BR102023013446A2 - FOLDED OPTICAL SYSTEM, IMAGE CAPTURE UNIT AND ELECTRONIC DEVICE - Google Patents

Abstract

A folded optical system includes an optical folding assembly and lens elements. The optical folding assembly has a first transmissive surface, a first reflecting surface, a second reflecting surface having substantially the same interface as the first transmissive surface, a third reflecting surface, and a second transmissive surface sequentially along an optical path. The optical path reaches the first reflecting surface via the first transmissive surface along a first optical axis to be redirected sequentially to a second optical axis, a third optical axis and a fourth optical axis, respectively, by the first reflecting surface, second surface reflecting surface, and third reflecting surface, and reaches an imaging surface through the second transmissive surface. The lens elements include at least one first lens element located on the first optical axis. The first lens element with positive refractive power has an incident light surface that is convex in a paraxial region of it.

Description

Technical Field

[0001] The present disclosure relates to a folded optical system, an image capture unit and an electronic device, more specifically to a folded optical system and an image capture unit applicable to an electronic device.

Description of the Related Technique

[0002] With the development of semiconductor manufacturing technology, the performance of image sensors has been improved, and the pixel size has been reduced. Therefore, high-quality imaging capabilities become one of the indispensable features of an optical system nowadays.

[0003] Furthermore, due to rapid changes in technology, electronic devices equipped with optical systems are moving towards multifunctionality for various applications, and therefore, functionality requirements for optical systems have grown. However, it is difficult for a conventional optical system to balance requirements such as high image quality, low sensitivity, adequate aperture size, miniaturization and a desirable field of view.

[0004] In recent years, electronic products tend to be light and thin, so that it is difficult for conventional photographic lenses to meet the requirements of high-specification and compactness, especially small lenses that feature a large aperture, a telephoto function or the like. . However, as optical zoom requirements become stricter (such as by increasing optical zoom magnification, etc.), conventional telephoto lenses become unable to meet technology demands and thus experience problems such as such as an excessively long overall length, an excessively small opening, insufficient quality and inability to compact. Therefore, it is necessary to introduce different optical features or a bent optical axis configuration to overcome the above-mentioned problems. What's more, due to the thickness limitation of electronic devices, the lens barrels or various lens elements in some optical lenses will be cut to remove the parts not used in imaging, so that the lens size in a specific direction be reduced. Furthermore, a reflective element can be additionally introduced to obtain a reduced size device, allowing the lens to have a total optical track length sufficient to present a telephoto function with a long focal length.

SUMMARY

[0005] According to one aspect of the present disclosure, a folded optical system includes an optical foldable assembly and a plurality of lens elements.

[0006] The optical folding assembly has a first transmissive surface, a first reflecting surface, a second reflecting surface, a third reflecting surface and a second transmissive surface sequentially along a direction of light displacement in an optical path. The first transmissive surface and the second transmissive surface are substantially the same interface. The optical path reaches the first reflecting surface via the first transmissive surface along a first optical axis, the optical path along the first optical axis is redirected to a second optical axis by the first reflecting surface, the optical path along the second optical axis is redirected to the third optical axis by the second reflecting surface, the optical path along the third optical axis is redirected to a fourth optical axis by the third reflecting surface, and the optical path reaches an imaging surface through the second transmissive surface. along the fourth optical axis.

[0007] Each of the plurality of lens elements has a light-inciding surface and a light-emitting surface sequentially along the direction of travel of the light in the optical path. The plurality of lens elements includes at least a first lens element. The first lens element is located on the first optical axis, the first lens element has a positive refractive power, and the light incident surface of the first lens element is convex in a paraxial region thereof.

[0008] According to another aspect of the present disclosure, the folded optical system includes an optical foldable assembly and a plurality of lens elements.

[0009] The optical folding assembly has a first transmissive surface, a first reflecting surface, a second reflecting surface, a third reflecting surface and a second transmissive surface sequentially along a direction of travel of light in the optical path. The first transmissive surface and the second reflective surface are substantially the same interface. The optical path reaches the first reflecting surface via the first transmissive surface along a first optical axis, the optical path along the first optical axis is redirected to a second optical axis by the first reflecting surface, the optical path along the second optical axis is redirected to the third optical axis by the second reflecting surface, the optical path along the third optical axis is redirected to the fourth optical axis by the third reflecting surface, and the optical path reaches an imaging surface through the second transmissive surface along the fourth optical axis. The first optical axis is substantially parallel to the normal direction of the imaging surface.

[0010] Each of the plurality of lens elements has a light-inciding surface and a light-emitting surface sequentially along the direction of travel of the light in the optical path. The plurality of lens elements includes a first lens element and a second lens element sequentially along the direction of travel of light in the optical path. The first lens element and the second lens element are located on the first optical axis, the first lens element has a positive refractive power, and the second lens element has a negative refractive power.

[0011] The optical collapsible assembly is located between the plurality of lens elements, or the optical collapsible assembly is located between the plurality of lens elements and the image surface along the direction of travel of light in the optical path.

[0012] Each of the plurality of lens elements is located on the first optical axis or the fourth optical axis.

[0013] When an axial distance along the first optical axis, the second optical axis, the third optical axis and the fourth optical axis between the light incident surface of the first lens element and the imaging surface is TL, and a focal length of the folded optical system is f, the following condition is satisfied: 0.90 < TL/f < 2.00,

[0014] According to another aspect of the present disclosure, an image capture unit includes one of the aforementioned folded optical systems and an image sensor, wherein the image sensor is disposed on the imaging surface of the folded optical system.

[0015] According to another aspect of the present disclosure, an electronic device includes the aforementioned image capture unit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The disclosure can be better understood by reading the detailed description of the embodiments, with reference made to the attached drawings as follows:

[0017] Figure 1 is a schematic view of an image capture unit according to the 1st embodiment of the present disclosure;

[0018] Figure 2 shows spherical aberration curves and astigmatic field curves of the image capture unit according to the 1st modality;

[0019] Figure 3 is a schematic view of an image capture unit according to the 2nd embodiment of the present disclosure;

[0020] Figure 4 shows spherical aberration curves and astigmatic field curves of the image capture unit according to the 2nd modality;

[0021] Figure 5 is a schematic view of an image capture unit according to the 3rd embodiment of the present disclosure;

[0022] Figure 6 shows spherical aberration curves and astigmatic field curves of the image capture unit according to the 3rd modality;

[0023] Figure 7 is a schematic view of an image capture unit in accordance with the 4th embodiment of the present disclosure;

[0024] Figure 8 shows spherical aberration curves and astigmatic field curves of the image capture unit according to the 4th modality;

[0025] Figure 9 is a schematic view of an image capture unit in accordance with the 5th embodiment of the present disclosure;

[0026] Figure 10 shows spherical aberration curves and astigmatic field curves of the image capture unit according to the 5th modality;

[0027] Figure 11 is a schematic view of an image capture unit in accordance with the 6th embodiment of the present disclosure;

[0028] Figure 12 shows spherical aberration curves and astigmatic field curves of the image capture unit according to the 6th modality;

[0029] Figure 13 is a schematic view of an image capture unit in accordance with the 7th embodiment of the present disclosure;

[0030] Figure 14 shows spherical aberration curves and astigmatic field curves of the image capture unit according to the 7th modality;

[0031] Figure 15 is a schematic view of an image capture unit in accordance with the 8th embodiment of the present disclosure;

[0032] Figure 16 shows spherical aberration curves and astigmatic field curves of the image capture unit according to the 8th modality;

[0033] Figure 17 is a schematic view of an image capture unit in accordance with the 9th embodiment of the present disclosure;

[0034] Figure 18 is a view of an electronic device according to the 10th embodiment of the present disclosure;

[0035] Figure 19 is another perspective of the electronic device of Figure 18;

[0036] Figure 20 is a cross-sectional view of the electronic device of Figure 18;

[0037] Figure 21 is a perspective view of the electronic device according to the 11th embodiment of the present disclosure;

[0038] Figure 22 is another perspective of the electronic device of Figure 21;

[0039] Figure 23 is a block diagram of the electronic device of Figure 21;

[0040] Figure 24 is a perspective view of the electronic device according to the 12th embodiment of the present disclosure;

[0041] Figure 25 shows a schematic view of Ly and Lz according to the 1st embodiment of the present disclosure;

[0042] Figure 26 shows a schematic view of Ly and Lz according to the 3rd embodiment of the present disclosure;

[0043] Figure 27 shows a schematic view of LOA1, LOA2, LOA3, LOA4 and θa, according to the 1st embodiment of the present disclosure; It is

[0044] Figure 28 shows a schematic view of ET2, ET12, SAG11, SAG22 and Y11, according to the 1st embodiment of the present disclosure.

DETAILED DESCRIPTION

[0045] A folded optical system includes an optical folding assembly and a plurality of lens elements and can be applied to an image capture unit and an electronic device. With the arrangement of the optical folding assembly, it is favorable to flexibly arrange the space of the folded optical system, thereby reducing the size of the folded optical system.

[0046] Preferably, the optical folding assembly has a first transmissive surface, a first reflecting surface, a second reflecting surface, a third reflecting surface and a second transmissive surface sequentially along the direction of travel of light in an optical path. Preferably, the optical path reaches the first reflecting surface via the first transmissive surface along a first optical axis, the optical path along the first optical axis is redirected to the second optical axis by the first reflecting surface, the optical path along the along the second optical axis is redirected to the third optical axis by the second reflecting surface, the optical path along the third optical axis is redirected to the fourth optical axis by the third reflecting surface, and the optical path reaches an imaging surface through the second transmissive surface along the fourth optical axis.

[0047] Preferably, the first transmissive surface and the second reflective surface are substantially the same interface. Preferably, the first transmissive surface, the second reflecting surface and the second transmissive surface may be in substantially the same plane, and a normal direction of said plane may be substantially parallel to the first optical axis. Therefore, it is favorable for achieving an appropriate balance between reducing the thickness and the difficulty of manufacturing the folded optical system, thus improving the manufacturing yield rate thereof. Preferably, the first optical axis may be substantially parallel to a normal direction of the imaging surface. Therefore, it is conducive to increasing the stability and reducing the sensitivity of the folded optical system.

[0048] Preferably, the optical path is redirected three times by the optical folding assembly, and the angle between each two adjacent optical axes may vary depending on actual requirements such as space arrangement. Preferably, the first reflective surface and the third reflective surface may be specular or may have a reflection coating, which may be used to redirect the optical path for specular reflection. As for the second reflecting surface, the main part of the total reflection can be used to redirect the optical path. Preferably, each of the reflective surfaces and transmissive surfaces of the optical folding assembly may be a planar surface, a spherical surface, an aspherical surface, an axisymmetric free-form surface, or a non-axisymmetric free-form surface. In this specification, a Q2D freeform asphere, which can be simplified to “Q2D” hereafter, can be a type of non-axisymmetric freeform surface.

