Optical element capable of reflecting stray light for multiple times

Abstract

The invention discloses an optical element capable of reflecting stray light for multiple times, which comprises a plurality of microstructures arranged around the central axis of the optical element. Each microstructure comprises a first reflecting surface and a second reflecting surface which are connected and is provided with a connecting line, and the connecting line is a boundary line of the first reflecting surface and the second reflecting surface. The extension line of the connecting line passes through the central shaft. Wherein the plurality of microstructures are arranged into a plurality of adjacent rings, and the plurality of microstructures of two adjacent rings are arranged in a staggered manner. The optical element can greatly suppress stray light, so that the optical quality of the optical system with the optical element can be effectively improved.

Description

Technical Field

[0001] The present invention relates to an optical element, and in particular to an optical element capable of causing stray light to be reflected multiple times. Background Art

[0002] In optical systems, stray light can cause contrast reduction, ghost image problems, and reduced signal-to-noise ratio, which can degrade image quality. Therefore, how to effectively suppress stray light is particularly important in optical design.

[0003] The conventional method of suppressing stray light is to set a microstructure on the surface of an optical element. However, when the incident angle of the light relative to the surface is too large, for example, when the incident line of the stray light is parallel to the surface with the microstructure in the optical element, the stray light is easily reflected once by the microstructure and enters the photosensitive element of the imaging system, making the suppression effect of the stray light very small.

[0004] In other conventional technologies, there are also microstructure designs that use millimeter structures plus nanostructures. However, due to the cumbersome processing and manufacturing process, the cost is high and it is not easy to popularize. And although stray light with a large angle of incidence can be suppressed, the attenuation effect of stray light is still limited when the incident angle of the stray light relative to the microstructure plane is 90 degrees. In addition, how to smoothly demold optical components with microstructures on the surface after molding is also a problem to be solved by relevant manufacturers. Summary of the invention

[0005] The object of the present invention is to provide an optical element that can significantly suppress stray light, so that an optical system having the optical element can effectively improve the optical quality.

[0006] The present invention provides an optical element for causing stray light to be reflected multiple times, characterized in that it comprises:

[0007] A plurality of microstructures are arranged around the central axis of the optical element, and each microstructure includes a first reflective surface and a second reflective surface connected to each other, and has a connecting line, which is a boundary line between the first reflective surface and the second reflective surface, and an extension line of the connecting line passes through the central axis.

[0008] The microstructures are arranged into a plurality of adjacent rings, and the microstructures of two adjacent rings in the rings are arranged alternately.

[0009] Further, the microstructure is substantially a pyramid, and further comprises:

[0010] a bottom surface connected to the first reflecting surface and the second reflecting surface, and

[0011] The vertex through which the connecting line passes.

[0012] Furthermore, the bottom surface includes an angle that is less than 90 degrees, and an extension line of the bisector of the angle passes through the central axis.

[0013] The present invention also provides an optical element for causing stray light to be reflected multiple times, characterized in that it comprises:

[0014] A plurality of microstructures are arranged around the central axis of the optical element, and each microstructure comprises:

[0015] bottom surface;

[0016] Vertex; and

[0017] A first reflecting surface and a second reflecting surface connected to each other are formed from the bottom surface to the vertex, and a connecting line is provided. The connecting line is a boundary line between the first reflecting surface and the second reflecting surface, and the orthographic projections of the first reflecting surface and the second reflecting surface on the bottom surface form an angle.

[0018] wherein the extension line of the angle bisector of the angle passes through the central axis,

[0019] The microstructures are arranged into a plurality of adjacent rings, and the microstructures of two adjacent rings in the rings are arranged alternately.

[0020] Furthermore, the spacing between the bottom surfaces of the microstructures in the same ring is smaller than the shortest side length of the bottom.

[0021] Furthermore, the reflectivity of the microstructure is less than 5%.

[0022] Furthermore, the optical element is a lens barrel.

[0023] Furthermore, the optical element is a ring-shaped optical element.

[0024] Furthermore, the microstructure satisfies the following relationship: α+β≦180 degrees, α≧90 degrees, β<90 degrees, wherein α is the angle between the bottom surface and the central axis, and β is the angle between the bottom surface and the connecting line.

