surface of the third lens element E3 is R5, the following condition is satisfied: (R1-R5) / (R1+R5) = -0.33.

[0096] When the radius of curvature of the image side surface of the second lens element E2 is R4 and a radius of curvature of the image side surface of the third lens element E3 is R6, the following condition is satisfied: (R4+R6) / (R4-R6) = 1.36.

[0097] When the axial distance between the object side surface of the first lens element E1 and the image side surface of the fourth lens element E4 is TD, a central thickness of the second lens element E2 is CT2, and an axial distance between the second lens element E2 and the third lens element E3 is T23, the following condition is satisfied: TD / (CT2+T23) = 4.86. In this embodiment, an axial distance between two adjacent lens elements is a distance in a paraxial region between two adjacent lens surfaces of the two adjacent lens elements.

[0098] When a central thickness of the first lens element E1 is CT1, the central thickness of the second lens element E2 is CT2, and a central thickness of the third lens element E3 is CT3, the following condition is satisfied: (CT2+CT3) / CT1 = 0.48.

[0099] When the central thickness of the second lens element E2 is CT2 and an axial distance between the third lens element E3 and the fourth lens element E4 is T34, the following condition is satisfied: CT2 / T34 = 0.39.

[0100] If the refractive index of the first lens element E1 is N1, the following condition is satisfied: N1 = 1.911.

[0101] If the Abbe number of the second lens element E2 is V2, the following condition is met: V2 = 25.6.

[0102] If an Abbe number of the first lens element E1 is V1 and the Abbe number of the second lens element E2 is V2, the following condition is satisfied: V1 / V2 = 1.38.

[0103] If an Abbe number of the third lens element E3 is V3 and an Abbe number of the fourth lens element E4 is V4, the following condition is satisfied: V3 / V4 = 0.33.

[0104] When a distance parallel to the optical axis between a position of the maximum effective radius of the object side surface of the second lens element E2 and a position of the maximum effective radius of the image side surface of the second lens element E2 is ET2 and the central thickness of the second lens element E2 is CT2, the following condition is satisfied: ET2 / CT2 = 1.23.

[0105] When the distance parallel to the optical axis between the position of the maximum effective radius of the object side surface of the second lens element E2 and the position of the maximum effective radius of the image side surface of the second lens element E2 is ET2 and a distance parallel to the optical axis between a position of the maximum effective radius of the object side surface of the third lens element E3 and a position of the maximum effective radius of the image side surface of the third lens element E3 is ET3, the following condition is satisfied: ET2 / ET3 = 0.58.

[0106] When a displacement parallel to the optical axis from an axial vertex of the object side surface of the third lens element E3 to the position of the maximum effective radius of the object side surface of the third lens element E3 is Sag3R1 and the central thickness of the third lens element E3 is CT3, the following condition is satisfied: Sag3R1 / CT3 = 1.19. In this embodiment, the direction of Sag3R1 points to the image side of the photographing optical lens system, and the value of Sag3R1 is positive.

[0107] The detailed optical information of the first embodiment is shown in Table 1A and the information of the aspherical surfaces is shown in Table 1B below. TABELLE 1A 1. Ausführungsform f = 14.74 mm, Fno = 2.28, HFOV = 13.6 Grad Oberfläche # Krümmungsradius Dicke Material Index Abbe # Brennweite 0 Objektiv Plano unendlich 1 Blende Plano -0.326 2 Linse 1 7.7757 (SPH) 1.490 Glas 1.911 35.3 7.57 3 -55.5556 (SPH) 0.040 4 Linse 2 9.1159 (ASP) 0.360 Kunststoff 1.614 25.6 24.79 5 22.4045 (ASP) 0.675 6 Aperturblende Plano -0.173 7 Linse 3 15.5768 (ASP) 0.350 Kunststoff 1.680 18.2 -6.52 8 3.4203 (ASP) 0.930 9 Linse 4 -9.8307 (ASP) 0.518 Kunststoff 1.544 56.0 57.42 10 -7.6165 (ASP) 0.030 11 Blende Plano 0.400 12 Prism Plano 15.750 Glas 1.804 46.6 - 13 Plano 0.200 14 Filter Plano 0.210 Glas 1.517 64.2 - 15 Plano 0.429 16 Bild Plano - Anmerkung: Die Referenzwellenlänge beträgt 587,6 nm (d-Linie). An effective radius of the aperture S1 (surface 1) is 3.267 mm. An effective radius of the aperture S2 (surface 11) is 2.194 mm. TABLE 1B Aspherical coefficients Surface # 4 5 7 8 k = 1.13918000E+00 -7.89066000E+01 0.00000000E+00 0.00000000E+00 A4 = -1.69827280E-02 -1.77867550E-02 -2.65134735E-03 -2.67494055E-03 A6 = 2.46432079E-02 4.87726817E-02 6.04044709E-02 4.76358147E-02 A8 = -2.22074711E-02 -4.80838313E-02 -8.23966473E-02 -7.19586522E-02 A10 = 1.44666933E-02 3.29905523E-02 6.72498535E-02 6.16874635E-02 A12 = -6.80437648E-03 -1.64497157E-02 -3.91217611E-02 -3.81157182E-02 A14 = 2.25209207E-03 5.84249275E-03 1.66061137E-02 1.74068640E-02 A16 = -5.20097734E-04 -1.45874194E-03 -5.11841079E-03 -5.74636616E-03 A18 = 8.31666959E-05 2.52972825E-04 1.13522864E-03 1.33415964E-03 A20 = -9.02149529E-06 -2.97537054E-05 -1.78501610E-04 -2.10594963E-04 A22 = 6.33470937E-07 2.25597680E-06 1.93529786E-05 2.13891569E-05 A24 = -2.59771911E-08 -9.85816823E-08 -1.37234651E-06 -1.25400692E-06 A26 = 4.72421193E-10 1.80100495E-09 5.71480400E-08 3.20691670E-08 A28 = - 5.81655049E-12 -1.05690705E-09 - Surface # 9 10 k = 0.00000000E+00 0.00000000E+00 A4 = 4.43701480E-03 2.15682601E-03 A6 = 1.26018361E-02 1.17284210E-02 A8 = -1.44812922E-02 -1.64246128E-02 A10 = 1.12169757E-02 1.58385620E-02 A12 = -6.53912640E-03 -1.08821362E-02 A14 = 2.74468610E-03 5.29933783E-03 A16 = -7.69812113E-04 -1.80428018E-03 A18 = 1.30156383E-04 4.22476733E-04 A20 = -9.64998157E-06 -6.61077076E-05 A22 = -5.36143421E-07 6.54154854E-06 A24 = 1.51888406E-07 -3.65419632E-07 A26 = -8.08485696E-09 8.60485725E-09

[0108] Table 1A shows the radius of curvature, thickness, and focal length in millimeters (mm). Surface numbers 0-16 represent the surfaces arranged along the optical axis from the object side to the image side. In Table 1B, k represents the conic coefficient of the aspherical surface profile equation. A4-A28 represent the aspherical coefficients from the 4th to the 28th. The tables shown below for each embodiment are the corresponding schematic parameter and aberration curves, and the definitions of the tables are the same as in Table 1A and Table 1B of Embodiment 1. Therefore, no further explanation will be given in this regard. 2. Embodiment

[0109] Fig. 3 is a schematic view of an image acquisition unit according to the second embodiment of the present disclosure. Fig.Figure 4 shows, in order from left to right, spherical aberration curves, astigmatic field curves, and a distortion curve of the image acquisition unit according to the second embodiment. Fig. 3, the image sensing unit 2 includes the photographing optical lens system (the reference numeral of which is omitted) of the present disclosure and an image sensor IS. The photographing optical lens system includes, in order from an object side to an image side along an optical path, a stop S1, a first lens element E1, a second lens element E2, an aperture stop ST, a third lens element E3, a fourth lens element E4, a diaphragm S2, a reflecting element E5, a filter E6, and an image surface IMG. The photographing optical lens system includes four lens elements (E1, E2, E3, and E4), and no additional lens element is disposed between each of the adjacent four lens elements.

[0110] The first lens element E1 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The first lens element E1 is made of glass material and has both the object side surface and the image side surface, both of which are aspherical. The image side surface of the first lens element E1 has a reversal point. The image side surface of the first lens element E1 has a concave critical point in an off-axis region thereof.

[0111] The second lens element E2 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The second lens element E2 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the second lens element E2 has two reversal points. The image side surface of the second lens element E2 has three reversal points. The image side surface of the second lens element E2 has a concave critical point in an off-axis region.

[0112] The third lens element E3 with a negative refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The third lens element E3 is made of plastic and has the object side surface and the image side surface, both of which are aspherical. The object side surface of the third lens element E3 has three reversal points. The image side surface of the third lens element E3 has one reversal point. The object side surface of the third lens element E3 has a convex critical point in an off-axis region thereof.

[0113] The fourth lens element E4 with a negative refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The fourth lens element E4 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the fourth lens element E4 has two reversal points. The image side surface of the fourth lens element E4 has two reversal points. The object side surface of the fourth lens element E4 has a convex critical point and a concave critical point in a deviating axial region therefrom. The image side surface of the fourth lens element E4 has a concave critical point in a deviating axial region therefrom.

[0114] The reflective element E5 is made of glass material and is located between the fourth lens element E4 and the image surface IMG along the optical axis without affecting the focal length of the optical lens system for photographing. The reflective element E5 is a prism with a folding property of the optical path. For simplicity of illustration, Fig. 3, the deflection of the beam path caused by the reflective element E5 is not shown. However, the reflective element E5 may have various configurations depending on the actual design requirements, resulting in different deflection effects on the beam path. Furthermore, the reflective element E5 of this embodiment may have a configuration corresponding, for example, to one of the configurations shown in Fig. 41 to Fig. 47 shown configurations, which are referred to in the above descriptions Fig. 41 to Fig. 47, and the details thereof will not be repeated. Furthermore, the reflective element E5 of this embodiment may have a configuration similar to that shown in Fig. 38, which deflects the beam path five times, as described in the above descriptions. Fig. 38, and the relevant details are not repeated.

[0115] The E6 filter is made of glass and is located between the reflective element E5 and the image surface IMG without affecting the focal length of the optical lens system for photographing. The IS image sensor is located on or near the image surface IMG of the optical lens system for photographing.