[0049] Preferably, the optical collapsible assembly may at least include a prism, and the prism may have a second reflective surface. Preferably, the optical collapsible assembly may also consist of a single prism. Preferably, the optical collapsible assembly may be located among the plurality of lens elements, or the optical collapsible assembly may be located between the plurality of lens elements and the imaging surface along the direction of travel of light in the optical path. Please see Figure 25, which shows the optical collapsible assembly that includes a prism PR1 in accordance with the 1st embodiment of the present disclosure, and the optical collapsible assembly is located between the lens elements (E1, E2 and E3). Please see Figure 26, which shows the optical collapsible assembly that includes two prisms PR1 and PR2, in accordance with the 3rd embodiment of the present disclosure, and the optical collapsible assembly is located between the group of lens elements (E1, E2 and E3 ) and the IMG imaging surface along the direction of light travel in the optical path.

[0050] Preferably, there may be one or more additional surfaces located between two adjacent ones of the first transmissive surface, the first reflective surface, the second reflective surface, the third reflective surface and the second transmissive surface. For example, when the optical collapsible assembly includes two prisms, there may be two additional surfaces through which the optical path passes and are located between the second reflecting surface and the third reflecting surface. Please see Figure 26, which shows the first corresponding surface OP1 and the second corresponding surface OP2 through which the optical path passes and is located between the second reflecting surface RF2 and the third reflecting surface RF3 in accordance with the 3rd embodiment of the present disclosure. .

[0051] Preferably, the material of the prism used as the optical folding assembly can be selected based on design requirements, such as glass or plastic. Furthermore, by definition of this specification, the prism with an optical path bending function does not belong to said plurality of lens elements.

[0052] Preferably, each of the lens elements may be located on the first optical axis or the fourth optical axis. In other words, there may be no lens element disposed on the second optical axis or the third optical axis. Therefore, it is favorable to provide sufficient space for the optical folding assembly to effect bending of the optical path in the folded optical system, thus facilitating the thickness of the product.

[0053] Preferably, each of the lens elements has a light-inciding surface and a light-emitting surface sequentially along the direction of travel of the light in the optical path. Preferably, the lens elements include a first lens element, and there is no additional lens element disposed between the first lens element and an image object. Preferably, the lens elements may additionally include a second lens element on a light-emitting side of the first lens element along the direction of travel of light in the optical path. That is, the lens elements at least include the first lens element and the second lens element sequentially along the direction of travel of light in the optical path. Preferably, the lens elements may additionally include a last lens element located closer to the imaging surface than the one or more remaining lens elements, the last element being located on the light-emitting sides of the one or more lens elements. along the direction of travel of light in the optical path, and there is no additional lens element disposed between the last lens element and the imaging surface. In other words, the last lens element is the third lens element when the plurality of lens elements includes a total of three lens elements; the last lens element is the fourth lens element when the plurality of lens elements includes a total of four lens elements; and the last lens element is the fifth lens element when the plurality of lens elements includes a total of five lens elements.

[0054] Preferably, the first lens element is located on the first optical axis. Preferably, the first lens element has a positive refractive power. Therefore, it is favorable to reduce the length of the folded optical system along the first optical axis, thereby reducing the thickness of the electronic device as a whole along the first optical axis. Preferably, the light incident surface of the first lens element may be convex in a paraxial region. Therefore, it is favorable to reduce the angle of incidence on the light incident surface of the first lens element in the off-axis field of view, thereby reducing the aperture size of the electronic device.

[0055] Preferably, the second lens element may be located on the first optical axis. Preferably, the second lens element may have negative refractive power. Therefore, it is favorable to balance the distribution of refractive power on the light incident side of the folded optical system so as to obtain a suitable balance between the reduction in thickness and the increase in image quality of the folded optical system. Preferably, the light-emitting surface of the second lens element may be concave in a paraxial region thereof. Therefore, it is conducive to effectively correcting aberrations generated by the first lens element so as to increase image quality.

[0056] Preferably, at least one of the lens elements can be made of plastic material, and the light-inciding surface and the light-emitting surface can both be aspherical. Therefore, it is favorable to effectively reduce the manufacturing cost and increase the design flexibility, thus increasing the image quality and the possibility of mass production.

[0057] Preferably, at least one of the lens elements may have a refractive power greater than 1.63. Therefore, it is conducive to effectively balancing the material distribution of lens elements, thereby reducing the overall size and correcting aberrations of the bent optical system.

[0058] When an axial distance along the first optical axis, the second optical axis, the third optical axis and the fourth optical axis between the light incident surface of the first lens element and the second lens element is TL, and a focal length of the folded optical system is f, the following condition can preferably be satisfied: 0.90 < TL/f < 2.00. Therefore, it is favorable to effectively balance the relationship between the total length of optical track and the focal length of the folded optical system, so as to meet the application requirements of the product. Furthermore, the following condition can also be preferably satisfied: 1.10 < TL/f < 1.60. Furthermore, the following condition can also be preferably satisfied: 1.20 < TL/f < 1.55.

[0059] When a radius of curvature of the light-inciding surface of the first lens element is R1, and a radius of curvature of the light-emitting surface of the first lens element is R2, the following condition may preferably be satisfied: -1.50 < R1/R2 < 0.90. Therefore, it is favorable for adjusting the lens shape of the first lens element, thereby increasing the controllability of the optical path of the light incident surface of the first lens element. Furthermore, the following condition can also be preferably satisfied: -1.00 < R1/R2 < 0.80.

[0060] When a focal length of the first lens element is f1, and a focal length of the second lens element is f2, the following condition may preferably be satisfied: -5.00 < f2/f1 < -0.03. Therefore, it is favorable for combining the first lens element and the second lens element to correct aberrations such as spherical aberrations. Furthermore, the following condition can also be preferably satisfied: -4.50 < f2/f1 < -0.10.

[0061] In the case of the second lens element located on the first optical axis, when a distance parallel to the first optical axis between a position of maximum effective radius of the light incident surface of the second lens element and a position of maximum effective radius of the light-emitting surface of the second lens element is ET2, and a central thickness of the second lens element on the first optical axis is CT2, the following condition can preferably be satisfied: 0.95 < ET2/CT2 < 3.50. Therefore, it is favorable to adjust the ratio of edge thickness to center thickness of the second lens element, thereby achieving a suitable balance between reducing manufacturing difficulty and reducing stray light within the lens element. Furthermore, the following condition can also be preferably satisfied: 1.00 < ET2/CT2 < 3.20. Please see Figure 28, which shows a schematic view of ET2 in accordance with the 1st embodiment of the present disclosure.

[0062] When the axial distance along the first optical axis, the second optical axis, the third optical axis and the fourth optical axis between the light incident surface of the first lens element and the imaging surface is TL and a distance perpendicular to the first optical axis between a position of maximum effective radius of the light incident surface of the first lens element and the first optical axis is Y11, the following condition can preferably be satisfied: 3.80 < TL/Y11 < 15, 00. Therefore, it is favorable to effectively control the relationship between the total length of the optical track and the size of the light incident surface of the first lens element of the folded optical system, and also effectively reduce the aperture of the lens so that the lens is applicable to various electronic devices. Furthermore, the following condition can also be preferably satisfied: 5.00 < TL/Y11 < 13.00. Please see Figure 28, which shows a schematic view of Y11 in accordance with the 1st embodiment of the present disclosure.

[0063] When half of a maximum field of view of the folded optical system is HFOV, the following condition may preferably be satisfied: 2.00 [gra.] < HFOV < 18.00 [gra.]. Therefore, it is favorable to have an adequate field of view of the folded optical system for telephoto application. Furthermore, the following condition can also be preferably satisfied: 4.00 [gram.] < HFOV < 16.50 [gram.]. Furthermore, the following condition can also be preferably satisfied: 5.00 [gram.] < HFOV < 15.80 [gram.].

[0064] When an axial distance along at least one of the first optical axis, the second optical axis, the third optical axis and the fourth optical axis between the light incident surface of the first lens element and the light-emitting surface light from the last lens element is TD, and the focal length of the folded optical system is f, the following condition can preferably be satisfied: 0.60 < TD/f < 1.80. Therefore, it is favorable for adjusting the lens distribution within the folded optical system so as to effectively utilize the space in the thickness direction of the electronic device. Furthermore, the following condition can also be preferably satisfied: 0.90 < TD/f < 1.70. It should be noted that if the last lens element is located on the first optical axis, the definition of TD is an axial distance along the first optical axis between the light-inciding surface of the first lens element and the light-emitting surface of the last lens element; If the last lens element is located on the fourth optical axis, the definition of TD is an axial distance along the first optical axis, the second optical axis, the third optical axis, and the fourth optical axis between the light-inciding surface of the first lens element and the light-emitting surface of the last lens element.

[0065] When the perpendicular distance of the first optical axis between an axial vertex of the light incident surface of the first lens element on the first optical axis and an intersection point of the imaging surface and the fourth optical axis is Ly, and a displacement maximum optical path parallel to the first optical axis from a folded optical system element that first receives light to the imaging surface is Lz, the following condition may preferably be satisfied: 0.60 < Ly/Lz < 1.50 . Therefore, it is favorable to adjust the ratio between the width and thickness of the folded optical system, thereby controlling the appearance of the folded optical system for the internal configuration of the product. Furthermore, the following condition may preferably be satisfied: 0.70 < Ly/Lz < 1.30, according to the present disclosure, said element of the folded optical system that first receives light may be aperture diaphragm, a diaphragm or a first lens element. Please see Figure 25, which shows a schematic view of Ly and Lz in accordance with the 1st embodiment of the present disclosure. Please see Figure 26, which shows a schematic view of Ly and Lz in accordance with the 3rd embodiment of the present disclosure.

[0066] When the maximum displacement of the optical path parallel to the first optical axis from the folded optical system that first receives light to the imaging surface is Lz, the following condition may preferably be satisfied: 5.00 [mm] < Lz < 11.00 [mm]. Therefore, it is favorable for adjusting the length of the folded optical system in the direction along the first optical axis, thereby facilitating the thickness of the folded optical system for various and diverse applications. Furthermore, the following condition can also be preferably satisfied: 5.50 [mm] < Lz < 10.00 [mm].

[0067] When a refractive index of the prism having the second reflecting surface is Np, the following condition can preferably be satisfied: 1.53 < Np < 1.95. Therefore, it is favorable because there is enough difference in the refractive indices between the prism and the air, which can adjust the critical angle to ensure the full reflection capable of being generated on the second reflecting surface. Furthermore, the following condition can also be preferably satisfied: 1.60 < Np < 1.95. Furthermore, the following condition can also be preferably satisfied: 1.70 < Np < 1.90,

[0068] When an angle between the first optical axis and the second optical axis is θa, the following condition can preferably be satisfied: 40.0 [gra.] < θa < 76.0 [gra.]. Therefore, it is favorable for adjusting the angle between the first optical axis and the second optical axis, thus avoiding the failure to generate full reflection on the second reflecting surface due to an excessively small angle between them and also preventing a large size of the optical system. bent due to an excessively large angle between them. Furthermore, the following condition can also be preferably satisfied: 46.0 [gra.] < θa < 72.0 [gra.]. See Figure 27, which shows a schematic view of θa in accordance with the 1st embodiment of the present disclosure.