[0025] Further, the microstructure satisfies the following relationship:

[0026] 90 degrees≦α≦135 degrees, wherein α is an angle between the bottom surface and the central axis, and the difference in the angles of the bottom surfaces of the microstructures is less than or equal to 5 degrees.

[0027] Further, the microstructure satisfies the following relationship:

[0028] 90 degrees≦α≦135 degrees, wherein α is an angle between the bottom surface and the central axis, and a difference between the maximum lengths of the bottom surfaces of the microstructures is less than or equal to 5%.

[0029] Furthermore, the shape of the bottom surface is substantially triangular.

[0030] Further, the microstructure satisfies the following relationship:

[0031] 55 degrees ≦θ ≦ 65 degrees, where θ is the angle of the bottom surface.

[0032] Further, the microstructure satisfies the following relationship:

[0033] 35 degrees ≦θ ≦ 45 degrees, where θ is the angle of the bottom surface.

[0034] Further, the microstructure satisfies the following relationship:

[0035] 0.45 micrometers / degree ≦ H / θ ≦ 9.1 micrometers / degree, wherein H is the vertical height from the bottom surface to the vertex, and θ is the angle of the bottom surface.

[0036] Further, the microstructure satisfies the following relationship:

[0037] 0.45 micrometers / degree ≦ L / θ ≦ 9.1 micrometers / degree, wherein L is the shortest side length of the bottom surface, and θ is the angle of the bottom surface.

[0038] Further, the microstructure satisfies the following relationship:

[0039] 0.6≦H / L≦1.0, wherein H is the vertical height from the base to the vertex, and L is the shortest side length of the base.

[0040] In one embodiment of the present invention, an optical element for causing multiple reflections of stray light includes a plurality of microstructures arranged around the central axis of the optical element. Each microstructure includes a first reflection surface and a second reflection surface connected to each other, and has a connecting line, which is a boundary line between the first reflection surface and the second reflection surface. An extension line of the connecting line passes through the central axis. The plurality of microstructures are arranged into a plurality of adjacent rings, and the plurality of microstructures of two adjacent rings in the rings are arranged alternately.

[0041] In another embodiment of the present invention, an optical element for multiple reflection of stray light includes a plurality of microstructures arranged around the central axis of the optical element, and each microstructure includes a bottom surface, a vertex, and a first reflection surface and a second reflection surface connected to each other from the bottom surface to the vertex, and has a connecting line. The connecting line is the boundary line between the first reflection surface and the second reflection surface, and the orthographic projections of the first reflection surface and the second reflection surface on the bottom surface form an angle, wherein the extension line of the angle bisector of the angle passes through the central axis. The plurality of microstructures are arranged into a plurality of adjacent rings, and the plurality of microstructures of two adjacent rings in the rings are arranged alternately.

[0042] Based on the above, in the optical element of the present invention, since the extension line of the connection line of the reflective surface of each microstructure passes through the central axis, it is suitable for splitting the stray light from the radial direction. And by forming multiple rings of microstructures around the central axis and staggered arrangement, the stray light incident on the microstructures will be reflected multiple times by the reflective surface of the staggered microstructures. Every time the stray light is reflected, the intensity of the stray light will be greatly attenuated. By splitting and reflecting the reflective surface of the microstructure multiple times, the stray light with different incident angles can be effectively suppressed. When the incident angle of the stray light is 90 degrees, that is, the incident direction of the stray light is parallel to the bottom surface of the microstructure, the stray light entering the second ring from the gap between the microstructures of the first ring can reach the maximum number of reflections between the microstructures, reducing the chance of the stray light leaving the multiple microstructures with only a single reflection, and further attenuating the stray light to a minimum. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a schematic diagram of a lens according to a first embodiment of the present invention.

[0044] Figure 2 is a schematic top view of the second optical element of the first embodiment.

[0045] Figure 3 yes Figure 2 Schematic diagram of the enlarged area A in the middle.

[0046] Figure 4 It is a schematic diagram of the light splitting principle of multiple microstructures in the first embodiment.

[0047] Figure 5 It is an enlarged schematic diagram of the microstructure of the first embodiment.

[0048] Figure 6 is a schematic top view of a second optical element according to a second embodiment of the present invention.

[0049] Figure 7 yes Figure 6 Schematic diagram of the enlarged area A'.