[0116] The detailed optical information of the 2nd embodiment is shown in Table 2A and the information of the aspherical surfaces is shown in Table 2B below. TABLE 2A 2. Embodiment f = 16.04 mm, Fno = 2.27, HFOV = 12.5 degrees Surface # radius of curvature thickness material index Abbe # Focal length 0 lens Plano infinite 1 aperture Plano -0.326 2 Lens 1 5.6925 (ASP) 1.935 Glass 1.782 37.1 7.17 3 -319.5034 (ASP) 0.040 4 Lens 2 13.1706 (ASP) 0.680 plastic 1.587 28.3 11.87 5 -14.5288 (ASP) -0.030 6 Aperture diaphragm Plano 0.070 7 Lens 3 -11.7363 (ASP) 0.605 plastic 1.660 20.4 -5.60 8 5.5034 (ASP) 0.966 9 Lens 4 -5.5626 (ASP) 0.411 plastic 1.614 25.6 -35.88 10 -7.6521 (ASP) 0.030 11 aperture Plano 0.400 12 Prism Plano 15.750 Glass 1.804 46.6 - 13 Plano 0.200 14 filter Plano 0.210 Glass 1.517 64.2 - 15 Plano 0.423 16 Picture Plano - Note: The reference wavelength is 587.6 nm (d-line). An effective radius of the aperture S1 (surface 1) is 3.560 mm. An effective radius of the aperture S2 (surface 11) is 2,300 mm. TABLE 2B Aspherical coefficients Surface # 2 3 4 5 k = -1.42028000E-01 9.90000000E+01 8.47472000E+00 1.50457000E+01 A4 = 3.19244346E-04 -6.74114925E-04 -9.37197643E-03 4.46406403E-02 A6 = -3.26539257E-06 -3.66127886E-05 8.09370171E-04 -6.60885328E-02 A8 = -7.92444549E-06 8.58645764E-06 8.38498497E-04 6.05841937E-02 A10 = 3.76996989E-07 -1.92744569E-07 -5.37255745E-04 -3.69979317E-02 A12 = - - 2.26266231 E-04 1.60221320E-02 A14 = - - -7.06738138E-05 -5.05956093E-03 A16 = - - 1.56703528E-05 1.17736098E-03 A18 = - - -2.38948366E-06 -2.01389893E-04 A20 = - - 2.43240211E-07 2.49457808E-05 A22 = - - -1.57267324E-08 -2.17075893E-06 A24 = - - 5.82126956E-10 1.25544404E-07 A26 = - - -9.36229574E-12 -4.32520829E-09 A28 = - - - 6.70913027E-11 Surface # 7 8 9 10 k = 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 A4 = 7.07529935E-02 3.48320708E-02 2.82534497E-02 1.74601766E-02 A6 = -8.02298181E-02 -2.66012854E-02 -5.68662945E-03 6.44926730E-03 A8 = 6.56859438E-02 1.92762125E-02 1.85151570E-04 -1.73386866E-02 A10 = -3.88245099E-02 -1.33715880E-02 1.60560048E-03 2.02056747E-02 A12 = 1.65092795E-02 7.43940095E-03 -1.68274251E-03 -1.50708691E-02 A14 = -5.11659072E-03 -3.16282064E-03 8.94419528E-04 7.55633636E-03 A16 = 1.16889164E-03 1.02166136E-03 -2.74223950E-04 -2.59201608E-03 A18 = -1.96992467E-04 -2.44326498E-04 4.83075985E-05 6.09598011E-04 A20 = 2.41816506E-05 4.13013511E-05 -4.12990297E-06 -9.66947764E-05 A22 = -2.09914494E-06 -4.61170024E-06 -1.19550517E-08 9.88989125E-06 A24 = 1.21870563E-07 3.02832613E-07 2.99875602E-08 -5.89053172E-07 A26 = -4.23768209E-09 -8.81793549E-09 -1.63837900E-09 1.55252988E-08 A28 = 6.66357188E-11 - - -

[0117] In Embodiment 2, the equation of the aspherical surface profiles of the aforementioned lens elements is the same as the equation of Embodiment 1. Also, the definitions of these parameters shown in Table 2C below are the same as those given in Embodiment 1, with corresponding values for Embodiment 2, so explanation thereof will not be repeated.

[0118] In addition, these parameters from Table 2A and Table 2B can be calculated as the following values and satisfy the following conditions: TABLE 2C Values of optical and physical parameters / definitions f [mm] 16.04 (R4+R6) / (R4-R6) 0.45 Fno 2.27 TD / (CT2+T23) 6.50 HFOV [degree] 12.5 (CT2+CT3) / CT1 0.66 TL / lmgH 6.05 CT2 / T34 0.70 TD / BL 0.27 N1 1.782 SD / TD 0.44 V2 28.3 |f2 / f4| 0.33 V1 / V2 1.31 |f12 / f4| 0.13 V3 / V4 0.80 |f / R4|+|f / R5| 2.47 ET2 / CT2 0.46 (R1+R4) / (R1-R4) -0.44 ET2 / ET3 0.23 (R1-R5) / (R1+R5) -2.88 Sag3R1 / CT3 -0.07 f / f3 -2.86 - - 3. Embodiment

[0119] Fig.5 is a schematic view of an image acquisition unit according to the 3rd embodiment of the present disclosure. Fig. Fig. 6 shows, in order from left to right, spherical aberration curves, astigmatic field curves, and a distortion curve of the image acquisition unit according to the third embodiment. Fig.5, the image sensing unit 3 includes the photographing optical lens system (the reference numeral of which is omitted) of the present disclosure and an image sensor IS. The photographing optical lens system includes, in order from the object side to the image side along an optical path, a stop S1, a first lens element E1, a second lens element E2, an aperture stop ST, a third lens element E3, a fourth lens element E4, a diaphragm S2, a reflective element E5, a filter E6, and an image surface IMG. The photographing optical lens system includes four lens elements (E1, E2, E3, and E4), and no additional lens element is disposed between each of the four adjacent lens elements.

[0120] The first lens element E1 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The first lens element E1 is made of glass material and has both an object side and an image side, both of which are spherical.

[0121] The second lens element E2 with a positive refractive index has an object side surface that is convex in a paraxial region and an image side surface that is concave in a paraxial region. The second lens element E2 is made of plastic material and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the second lens element E2 has two reversal points. The image side surface of the second lens element E2 has two reversal points.

[0122] The third lens element E3 with a negative refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The third lens element E3 is made of plastic and has both the object side surface and the image side surface, which are aspherical.

[0123] The fourth lens element E4 with a positive refractive index has an object side surface that is convex in a paraxial region and an image side surface that is convex in a paraxial region. The fourth lens element E4 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The image side surface of the fourth lens element E4 has two reversal points.

[0124] The reflective element E5 is made of glass material and is located between the fourth lens element E4 and the image surface IMG along the optical axis without affecting the focal length of the optical lens system for photographing. The reflective element E5 is a prism with a folding property of the optical path. For simplicity of illustration, Fig. 5, the deflection of the beam path caused by the reflective element E5 is not shown. However, the reflective element E5 can have various configurations depending on the actual design requirements, causing different deflection effects on the beam path. In addition, the reflective element E5 of this embodiment can have a configuration that, for example, corresponds to one of the Fig. 41 to Fig. 47 shown configurations, which in the above descriptions are referred to as Fig. 41 to Fig.47, and the details thereof will not be repeated. Furthermore, the reflective element E5 of this embodiment may have a configuration similar to that shown in Fig. 38, which deflects the beam path five times, as described in the above descriptions. Fig. 38, and the details thereof are not repeated.

[0125] The E6 filter is made of glass and is located between the reflective element E5 and the image surface IMG without affecting the focal length of the optical lens system for photographing. The IS image sensor is located on or near the image surface IMG of the optical lens system for photographing.

[0126] The detailed optical information of the third embodiment is shown in Table 3A and the information of the aspherical surface is shown in Table 3B below. TABLE 3A 3. Embodiment f = 14.85 mm, Fno = 2.30, HFOV = 13.5 degrees Surface # radius of curvature thickness material index Abbe # Focal length 0 lens Plano infinite 1 aperture Plano -0.326 2 Lens 1 6.6531 (SPH) 1.522 Glass 1.954 32.3 7.19 3 201.6287 (SPH) 0.146 4 Lens 2 11.1233 (ASP) 0.360 plastic 1.587 28.3 26.08 5 40.1546 (ASP) 0.550 6 Aperture diaphragm Plano -0.215 7 Lens 3 177.6329 (ASP) 0.466 plastic 1.660 20.4 -5.32 8 3.4410 (ASP) 0.797 9 Lens 4 55.5556 (ASP) 0.638 plastic 1.544 56.0 22.97 10 -16.0571 (ASP) 0.030 11 aperture Plano 0.400 12 Prism Plano 15.750 Glass 1.804 46.6 - 13 Plano 0.200 14 filter Plano 0.210 Glass 1.517 64.2 - 15 Plano 0.475 16 Picture Plano - Note: The reference wavelength is 587.6 nm (d-line). An effective radius of the aperture S1 (surface 1) is 3.258 mm. An effective radius of the aperture S2 (surface 11) is 2.175 mm. TABLE 3B Aspherical coefficients Surface # 4 5 7 8 k = 1.64240000E+00 4.75669000E+01 0.00000000E+00 0.00000000E+00 A4 = -9.74753547E-03 -1.88610074E-02 -5.24334779E-03 7.23966525E-03 A6 = -2.29552248E-02 -1.51768285E-02 3.51738437E-02 3.72746777E-02 A8 = 4.66611601E-02 7.28714072E-02 -7.50999928E-03 -4.83842009E-02 A10 = -3.80271688E-02 -7.42161527E-02 -1.88494446E-02 3.46529533E-02 A12 = 1.82716097E-02 4.08456387E-02 1.79866645E-02 -2.28423116E-02 A14 = -5.76614790E-03 -1.42903820E-02 -7.98265210E-03 1.41361582E-02 A16 = 1.24412730E-03 3.35822620E-03 2.09536454E-03 -6.69034707E-03 A18 = -1.85204310E-04 -5.37599572E-04 -3.32706261E-04 2.17073124E-03 A20 = 1.87394786E-05 5.78010702E-05 2.80002153E-05 -4.62835331E-04 A22 = -1.23187623E-06 -3.97674787E-06 -2.32376331E-07 6.19867363E-05 A24 = 4.74793808E-08 1.55948974E-07 -1.88865584E-07 -4.73259206E-06 A26 = -8.14561976E-10 -2.45802266E-09 1.66939486E-08 1.57291654E-07 A28 = - -1.15477067E-11 -4.79795925E-10 - Surface # 9 10 k = 0.00000000E+00 0.00000000E+00 A4 = 1.56846721E-02 1.33911494E-02 A6 = -1.58480011E-03 -1.89061275E-02 A8 = -5.32383277E-03 2.76338120E-02 A10 = 1.32029294E-02 -2.59735586E-02 A12 = -1.67007413E-02 1.52835596E-02 A14 = 1.25034482E-02 -5.55272548E-03 A16 = -5.93270967E-03 1.12927170E-03 A18 = 1.84071573E-03 -6.37903221E-05 A20 = -3.73366793E-04 -2.61183662E-05 A22 = 4.77864357E-05 6.92283274E-06 A24 = -3.50611799E-06 -7.04736648E-07 A26 = 1.12502583E-07 2.74976310E-08

[0127] In the third embodiment, the equation for the aspherical surface profiles of the aforementioned lens elements is the same as the equation for the first embodiment. The definitions of these parameters shown in Table 3C below are also the same as those given in the first embodiment, with corresponding values for the third embodiment, so explanation thereof will not be repeated.

[0128] In addition, these parameters can be calculated from Table 3A and Table 3B as the following values and satisfy the following conditions: TABLE 3C Values of optical and physical parameters / definitions f [mm] 14.85 (R4+R6) / (R4-R6) 1.19 Fno 2.30 TD / (CT2+T23) 6.14 HFOV [degree] 13.5 (CT2+CT3) / CT1 0.54 TL / lmgH 5.95 CT2 / T34 0.45 TD / BL 0.25 N1 1.954 SD / TD 0.40 V2 28.3 |f2 / f4| 1.14 V1 / V2 1.14 |f12 / f4| 0.25 V3 / V4 0.36 |f / R4|+|f / R5| 0.45 ET2 / CT2 1.25 (R1+R4) / (R1-R4) -1.40 ET2 / ET3 0.42 (R1-R5) / (R1+R5) -0.93 Sag3R1 / CT3 0.61 f / f3 -2.79 - - 4. Embodiment

[0129] Fig.7 is a schematic view of an image acquisition unit according to the 4th embodiment of the present disclosure. Fig. Fig. 8 shows, in order from left to right, spherical aberration curves, astigmatic field curves, and a distortion curve of the image acquisition unit according to the fourth embodiment. Fig.7, the image sensing unit 4 includes the optical lens system (the reference numeral of which is omitted) of the present disclosure and an image sensor IS. The optical lens system for photographing includes, in order from the object side to the image side along an optical path, an aperture stop ST, a first lens element E1, a second lens element E2, a third lens element E3, a fourth lens element E4, a stop S1, a reflective element E5, a filter E6, and an image surface IMG. The optical lens system for photographing includes four lens elements (E1, E2, E3, and E4) with no additional lens element disposed between each of the adjacent four lens elements.