[0069] When a radius of curvature of the light-inciding surface of the second lens element is R3, and a radius of curvature of the light-emitting surface of the second lens element is R4, the following condition may preferably be satisfied: -0.05 < (R3 - R4)/(R3+R4) < 3.00. Therefore, it is favorable to adjust the shape of the lens and the refractive power of the second lens element, thereby adjusting the optical path so as to increase the image quality. Furthermore, the following condition can also be preferably satisfied: 0.01 < (R3- R4)/(R3+R4) < 2.50.

[0070] When the focal length of the folded optical system is f, and the maximum displacement of the optical path parallel to the first optical axis of the element of the folded optical system that first receives light to the imaging surface is Lz, the following condition can be preference satisfied: 1.50 < f/Lz < 3.50. Therefore, it is favorable to adjust the ratio of the focal length of the folded optical system and the length of the folded optical system in the direction along the first optical axis, thereby reducing the thickness of the folded optical system. Furthermore, the following condition can also be preferably satisfied: 1.65 < f/Lz < 3.00.

[0071] When the focal length of the folded optical system is f, and a composite focal length of one or more of the lens elements located on the first optical axis is fG1, the following condition may preferably be satisfied: 0.50 <f/ fG1 < 2.00. Therefore, it is favorable to adjust the refractive power of one or more lens elements located on the first optical axis, thereby reducing the thickness of the optical collapsible assembly in the direction along the first optical axis. Furthermore, the following condition can also be preferably satisfied: 0.75 < f/fG1 < 1.60. Furthermore, the following condition can also be preferably satisfied: 1.00 < f/fG1 < 1.50.

[0072] When an axial distance along the first optical axis between the light-inciding surface of the first lens element and the first reflecting surface is LOA1, an axial distance along the second optical axis between the first reflecting surface and the second reflecting surface is LOA2, an axial distance along the third optical axis between the second reflecting surface and the third reflecting surface is LOA3, and an axial distance along the fourth optical axis between the third reflecting surface and the imaging surface is LOA4, the following condition can preferably be satisfied: 0.55 < (LOA2+LOA3)/(LOA1+LOA4) < 1.00. Therefore, it is favorable to adjust the ratio of light travel distances between optical axes, thus maintaining a long focal length to provide sufficient magnification while reducing the thickness of the folded optical system. Furthermore, the following condition can also be preferably satisfied: 0.58 < (LOA2+LOA3)/(LOA1+LOA4) < 0.98. Furthermore, the following condition can also be preferably satisfied: 0.60 < (LOA2+LOA3)/(LOA1+LOA4) < 0.95. Please refer to Figure 27, which shows a schematic view of LOA1, LOA2, LOA3 and LOA4 in accordance with the 1st embodiment of the present disclosure.

[0073] When the focal length of the first lens element is f1, and a central thickness of the first lens element on the first optical axis is CT1, the following condition may preferably be satisfied: 2.50 < f1/CT1 < 15, 00. Therefore, it is favorable to adjust the ratio of the focal length to the thickness of the first lens element, so that the first lens element is capable of providing sufficient convergence capability for the folded optical system. Furthermore, the following condition can also be preferably satisfied: 2.80 < f1/CT1 < 13.00. Furthermore, the following condition can also be preferably satisfied: 3.00 < f1/CT1 < 10.00.

[0074] When an f number of the folded optical system is Fno, the following condition can preferably be satisfied: 2.00 < Fno < 4.00. Therefore, it is favorable to obtain a suitable balance between illuminance and depth of field, so as to increase the amount of incident light to increase image quality and avoid vignetting at the periphery of the image. Furthermore, the following condition can also be preferably satisfied: 2.10 < Fno < 3.60.

[0075] When the distance perpendicular to the first optical axis between the maximum effective radius position of the light incident surface of the first lens element and the first optical axis is Y11, and a maximum image height of the folded optical system is (which may be half a diagonal length of an effective photosensitive area of the image sensor) ImgH, the following condition may preferably be satisfied: 0.40 < Y11/ImgH < 2.00. Therefore, it is favorable for adjusting the size of the light beam, thereby reducing the aperture of the folded optical system for an aesthetic appearance of the electronic device while increasing the light absorption area of the image sensor to increase the image quality. Furthermore, the following condition can also be preferably satisfied: 0.50 < Y11/ImgH < 1.80.

[0076] In the case of the second lens element located on the first optical axis, when a displacement parallel to the first optical axis from the axial vertex to the position of maximum effective radius on the light incident surface of the first lens element is SAG11, a displacement parallel to the first optical axis from an axial vertex to the position of maximum effective radius on the light-emitting surface of the second lens element is SAG22 and a distance parallel to the first optical axis between a position of maximum effective radius of the light-emitting surface of the first lens element and the position of the maximum effective radius of the light incident surface of the second lens element is ET12, the following condition can preferably be satisfied: 1.60 < (SAG11+SAG22)/ET12 < 13.00. Therefore, it is favorable to adjust the proportion of the shape of the peripheral lens to the peripheral range of the first two lenses on the side of incidence of light, thus having sufficient refractive powers at the peripheries of the lens for correction in off-axis aberrations, avoiding an excessively long long gap between the lenses, so that the length of the optical system folded along the first optical axis can be reduced and the polarization error thereof can be avoided. Furthermore, the following condition can also be preferably satisfied: 1.80 < (SAG11+SAG22)/ET12 < 12.00. Furthermore, the following condition can also be preferably satisfied: 2.50 < (SAG11+SAG22)/ET12 < 11.50. Please refer to Figure 28, which shows a schematic view of SAG11 and SAG22 in accordance with the 1st embodiment of the present disclosure. It should be noted that the definitions of SAG11 and SAG22 are vectors, each of which has a positive value if the displacement is along the optical path or a negative value if the displacement is against the optical path. Each of SAG11 and SAG22, as shown in Figure 28, is a vector that follows the optical path, so each of them has a positive value.

[0077] According to the present disclosure, the above-mentioned resources and conditions can be used in numerous combinations in order to achieve the corresponding effects.

[0078] According to the present disclosure, the lens elements of the folded optical system can be made of glass or plastic material. When the lens elements are made of glass material, the refractive power distribution of the folded optical system can be more flexible and the influence on the image caused by the temperature change of the external environment can be reduced. The glass lens element can be made by grinding or molding. When lens elements are made of plastic material, manufacturing costs can be effectively reduced. Furthermore, the surfaces of each lens element may be arranged to be spherical or aspherical. Spherical lens elements are simple to manufacture. The design of the aspherical lens element allows more control variables to eliminate its aberrations and reduce the required number of lens elements, and the total track length of the folded optical system can therefore be effectively shortened. Additionally, aspherical surfaces can be formed by plastic injection molding or glass molding.

[0079] According to the present disclosure, when a lens surface is aspherical, it means that the lens surface has an aspherical shape throughout its optically effective area, or a portion thereof. Furthermore, unless otherwise indicated, the aspherical surface in the embodiments may refer to an axisymmetric aspheric surface and the freeform surface in the embodiments may refer to a non-axisymmetric aspheric surface.

[0080] In accordance with the present disclosure, one or more lens element materials may optionally include an additive that generates light absorption and interference effects and changes the transmittance of the lens elements in a specific wavelength range to a reduction in unwanted stray light or color deviation. For example, the additive may optionally filter light in the wavelength range of 600 nm to 800 nm to reduce excessive red light and/or near infrared light; or can optionally filter light in the 350 nm to 450 nm wavelength range to reduce excessive blue light and/or near ultraviolet light from interfering with the final image. The additive may be mixed homogeneously with a plastic material to be used in manufacturing a mixed material lens element by injection molding. Furthermore, the additive can be coated on the lens surfaces to provide the aforementioned effects.

[0081] According to the present disclosure, each of a light-inciding surface and a light-emitting 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. In particular, unless otherwise indicated, when the lens element has a convex surface it indicates that the surface is convex in its paraxial region; when the lens element has a concave surface, it indicates that the surface is concave in the paraxial region thereof. Furthermore, when a region of refractive power or focus of a lens element is not defined, this indicates that the region of refractive power or focus of the lens element is in the paraxial region thereof.

[0082] According to the present disclosure, the imaging surface of the folded optical system, based on the corresponding image sensor, may be flat or curved, especially a curved surface that is concave facing the light incident side of the optical system. folded up.

[0083] In accordance with the present disclosure, an image correction unit, such as a field flattener, may optionally be disposed between the lens element closest to the light-emitting side of the optical system bent along the optical path. and the imaging surface for correcting 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 image design. image capture unit. In general, a preferable image correction unit is, for example, a thin transparent element with a concave light-inciding surface and a flat light-emitting surface, and the thin transparent element is arranged close to the imaging surface.

[0084] According to the present disclosure, the folded optical system may include at least one diaphragm, such as an aperture diaphragm, a brightness diaphragm, or a field diaphragm. Said brightness diaphragm or said field diaphragm is adjusted to eliminate diffuse light and thus increase image quality thereof.

[0085] According to the present disclosure, an aperture diaphragm can be configured as a front diaphragm or an intermediate diaphragm. A front diaphragm disposed between an imaging object and the first lens element can provide a greater distance between an exit pupil of the folded optical system and the imaging surface to produce a telecentric effect and thus increase image detection efficiency. of an image sensor (e.g. CCD or CMOS). An intermediate diaphragm disposed between the first lens element and the imaging surface is conducive to widening the viewing angle of the folded optical system and thus provides a wider field of view for the same.

[0086] According to the present disclosure, the folded optical system may include an aperture control unit. The aperture control unit can be a mechanical component or a light modulator, which can control the size and shape of the aperture through electricity or electrical signals. The mechanical component may include a movable member, such as a blade assembly or a light shielding sheet. 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 exposure time to enhance the ability to adjust image quality. Furthermore, the aperture control unit may be the aperture diaphragm of the present disclosure, which changes the f-number to achieve different image effects such as depth of field or lens speed.

[0087] According to the present disclosure, the folded optical system may include one or more optical elements to limit the way light passes through the folded optical system. Each optical element may be, but not limited to, a filter, a polarizer, etc., and each optical element may be, but not limited to, a one-piece element, a composite component, a thin film, etc. element may be located on the light incident side or the light emitting side of the folded optical system or between any two adjacent lens elements so as to allow the passage of light in a specific shape, thereby meeting application requirements.

[0088] In accordance with the above description of the present disclosure, the following specific embodiments are provided for further explanation.