[0050] Figure 8 Schematic diagram of the light splitting principle of multiple microstructures in the second embodiment.

[0051] Fig. 9 It is an enlarged schematic diagram of the microstructure of the second embodiment.

[0052] Fig.10 is a schematic top view of the third optical element of the first embodiment.

[0053] Fig.11 yes Fig.10 Schematic diagram of the enlarged surface of the third optical element.

[0054] Fig.12 yes Fig.10 A schematic cross-sectional view of a third optical element.

[0055] Fig.13 yes Fig.12 An enlarged schematic cross-sectional view of the surface of the third optical element.

[0056] Fig.14 It is a schematic diagram for deducing the theoretical maximum reflection number range and the theoretical minimum reflection number range between the two microstructures of the present invention.

[0057] Fig.15 It is a cross-sectional schematic diagram of the microstructure of the present invention.

[0058] Figures 16 to 18 It is an optical simulation diagram of the number of stray light reflections at different angles on the bottom surface of the microstructure of the present invention. DETAILED DESCRIPTION

[0059] Before describing the present invention in detail, the symbols in the accompanying drawings are first clearly indicated: 10: lens; 100: first optical element; 110, 110': second optical element; 101, 111, 112, 113, 121, 122: surface; 114, 123: fixed surface; 120: third optical element; 130: lens group; 131: first lens; 132: second lens; 133: third lens; 134: fourth lens; 140, 140': microstructure; 140e, 140'e: extension Line; 141, 141': first reflection surface; 142, 142': second reflection surface; 143, 143', 149: connecting line; 144, 144': bottom surface; 145, 145': vertex; 146, 146': angle bisector; 147: third reflection surface; 148: fourth reflection surface; A, A': area AB, AC, BD: distance; a, b, c: length; G: depth; CA: central axis; CA': auxiliary line; H, K: height; L: side length; IS: image side; OS: object side;

[0060] r1: first ring; r2: second ring; SG: gate; SL: stray light; SL1: first sub-stray light; SL2: second sub-stray light; T: range of maximum reflection times; T': range of minimum reflection times; θ, α, β: angles.

[0061] As used herein, "about", "approximately", "essentially", or "substantially" include the stated value and the average value within an acceptable deviation range of the particular value determined by one of ordinary skill in the art, taking into account the measurement in question and the particular amount of error associated with the measurement (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or within, for example, ±30%, ±20%, ±15%, ±10%, ±5%. Furthermore, as used herein, "about", "approximately", "essentially", or "substantially" can select a more acceptable deviation range or standard deviation depending on the measured property, cutting property or other property, and can apply to all properties without one standard deviation.

[0062] Exemplary embodiments are described herein with reference to cross-sectional views as schematic diagrams of idealized embodiments. Therefore, variations in the shape of the diagrams as a result of, for example, manufacturing techniques and / or (and / or) tolerances can be expected. Therefore, the embodiments described herein should not be interpreted as being limited to the specific shapes of the regions shown herein, but rather include shape deviations, for example, caused by manufacturing. For example, a region shown or described as flat may typically have rough and / or nonlinear features. In addition, the acute angles shown may be rounded in actual manufacturing, so the angle between the two sides may be the angle between the extended lines of the two sides. For example, the side length of a polygon (e.g., the three sides of a triangle) may refer to the distance between the intersections of the extension lines of the adjacent two sides. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shapes of the regions.

[0063] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and description to refer to the same or like parts.

[0064] Figure 1 is a schematic diagram of a lens according to the first embodiment of the present invention. Figure 1The lens 10 of the present invention includes a first optical element 100, a second optical element 110, a third optical element 120 and a lens group 130. The first optical element 100 is, for example, a lens barrel of the lens 10, and has a space for accommodating the second optical element 110, the third optical element 120 and the lens group 130. It is particularly mentioned that the optical axes of the lens 10 and the above optical elements can be coaxially arranged. In other words, the lens 10, the first optical element 100, the second optical element 110, the third optical element 120 and the lens group 130 can all be axisymmetric optical elements. Further, the first optical element 100, the second optical element 110, and the third optical element 120 can be annular optical elements, and the symmetry axis of each of the above elements is the central axis CA, and the central axes CA of the above elements overlap with each other and have a common central axis CA. The second optical element 110 is, for example, a fixing ring of the lens 10, and the third optical element 120 is, for example, a gasket or a spacer ring of the lens 10. The fixing surface 114 of the second optical element 110 and the fixing surface 123 of the third optical element 120 can be used to fix the lens group 130 , and a focusing member (not shown) can be used to move the lens 10 relative to the image side surface IS to achieve the purpose of adjusting the focal length of the lens 10 , but the present invention is not limited thereto.