[0130] The first lens element E1 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The first lens element E1 is made of glass material and has both the object side surface and the image side surface, both of which are spherical.

[0131] The second lens element E2 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic material and has the object side surface and the image side surface, both of which are aspherical. The object side surface of the second lens element E2 has one reversal point. The image side surface of the second lens element E2 has two reversal points. The image side surface of the second lens element E2 has a convex critical point and a concave critical point in an off-axis region.

[0132] The third lens element E3 with a negative refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The third lens element E3 is made of plastic and has the object side surface and the image side surface, both of which are aspherical. The object side surface of the third lens element E3 has two reversal points. The object side surface of the third lens element E3 has a convex critical point and a concave critical point in an off-axis region thereof.

[0133] The fourth lens element E4 with a positive refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The fourth lens element E4 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the fourth lens element E4 has a reversal point. The image side surface of the fourth lens element E4 has a reversal point. The object side surface of the fourth lens element E4 has a convex critical point in an off-axis region thereof.

[0134] The reflective element E5 is made of glass material and is located between the fourth lens element E4 and the image surface IMG along the optical axis without affecting the focal length of the optical lens system for photographing. The reflective element E5 is a prism with a folding property of the optical path. For simplicity of illustration, Fig. 7, the deflection of the beam path caused by the reflective element E5 is not shown. However, the reflective element E5 can have various configurations depending on the actual design requirements, causing different deflection effects on the beam path. Furthermore, the reflective element E5 of this embodiment can have a similar configuration to, for example, one of the Fig. 41 to Fig. 47 shown configurations, which can be referred to with reference to the above descriptions Fig.41 to Fig. 47, the details of which will not be repeated. Furthermore, the reflective element E5 of this embodiment may have a configuration similar to that shown in Fig. 38, which deflects the beam path five times, as explained in the previous descriptions. Fig. 38, and the details in this regard are not repeated.

[0135] The E6 filter is made of glass and is located between the reflective element E5 and the image surface IMG without affecting the focal length of the optical lens system for photographing. The IS image sensor is located on or near the image surface IMG of the optical lens system for photographing.

[0136] The detailed optical information of the fourth embodiment is shown in Table 4A and the information of the aspherical surface is shown in Table 4B below. TABLE 4A 4. Embodiment f = 14.60 mm, Fno = 2.27, HFOV = 13.7 degrees Surface # radius of curvature thickness material index Abbe # Focal length 0 lens Plano infinite 1 Aperture diaphragm Plano -0.697 2 Lens 1 7.6240 (SPH) 1.389 Glass 1.954 32.3 7.74 3 -209.2260 (SPH) 0.040 4 Lens 2 7.9649 (ASP) 0.569 plastic 1.544 56.0 25.55 5 18.1875 (ASP) 0.287 6 Lens 3 11.2966 (ASP) 0.522 plastic 1.660 20.4 -5.84 7 2.8209 (ASP) 0.976 8 Lens 4 -11.0211 (ASP) 0.457 plastic 1.544 56.0 25.94 9 -6.2785 (ASP) -0.165 10 aperture Plano 0.480 11 Prism Plano 15.750 Glass 1.804 46.6 - 12 Plano 0.350 13 filter Plano 0.110 Glass 1.517 64.2 - 14 Plano 0.406 15 Picture Plano - Note: The reference wavelength is 587.6 nm (d-line). An effective radius of the aperture S1 (surface 10) is 2.258 mm. TABLE 4B Aspherical coefficients Surface # 4 5 6 7 k = -4.98388000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 A4 = 6.27654166E-03 2.58364976E-02 7.83194517E-03 -1.37898347E-02 A6 = -1.96289280E-03 -2.09322157E-02 -3.00708161E-02 -2.15365648E-02 A8 = 2.20661478E-04 1.22262914E-02 2.52106304E-02 2.36189851E-02 A10 = 1.74028971E-04 -5.74500452E-03 -1.48267955E-02 -1.69101338E-02 A12 = -1.30487027E-04 2.13391752E-03 6.85486937E-03 9.20837933E-03 A14 = 4.95703250E-05 -5.75169156E-04 -2.40207525E-03 -3.69451827E-03 A16 = -1.19901975E-05 1.07162972E-04 6.10281168E-04 1.03784435E-03 A18 = 1.83298616E-06 -1.39435435E-05 -1.09394165E-04 -1.96152473E-04 A20 = -1.69102297E-07 1.33462849E-06 1.34604501E-05 2.37158869E-05 A22 = 8.53511542E-09 -9.76594402E-08 -1.08235909E-06 -1.65908577E-06 A24 = -1.79900813E-10 4.96406210E-09 5.12276888E-08 5.11940514E-08 A26 = - -1.22989074E-10 -1.08128237E-09 - Surface # 8 9 k = 0.00000000E+00 0.00000000E+00 A4 = 6.14945058E-03 5.13251964E-03 A6 = -9.43754281E-03 -6.39309026E-03 A8 = 1.09685727E-02 8.25604912E-03 A10 = -1.07254573E-02 -8.02719818E-03 A12 = 7.38684613E-03 5.35170590E-03 A14 = -3.36919602E-03 -2.36271141E-03 A16 = 1.01166228E-03 6.89636262E-04 A18 = -1.98276717E-04 -1.31631342E-04 A20 = 2.44947566E-05 1.58181467E-05 A22 = -1.73733337E-06 -1.08748988E-06 A24 = 5.41051946E-08 3.26597262E-08

[0137] In the fourth embodiment, the equation for the aspherical surface profiles of the aforementioned lens elements is the same as the equation for the first embodiment. The definitions of these parameters shown in Table 4C below are also the same as those given in the first embodiment, with corresponding values for the fourth embodiment, so explanation thereof will not be repeated.

[0138] In addition, these parameters can be calculated from Table 4A and Table 4B as the following values and satisfy the following conditions: TABLE 4C Values of optical and physical parameters / definitions f [mm] 14.60 (R4+R6) / (R4-R6) 1.37 Fno 2.27 TD / (CT2+T23) 4.95 HFOV [degree] 13.7 (CT2+CT3) / CT1 0.79 TL / lmgH 5.91 CT2 / T34 0.58 TD / BL 0.25 N1 1.954 SD / TD 0.84 V2 56.0 |f2 / f4| 0.98 V1 / V2 0.58 |f12 / f4| 0.23 V3 / V4 0.36 |f / R4|+|f / R5| 2.09 ET2 / CT2 0.65 (R1+R4) / (R1-R4) -2.44 ET2 / ET3 0.32 (R1-R5) / (R1+R5) -0.19 Sag3R1 / CT3 0.07 f / f3 -2.50 - - 5. Embodiment

[0139] Fig.9 is a schematic view of an image acquisition unit according to the 5th embodiment of the present disclosure. Fig. Fig. 10 shows, in order from left to right, spherical aberration curves, astigmatic field curves, and a distortion curve of the image acquisition unit according to the 5th embodiment. Fig.9, the image sensing unit 5 includes the photographing optical lens system (the reference numeral of which is omitted) of the present disclosure and an image sensor IS. The photographing optical lens system includes, in order from the object side to the image side along an optical path, a stop S1, a first lens element E1, a second lens element E2, an aperture stop ST, a third lens element E3, a fourth lens element E4, a diaphragm S2, a reflecting element E5, a filter E6, and an image surface IMG. The photographing optical lens system includes four lens elements (E1, E2, E3, and E4), and no additional lens element is arranged between each adjacent four lens elements.

[0140] The first lens element E1 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The first lens element E1 is made of glass material and has both an object side and an image side, both of which are spherical.

[0141] The second lens element E2 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The second lens element E2 is made of plastic material and has the object side surface and the image side surface, both of which are aspherical. The object side surface of the second lens element E2 has a reversal point. The image side surface of the second lens element E2 has a reversal point. The image side surface of the second lens element E2 has a concave critical point in an off-axis region thereof.

[0142] The third lens element E3 with a negative refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The third lens element E3 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the third lens element E3 has two reversal points. The image side surface of the third lens element E3 has one reversal point.

[0143] The fourth lens element E4 with a positive refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The fourth lens element E4 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the fourth lens element E4 has a reversal point. The image side surface of the fourth lens element E4 has a reversal point. The object side surface of the fourth lens element E4 has a convex critical point in a deviated axial region therefrom. The image side surface of the fourth lens element E4 has a concave critical point in a deviated axial region therefrom.

[0144] The reflective element E5 is made of glass material and is located between the fourth lens element E4 and the image surface IMG along the optical axis and does not affect the focal length of the optical lens system for photography. The reflective element E5 is a prism with a folding property of the optical path. For simplicity of illustration, Fig. 9, the deflection of the beam path caused by the reflective element E5 is not shown. However, the reflective element E5 can have various configurations depending on the actual design requirements, causing different deflection effects on the beam path. In addition, the reflective element E5 of this embodiment can have a configuration that, for example, corresponds to one of the Fig. 41 to Fig. 47 shown configurations, which are referred to in the above descriptions Fig.41 to Fig. 47, and the details thereof will not be repeated. Furthermore, the reflective element E5 of this embodiment may have a configuration similar to, for example, that shown in Fig. 38, which deflects the beam path five times, whereupon the above descriptions refer to Fig. 38, and the details in this regard are not repeated.

[0145] The E6 filter is made of glass and is located between the reflective element E5 and the image surface IMG without affecting the focal length of the optical lens system for photographing. The IS image sensor is located on or near the image surface IMG of the optical lens system for photographing.