1st modality

[0089] Figure 1 is a schematic view of an image capture unit according to the 1st embodiment of the present disclosure. Figure 2 shows, in order from left to right, spherical aberration curves and astigmatic field curves of the image capture unit according to the 1st modality. In Figure 1, the image capture unit 1 includes the folded optical system (its reference number is omitted) of the present disclosure and an IS image sensor. The folded optical system includes, in order from a light incident side to a light emission side along a direction of light travel in an optical path, a diaphragm S1, a first lens element E1, a second lens element E2 lens, an ST aperture diaphragm, an optical folding assembly (its reference number is omitted), an E3 third lens element, an E6 filter, and an IMG imaging surface. Furthermore, said optical collapsible assembly includes a prism PR1 made of glass material. The prism PR1 has a first transmissive surface TM1, a first reflecting surface RF1, a second reflecting surface RF2, a third reflecting surface RF3 and a second transmissive surface TM2 sequentially along the direction of travel of the light in the optical path.

[0090] The optical path reaches the first reflecting surface RF1 through the first transmissive surface TM1 along a first optical axis OA1, the optical path along the first optical axis OA1 is redirected to a second optical axis OA2 by the first reflecting surface RF1, the optical path along the second optical axis OA2 is redirected to a third optical axis OA3 by the second reflecting surface RF2, the optical path along the third optical axis OA3 is redirected to a fourth optical axis OA4 by the third reflecting surface RF3 and the optical path reaches the IMG imaging surface through the second transmissive surface TM2 along the fourth optical axis OA4.

[0091] The first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are substantially in the same plane. The first optical axis OA1 is substantially parallel to a normal direction of said plane where the first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are located. The first optical axis OA1 is also substantially parallel to a normal direction of the IMG imaging surface. The folded optical system includes three lens elements (E1, E2 and E3) with no additional lens elements disposed between each of the three adjacent lens elements. Furthermore, the first lens element E1 and the second lens element E2 are located on the first optical axis OA1 and the third lens element E3 is located on the fourth optical axis OA4.

[0092] The first lens element E1 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is convex in a paraxial region thereof. The first lens element E1 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[0093] The second lens element E2 with negative refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[0094] The third lens element E3 with negative refractive power has a light-inciding surface that is concave in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The third E3 lens element is made of glass material and with the light-inciding surface and the light-emitting surface both being aspherical.

[0095] Among the three lens elements (E1, E2 and E3), the second lens element E2 and the third lens element E3 each have a refractive index greater than 1.63.

[0096] The E6 filter is made of glass material and located between the third element of the E3 lens and the IMG imaging surface, and will not affect the focal length of the folded optical system. The IS image sensor is disposed on or near the IMG imaging surface of the folded optical system.

[0097] The equation of the axisymmetric aspheric surface profiles of the above-mentioned lens elements of the 1st embodiment is expressed as follows: where, Z is the displacement in parallel with an optical axis where the aspherical surface is located from an axial vertex on the aspherical surface to a point at a distance of Y from the optical axis on the aspherical surface; Y is the vertical distance from the point on the aspheric surface to the optical axis where the aspheric surface is located; R is the radius of curvature; k is the conic coefficient; and Ai is the ith aspherical coefficient and, in embodiments, i may be, but is not limited to, 4, 6, 8, 10, 12, 14, 16 and 18.

[0098] In the folded optical system of the image capture unit 1 according to the 1st embodiment, when a focal length of the folded optical system is f, an f-number of the folded optical system is Fno and half a maximum field of view of the Folded optical system is HFOV, these parameters have the following values: f = 16.93 millimeters (mm), Fno = 2.59, HFOV = 12.6 degrees (degrees).

[0099] When a radius of curvature of the light-inciding surface of the first lens element E1 is R1, and a radius of curvature of the light-emitting surface of the first lens element E1 is R2, the following condition is satisfied: R1 /R2 = -0.28.

[00100] When a radius of curvature of the light-inciding surface of the second lens element E2 is R3, and a radius of curvature of the light-emitting surface of the second lens element E2 is R4, the following condition is satisfied: ( R3-R4)/(R3 +R4) = 0.78.

[00101] When a focal length of the first lens element E1 is f1, and a focal length of the second lens element E2 is f2, the following conditions are satisfied: f1 = 9.91 [mm]; f2 = -26.00 [mm]; and f2/f1 = - 2.62.

[00102] When the focal length of the folded optical system is f, and a composite focal length of one or more of the lens elements located on the first optical axis OA1 is fG1, the following condition is satisfied: f/fG1 = 1.16.

[00103] In this embodiment, the first lens element E1 and the second lens element E2 are located on the first optical axis OA1 and, therefore, fG1 is the composite focal length of the first lens element E1 and the second lens element E2.

[00104] When the focal length of the first lens element E1 is f1, and a central thickness of the first lens element E1 on the first optical axis OA1 is CT1, the following condition is satisfied: f1/CT1 = 5.51.

[00105] When an axial distance along the first optical axis OA1, the second optical axis OA2, the third optical axis OA3 and the fourth optical axis OA4 between the light incident surface of the first lens element E1 and the emission surface of light from the third lens element E3 is TD and the focal length of the folded optical system is f, the following condition is satisfied: TD/f = 1.26.

[00106] When an axial distance along the first optical axis OA1, the second optical axis OA2, the third optical axis OA3 and the fourth optical axis OA4 between the light incident surface of the first lens element E1 and the imaging surface IMG is TL, and the focus length of the folded optical system is f, the following condition is satisfied: TL/f = 1.34.

[00107] When the focal length of the folded optical system is f, and a maximum displacement of the optical path parallel to the first optical axis OA1 from an element of the folded optical system that first receives light to the IMG imaging surface is Lz, the following condition is satisfied: f/Lz = 2.14. In this embodiment, the optical path extends into the folded optical system through a surface on the S1 diaphragm, and therefore Lz is the maximum displacement of the optical path parallel to the first optical axis OA1 from the S1 diaphragm to the IMG imaging surface.

[00108] When a distance perpendicular to the first optical axis OA1 between an axial vertex of the incident light surface of the first lens element E1 on the first optical axis OA1 and a point of intersection of the IMG imaging surface and the fourth optical axis OA4 is Ly , and the maximum displacement of the optical path parallel to the first optical axis OA1 of the folded optical system element that first receives light to the IMG imaging surface is Lz, the following condition is satisfied: Ly/Lz = 1.27.

[00109] When the maximum displacement of the optical path parallel to the first optical axis OA1 of the folded optical system element that first receives light to the IMG imaging surface is Lz, the following condition is satisfied: Lz = 7.90 [mm].

[00110] When the axial distance along the first optical axis OA1, the second optical axis OA2, the third optical axis OA3 and the fourth optical axis OA4 between the light incident surface of the first lens element E1 and the imaging surface IMG is TL, and a distance perpendicular to the first optical axis OA1 between a position of maximum effective radius of the light incident surface of the first lens element E1 and the first optical axis OA1 is Y11, the following condition is satisfied: TL/Y11 = 6.52.

[00111] When a distance parallel to the first optical axis OA1 between a position of maximum effective radius of the light-inciding surface of the second lens element E2 and a position of maximum effective radius of the light-emitting surface of the second lens element E2 is ET2, and a central thickness of the second lens element E2 on the first optical axis OA1 is CT2, the following condition is satisfied: ET2/CT2 = 1.26.

[00112] When the distance perpendicular to the first optical axis OA1 between the position of the maximum effective radius of the light incident surface of the first lens element E1 and the first optical axis OA1 is Y11 and a maximum image height of the folded optical system is ImgH, the following condition is satisfied: Y11/ImgH = 0.91.

[00113] When a displacement parallel to the first optical axis OA1 from the axial vertex to the position of maximum effective radius on the light incident surface of the first lens element E1 is SAG11, a displacement parallel to the first optical axis OA1 from an axial vertex to the maximum effective ray position on the light-emitting surface of the second lens element E2 is SAG22, and a distance parallel to the first optical axis OA1 between a maximum effective ray position of the light-emitting surface of the first lens element E1 and the maximum effective ray position of the incident light surface of the second lens element E2 is ET12, the following condition is satisfied: (SAG11+SAG22)/ET12 = 3.02.

[00114] When an axial distance along the first optical axis OA1 between the light incident surface of the first lens element E1 and the first reflecting surface RF1 is LOA1, an axial distance along the second optical axis OA2 between the first surface reflecting surface RF1 and the second reflecting surface RF2 is LOA2, an axial distance along the third optical axis OA3 between the second reflecting surface RF2 and the third reflecting surface RF3 is LOA3, and an axial distance along the fourth optical axis OA4 between the third reflecting surface reflector RF3 and the IMG image surface is LOA4, the following condition is satisfied: (LOA2+LOA3)/(LOA1+LOA4) = 0.97.

[00115] When a refractive index of the prism PR1 is Np, the following condition is satisfied: Np = 1.773.

[00116] When an angle between the first optical axis OA1 and the second optical axis OA2 is θa, the following condition is satisfied: θa = 64.0 [gra.].

[00117] The detailed optical data of the 1st modality is shown in Table 1A and the aspheric surface data is shown in Table 1B below.

[00118] In Table 1A, the radius of curvature and thickness are shown in millimeters (mm). Surface numbers 0-16 represent surfaces arranged sequentially from the light incident side to the light emission side along the optical path direction. In Table 1B, k represents the conic coefficient of the equation of profiles of axisymmetric aspheric surfaces. A4-A18 represent the axisymmetric aspheric coefficients ranging from the 4th order to the 18th order. The tables presented below for each modality are the corresponding schematic parameters and aberration curves, and the definitions of the tables are the same as Table 1A and Table 1B of the 1st modality. Therefore, an explanation in this regard will not be provided again.

2nd Mode

[00119] Figure 3 is a schematic view of an image capture unit according to the 2nd embodiment of the present disclosure. Figure 4 shows, in order from left to right, spherical aberration curves and astigmatic field curves of the image capture unit according to the 2nd modality. In Figure 3, the image capture unit 2 includes the folded optical system (its reference number is omitted) of the present disclosure and an IS image sensor. The folded optical system includes, in order from a light incident side to a light emission side along a direction of light travel in an optical path, a diaphragm S1, a first lens element E1, a second lens element E2 lens, a third E3 lens element, an ST aperture diaphragm, an optical folding assembly (its reference number is omitted), an E6 filter, and an IMG imaging surface. Furthermore, said optical collapsible assembly includes a prism PR1 made of glass material. The prism PR1 has a first transmissive surface TM1, a first reflecting surface RF1, a second reflecting surface RF2, a third reflecting surface RF3 and a second transmissive surface TM2 sequentially along the direction of travel of the light in the optical path.