[0146] The detailed optical information of the 5th embodiment is shown in Table 5A and the information of the aspherical surface is shown in Table 5B below. TABLE 5A 5. Embodiment f = 14.34 mm, Fno = 2.27, HFOV = 14.0 degrees Surface # radius of curvature thickness material index Abbe # Focal length 0 lens Plano infinite 1 aperture Plano -0.316 2 Lens 1 8.5045 (SPH) 1.340 Glass 1.954 32.3 8.38 3 -123.5800 (SPH) 0.050 4 Lens 2 8.2283 (ASP) 0.493 plastic 1.587 28.3 11.06 5 -30.1688 (ASP) 0.521 6 Aperture diaphragm Plano -0.174 7 Lens 3 200.0000 (ASP) 0.489 plastic 1.660 20.4 -4.45 8 2.8932 (ASP) 0.820 9 Lens 4 -18.6996 (ASP) 0.604 plastic 1.544 56.0 21.04 10 -7.1804 (ASP) 0.085 11 aperture Plano 0.400 12 Prism Plano 15.750 Glass 1.804 46.6 - 13 Plano 0.350 14 filter Plano 0.110 Glass 1.517 64.2 - 15 Plano 0.312 16 Picture Plano - Note: The reference wavelength is 587.6 nm (d-line). An effective radius of the aperture S1 (surface 1) is 3.180 mm. An effective radius of the aperture S2 (surface 11) is 2.214 mm. TABLE 5B Aspherical coefficients Surface # 4 5 7 8 k = 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 A4 = -1.78768290E-03 2.98578274E-02 5.69273917E-02 3.06775195E-02 A6 = 2.28302874E-02 4.09732948E-02 -8.30470428E-03 -1.87786045E-02 A8 = -2.88132947E-02 -8.98533769E-02 -8.95928855E-02 -8.29786594E-02 A10 = 1.84785206E-02 7.70699654E-02 1.23764470E-01 1.50262281E-01 A12 = -7.08738464E-03 -3.85232545E-02 -8.69288222E-02 -1.29095500E-01 A14 = 1.62148619E-03 1.22525906E-02 3.91291679E-02 6.97196272E-02 A16 = -1.56128047E-04 -2.42721835E-03 -1.21465679E-02 -2.57173662E-02 A18 = -2.69466615E-05 2.40618163E-04 2.66663326E-03 6.66400769E-03 A20 = 1.23771924E-05 9.06815259E-06 -4.13918896E-04 -1.21351297E-03 A22 = -2.11507648E-06 -6.21090804E-06 4.44529601E-05 1.51911907E-04 A24 = 1.99689921E-07 8.31687890E-07 -3.14158932E-06 -1.24250765E-05 A26 = -1.02510999E-08 -5.22490288E-08 1.31384151E-07 5.96739928E-07 A28 = 2.24188185E-10 1.32694486E-09 -2.46254181E-09 -1.27455528E-08 Surface # 9 10 k = 0.00000000E+00 0.00000000E+00 A4 = 1.07103222E-02 3.85520374E-03 A6 = 1.34398774E-02 1.34575320E-02 A8 = -5.12947325E-02 -4.02738719E-02 A10 = 6.72476547E-02 5.56117225E-02 A12 = -5.10581625E-02 -4.72332157E-02 A14 = 2.55112770E-02 2.72024033E-02 A16 = -8.76120653E-03 -1.10542853E-02 A18 = 2.08226109E-03 3.21373692E-03 A20 = -3.36012447E-04 -6.65728192E-04 A22 = 3.50395810E-05 9.60984663E-05 A24 = -2.12294936E-06 -9.20031389E-06 A26 = 5.65487308E-08 5.25932378E-07 A28 = - -1.36107350E-08

[0147] In the fifth embodiment, the equation of the aspherical surface profiles of the aforementioned lens elements is the same as the equation of the first embodiment. Also, the definitions of these parameters shown in Table 5C below are the same as those given in the first embodiment, with corresponding values for the fifth embodiment, so explanation thereof will not be repeated.

[0148] In addition, these parameters from Table 5A and Table 5B can be calculated as the following values and satisfy the following conditions: TABLE 5C Values of optical and physical parameters / definitions f [mm] 14.34 (R4+R6) / (R4-R6) 0.82 Fno 2.27 TD / (CT2+T23) 4.93 HFOV [degree] 14.0 (CT2+CT3) / CT1 0.73 TL / ImgH 5.90 CT2 / T34 0.60 TD / BL 0.24 N1 1.954 SD / TD 0.42 V2 28.3 |f2 / f4| 0.53 V1 / V2 1.14 |f12 / f4| 0.24 V3 / V4 0.36 |f / R4|+|f / R5| 0.55 ET2 / CT2 0.79 (R1+R4) / (R1-R4) -0.56 ET2 / ET3 0.36 (R1-R5) / (R1+R5) -0.92 Sag3R1 / CT3 0.41 f / f3 -3.22 - - 6. Embodiment

[0149] Fig.11 is a schematic view of an image acquisition unit according to the 6th embodiment of the present disclosure. Fig. Fig. 12 shows, in order from left to right, spherical aberration curves, astigmatic field curves, and a distortion curve of the image acquisition unit according to the 6th embodiment. Fig.11, the image sensing unit 6 includes the photographing optical lens system (the reference numeral of which is omitted) of the present disclosure and an image sensor IS. The photographing optical lens system includes, in order from an object side to an image side along an optical path, a stop S1, a first lens element E1, a second lens element E2, an aperture stop ST, a third lens element E3, a fourth lens element E4, a diaphragm S2, a reflecting element E5, a filter E6, and an image surface IMG. The photographing optical lens system includes four lens elements (E1, E2, E3, and E4), and no additional lens element is arranged between each adjacent four lens elements.

[0150] The first lens element E1 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The first lens element E1 is made of plastic and has both the object side and the image side, both of which are aspherical. The image side of the first lens element E1 has a reversal point.

[0151] The second lens element E2 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the second lens element E2 has one reversal point. The image side surface of the second lens element E2 has three reversal points.

[0152] The third lens element E3 with a negative refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The third lens element E3 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the third lens element E3 has a reversal point. The image side surface of the third lens element E3 has a reversal point. The object side surface of the third lens element E3 has a convex critical point in a deviating axial region therefrom.

[0153] The fourth lens element E4 with a positive refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The fourth lens element E4 is made of plastic and has the object side and the image side, both of which are aspherical. The object side surface of the fourth lens element E4 has two reversal points. The image side surface of the fourth lens element E4 has one reversal point. The object side surface of the fourth lens element E4 has a convex critical point in an off-axis region thereof. The image side surface of the fourth lens element E4 has a concave critical point in an off-axis region therefrom.

[0154] The reflective element E5 is made of glass material and is located between the fourth lens element E4 and the image surface IMG along the optical axis without affecting the focal length of the optical lens system for photographing. The reflective element E5 is a prism with a folding property of the optical path. For simplicity of illustration, Fig. 11, the deflection of the beam path caused by the reflective element E5 is not shown. However, the reflective element E5 can have various configurations depending on the actual design requirements, causing different deflection effects on the beam path. Furthermore, the reflective element E5 of this embodiment can have a configuration that, for example, corresponds to one of the Fig. 41 to Fig. 47 shown configurations, to which reference is made in the preceding descriptions Fig. 41 to Fig. 47, and the details thereof will not be repeated. Furthermore, the reflective element E5 of this embodiment may have a configuration similar to that shown in Fig. 38, which deflects the beam path five times, as described in the above descriptions. Fig. 38, and the details thereof are not repeated.

[0155] The E6 filter is made of glass and is located between the reflective element E5 and the image surface IMG without affecting the focal length of the optical lens system for photographing. The IS image sensor is located on or near the image surface IMG of the optical lens system for photographing.

[0156] The detailed optical information of the sixth embodiment is shown in Table 6A and the information of the aspherical surface is shown in Table 6B below. TABLE 6A 6. Embodiment f = 14.65 mm, Fno = 2.26, HFOV = 13.5 degrees Surface # radius of curvature thickness material index Abbe # Focal length 0 lens Plano infinite 1 aperture Plano -0.326 2 Lens 1 10.9265 (ASP) 1.295 plastic 1.544 56.0 9.42 3 -9.2455 (ASP) 0.040 4 Lens 2 5.4226 (ASP) 0.773 plastic 1.642 22.5 10.15 5 30.6543 (ASP) 0.572 6 Aperture diaphragm Plano -0.096 7 Lens 3 -48.2931 (ASP) 0.399 plastic 1.650 21.8 -4.50 8 3.1188 (ASP) 0.856 9 Lens 4 -22.2262 (ASP) 0.461 plastic 1.544 56.0 26.23 10 -8.7543 (ASP) 0.030 11 aperture Plano 0.400 12 Prism Plano 15.000 Glass 1.804 46.6 - 13 Plano 0.200 14 filter Plano 0.210 Glass 1.517 64.2 - 15 Plano 0.639 16 Picture Plano - Note: The reference wavelength is 587.6 nm (d-line). An effective radius of the aperture S1 (surface 1) is 3.256 mm. An effective radius of the aperture S2 (surface 11) is 2.165 mm. TABLE 6B Aspherical coefficients Surface # 2 3 4 5 k = -1.17090000E+00 -2.77270000E+01 8.14900000E-01 -8.87749000E+01 A4 = 2.46983012E-03 -5.15302429E-03 -2.29391295E-02 -3.22148921E-02 A6 = -1.30108367E-03 5.29665699E-03 1.34671615E-02 3.88360602E-02 A8 = 3.81719362E-04 -2.35823917E-03 -4.44255607E-03 -2.33387911E-02 A10 = -8.17559819E-05 5.79368713E-04 1.43175360E-03 1.12784031E-02 A12 = 1.21349965E-05 -8.75490087E-05 -5.29877929E-04 -4.50437653E-03 A14 = -1.18777798E-06 8.39794177E-06 1.60464169E-04 1.40160649E-03 A16 = 7.40378981E-08 -4.99390678E-07 -3.29107167E-05 -3.26525509E-04 A18 = -2.71803781E-09 1.67651095E-08 4.37459506E-06 5.62829661E-05 A20 = 4.62793748E-11 -2.40590464E-10 -3.62680723E-07 -7.14026934E-06 A22 = - - 1.67584790E-08 6.53397813E-07 A24 = - - -2.85734737E-10 -4.09157921E-08 A26 = - - -3.21818806E-12 1.56572393E-09 A28 = - - - -2.75189093E-11 Surface # 7 8 9 10 k = 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 A4 = 6.28715744E-03 1.88096655E-02 1.36625101E-02 7.84372784E-03 A6 = 5.95056797E-02 3.16002688E-02 -2.73924147E-03 3.53441222E-04 A8 = -7.99701235E-02 -5.84979233E-02 1.40477831E-02 6.68831459E-03 A10 = 5.93692393E-02 3.54201660E-02 -3.11013113E-02 -1.80737503E-02 A12 = -3.02664688E-02 -6.65305722E-03 3.35084400E-02 2.11640864E-02 A14 = 1.12145563E-02 -4.38731044E-03 -2.20438867E-02 -1.47231071E-02 A16 = -3.05828738E-03 3.80657081E-03 9.59532926E-03 6.69308057E-03 A18 = 6.11273005E-04 -1.42858669E-03 -2.82629836E-03 -2.04416621E-03 A20 = -8.81882721E-05 3.18037500E-04 5.57923215E-04 4.16490470E-04 A22 = 8.91490562E-06 -4.32229788E-05 -7.07431244E-05 -5.43326830E-05 A24 = -5.97796761E-07 3.32654955E-06 5.20881315E-06 4.10605910E-06 A26 = 2.38396098E-08 -1.11502635E-07 -1.69311447E-07 -1.36730090E-07 A28 = -4.27373831E-10 - - -

[0157] In the sixth embodiment, the equation for the aspherical surface profiles of the aforementioned lens elements is the same as the equation for the first embodiment. The definitions of these parameters shown in Table 6C below are also the same as those given in the first embodiment, with corresponding values for the sixth embodiment, so explanations thereof will not be repeated.

[0158] In addition, these parameters can be calculated from Table 6A and Table 6B as the following values and satisfy the following conditions: TABLE 6C Values of optical and physical parameters / definitions f [mm] 14.65 (R4+R6) / (R4-R6) 1.23 Fno 2.26 TD / (CT2+T23) 3.44 HFOV [degree] 13.5 (CT2+CT3) / CT1 0.91 TL / ImgH 5.85 CT2 / T34 0.90 TD / BL 0.26 N1 1.544 SD / TD 0.38 V2 22.5 |f2 / f4| 0.39 V1 / V2 2.49 |f12 / f4| 0.19 V3 / V4 0.39 |f / R4|+|f / R5| 0.78 ET2 / CT2 0.45 (R1+R4) / (R1-R4) -2.11 ET2 / ET3 0.35 (R1-R5) / (R1+R5) -1.58 Sag3R1 / CT3 0.73 f / f3 -3.26 - - 7. Embodiment

[0159] Fig.13 is a schematic view of an image acquisition unit according to the 7th embodiment of the present disclosure. Fig. Fig. 14 shows, in order from left to right, spherical aberration curves, astigmatic field curves, and a distortion curve of the image acquisition unit according to the 7th embodiment. Fig.13, the image sensing unit 7 includes the photographing optical lens system (the reference numeral of which is omitted) of the present disclosure and an image sensor IS. The photographing optical lens system includes, in order from the object side to the image side along an optical path, a stop S1, a first lens element E1, a second lens element E2, an aperture stop ST, a third lens element E3, a fourth lens element E4, a diaphragm S2, a reflecting element E5, a filter E6, and an image surface IMG. The photographing optical lens system includes four lens elements (E1, E2, E3, and E4), and no additional lens element is disposed between each of the adjacent four lens elements.