[00120] The optical path reaches the first reflecting surface RF1 through the first transmissive surface TM1 along a first optical axis OA1, the optical path along the first optical axis OA1 is redirected to a second optical axis OA2 by the first reflecting surface RF1, the optical path along the second optical axis OA2 is redirected to a third optical axis OA3 by the second reflecting surface RF2, the optical path along the third optical axis OA3 is redirected to a fourth optical axis OA4 by the third reflecting surface RF3 and the optical path reaches the IMG imaging surface through the second transmissive surface TM2 along the fourth optical axis OA4.

[00121] The first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are substantially in the same plane. The first optical axis OA1 is substantially parallel to a normal direction of said plane where the first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are located. The first optical axis OA1 is also substantially parallel to a normal direction of the IMG imaging surface. The folded optical system includes three lens elements (E1, E2 and E3) with no additional lens elements disposed between each of the three adjacent lens elements. Furthermore, the first lens element E1, the second lens element E2 and the third lens element E3 are located on the first optical axis OA1.

[00122] The first lens element E1 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The first lens element E1 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00123] The second lens element E2 with negative refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00124] The third lens element E3 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The third E3 lens element is made of glass material and with the incident light surface and the light-emitting surface both being spherical.

[00125] Among the three lens elements (E1, E2 and E3), the third lens element E3 has a refractive index greater than 1.63.

[00126] The E6 filter is made of glass material and located between the PR1 prism and the IMG imaging surface, and will not affect the focal length of the folded optical system. The IS image sensor is disposed on or near the IMG imaging surface of the folded optical system.

[00127] The detailed optical data of the 2nd modality is shown in Table 2A and the aspheric surface data is shown in Table 2B below.

[00128] In the 2nd modality, the equation of the axisymmetric aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st modality. Furthermore, the definitions of these parameters shown in Table 2C are the same as those indicated in the 1st modality with corresponding values for the 2nd modality, therefore, an explanation in this regard will not be provided again.

[00129] Furthermore, these parameters can be calculated from Table 2A and Table 2B according to the following values and satisfy the following conditions:

3rd modality

[00130] Figure 5 is a schematic view of an image capture unit according to the 3rd embodiment of the present disclosure. Figure 6 shows, in order from left to right, spherical aberration curves and astigmatic field curves of the image capture unit according to the 3rd modality. In Figure 5, the image capture unit 3 includes the folded optical system (its reference number is omitted) of the present disclosure and an IS image sensor. The folded optical system includes, in order from a light incident side to a light emission side along a direction of light travel in an optical path, a diaphragm S1, a first lens element E1, a second lens element E2 lens, a third E3 lens element, an ST aperture diaphragm, an optical folding assembly (its reference number is omitted), an E6 filter, and an IMG imaging surface. Furthermore, said optical collapsible assembly includes a prism PR1 made of glass material and a prism PR2 made of glass material. The prism PR1 has a first transmissive surface TM1, a first reflecting surface RF1, a second reflecting surface RF2 and a first corresponsive surface OP1 sequentially along the direction of travel of the light in the optical path. The prism PR2 has a corresponding second surface OP2, a third reflecting surface RF3 and a second transmissive surface TM2 sequentially along the direction of light travel in the optical path.

[00131] The optical path reaches the first reflecting surface RF1 through the first transmissive surface TM1 along a first optical axis OA1, the optical path along the first optical axis OA1 is redirected to a second optical axis OA2 by the first reflecting surface RF1, the optical path along the second optical axis OA2 is redirected to a third optical axis OA3 by the second reflecting surface RF2, the optical path along the third optical axis OA3 passes through the first corresponding surface OP1 and the second corresponding surface OP2 and then it is redirected to a fourth optical axis OA4 by the third reflecting surface RF3, and the optical path reaches the IMG imaging surface through the second transmissive surface TM2 along the fourth optical axis OA4.

[00132] The first transmissive surface TM1 and the second reflecting surface RF2 are substantially in the same plane. The first corresponding surface OP1 is a spherical and convex surface facing the second corresponding surface OP2. The second corresponding surface OP2 is a spherical and concave surface facing the first corresponding surface OP1. The second transmissive surface TM2 is a spherical concave surface facing the IMG imaging surface. The first optical axis OA1 is substantially parallel to a normal direction of said plane where the first transmissive surface TM1 and the second reflecting surface RF2 are located. The first optical axis OA1 is also substantially parallel to a normal direction of the IMG imaging surface. The folded optical system includes three lens elements (E1, E2 and E3) with no additional lens elements disposed between each of the three adjacent lens elements. Furthermore, the first lens element E1, the second lens element E2 and the third lens element E3 are located on the first optical axis OA1.

[00133] The first lens element E1 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The first lens element E1 is made of glass material and has the light-inciding surface and the light-emitting surface both being spherical.

[00134] The second lens element E2 with negative refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00135] The third lens element E3 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is convex in a paraxial region thereof. The third E3 lens element is made of plastic material and with the light-inciding surface and the light-emitting surface both being aspherical.

[00136] Among the three lens elements (E1, E2 and E3), the first lens element E1 has a refractive index greater than 1.63.

[00137] The E6 filter is made of glass material and located between the PR2 prism and the IMG imaging surface, and will not affect the focal length of the folded optical system. The IS image sensor is disposed on or near the IMG imaging surface of the folded optical system.

[00138] The detailed optical data of the 3rd modality is shown in Table 3A and the aspheric surface data is shown in Table 3B below.

[00139] In the 3rd modality, the equation of the axisymmetric aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st modality. Furthermore, the definitions of these parameters shown in Table 3C are the same as those indicated in the 1st modality with corresponding values for the 3rd modality, therefore, an explanation in this regard will not be provided again.

[00140] Furthermore, these parameters can be calculated from Table 3A and Table 3B according to the following values and satisfy the following conditions:

4th modality

[00141] Figure 7 is a schematic view of an image capture unit in accordance with the 4th embodiment of the present disclosure. Figure 8 shows, in order from left to right, spherical aberration curves and astigmatic field curves of the image capture unit according to the 4th modality. In Figure 7, the image capture unit 4 includes the folded optical system (its reference number is omitted) of the present disclosure and an IS image sensor. The folded optical system includes, in order from a light incident side to a light emission side along a direction of light travel in an optical path, a diaphragm S1, a first lens element E1, a second lens element E2 lens, a third E3 lens element, an ST aperture diaphragm, an optical folding assembly (its reference number is omitted), a fourth E4 lens element, an E6 filter, and an IMG imaging surface. Furthermore, said optical collapsible assembly includes a prism PR1 made of glass material. The prism PR1 has a first transmissive surface TM1, a first reflecting surface RF1, a second reflecting surface RF2, a third reflecting surface RF3 and a second transmissive surface TM2 sequentially along the direction of travel of the light in the optical path.

[00142] The optical path reaches the first reflecting surface RF1 through the first transmissive surface TM1 along a first optical axis OA1, the optical path along the first optical axis OA1 is redirected to a second optical axis OA2 by the first reflecting surface RF1, the optical path along the second optical axis OA2 is redirected to a third optical axis OA3 by the second reflecting surface RF2, the optical path along the third optical axis OA3 is redirected to a fourth optical axis OA4 by the third reflecting surface RF3 and the optical path reaches the IMG imaging surface through the second transmissive surface TM2 along the fourth optical axis OA4.

[00143] The first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are substantially in the same plane. The first optical axis OA1 is substantially parallel to a normal direction of said plane where the first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are located. The first optical axis OA1 is also substantially parallel to a normal direction of the IMG imaging surface. The folded optical system includes four lens elements (E1, E2, E3 and E4) with no additional lens elements disposed between each of the four adjacent lens elements. Furthermore, the first lens element E1, the second lens element E2 and the third lens element E3 are located on the first optical axis OA1 and the fourth lens element E4 is located on the fourth optical axis OA4.

[00144] The first lens element E1 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is convex in a paraxial region thereof. The first lens element E1 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00145] The second lens element E2 with negative refractive power has an incident light surface that is concave in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00146] The third lens element E3 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is convex in a paraxial region thereof. The third E3 lens element is made of plastic material and with the light-inciding surface and the light-emitting surface both being aspherical.

[00147] The fourth lens element E4 with negative refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The fourth lens element E4 is made of glass material and with the incident light surface and the light-emitting surface both being aspherical.

[00148] Among the four lens elements (E1, E2, E3 and E4), the fourth lens element E4 has a refractive index greater than 1.63.

[00149] The E6 filter is made of glass material and located between the fourth element of the E4 lens and the IMG imaging surface, and will not affect the focal length of the folded optical system. The IS image sensor is disposed on or near the IMG imaging surface of the folded optical system.

[00150] The detailed optical data of the 4th modality is shown in Table 4A and the aspheric surface data is shown in Table 4B below.

[00151] In the 4th modality, the equation of the axisymmetric aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st modality. Furthermore, the definitions of these parameters shown in Table 4C are the same as those indicated in the 1st modality with corresponding values for the 4th modality, therefore, an explanation in this regard will not be provided again.

[00152] Furthermore, these parameters can be calculated from Table 4A and Table 4B according to the following values and satisfy the following conditions:

5th modality

[00153] Figure 9 is a schematic view of an image capture unit in accordance with the 5th embodiment of the present disclosure. Figure 10 shows, in order from left to right, spherical aberration curves and astigmatic field curves of the image capture unit according to the 5th modality. In Figure 9, the image capture unit 5 includes the folded optical system (its reference number is omitted) of the present disclosure and an IS image sensor. The folded optical system includes, in order from a light incident side to a light emission side along a direction of light travel in an optical path, an ST aperture diaphragm, a first E1 lens element, a second lens element E2, a third lens element E3, an optical folding assembly (its reference number is omitted), a fourth lens element E4, an E6 filter, and an IMG imaging surface. Furthermore, said optical folding assembly includes a prism PR1 made of plastic material. The prism PR1 has a first transmissive surface TM1, a first reflecting surface RF1, a second reflecting surface RF2, a third reflecting surface RF3 and a second transmissive surface TM2 sequentially along the direction of travel of the light in the optical path.

[00154] The optical path reaches the first reflecting surface RF1 through the first transmissive surface TM1 along a first optical axis OA1, the optical path along the first optical axis OA1 is redirected to a second optical axis OA2 by the first reflecting surface RF1, the optical path along the second optical axis OA2 is redirected to a third optical axis OA3 by the second reflecting surface RF2, the optical path along the third optical axis OA3 is redirected to a fourth optical axis OA4 by the third reflecting surface RF3 and the optical path reaches the IMG imaging surface through the second transmissive surface TM2 along the fourth optical axis OA4.

[00155] The first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are substantially in the same plane. The first optical axis OA1 is substantially parallel to a normal direction of said plane where the first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are located. The first optical axis OA1 is also substantially parallel to a normal direction of the IMG imaging surface. The folded optical system includes four lens elements (E1, E2, E3 and E4) with no additional lens elements disposed between each of the four adjacent lens elements. Furthermore, the first lens element E1, the second lens element E2 and the third lens element E3 are located on the first optical axis OA1 and the fourth lens element E4 is located on the fourth optical axis OA4.