[0160] The first lens element E1 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The first lens element E1 is made of glass material and has both an object side and an image side, both of which are spherical.

[0161] The second lens element E2 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic material and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the second lens element E2 has one reversal point. The image side surface of the second lens element E2 has three reversal points.

[0162] The third lens element E3 with a negative refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The third lens element E3 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the third lens element E3 has three reversal points. The object side surface of the third lens element E3 has a convex critical point in a deviated axial region thereof.

[0163] The fourth lens element E4 with a positive refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The fourth lens element E4 is made of plastic and has the object side surface and the image side surface, both of which are aspherical. The object side surface of the fourth lens element E4 has a reversal point. The image side surface of the fourth lens element E4 has a reversal point. The object side surface of the fourth lens element E4 has a convex critical point in an off-axis region thereof. The image side surface of the fourth lens element E4 has a concave critical point in an off-axis region therefrom.

[0164] The reflective element E5 is made of glass material and is located between the fourth lens element E4 and the image surface IMG along the optical axis and does not affect the focal length of the optical lens system for photographing. The reflective element E5 is a prism with a folding property of the optical path. For simplicity of illustration, Fig. 13, the deflection of the optical path caused by the reflective element E5 is not shown. However, the reflective element E5 can have various configurations depending on the actual design requirements, causing different deflection effects on the optical path. In addition, the reflective element E5 of this embodiment can have a configuration corresponding, for example, to one of the Fig. 41 to Fig. 47 shown configurations, which in the above descriptions are referred to as Fig. 41 to Fig. 47, and the details thereof will not be repeated. Furthermore, the reflective element E5 of this embodiment may have a configuration similar to that shown in Fig. 38, which deflects the beam path five times, whereupon the above descriptions refer to Fig. 38, and the details thereof are not repeated.

[0165] The E6 filter is made of glass and is located between the reflective element E5 and the image surface IMG without affecting the focal length of the optical lens system for photographing. The IS image sensor is located on or near the image surface IMG of the optical lens system for photographing.

[0166] The detailed optical information of the 7th embodiment is shown in Table 7A and the information of the aspherical surface is shown in Table 7B below. TABLE 7A 7. Embodiment f = 14.56 mm, Fno = 2.27, HFOV = 13.7 degrees Surface # radius of curvature thickness material index Abbe # Focal length 0 lens Plano infinite 1 aperture Plano -0.326 2 Lens 1 7.9984 (SPH) 1.295 Glass 1.954 32.3 8.51 3 515.6319 (SPH) 0.079 4 Lens 2 5.3363 (ASP) 0.496 plastic 1.587 28.3 11.40 5 25.3762 (ASP) 0.441 6 Aperture diaphragm Plano -0.197 7 Lens 3 -103.0649 (ASP) 0.502 plastic 1.660 20.4 -4.91 8 3.3536 (ASP) 0.979 9 Lens 4 -14.8684 (ASP) 0.595 plastic 1.544 56.0 31.84 10 -8.1139 (ASP) 0.040 11 aperture Plano 0.400 12 Prism Plano 15.750 Glass 1.804 46.6 - 13 Plano 0.200 14 filter Plano 0.210 Glass 1.517 64.2 - 15 Plano 0.427 16 Picture Plano - Note: The reference wavelength is 587.6 nm (d-line). An effective radius of the aperture S1 (surface 1) is 3.232 mm. An effective radius of the aperture S2 (surface 11) is 2.205 mm. TABLE 7B Aspherical coefficients Surface # 4 5 7 8 k = 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 A4 = -1.83857902E-02 -4.22864828E-02 -1.38500218E-03 3.16089405E-02 A6 = 2.36528771E-03 5.33823869E-02 7.42548540E-02 3.37045712E-02 A8 = 1.03218861E-02 -7.74905522E-03 -7.68976933E-02 -7.40923564E-02 A10 = -9.75560509E-03 -2.44889915E-02 3.52600024E-02 5.17492736E-02 A12 = 4.38626207E-03 2.30384907E-02 -7.54355034E-03 -1.84016569E-02 A14 = -1.19528153E-03 -1.09905297E-02 7.27208390E-05 2.93944238E-03 A16 = 2.19438346E-04 3.41340406E-03 3.70986127E-04 2.56968735E-04 A18 = -2.94286035E-05 -7.37271949E-04 -9.51891067E-05 -2.42576647E-04 A20 = 3.03058128E-06 1.11619262E-04 1.08165118E-05 5.87833097E-05 A22 = -2.32275185E-07 -1.15510350E-05 -3.58811251E-07 -7.79380939E-06 A24 = 1.14499115E-08 7.71617112E-07 -4.91079599E-08 5.71966377E-07 A26 = -2.60812259E-10 -2.96674178E-08 5.76237321E-09 -1.82234328E-08 A28 = - 4.92004862E-10 -1.87884667E-10 - Surface # 9 10 k = 0.00000000E+00 0.00000000E+00 A4 = 3.00812886E-02 1.85881754E-02 A6 = -5.57499188E-03 -9.44834384E-03 A8 = -3.73450580E-03 8.39100564E-03 A10 = 3.07069504E-03 -9.31399559E-03 A12 = -1.29185253E-03 7.44863919E-03 A14 = 6.15289185E-04 -3.96524672E-03 A16 = -2.68121011E-04 1.46072260E-03 A18 = 7.48808728E-05 -3.79305065E-04 A20 = -1.21388303E-05 6.83407236E-05 A22 = 1.06297929E-06 -8.10213030E-06 A24 = -4.13138137E-08 5.65234628E-07 A26 = 2.72603953E-10 -1.74951793E-08

[0167] In the 7th embodiment, the equation of the aspherical surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in Table 7C below are the same as those given in the 1st embodiment, with corresponding values for the 7th embodiment, so explanation thereof will not be repeated.

[0168] In addition, these parameters can be calculated from Table 7A and Table 7B as the following values and satisfy the following conditions: TABLE 7C Values of optical and physical parameters / definitions f [mm] 14.56 (R4+R6) / (R4-R6) 1.30 Fno 2.27 TD / (CT2+T23) 5.66 HFOV [degree] 13.7 (CT2+CT3) / CT1 0.77 TL / ImgH 5.92 CT2 / T34 0.51 TD / BL 0.25 N1 1.954 SD / TD 0.45 V2 28.3 |f2 / f4| 0.36 V1 / V2 1.14 |f12 / f4| 0.16 V3 / V4 0.36 |f / R4|+|f / R5| 0.72 ET2 / CT2 0.63 (R1+R4) / (R1-R4) -1.92 ET2 / ET3 0.27 (R1-R5) / (R1+R5) -1.17 Sag3R1 / CT3 0.53 f / f3 -2.97 - - 8. Embodiment

[0169] Fig.15 is a schematic view of an image acquisition unit according to the 8th embodiment of the present disclosure. Fig. 16 shows, in order from left to right, spherical aberration curves, astigmatic field curves, and a distortion curve of the image pickup unit according to the 8th embodiment. In Fig.15, the image sensing unit 8 includes the photographing optical lens system (the reference numeral of which is omitted) of the present disclosure and an image sensor IS. The photographing optical lens system includes, in order from the object side to the image side along an optical path, a stop S1, a first lens element E1, a second lens element E2, an aperture stop ST, a third lens element E3, a fourth lens element E4, a diaphragm S2, a reflecting element E5, a filter E6, and an image surface IMG. The photographing optical lens system includes four lens elements (E1, E2, E3, and E4), and no additional lens element is disposed between each of the adjacent four lens elements.

[0170] The first lens element E1 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The first lens element E1 is made of glass material and has both the object side surface and the image side surface, which are spherical.

[0171] The second lens element E2 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The second lens element E2 is made of plastic material and has the object side surface and the image side surface, both of which are aspherical. The object side surface of the second lens element E2 has a reversal point. The image side surface of the second lens element E2 has a reversal point. The image side surface of the second lens element E2 has a concave critical point in an off-axis region thereof.

[0172] The third lens element E3 with a negative refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The third lens element E3 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the third lens element E3 has three reversal points. The object side surface of the third lens element E3 has a convex critical point in a deviated axial region thereof.

[0173] The fourth lens element E4 with a positive refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The fourth lens element E4 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the fourth lens element E4 has a reversal point. The image side surface of the fourth lens element E4 has a reversal point. The object side surface of the fourth lens element E4 has a convex critical point in an off-axis region thereof.

[0174] The reflective element E5 is made of glass material and is located between the fourth lens element E4 and the image surface IMG along the optical axis. It does not affect the focal length of the optical lens system for photography. The reflective element E5 is a prism with a folding property of the optical path. For simplicity of illustration, Fig. 15, the deflection of the beam path caused by the reflective element E5 is not shown. However, the reflective element E5 can have various configurations depending on the actual design requirements, causing different deflection effects on the beam path. Furthermore, the reflective element E5 of this embodiment can have a configuration similar to, for example, one of the Fig. 41 to Fig. 47 shown configurations, which with reference to the above descriptions with Fig. 41 to Fig. 47, the details of which will not be repeated. Furthermore, the reflective element E5 of this embodiment may have a configuration similar to that shown in Fig. 38, which deflects the beam path five times, refer to the corresponding descriptions above. Fig. 38, and the details in this regard are not repeated.

[0175] The E6 filter is made of glass and is located between the reflective element E5 and the image surface IMG, without affecting the focal length of the optical lens system for photography. The IS image sensor is located on or near the image surface IMG of the optical lens system for photography.

[0176] The detailed optical information of the 8th embodiment is shown in Table 8A and the information of the aspherical surface is shown in Table 8B below. TABLE 8A 8. Embodiment f = 12.54 mm, Fno = 2.29, HFOV = 13.3 degrees Surface # radius of curvature thickness material index Abbe # Focal length 0 lens Plano infinite 1 aperture Plano -0.326 2 Lens 1 5.6323 (SPH) 1.500 Glass 1.911 35.2 6.29 3 301.8005 (SPH) 0.084 4 Lens 2 8.6569 (ASP) 0.413 plastic 1.614 25.6 13.76 5 -335.0991 (ASP) 0.228 6 Aperture diaphragm Plano -0.008 7 Lens 3 -14.9793 (ASP) 0.387 plastic 1.669 19.5 -4.78 8 4.1131 (ASP) 0.716 9 Lens 4 -15.3886 (ASP) 0.855 plastic 1.544 56.0 68.76 10 -11.1166 (ASP) 0.030 11 aperture Plano 0.400 12 Prism Plano 12.000 Glass 1.804 46.6 - 13 Plano 0.200 14 filter Plano 0.210 Glass 1.517 64.2 - 15 Plano 0.514 16 Picture Plano - Note: The reference wavelength is 587.6 nm (d-line). An effective radius of the aperture S1 (surface 1) is 2.763 mm. An effective radius of the aperture S2 (surface 11) is 1.739 mm. TABLE 8B Aspherical coefficients Surface # 4 5 7 8 k = 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 A4 = -1.83857247E-02 -4.22864319E-02 -8.73832590E-03 2.12472987E-02 A6 = 2.36497922E-03 5.33820501E-02 1.02598837E-01 6.00376639E-02 A8 = 1.03225015E-02 -7.74817556E-03 -1.14778575E-01 -9.61850581E-02 A10 = -9.75627677E-03 -2.44902317E-02 7.03072506E-02 6.83537627E-02 A12 = 4.38671204E-03 2.30395655E-02 -3.35690068E-02 -3.68316101E-02 A14 = -1.19547805E-03 -1.09911425E-02 1.54791060E-02 2.13098113E-02 A16 = 2.19496011E-04 3.41364257E-03 -6.50391847E-03 -1.18570519E-02 A18 = -2.94400637E-05 -7.37336387E-04 2.12841818E-03 4.93074960E-03 A20 = 3.03210312E-06 1.11631345E-04 -4.98187819E-04 -1.37879313E-03 A22 = -2.32404494E-07 -1.15525775E-05 7.99116103E-05 2.45033796E-04 A24 = 1.14562678E-08 7.71745007E-07 -8.35284015E-06 -2.50948329E-05 A26 = -2.60949720E-10 -2.96736264E-08 5.13784763E-07 1.13035784E-06 A28 = - 4.92138769E-10 -1.41418137E-08 - Surface # 9 10 k = 0.00000000E+00 0.00000000E+00 A4 = 1.32263072E-02 7.50309516E-03 A6 = 1.12688940E-02 -4.38835781E-04 A8 = -1.31266370E-02 1.05682628E-02 A10 = 5.82052132E-03 -2.82748709E-02 A12 = -1.36020617E-03 3.85097459E-02 A14 = 4.10007734E-04 -3.33743255E-02 A16 = -2.44051400E-04 1.96643652E-02 A18 = 1.18430818E-04 -7.97895084E-03 A20 = -4.38649973E-05 2.19284524E-03 A22 = 1.16395164E-05 -3.89425121E-04 A24 = -1.79692833E-06 4.02921158E-05 A26 = 1.16192513E-07 -1.84394430E-06