[00156] The first lens element E1 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is convex in a paraxial region thereof. The first lens element E1 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00157] The second lens element E2 with negative refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00158] The third lens element E3 with negative refractive power has a light-inciding surface that is concave in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The third E3 lens element is made of plastic material and with the light-inciding surface and the light-emitting surface both being aspherical.

[00159] The fourth lens element E4 with negative refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The fourth E4 lens element is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00160] The E6 filter is made of glass material and located between the fourth element of the E4 lens and the IMG imaging surface, and will not affect the focal length of the folded optical system. The IS image sensor is disposed on or near the IMG imaging surface of the folded optical system.

[00161] The detailed optical data of the 5th modality is shown in Table 5A and the aspheric surface data is shown in Table 5B below.

[00162] In the 5th modality, the equation of the axisymmetric aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st modality. Furthermore, the definitions of these parameters shown in Table 5C are the same as those indicated in the 1st modality with corresponding values for the 5th modality, therefore, an explanation in this regard will not be provided again.

[00163] Furthermore, these parameters can be calculated from Table 5A and Table 5B according to the following values and satisfy the following conditions:

6th modality

[00164] Figure 11 is a schematic view of an image capture unit in accordance with the 6th embodiment of the present disclosure. Figure 12 shows, in order from left to right, spherical aberration curves and astigmatic field curves of the image capture unit according to the 6th modality. In Figure 11, the image capture unit 6 includes the folded optical system (its reference number is omitted) of the present disclosure and an IS image sensor. The folded optical system includes, in order from a light incident side to a light emission side along a direction of light travel in an optical path, an ST aperture diaphragm, a first E1 lens element, a second E2 lens element, a third E3 lens element, an optical folding assembly (its reference number is omitted), a fourth E4 lens element, a fifth E5 lens element, an E6 filter, and an IMG imaging surface. Furthermore, said optical folding assembly includes a prism PR1 made of plastic material. The prism PR1 has a first transmissive surface TM1, a first reflecting surface RF1, a second reflecting surface RF2, a third reflecting surface RF3 and a second transmissive surface TM2 sequentially along the direction of travel of the light in the optical path.

[00165] The optical path reaches the first reflecting surface RF1 through the first transmissive surface TM1 along a first optical axis OA1, the optical path along the first optical axis OA1 is redirected to a second optical axis OA2 by the first reflecting surface RF1, the optical path along the second optical axis OA2 is redirected to a third optical axis OA3 by the second reflecting surface RF2, the optical path along the third optical axis OA3 is redirected to a fourth optical axis OA4 by the third reflecting surface RF3 and the optical path reaches the IMG imaging surface via the second transmissive surface TM2 along the fourth optical axis OA4.

[00166] The first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are substantially in the same plane. The first optical axis OA1 is substantially parallel to a normal direction of said plane where the first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are located. The first optical axis OA1 is also substantially parallel to a normal direction of the IMG imaging surface. The folded optical system includes five lens elements (E1, E2, E3, E4 and E5) with no additional lens elements disposed between each of the five adjacent lens elements. Furthermore, the first lens element E1, the second lens element E2 and the third lens element E3 are located on the first optical axis OA1, and the fourth lens element E4 and the fifth lens element E5 are located on the fourth axis OA4 optic.

[00167] The first lens element E1 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is convex in a paraxial region thereof. The first lens element E1 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00168] The second lens element E2 with negative refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00169] The third lens element E3 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The third E3 lens element is made of plastic material and with the light-inciding surface and the light-emitting surface both being aspherical.

[00170] The fourth lens element E4 with negative refractive power has a light-inciding surface that is concave in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The fourth E4 lens element is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00171] The fifth lens element E5 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The fifth E5 lens element is made of plastic material and with the light-inciding surface and the light-emitting surface both being aspherical.

[00172] Among the five lens elements (E1, E2, E3, E4 and E5), the fourth lens element E4 has a refractive index greater than 1.63.

[00173] The E6 filter is made of glass material and located between the fifth element of the E5 lens and the IMG imaging surface, and will not affect the focal length of the folded optical system. The IS image sensor is disposed on or near the IMG imaging surface of the folded optical system.

[00174] The detailed optical data of the 6th modality is shown in Table 6A and the aspherical surface data is shown in Table 6B below. [0179] In the 6th modality, the equation of the axisymmetric aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st modality. Furthermore, the definitions of these parameters shown in Table 6C are the same as those indicated in the 1st modality with corresponding values for the 6th modality, therefore, an explanation in this regard will not be provided again. [0180] Furthermore, these parameters can be calculated from Table 6A and Table 6B according to the following values and satisfy the following conditions:

7th modality

[00175] Figure 13 is a schematic view of an image capture unit in accordance with the 7th embodiment of the present disclosure. Figure 14 shows, in order from left to right, spherical aberration curves and astigmatic field curves of the image capture unit according to the 7th modality. In Figure 13, the image capture unit 7 includes the folded optical system (its reference number is omitted) of the present disclosure and an IS image sensor. The folded optical system includes, in order from a light incident side to a light emission side along a direction of light travel in an optical path, a first E1 lens element, an ST aperture diaphragm, a second E2 lens element, a third E3 lens element, an optical folding assembly (its reference number is omitted), an E6 filter, and an IMG imaging surface. Furthermore, said optical collapsible assembly includes a prism PR1 made of glass material. The prism PR1 has a first transmissive surface TM1, a first reflecting surface RF1, a second reflecting surface RF2, a third reflecting surface RF3 and a second transmissive surface TM2 sequentially along the direction of travel of the light in the optical path.

[00176] The optical path reaches the first reflecting surface RF1 through the first transmissive surface TM1 along a first optical axis OA1, the optical path along the first optical axis OA1 is redirected to a second optical axis OA2 by the first reflecting surface RF1, the optical path along the second optical axis OA2 is redirected to a third optical axis OA3 by the second reflecting surface RF2, the optical path along the third optical axis OA3 is redirected to a fourth optical axis OA4 by the third reflecting surface RF3 and the optical path reaches the IMG imaging surface through the second transmissive surface TM2 along the fourth optical axis OA4.

[00177] The first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are substantially in the same plane. The first optical axis OA1 is substantially parallel to a normal direction of said plane where the first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are located. The first optical axis OA1 is also substantially parallel to a normal direction of the IMG imaging surface. The folded optical system includes three lens elements (E1, E2 and E3) with no additional lens elements disposed between each of the three adjacent lens elements. Furthermore, the first lens element E1, the second lens element E2 and the third lens element E3 are located on the first optical axis OA1.

[00178] The first lens element E1 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The first lens element E1 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00179] The second lens element E2 with negative refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00180] The third lens element E3 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The third E3 lens element is made of glass material and with the light-inciding surface and the light-emitting surface both being aspherical.

[00181] Among the three lens elements (E1, E2 and E3), the second lens element E2 and the third lens element E3 each have a refractive index greater than 1.63.

[00182] The E6 filter is made of glass material and located between the PR1 prism and the IMG imaging surface, and will not affect the focal length of the folded optical system. The IS image sensor is disposed on or near the IMG imaging surface of the folded optical system.

[00183] The detailed optical data of the 7th modality is shown in Table 7A and the aspheric surface data is shown in Table 7B below.

[00184] In the 7th modality, the equation of the axisymmetric aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st modality. Furthermore, the definitions of these parameters shown in Table 7C are the same as those indicated in the 1st modality with corresponding values for the 7th modality, therefore, an explanation in this regard will not be provided again.

[00185] Furthermore, these parameters can be calculated from Table 7A and Table 7B according to the following values and satisfy the following conditions:

8th modality

[00186] Figure 15 is a schematic view of an image capture unit in accordance with the 8th embodiment of the present disclosure. Figure 16 shows, in order from left to right, spherical aberration curves and astigmatic field curves of the image capture unit according to the 8th modality. In Figure 15, the image capture unit 8 includes the folded optical system (its reference number is omitted) of the present disclosure and an IS image sensor. The folded optical system includes, in order from a light incident side to a light emission side along a direction of light travel in an optical path, a diaphragm S1, a first lens element E1, a second lens element E2 lens, an ST aperture diaphragm, an optical folding assembly (its reference number is omitted), an E3 third lens element, an E6 filter, and an IMG imaging surface. Furthermore, said optical collapsible assembly includes a prism PR1 made of glass material. The prism PR1 has a first transmissive surface TM1, a first reflecting surface RF1, a second reflecting surface RF2, a third reflecting surface RF3 and a second transmissive surface TM2 sequentially along the direction of travel of the light in the optical path.

[00187] The optical path reaches the first reflecting surface RF1 through the first transmissive surface TM1 along a first optical axis OA1, the optical path along the first optical axis OA1 is redirected to a second optical axis OA2 by the first reflecting surface RF1, the optical path along the second optical axis OA2 is redirected to a third optical axis OA3 by the second reflecting surface RF2, the optical path along the third optical axis OA3 is redirected to a fourth optical axis OA4 by the third reflecting surface RF3 and the optical path reaches the IMG imaging surface through the second transmissive surface TM2 along the fourth optical axis OA4.

[00188] The first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are substantially in the same plane. The first optical axis OA1 is substantially parallel to a normal direction of said plane where the first transmissive surface TM1, the second reflecting surface RF2 and the second transmissive surface TM2 are located. The first optical axis OA1 is also substantially parallel to a normal direction of the IMG imaging surface. The folded optical system includes three lens elements (E1, E2 and E3) with no additional lens elements disposed between each of the three adjacent lens elements. Furthermore, the first lens element E1 and the second lens element E2 are located on the first optical axis OA1 and the third lens element E3 is located on the fourth optical axis OA4.

[00189] The first lens element E1 with positive refractive power has a light-inciding surface that is convex in a paraxial region thereof and a light-emitting surface that is convex in a paraxial region thereof. The first lens element E1 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00190] The second lens element E2 with negative refractive power has an incident light surface that is concave in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The second lens element E2 is made of plastic material and with the incident light surface and the light-emitting surface both being aspherical.

[00191] The third lens element E3 with negative refractive power has a light-inciding surface that is concave in a paraxial region thereof and a light-emitting surface that is concave in a paraxial region thereof. The third E3 lens element is made of glass material and with the light-inciding surface and the light-emitting surface both being aspherical.

[00192] Among the three lens elements (E1, E2 and E3), the second lens element E2 and the third lens element E3 each have a refractive index greater than 1.63.

[00193] The E6 filter is made of glass material and located between the third element of the E3 lens and the IMG imaging surface, and will not affect the focal length of the folded optical system. The IS image sensor is disposed on or near the IMG imaging surface of the folded optical system.

[00194] The detailed optical data of the 8th modality is shown in Table 8A and the aspheric surface data is shown in Table 8B below.

[00195] In the 8th modality, the equation of the axisymmetric aspheric surface profiles of the aforementioned lens elements is the same as the equation of the 1st modality.

[00196] Furthermore, each of the first reflecting surface RF1 and the third reflecting surface RF3 of the optical folding assembly is a non-axisymmetric freeform (Q2D) surface, and the equation of the non-axisymmetric Q2D freeform aspheric surface profiles is expressed as follows: lens) in the direction of the specified coordinate surface normal on the conical base surface, where the coordinate origin can be offset from the vertex of the conical base surface in the YZ plane; are the coordinates of a point on the surface in cylindrical coordinates, in the off-axis coordinate system; •'■-.iA.i are the coordinates of a point on the surface in Cartesian coordinates in the off-axis coordinate system. For a given l.θl.θ , = rcos0; , = rsinθx = rcosθ; , = f$inθf e - --Jas a variable representing the radial distance from the center of the added aspherical departure, relative to the normalization radius in the off-axis coordinate system. where ' : is the normalization radius; e is the offset value of ■'-f'; (x and y displacement terms); is the displacement value of ; ; (x and y displacement terms); Where is a curvature (in lens units) of the conical base surface in the direction of the surface normal at the specified coordinate origin; is the off-axis angle; for an off-axis point on the surface that defines the origin of the coordinate, is the angle that the surface normal at the off-axis point makes with the axis of the conic; -- is the radius of curvature; ' is the conic constant; It is ■ ... ■ . . is an additive departure from the curvature of the base conical surface, in the direction of the surface normal at the coordinate origin.

[00197] The free-form surface data of the first reflective surface RF1 and the third reflective surface RF3 are shown respectively in Table 8C and Table 8D below.

9th modality

[00198] Figure 17 is a perspective view of an image capture unit in accordance with the 9th embodiment of the present disclosure. In this embodiment, an image capture unit 100 is a camera module that includes a lens unit 101, a drive device 102, an image sensor 103, and an image stabilizer 104. The lens unit 101 includes the optical system folded revealed in the 1st embodiment, a cylinder and a support element (their reference numbers are omitted) for holding the folded optical system. However, the lens unit 101 may alternatively be provided with the folded optical system disclosed in other embodiments of the present disclosure, and the present disclosure is not limited thereto. The image light converges on the lens unit 101 of the image capture unit 100 to generate an image with the drive device 102 used for image focusing on the image sensor 103, and the generated image is then digitally transmitted to another electronic component for further processing.

[00199] The drive device 102 may have autofocus functionality and different drive configurations may be achieved through the use of voice coil motors (VCM), micro-electromechanical systems (MEMS), piezoelectric systems or alloy materials with shape memory. The driving device 102 is conducive to obtaining a better image position of the lens unit 101, so that a clear image of the photographed object can be captured by the lens unit 101 with different object distances. The image sensor 103 (e.g., CCD or CMOS), which can exhibit high photosensitivity and low noise, is disposed on the imaging surface of the folded optical system to provide higher image quality.

[00200] The image stabilizer 104, such as an accelerometer, a gyroscope sensor, and a Hall effect sensor, is configured to work with the drive device 102 to provide optical image stabilization (OIS). The drive device 102 that works with the image stabilizer 104 is conducive to compensating for panning and tilting of each lens element or the optical collapsible assembly in the folded optical system to reduce blur associated with movement during exposure. In some cases, compensation may be provided by electronic image stabilization (EIS) with image processing software, thereby increasing image quality in motion or in low light conditions. Preferably, when the optical collapsible assembly includes two or more prisms, the image stabilizer 104 can be used to control the position of the prism having the third reflecting surface so as to achieve image optimization.

10th modality

[00201] Figure 18 is a perspective view of an electronic device according to the 10th embodiment of the present disclosure. Figure 19 is another perspective view of the electronic device in Figure 18. Figure 20 is a cross-sectional view of the electronic device in Figure 18.

[00202] In this embodiment, an electronic device 200 is a smart phone that includes the image capture unit 100 disclosed in the 9th embodiment, an image capture unit 100a, an image capture unit 100b, an image capture unit 100c and a display unit 201. As shown in Figure 18, 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 facing the same side, and each of the image capture units 100, 100a and 100b has a single focal point. As shown in Figure 19, the image capture unit 100c and the display unit 201 are arranged on the opposite side of the electronic device 200, so that the image capture unit 100c can be a front camera of the electronic device 200 for taking self-portraits, but the present revelation is not limited to that. In Figure 20, the image capture unit 100 with the optical collapsible assembly including the prism PR1 is exemplarily shown. The optical folding assembly, as an optical path bending element, is capable of making the folded optical system more flexible in space arrangement, and therefore, the dimensions of the electronic device 200 are not restricted by the total length of the optical beam path of the folded optical system. Furthermore, each of the image capture units 100a, 100b and 100c may include the folded optical system of the present disclosure and may have a configuration similar to that of the image capture unit 100. In detail, each of the image capture units image 100a, 100b and 100c may include a lens unit, a drive device, an image sensor, an image stabilizer and an optical folding assembly as an optical path bending element, and each lens unit may include a system folded optical system, such as the folded optical system of the present disclosure, a cylinder and a support member for holding the folded optical system.

[00203] Image capture unit 100 is a telephoto image capture unit, image capture unit 100a is a wide-angle image capture unit, image capture unit 100b is a ultra wide angle image and the 100c image capture unit is a wide angle 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 various magnification ratios to meet the optical zoom functionality requirement. Furthermore, the edge of the lens barrel or lens element in the folded optical system of the image capture unit 100, 100a, 100b or 100c may be cut so as to enhance the compact size feature in one dimension thereof, so as to so that the total size can be reduced and the miniaturization of the module is even easier to carry out. In this embodiment, the electronic device 200 includes multiple image capture units 100, 100a, 100b and 100c, but the present disclosure is not limited to the number and arrangement of the image capture units.

11th modality

[00204] Figure 21 is a perspective view of an electronic device according to the 11th embodiment of the present disclosure. Figure 22 is another perspective view of the electronic device in Figure 21. Figure 23 is a block diagram of the electronic device in Figure 21.

[00205] In this embodiment, an electronic device 300 is a smart phone that includes the image capture unit 100 disclosed in the 9th embodiment, an image capture unit 100d, an image capture unit 100e, a image 100f, an image capture unit 100g, an image capture unit 100h, a flash module 301, a focus assist module 302, an image signal processor 303, a display module 304, and a software processor image 305. The image capture unit 100, the image capture unit 100d, and the image capture unit 100e are disposed on the same side of the electronic device 300. The focus assist module 302 may be a laser rangefinder or a ToF (time of flight) module, but the present disclosure is not limited to that. The image capture unit 100f, the image capture unit 100g, the image capture unit 100h and the display module 304 are disposed on the opposite side of the electronic device 300 and the display module 304 may be a user interface , so that the image capture units 100f, 100g, 100h may be front cameras of the electronic device 300 for taking self-portraits, but the present disclosure is not limited to them. Furthermore, each of the image capture units 100d, 100e, 100f, 100g and 100h may include the folded optical system of the present disclosure and may have a configuration similar to that of the image capture unit 100. In detail, each of the image capture units, the 100d, 100e, 100f, 100g and 100h units, may include a lens unit, a drive device, an image sensor, an image stabilizer and an optical folding assembly as a folding element. optical path, and each of the lens units may include a folded optical system sensor such as the folded optical system of the present disclosure, a cylinder, and a support member for holding the folded optical system.

[00206] The image capture unit 100 is a telephoto image capture unit with the optical folding assembly, the image capture unit 100d is a wide-angle image capture unit, the image capture unit 100e is an ultra wide angle image capture unit, the image capture unit the 100f unit is a wide angle image capture unit, the 100g image capture unit is an ultra wide angle image capture unit and The 100h image capture unit is a ToF image capture unit. In this embodiment, the image capture units 100, 100d, and 100e have different fields of view, so that the electronic device 300 can have various magnification ratios to meet the optical zoom functionality requirement. Furthermore, the image capture unit 100h can determine depth information of the imaged object. In this embodiment, the electronic device 300 includes multiple image capture units 100, 100d, 100e, 100f, 100g, and 100h, but the present disclosure is not limited to the number and arrangement of the image capture units.

[00207] When a user captures images of an object 306, the light rays converge on the image capture unit 100, the image capture unit 100d, or the image capture unit 100e to generate images and the flash module 301 is activated for light supplement. The focus assist module 302 detects the distance of the image object from the object 306 to achieve fast autofocus. The image signal processor 303 is configured to optimize the captured image to increase image quality. The light beam emitted by the focus assist module 302 may be conventional infrared or laser. Additionally, light rays can converge at the 100f, 100g, or 100h image capture unit to generate images. The display module 304 may include a touch screen and the user is able to interact with the display module 304 and the image software processor 305 which has multiple functions for capturing images and completing image processing. Alternatively, the user can capture images via a physical button. The image processed by the image software processor 305 may be displayed on the display module 304.

12th modality

[00208] Figure 24 is a perspective view of an electronic device according to the 12th embodiment of the present disclosure.

[00209] In this embodiment, an electronic device 400 is a smart phone that includes the image capture unit 100 disclosed in the 9th embodiment, an image capture unit 100i, an image capture unit 100j, an image capture unit 100k, one 100m image capture unit, one 100n image capture unit, one 100p image capture unit, one 100q image capture unit, one 100r image capture unit, one 401 flash module, one auxiliary module focus 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 disposed on the same side of the electronic device 400, while the display module is disposed 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 folded optical system of the present disclosure and may have a configuration similar to that of the image capture unit 100 and the details in this regard will not be provided again.

[00210] Image capture unit 100 is a telephoto image capture unit with an optical collapsible assembly, image capture unit 100i is a telephoto image capture unit with an optical collapsible assembly, the image capture unit 100i is a telephoto image capture unit with an optical collapsible assembly, the image capture unit 100i is a telephoto image capture unit with an optical collapsible assembly, the image 100j is a wide-angle image capture unit, the image capture unit 100k is a wide-angle image capture unit, the image capture unit 100m is an ultra-wide-angle image capture unit, the 100n image capture unit is an ultra wide angle image capture unit, 100p image capture unit is a telephoto image capture unit, 100q image capture unit is a telephoto image capture unit and The 100r image capture unit is a ToF image capture unit. In this embodiment, the image capture units 100, 100i, 100j, 100k, 100m, 100n, 100p and 100q have different fields of view, so that the electronic device 400 can have various magnification ratios to meet the requirement of imaging functionality. optical zoom. Furthermore, the configuration of the optical folding assembly of the image capture unit 100 may be similar, for example, to the structure shown in Figure 20, which may be referred to in the previous descriptions corresponding to Figure 20, and details in this regard will not be be provided again. Furthermore, the image capture unit 100r can determine depth information of the imaged object. In this embodiment, the electronic device 400 includes multiple image capture units 100, 100i, 100j, 100k, 100m, 100n, 100p, 100q, and 100r, but the present disclosure is not limited to the number and arrangement of the image capture units. When a user captures images of an object, light rays converge on the image capture unit 100, 100i, 100j, 100k, 100m, 100n, 100p, 100q or 100r to generate images and the flash module 401 is activated to supplement light. Furthermore, the subsequent processes are carried out in a similar manner to the above-mentioned embodiments and details in this regard will not be provided again.