[0177] In the 8th embodiment, the equation of the aspherical surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. Also, the definitions of these parameters shown in Table 8C below are the same as those given in the 1st embodiment, with corresponding values for the 8th embodiment, so explanation thereof will not be repeated.

[0178] In addition, these parameters can be calculated from Table 8A and Table 8B as the following values and satisfy the following conditions: TABLE 8C Values of optical and physical parameters / definitions f [mm] 12.54 (R4+R6) / (R4-R6) 0.98 Fno 2.29 TD / (CT2+T23) 6.60 HFOV [degree] 13.3 (CT2+CT3) / CT1 0.53 TL / ImgH 5.84 CT2 / T34 0.58 TD / BL 0.31 N1 1.911 SD / TD 0.47 V2 25.6 |f2 / f4| 0.20 V1 / V2 1.38 |f12 / f4| 0.07 V3 / V4 0.35 |f / R4|+|f / R5| 0.87 ET2 / CT2 0.75 (R1+R4) / (R1-R4) -0.97 ET2 / ET3 0.35 (R1-R5) / (R1+R5) -2.21 Sag3R1 / CT3 0.21 f / f3 -2.62 - - 9. Embodiment

[0179] Fig.17 is a schematic view of an image acquisition unit according to the 9th embodiment of the present disclosure. Fig. Fig. 18 shows, in order from left to right, spherical aberration curves, astigmatic field curves, and a distortion curve of the image pickup unit according to the 9th embodiment. In Fig.17, the image sensing unit 9 includes the photographing optical lens system (the reference numeral of which is omitted) of the present disclosure and an image sensor IS. The photographing optical lens system includes, in order from the object side to the image side along an optical path, a stop S1, a first lens element E1, a second lens element E2, an aperture stop ST, a third lens element E3, a fourth lens element E4, a diaphragm S2, a reflecting element E5, a filter E6, and an image surface IMG. The photographing optical lens system includes four lens elements (E1, E2, E3, and E4), and no additional lens element is disposed between each of the adjacent four lens elements.

[0180] The first lens element E1 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The first lens element E1 is made of glass material and has the object side surface and the image side surface, both of which are aspherical. The image side surface of the first lens element E1 has a reversal point. The image side surface of the first lens element E1 has a concave critical point in an off-axis region thereof.

[0181] The second lens element E2 with a positive refractive index has an object side surface that is convex in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the second lens element E2 has a reversal point. The image side surface of the second lens element E2 has a reversal point.

[0182] The third lens element E3 with a negative refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is concave in a paraxial region thereof. The third lens element E3 is made of plastic and has both the object side surface and the image side surface, both of which are aspherical. The object side surface of the third lens element E3 has two reversal points. The object side surface of the third lens element E3 has a convex critical point in an off-axis region thereof.

[0183] The fourth lens element E4 with a positive refractive index has an object side surface that is concave in a paraxial region thereof and an image side surface that is convex in a paraxial region thereof. The fourth lens element E4 is made of plastic and has the object side surface and the image side surface, both of which are aspherical. The object side surface of the fourth lens element E4 has a reversal point. The image side surface of the fourth lens element E4 has a reversal point. The object side surface of the fourth lens element E4 has a convex critical point in a deviated axial region therefrom. The image side surface of the fourth lens element E4 has a concave critical point in a deviated axial region therefrom.

[0184] The reflective element E5 is made of glass material and is located between the fourth lens element E4 and the image surface IMG along the optical axis without affecting the focal length of the optical lens system for photographing. The reflective element E5 is a prism with a folding property of the optical path. For simplicity of illustration, Fig. 17, the deflection of the beam path caused by the reflective element E5 is not shown. However, the reflective element E5 can have different configurations depending on the actual design requirements, causing different deflection effects on the beam path. See, for example, Fig. 48, which shows a schematic view of a configuration of another reflective element and the associated optical path deflection in the image acquisition unit according to the 9th embodiment. In Fig.48, the reflective element E5 has, in a sequence of light propagation on the beam path, a first light-transmitting surface LP1, a first reflective surface RF1, a second reflective surface RF2, a third reflective surface RF3, a fourth reflective surface RF4, a fifth reflective surface RF5 and a second light-transmitting surface LP2.The first reflective surface RF1 deflects the beam path from a first optical axis OA1 to a second optical axis OA2, the second reflective surface RF2 deflects the beam path from the second optical axis OA2 to a third optical axis OA3, the third reflective surface RF3 deflects the beam path from the third optical axis OA3 to a fourth optical axis OA4, the fourth reflective surface RF4 deflects the beam path from the fourth optical axis OA4 to a fifth optical axis OA5, the fifth reflective surface RF5 deflects the beam path from the fifth optical axis OA5 to a sixth optical axis OA6, and the beam path impinges on the image surface IMG along the sixth optical axis OA6. In . Fig.48, the reflective element E5 deflects the optical path five times, wherein an angle between a vector of the optical axis on the object side (e.g., the first optical axis OA1) and a vector of the optical axis on the image side (e.g., the sixth optical axis OA6) may be 180 degrees. Furthermore, the reflective element E5 of this embodiment may have a configuration corresponding, for example, to one of the Fig. 41 to Fig. 47 shown configurations, which can be accessed with reference to the above descriptions Fig. 41 to Fig. 47 and the relevant details are not repeated.

[0185] The E6 filter is made of glass and is located between the reflective element E5 and the image surface IMG without affecting the focal length of the optical lens system for photographing. The IS image sensor is located on or near the image surface IMG of the optical lens system for photographing.

[0186] The detailed optical information of the 9th embodiment is shown in Table 9A and the information of the aspherical surface is shown in Table 9B below. TABLE 9A 9. Embodiment f = 17.21 mm, Fno = 2.80, HFOV = 13.0 degrees Surface # radius of curvature thickness material index Abbe # Focal length 0 lens Plano infinite 1 aperture Plano -0.326 2 Lens 1 7.8785 (ASP) 1.295 Glass 1.954 32.3 7.72 3 -104.0422 (ASP) 0.502 4 Lens 2 15.5091 (ASP) 0.360 plastic 1.639 23.5 33.11 5 57.6578 (ASP) 0.488 6 Aperture diaphragm Plano -0.156 7 Lens 3 -53.0407 (ASP) 0.350 plastic 1.669 19.5 -6.16 8 4.4816 (ASP) 0.625 9 Lens 4 -23.3445 (ASP) 0.526 plastic 1.544 56.0 31.36 10 -9.9356 (ASP) 0.030 11 aperture Plano 0.400 12 Prism Plano 20.000 Glass 1.804 46.6 - 13 Plano 0.200 14 filter Plano 0.210 Glass 1.517 64.2 - 15 Plano 0.320 16 Picture Plano - Note: The reference wavelength is 587.6 nm (d-line). An effective radius of the aperture S1 (surface 1) is 3,100 mm. An effective radius of the aperture S2 (surface 11) is 2.179 mm. TABLE 9B Aspherical coefficients Surface # 2 3 4 5 k = -2.11008000E-01 2.01555000E+01 -6.14001000E+00 -2.82868000E+01 A4 = -8.04515054E-04 -5.17055372E-03 -2.01020064E-02 1.16908272E-02 A6 = 2.73677131E-04 4.36209605E-03 3.09176530E-02 2.11731275E-02 A8 = -1.69738373E-05 -1.72585811E-03 -2.13522538E-02 -3.45405983E-02 A10 = -1.70723939E-05 4.09918997E-04 1.04805551E-02 3.16442300E-02 A12 = 5.94389394E-06 -6.15279909E-05 -3.93832906E-03 -1.99034959E-02 A14 = -9.26433291E-07 5.83384022E-06 1.15310569E-03 9.20853684E-03 A16 = 7.87222562E-08 -3.34070810E-07 -2.69221922E-04 -3.20731623E-03 A18 = -3.52545814E-09 1.03174861E-08 5.13871747E-05 8.35560277E-04 A20 = 6.52411414E-11 -1.26582112E-10 -7.99490285E-06 -1.58838330E-04 A22 = - - 9.61397699E-07 2.11876434E-05 A24 = - - -8.10916546E-08 -1.86540419E-06 A26 = - - 4.15039610E-09 9.68563514E-08 A28 = - - -9.54039676E-11 -2.23872549E-09 Surface # 7 8 9 10 k = 0.00000000E+00 0.00000000E+00 0.00000000E+00 0.00000000E+00 A4 = 7.95821459E-02 6.27655715E-02 1.42951585E-02 5.79657909E-03 A6 = -8.02866781E-02 -8.32940922E-02 -1.02011303E-02 -2.94407425E-03 A8 = 4.27471919E-02 5.58946547E-02 8.88203869E-03 4.15901276E-03 A10 = -1.04496816E-02 -2.33387505E-02 -8.49610562E-03 -5.02568453E-03 A12 = -8.72712439E-04 7.27011779E-03 7.61198822E-03 4.65726395E-03 A14 = 1.57724588E-03 -2.35700439E-03 -4.81901841E-03 -2.93541859E-03 A16 = -6.06538191E-04 8.59845596E-04 2.03267900E-03 1.24397036E-03 A18 = 1.43504108E-04 -2.59026299E-04 -5.72674568E-04 -3.55785921E-04 A20 = -2.42494041 E-05 5.31549476E-05 1.07249516E-04 6.79718590E-05 A22 = 2.99981886E-06 -6.87091954E-06 -1.28896779E-05 -8.33489535E-06 A24 = -2.57802169E-07 5.07421666E-07 9.03222049E-07 5.94278816E-07 A26 = 1.35318539E-08 -1.64093952E-08 -2.81178852E-08 -1.87487953E-08 A28 = -3.21650948E-10 - - -

[0187] In the 9th embodiment, the equation of the aspherical surface profiles of the aforementioned lens elements is the same as the equation of the 1st embodiment. The definitions of these parameters shown in Table 9C below are also the same as those given in the 1st embodiment, with corresponding values for the 9th embodiment, so explanation thereof will not be repeated.

[0188] In addition, these parameters can be calculated from Table 9A and Table 9B as the following values and satisfy the following conditions: TABLE 9C Values of optical and physical parameters / definitions f[mm] 17.21 (R4+R6) / (R4-R6) 1.17 Fno 2.80 TD / (CT2+T23) 5.77 HFOV [degree] 13.0 (CT2+CT3) / CT1 0.55 TL / lmgH 6.32 CT2 / T34 0.58 TD / BL 0.19 N1 1.954 SD / TD 0.34 V2 23.5 |f2 / f4| 1.06 V1 / V2 1.37 |f12 / f4| 0.20 V3 / V4 0.35 |f / R4|+|f / R5| 0.62 ET2 / CT2 1.46 (R1+R4) / (R1-R4) -1.32 ET2 / ET3 0.73 (R1-R5) / (R1+R5) -1.35 Sag3R1 / CT3 0.75 f / f3 -2.79 - - 10. Embodiment

[0189] Fig.19 is a perspective view of an image sensing unit according to the 10th embodiment of the present disclosure. In this embodiment, an image sensing unit 100 is a camera module including a lens unit 101, a drive unit 102, an image sensor 103, and an image stabilizer 104. The lens unit 101 includes the optical lens system for photographing disclosed in the first embodiment, a barrel, and a holding member (the reference numerals of which are omitted) for holding the optical lens system for photographing. However, the lens unit 101 may alternatively be provided with the optical lens system for photographing disclosed in other embodiments of the present disclosure, and the present disclosure is not limited thereto.The imaging light is converged in the lens unit 101 of the image acquisition unit 100 to form an image with the drive unit 102, which is used to focus the image onto the image sensor 103, and the formed image is then digitally transmitted to another electronic component for further processing.

[0190] The drive unit 102 may have autofocus functionality, and different drive configurations can be achieved by using voice coil motors (VCMs), microelectromechanical systems (MEMS), piezoelectric systems, or shape memory alloy materials. The drive unit 102 is advantageous for obtaining a better imaging position of the lens unit 101, so that a clear image of the imaged object can be captured by the lens unit 101 at different object distances. The image sensor 103 (for example, CMOS or CCD), which may have high light sensitivity and low noise, is arranged on the image surface of the optical lens system for photographing to achieve higher image quality.

[0191] The image stabilizer 104, such as an accelerometer, a gyro sensor, and a Hall-effect sensor, is configured to cooperate with the drive unit 102 to provide optical image stabilization (OIS). The drive unit 102, which cooperates with the image stabilizer 104, is advantageous for compensating for pan and tilt of the lens unit 101, thereby reducing motion blur during exposure. In some cases, compensation can be provided by electronic image stabilization (EIS) with image processing software, thereby improving image quality in motion or low-light conditions. 11. Embodiment

[0192] Fig. 20 is a perspective view of an electronic device according to the 11th embodiment of the present disclosure, wherein Fig. 21 another perspective view of the electronic device in Fig. 20 and where Fig. 22 a block diagram of the electronic device in Fig. 20 is.

[0193] In this embodiment, an electronic device 200 is a smartphone that includes the image capture unit 100 according to the 10th embodiment, an image capture unit 100a, an image capture unit 100b, an image capture unit 100c, an image capture unit 100d, an image capture unit 100e, a flash module 201, a focus assist module 202, an image signal processor 203, a display module 204, and an image software processor 205. The image capture unit 100, the image capture unit 100a, and the image capture unit 100b are arranged on the same side of the electronic device 200, and each of the image capture units 100, 100a, and 100b has a single focal point. The focus assist module 202 may be a laser distance meter or a time-of-flight (ToF) module, although the present disclosure is not limited thereto.The image capture unit 100c, the image capture unit 100d, the image capture unit 100e, and the display module 204 are arranged on the opposite side of the electronic device 200, and the display module 204 may be a user interface, so that the image capture units 100c, 100d, and 100e may be front-facing cameras of the electronic device 200 for taking selfies, although the present disclosure is not limited thereto. Furthermore, each of the image capture units 100a, 100b, 100c, 100d, and 100e may include the optical lens system for taking photographs of the present disclosure and have a similar configuration to the image capture unit 100. Specifically, each of the image acquisition units 100a, 100b, 100c, 100d, and 100e may include a lens unit, a drive unit, an image sensor, and an image stabilizer, and may also include a light folding element for folding the optical path.In addition, each lens unit of the image capturing units 100a, 100b, 100c, 100d, and 100e may include the optical lens system for photographing of the present disclosure, a barrel, and a holding member for holding the optical lens system for photographing.

[0194] The image capture unit 100 is a telephoto image capture unit with optical path folding characteristics, wherein the image capture unit 100a is a wide-angle image capture unit, wherein the image capture unit 100b is an ultra-wide-angle image capture unit, wherein the image capture unit 100c is a wide-angle image capture unit, wherein the image capture unit 100d is an ultra-wide-angle image capture unit, and wherein the image capture unit 100e is a time-of-flight image capture unit. In this embodiment, the image capture units 100, 100a, and 100b have different fields of view, so that the electronic device 200 can have different magnification ratios to meet the requirement of the optical zoom characteristic. In addition, the image capture unit 100e can capture depth information of the imaged object. Furthermore, the light folding configuration of the image capture unit 100 can, for example, be one of the Fig. 30 to Fig. 40 shown configurations, which are referred to in the above descriptions with Fig. 30 to Fig. 40, and the details thereof will not be repeated. In this embodiment, the electronic device 200 includes a plurality of image capture units 100, 100a, 100b, 100c, 100d, and 100e, but the present disclosure is not limited to the number and configuration of the image capture units.

[0195] When a user captures images of an object 206, the light beams converge in the image capture unit 100, the image capture unit 100a, or the image capture unit 100b to create images, and the flash module 201 is activated to add light. The focus assist module 202 detects the object distance of the imaged object 206 to achieve fast autofocusing. The image signal processor 203 is configured to optimize the captured image to improve image quality. The light beam emitted by the focus assist module 202 can be either conventional infrared light or laser light. Additionally, the light beams can converge in the image capture unit 100c, 100d, or 100e to create images.The display module 204 may include a touchscreen, and the user may interact with the display module 204 and the image software processor 205, which has multiple functions for capturing images and performing image processing. Alternatively, the user may capture images via a physical button. The image processed by the image software processor 205 may be displayed on the display module 204. 12. Embodiment

[0196] Fig. 23 is a schematic view of an electronic device according to the 12th embodiment of the present disclosure, and Fig. 24 is another schematic view of the electronic device in Fig. 23.

[0197] In this embodiment, an electronic device 300 is a smartphone that includes the image capture unit 100 as disclosed in the 10th embodiment, an image capture unit 100f, an image capture unit 100g, an image capture unit 100h, and a display module 304. As in Fig. 23, the image capture unit 100, the image capture unit 100f, and the image capture unit 100g are arranged on the same side of the electronic device 300, and each of the image capture units 100, 100f, and 100g has a single focal point. As shown in Fig.As shown in Figure 24, the image capture unit 100h and the display module 304 are arranged on the opposite side of the electronic device 300, so that the image capture unit 100h may be a front-facing camera of the electronic device 300 for taking selfies, but the present disclosure is not limited thereto. Further, each of the image capture units 100f, 100g, and 100h may include the optical lens system for taking photographs of the present disclosure and have a configuration similar to that of the image capture unit 100. Specifically, each of the image capture units 100f, 100g, and 100h may include a lens unit, a drive unit, an image sensor, and an image stabilizer.In addition, each lens unit of the image capturing units 100f, 100g, and 100h may include the optical lens system for photographing of the present disclosure, a cylinder, and a holding member for holding the optical lens system for photographing.

[0198] The image capture unit 100 is a telephoto image capture unit, the image capture unit 100f is a wide-angle image capture unit, the image capture unit 100g is an ultra-wide-angle image capture unit, and the image capture unit 100h is a wide-angle image capture unit. In this embodiment, the image capture units 100, 100f, and 100g have different fields of view, so that the electronic device 300 can have different magnification ratios to meet the requirement of the optical zoom property. Furthermore, the image capture unit 100h, as shown in Fig.24, have a non-circular opening, and the cylinder or lens elements in the image capture unit 100h may have shortened edges at their outermost positions to conform to the shape of the non-circular opening. Therefore, the length of the major axis and / or the minor axis of the image capture unit 100h can be further reduced, providing the advantage of reducing the size of the image capture unit 100h, thereby increasing the ratio of the area of the display module 304 to that of the electronic device 300 and reducing the thickness of the electronic device 300, thereby achieving compactness. In this embodiment, the electronic device 300 includes a plurality of image capture units 100, 100f, 100g, and 100h, but the present disclosure is not limited to the number and configuration of the image capture units. 13. Embodiment

[0199] Fig.25 is a perspective view of an electronic device according to the 13th embodiment of the present disclosure.

[0200] In this embodiment, an electronic device 400 is a smartphone that includes the image capture unit 100 according to the 10th embodiment, an image capture unit 100i, an image capture unit 100j, an image capture unit 100k, an image capture unit 100m, an image capture unit 100n, an image capture unit 100p, an image capture unit 100q, an image capture unit 100r, a flash module 401, a focus assist module, an image signal processor, a display module, and an image software processor (not shown). The image capture units 100, 100i, 100j, 100k, 100m, 100n, 100p, 100q and 100r are arranged on the same side of the electronic device 400, while the display module is arranged on the opposite side of the electronic device 400.Furthermore, each of the image capture units 100i, 100j, 100k, 100m, 100n, 100p, 100q, and 100r may include the optical lens system for photographing of the present disclosure and have a similar configuration to the image capture unit 100, the details of which will not be repeated.

[0201] The image capture unit 100 is a telephoto image capture unit with a folding property of the optical path, wherein the image capture unit 100i is a telephoto image capture unit with a folding property of the optical path, wherein the image capture unit 100j is a wide-angle image capture unit, wherein the image capture unit 100k is a wide-angle image capture unit, wherein the image capture unit 100m is an ultra-wide-angle image capture unit, wherein the image capture unit 100n is an ultra-wide-angle image capture unit, wherein the image capture unit 100p is a telephoto image capture unit, wherein the image capture unit 100q is a telephoto image capture unit and wherein the image capture unit 100r is a time-of-flight (ToF) image capture unit.In this embodiment, the image acquisition units 100, 100i, 100j, 100k, 100m, 100n, 100p, and 100q have different fields of view, so that the electronic device 400 can have different magnification ratios to meet the requirement of the optical zoom property. Furthermore, the image acquisition unit 100r can determine depth information of the imaged object. Furthermore, the light folding configuration of the image acquisition units 100 and 100i can be, for example, one of the configurations shown in FIG. Fig. 30 to Fig. 40 shown structures, which are referred to with reference to the above descriptions with Fig. 30 to Fig.40, the details thereof will not be repeated. In this embodiment, the electronic device 400 includes a plurality of image capture units 100, 100i, 100j, 100k, 100m, 100n, 100p, 100q, and 100r, and the present disclosure is not limited to the number and configuration of the image capture units. When a user captures images of an object, the light beams converge in the image capture unit 100, 100i, 100j, 100k, 100m, 100n, 100p, 100q, or 100r to form images and to activate the flash module 401 for light assistance. Furthermore, the subsequent processes are performed similarly to the above-mentioned embodiments, the details thereof will not be repeated.