[00211] The smart phone in this embodiment is only exemplary for showing the image capture unit of the present disclosure installed in an electronic device, and the present disclosure is not limited thereto. The image capture unit can optionally be applied to moving focus optical systems. Furthermore, the folded optical system of the image capture unit has good aberration correction capacity and high image quality, and can be applied to 3D (three-dimensional) image capture applications in products such as digital cameras, mobile devices, digital tablets, smart televisions, network surveillance devices, dashboard cameras, vehicle security cameras, multi-camera devices, image recognition systems, motion detection input devices, wearable devices and other electronic imaging devices.

[00212] The previous description, for purposes of explanation, was described with reference to specific embodiments. It should be noted that TABLES 1A-8E show different data from the different modalities; however, data from different modalities are obtained from experiments. Embodiments have been chosen and described to better explain the principles of disclosure and their practical applications, so as to enable others skilled in the art to better utilize disclosure and various modalities with various modifications as are suitable for the specific use contemplated. The embodiments described above 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 shapes disclosed. Many modifications and variations are possible in view of the above teachings.

Claims (26)

1. Folded optical system, characterized by comprising: an optical foldable assembly, which has a first transmissive surface, a first reflecting surface, a second reflecting surface, a third reflecting surface and a second transmissive surface sequentially along a direction of displacement of the light in an optical path, in which the first transmissive surface and the second reflecting surface are the same interface; the optical path reaches the first reflecting surface via the first transmissive surface along a first optical axis, the optical path along the first optical axis is redirected to a second optical axis by the first reflecting surface, the optical path along the second optical axis is redirected to a third optical axis by the second reflecting surface, the optical path along the third optical axis is redirected to a fourth optical axis by the third reflecting surface, and the optical path reaches an imaging surface through the second transmissive surface along the fourth optical axis; and a plurality of lens elements, each having an incident light surface and a light-emitting surface sequentially along the direction of travel of the light in the optical path, wherein the plurality of lens elements comprises at least one first element of lens, the first lens element is located on the first optical axis, the first lens element has positive refractive power, and the light incident surface of the first lens element is convex in a paraxial region thereof. 2. The folded optical system of claim 1, wherein the first optical axis is parallel to a normal direction of the imaging surface and each of the plurality of lens elements is located on the first optical axis or the fourth optical axis. 3. Folded optical system according to claim 1, characterized in that a radius of curvature of the light-inciding surface of the first lens element is R1, a radius of curvature of the light-emitting surface of the first lens element is R2 and the following condition is satisfied: -1.50 < R1/R2 < 0.90. 4. Folded optical system according to claim 1, characterized in that the plurality of lens elements comprises the first lens element and a second lens element sequentially along the direction of travel of light in the optical path, the second lens element lens is located on the first optical axis, a focal length of the first lens element is f1, a focal length of the second lens element is f2, and the following condition is satisfied: -5.00 < f2/f1 < -0.03. 5. Folded optical system according to claim 4, characterized by a distance parallel to the first optical axis between a position of maximum effective radius of the light incident surface of the second lens element and a position of maximum effective radius of the surface of light emission of the second lens element be ET2, a central thickness of the second lens element in the first optical axis be CT2 and the following condition be satisfied: 0.95 < ET2/CT2 < 3.50. 6. Folded optical system according to claim 1, characterized by an axial distance along the first optical axis, the second optical axis, the third optical axis and the fourth optical axis between the light incident surface of the first optical element lens and the imaging surface is TL, a distance perpendicular to the first optical axis between a position of maximum effective radius of the light-inciding surface of the first lens element and the first optical axis is Y11 and the following condition is satisfied: 3, 80 < TL/Y11 < 15.00. 7. Folded optical system according to claim 1, characterized in that half of a maximum field of view of the folded optical system is HFOV and the following condition is satisfied: 2.00 [g.] < HFOV < 18.00 [g. .]. 8. Folded optical system according to claim 1, characterized in that the plurality of lens elements further comprises a last lens element located closer to the imaging surface than one or more remaining lens elements of the plurality of lens elements , an axial distance along at least one of the first optical axis, the second optical axis, the third optical axis and the fourth optical axis between the light-inciding surface of the first lens element and the light-emitting surface of the last lens element be TD, a focal length of the folded optical system be f, and the following condition be satisfied: 0.60 < TD/f < 1.80. 9. Folded optical system according to claim 1, characterized by a distance perpendicular to the first optical axis between an axial vertex of the light incident surface of the first lens element on the first optical axis and an intersection point of the imaging surface and the fourth optical axis is Ly, a maximum displacement of the optical path parallel to the first optical axis of a folded optical system element that first receives light for the imaging surface is Lz and the following condition is satisfied: 0.60 < Ly/ Lz < 1.50. 10. Folded optical system according to claim 1, characterized in that a maximum displacement of the optical path parallel to the first optical axis of an element of the folded optical system that first receives light for the imaging surface is Lz and the following condition is satisfied : 5.00 [mm] < Lz < 11.00 [mm]. 11. Folded optical system according to claim 1, characterized in that the foldable optical assembly comprises at least one prism with the second reflecting surface, a refractive index of the prism is Np and the following condition is satisfied: 1.53 < Np < 1.95. 12. Folded optical system according to claim 1, characterized in that an angle between the first optical axis and the second optical axis is θa and the following condition is satisfied: 40.0 [degrees] < θa < 76.0 [degrees] ]. 13. Folded optical system, according to claim 1, characterized in that the foldable optical assembly comprises at least one prism, the first transmissive surface, the second reflecting surface and the second transmissive surface are in the same plane and in a normal direction of the same plane be parallel to the first optical axis. 14. Image capture unit, characterized by comprising: the folded optical system as defined in claim 1; and an image sensor disposed on the imaging surface of the folded optical system. 15. Electronic device, characterized by comprising: the image capture unit as defined in claim 14. 16. Folded optical system, characterized by comprising: an optical foldable assembly, which has a first transmissive surface, a first reflecting surface, a second reflecting surface, a third reflecting surface and a second transmissive surface sequentially along a direction of displacement of the light in an optical path, in which the first transmissive surface and the second reflecting surface are substantially the same interface; the optical path reaches the first reflecting surface via the first transmissive surface along a first optical axis, the optical path along the first optical axis is redirected to a second optical axis by the first reflecting surface, the optical path along the second optical axis is redirected to a third optical axis by the second reflecting surface, the optical path along the third optical axis is redirected to a fourth optical axis by the third reflecting surface, the optical path reaches an imaging surface through the second transmissive surface along of the fourth optical axis, and the first optical axis is parallel to a normal direction of the imaging surface; and a plurality of lens elements, each having a light-inciding surface and a light-emitting surface sequentially along the direction of travel of light in the optical path, wherein the plurality of lens elements comprises at least one first lens element and a second lens element sequentially along the direction of travel of light in the optical path, the first lens element and the second lens element are located on the first optical axis, the first lens element has positive refractive power and the second lens element has negative refractive power; wherein the optical collapsible assembly is located between the plurality of lens elements, or the optical collapsible assembly is located between the plurality of lens elements and the imaging surface along the direction of travel of light in the optical path; wherein each of the plurality of lens elements is located on the first optical axis or the fourth optical axis; wherein an axial distance along the first optical axis, the second optical axis, the third optical axis and the fourth optical axis between the light incident surface of the first lens element and the imaging surface is TL, a focal distance of the folded optical system is f, and the following condition is satisfied: 0.90 < TL/f < 2.00. 17. Folded optical system according to claim 16, characterized in that the light-emitting surface of the second lens element is concave in a paraxial region thereof, a radius of curvature of the light-inciding surface of the second lens element is R3, a radius of curvature of the light-emitting surface of the second lens element is R4 and the following condition is satisfied: -0.05 < (R3-R4)/(R3+R4) < 3.00. 18. Folded optical system according to claim 16, characterized in that the focal length of the folded optical system is f, a maximum displacement of the optical path parallel to the first optical axis of an element of the folded optical system that first receives light for imaging surface be Lz, and the following condition is satisfied: 1.50 < f/Lz < 3.50. 19. Folded optical system according to claim 16, characterized in that the focal length of the folded optical system is f, a focal length composed of one or more of the plurality of lens elements located on the first optical axis is fG1 and the following condition be satisfied: 0.50 < f/fG1 < 2.00. 20. Folded optical system according to claim 16, characterized in that an axial distance along the first optical axis between the light-inciding surface of the first lens element and the first reflecting surface is LOA1, an axial distance along the second optical axis between the first reflecting surface and the second reflecting surface being LOA2, an axial distance along the third optical axis between the second reflecting surface and the third reflecting surface being LOA3, an axial distance along the fourth optical axis between the third reflecting surface and the imaging surface is LOA4, and the following condition is satisfied: 0.55 < (LOA2+LOA3)/(LOA1+LOA4) < 1.00. 21. Folded optical system according to claim 16, characterized in that a focal length of the first lens element is f1, a central thickness of the first lens element in the first optical axis is CT1 and the following condition is satisfied: 2.50 < f1/CT1 < 15.00. 22. Folded optical system according to claim 16, characterized in that a number f of the folded optical system is Fno and the following condition is satisfied: 2.00 < Fno < 4.00. 23. Folded optical system according to claim 16, characterized in that a distance perpendicular to the first optical axis between a position of maximum effective radius of the light incidence surface of the first lens element and the first optical axis is Y11, a height maximum image of the folded optical system will be ImgH, and the following condition will be satisfied: 0.40 < Y11/ImgH < 2.00. 24. Folded optical system according to claim 16, characterized in that a displacement parallel to the first optical axis of an axial vertex to a position of maximum effective radius on the light incident surface of the first lens element is SAG11, a parallel displacement to the first optical axis from an axial vertex to a position of maximum effective radius on the light-emitting surface of the second lens element is SAG22, a distance parallel to the first optical axis between a position of maximum effective radius of the light-emitting surface of the first lens element and a position of maximum effective radius of the light incident surface of the second lens element is ET12 and the following condition is satisfied: 1.60 < (SAG11+SAG22)/ET12 < 13.00. 25. Folded optical system according to claim 16, characterized in that at least one of the plurality of lens elements is made of plastic material, and the light-inciding surface and the light-emitting surface of at least one of the plurality of lens elements both being spherical. 26. Folded optical system according to claim 16, characterized in that at least one of the plurality of lens elements has a refractive power greater than 1.63.