[0202] The smartphones in the embodiments are only examples to show the image sensing unit of the present disclosure in an electronic device, and the present disclosure is not limited thereto. The image sensing unit can optionally be applied to moving focus optical systems. Furthermore, the optical lens system for photographing the image sensing unit features good aberration correction and high image quality, and can be used for 3D image capture (three-dimensional image capture) in products such as digital cameras, mobile devices, digital tablets, smart TVs, network monitoring devices, dashboard cameras, vehicle rearview cameras, multi-camera devices, image recognition systems, motion sensor input devices, unmanned aerial vehicles, wearable devices, portable video recorders, and other electronic imaging devices.

[0203] The foregoing description has been made for the purpose of illustration with reference to specific embodiments. It should be noted that TABLES 1A-9C show different information of the various embodiments. However, the information of the various embodiments was obtained from experimentation. The embodiments were chosen and described in order to best explain the principles of the disclosure and their practical applications to enable others skilled in the art to best utilize the disclosure and various embodiments with various modifications as are suited to the particular use contemplated. The above-illustrated embodiments and the accompanying drawings are exemplary and are not intended to be exhaustive or to limit the scope of the present disclosure to the precise forms disclosed. Many modifications and variations are possible in light of the above teachings.

Claims

[1] An optical lens system for photographing, comprising four lens elements (E1, E2, E3 and E4), the four lens elements (E1, E2, E3 and E4) being, in order from an object side to an image side along an optical path, a first lens element (E1), a second lens element (E2), a third lens element (E3) and a fourth lens element (E4), each of the four lens elements (E1, E2, E3 and E4) having an object side surface facing the object side and an image side surface facing the image side; wherein the first lens element (E1) has a positive refractive index, the object side surface of the first lens element (E1) being convex in a paraxial region thereof, the second lens element (E2) having a positive refractive index, the object side surface of the second lens element (E2) being convex in a paraxial region thereof, the third lens element (E3) having a negative refractive index, the image side surface of the third lens element (E3) being concave in a paraxial region thereof, the image side surface of the fourth lens element (E4) being convex in a paraxial region thereof, and at least one surface of at least one lens element in the optical lens system for photographing has at least one inversion point (P); wherein an axial distance between the object side surface of the first lens element (E1) and the image side surface of the fourth lens element (E4) is TD, wherein an axial distance between the image side surface of the fourth lens element (E4) and an image surface (IMG) is BL, wherein a focal length of the second lens element (E2) is f2, wherein a focal length of the fourth lens element (E4) is f4, wherein a central thickness of the first lens element (E1) is CT1, wherein a central thickness of the second lens element (E2) is CT2, wherein a central thickness of the third lens element (E3) is CT3, wherein a radius of curvature of the object side surface of the first lens element (E1) is R1, wherein a radius of curvature of the object side surface of the third lens element (E3) is R5, and wherein the following conditions are met: 0.05 <TD / BL<0,60; 0.05<|f2 / f4|<1.50; 0.10<(CT2+CT3) / CT1<1.00; and −4.50<(R1−R5) / (R1+R5)<0.

25. [2] An optical lens system for photographing according to claim 1, wherein the fourth lens element (E4) has a positive refractive index, and wherein at least one of the object side surfaces and the image side surface of the fourth lens element (E4) has at least one reversal point (P). [3] The optical lens system for photographing according to claim 1, wherein the central thickness of the first lens element (E1) is CT1, the central thickness of the second lens element (E2) is CT2, the central thickness of the third lens element (E3) is CT3, a focal length of the optical lens system for photographing is f, a focal length of the third lens element (E3) is f3, and the following conditions are satisfied: 0.30<(CT2+CT3) / CT1<0.85; and −5.00 <f / f3<−1,80. [4] The photographing optical lens system according to claim 1, wherein a focal length of the photographing optical lens system is f, a radius of curvature of the image side surface of the second lens element (E2) is R4, a radius of curvature of the object side surface of the third lens element (E3) is R5, and the following condition is satisfied: 0.05<|f / R4|+|f / R5|<2.

80. [5] An optical lens system for photographing according to claim 1, wherein a radius of curvature of the image side surface of the second lens element (E2) is R4, a radius of curvature of the image side surface of the third lens element (E3) is R6, and the following condition is satisfied: 0.20<(R4+R6) / (R4−R6)<1.

80. [6] The photographing optical lens system according to claim 1, wherein an F-number of the photographing optical lens system is Fno, half of a maximum field of view of the photographing optical lens system is HFOV, and the following conditions are satisfied: 1.50 <Fno<2,50; und 5.0 degrees <GFOV<20,0Grad. [7] The optical lens system for photographing according to claim 1, further comprising an aperture stop (ST), wherein an axial distance between the aperture stop (ST) and the image side surface of the fourth lens element (E4) is SD, wherein the axial distance between the object side surface of the first lens element (E1) and the image side surface of the fourth lens element (E4) is TD, and wherein the following condition is satisfied: 0.05 <SD / TD<0,90. [8] An optical lens system for photographing according to claim 1, wherein an Abbe number of the third lens element (E3) is V3, wherein an Abbe number of the fourth lens element (E4) is V4, and wherein the following condition is satisfied: 0.10 <V3 / V4<0,85 [9] An optical lens system for photographing according to claim 1, wherein a displacement parallel to an optical axis from an axial vertex of the object side surface of the third lens element (E3) to a position of the maximum effective radius of the object side surface of the third lens element (E3) is Sag3R1, the central thickness of the third lens element (E3) is CT3, and the following condition is satisfied: −0.10 <Sag3R1 / CT3<0,80. [10] An optical lens system for photographing according to claim 1, wherein a distance parallel to an optical axis between a position of the maximum effective radius of the object side surface of the second lens element (E2) and a position of the maximum effective radius of the image side surface of the second lens element (E2) is ET2, the central thickness of the second lens element (E2) is CT2, and the following condition is satisfied: 0.50 <ET2 / CT2<1,50. [11] An optical lens system for photographing according to claim 1, wherein the axial distance between the object side surface of the first lens element (E1) and the image side surface of the fourth lens element (E4) is TD, the axial distance between the image side surface of the fourth lens element (E4) and the image surface (IMG) is BL, the focal length of the second lens element (E2) is f2, the focal length of the fourth lens element (E4) is f4, the central thickness of the first lens element (E1) is CT1, the central thickness of the second lens element (E2) is CT2, the central thickness of the third lens element (E3) is CT3, the radius of curvature of the object side surface of the first lens element (E1) is R1, the radius of curvature of the object side surface of the third lens element (E3) is R5, a refractive index of the first lens element (E1) is N1, an Abbe number of the second lens element (E2) is V2,wherein an axial distance between the third lens element (E3) and the fourth lens element (E4) is T34, and wherein the following conditions are met:, 0.19≤TD / BL≤0.31; 0.2≤|f2 / f4|≤1.14; 0.48≤(CT2+CT3) / CT1≤1.14; −2.88≤(CT2+CT3) / CT1≤−0.19; 1.544≤N1≤1.954; 22.5≤V2≤56.0; and 0.39≤CT2 / T34≤0.

90. [12] An optical lens system for photographing according to claim 1, further comprising a reflective element (E5) disposed between the fourth lens element (E4) and the image surface (IMG) along a direction of the optical path. [13] An optical lens system for photographing according to claim 12, wherein the reflecting element (E5) has at least two reflecting surfaces (RF1, RF2). [14] Image acquisition unit (1, 100), comprising: the optical lens system for photographing according to claim 1; and an image sensor (IS, 103) arranged on the image surface (IMG) of the optical lens system for photographing. [15] An electronic device (200) comprising: the image capture unit (1, 100) according to claim 14. [16] An optical lens system for photographing, comprising four lens elements (E1, E2, E3 and E4), the four lens elements (E1, E2, E3 and E4) being, in order from an object side to an image side along an optical path, a first lens element (E1), a second lens element (E2), a third lens element (E3) and a fourth lens element (E4), each of the four lens elements (E1, E2, E3 and E4) having an object side surface facing the object side and an image side surface facing the image side; wherein the first lens element (E1) has a positive refractive index, the object side surface of the first lens element (E1) being convex in a paraxial region thereof, the second lens element (E2) having a positive refractive index, the third lens element (E3) having a negative refractive index, the image side surface of the third lens element (E3) being concave in a paraxial region thereof, and at least one surface of at least one lens element in the optical lens system for photographing has at least one inflection point (P); wherein an axial distance between the object side surface of the first lens element (E1) and the image side surface of the fourth lens element (E4) is TD, wherein an axial distance between the image side surface of the fourth lens element (E4) and an image surface (IMG) is BL, wherein a refractive index of the first lens element (E1) is N1, wherein an Abbe number of the second lens element (E2) is V2, wherein a central thickness of the second lens element (E2) is CT2, wherein an axial distance between the third lens element (E3) and the fourth lens element (E4) is T34, and wherein the following conditions are met: 0.05 <TD / BL<0,60; 1,650 <N1<2,200 10.0 <V2<45,0; und 0.05 <CT2 / T34<1,00. [17] An optical lens system for photographing according to claim 16, wherein the first lens element (E1) is made of a glass material; wherein the Abbe number of the second lens element (E2) is V2 and the following condition is satisfied: 15.0 <V2<40,0. [18] An optical lens system for photographing according to claim 16, wherein the refractive index of the first lens element (E1) is N1, an Abbe number of the first lens element (E1) is V1, the Abbe number of the second lens element (E2) is V2, and the following conditions are satisfied: 1,750 <N1<2,100; und 0.80 <V1 / V2<2,00. [19] An optical lens system for photographing according to claim 16, wherein the axial distance between the object side surface of the first lens element (E1) and the image side surface of the fourth lens element (E4) is TD, the axial distance between the image side surface of the fourth lens element (E4) and the image surface (IMG) is BL, and the following condition is satisfied: 0.12 <TD / BL<0,35. [20] An optical lens system for photographing according to claim 16, wherein a radius of curvature of the object side surface of the first lens element (E1) is R1, a radius of curvature of the image side surface of the second lens element (E2) is R4, and the following condition is satisfied: −3.00<(R1+R4) / (R1−R4)<0. [21] An optical lens system for photographing according to claim 16, wherein the axial distance between the object side surface of the first lens element (E1) and the image side surface of the fourth lens element (E4) is TD, the central thickness of the second lens element (E2) is CT2, an axial distance between the second lens element (E2) and the third lens element (E3) is T23, and the following condition is satisfied: 4.50 <TD / (CT2+T23)<8,00. [22] An optical lens system for photographing according to claim 16, wherein a combined focal length of the first lens element (E1) and the second lens element (E2) is f12, a focal length of the fourth lens element (E4) is f4, and the following condition is satisfied: 0.01<|f12 / f4|<0.

27. [23] An optical lens system for photographing according to claim 16, wherein the object side surface of the fourth lens element (E4) has at least one critical point (C) in an off-axis region thereof; wherein an axial distance between the object side surface of the first lens element (E1) and the image surface (IMG) is TL, wherein a maximum image height of the optical lens system for photographing is ImgH, and wherein the following condition is satisfied: 5.50 <TL / ImgH<7,00. [24] The optical lens system for photographing according to claim 16, wherein a distance parallel to an optical axis between a position of the maximum effective radius of the object side surface of the second lens element (E2) and a position of the maximum effective radius of the image side surface of the second lens element (E2) is ET2, wherein a distance parallel to the optical axis between a position of the maximum effective radius of the object side surface of the third lens element (E3) and a position of the maximum effective radius of the image side surface of the third lens element (E3) is ET3, and wherein the following condition is satisfied: 0.10 < ET2 / ET3 < 0.85 [25] An optical lens system for photographing according to claim 16, further comprising a reflective element (E5) located between the fourth lens element (E4) and the image surface (IMG) along a direction of the optical path, the reflective element (E5) having at least three reflective surfaces (RF1, RF2, RF3).

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