[0065] The lens group 130 may include a first lens 131, a second lens 132, a third lens 133, and a fourth lens 134 arranged in sequence from the object side surface OS to the image side surface IS. The material of each lens of the lens group 130 may be, for example, glass or plastic, but the present invention does not limit the number of lenses in the lens group 130. Among them, the light from the object side surface OS may be sequentially transmitted to the photosensitive element (not shown) on the image side surface IS through the first lens 131, the second lens 132, the third lens 133, and the fourth lens 134, and the photosensitive element senses the light from the outside and converts it into an image. However, when the light enters the lens 10, it is inevitable that unexpected reflection will occur on the inner surface of the lens 10 or between the interface of the lens group 130 and the air to form stray light, thereby affecting the imaging quality of the photosensitive element. In order to solve the above problems, the first optical element 100 , the second optical element 110 and the third optical element 120 of the present invention may each include a plurality of microstructures 140 disposed around the central axis CA of the first optical element 100 , the second optical element 110 and the third optical element 120 .

[0066] Specifically, the first optical element 100 may have a surface 101 surrounding the central axis CA and facing the image side surface IS, and the plurality of microstructures 140 may be disposed on the surface 101 of the first optical element 100 and protrude toward the image side surface IS, and thus also disposed around the central axis CA.

[0067] In addition, the second optical element 110 also includes a surface 111 surrounding the central axis CA, a surface 112 surrounding the central axis CA, and a surface 113 surrounding the central axis CA. The surface 111 faces the radial direction of the lens 10 and forms an angle with the central axis CA, for example, 42 degrees; the surface 112 faces the image side surface IS; and the surface 113 faces the image side surface IS and is located between the surface 101 and the surface 112 of the first optical element 100 in the radial direction of the lens 10. The plurality of microstructures 140 can be disposed on the surface 111, the surface 112, and the surface 113 of the second optical element 110, and are therefore also disposed around the central axis CA.

[0068] Similarly, the third optical element 120 may also include a surface 121 and a surface 122 surrounding the central axis CA, and a plurality of microstructures 140 may be disposed on the surface 121 and the surface 122 of the third optical element 120 and protrude toward the central axis CA, so that the plurality of microstructures 140 are also disposed around the central axis CA. It is worth mentioning that the angles between the surface 121 and the surface 122 and the central axis CA in the cross section of the lens 10 may be substantially the same or different. For example, the angle between the central axis CA and the central axis CA on the surface 121 may be substantially 20 degrees, which means that the surface 121 is substantially inclined 20 degrees relative to the central axis CA, but the present invention is not limited thereto. In other embodiments not shown, the plurality of microstructures 140 may also be disposed on the inner surface of the first optical element 100. That is, the surface of the first optical element 100 facing the lens group 130 in the radial direction but not contacting the lens group 130 may also be provided with the microstructure 140, but the present invention is not limited thereto.

[0069] It is worth mentioning that, through the design and arrangement of the multiple microstructures 140 of the present invention, the stray light incident on the multiple microstructures 140 can be effectively split and absorbed. The following will be described using the multiple optical microstructures 140 of the second optical element 110 and the third optical element 120 as an example.

[0070] Figure 2 4 is a schematic top view of the image side of the second optical element of the first embodiment. Figure 3 yes Figure 2 Schematic diagram of the enlarged area A in the middle. Figure 4 It is a schematic diagram of the light splitting principle of multiple microstructures in the first embodiment. Figure 5 This is an enlarged schematic diagram of the microstructure of the first embodiment. Figures 2 to 4Each of the multiple microstructures 140 on the surface 111, the surface 112 and the surface 113 of the second optical element 110 includes a first reflective surface 141 and a second reflective surface 142 connected to each other. There is a connecting line 143 between the two reflective surfaces, and the connecting line 143 is the boundary line between the first reflective surface 141 and the second reflective surface 142. The extension line 140e of the connecting line 143 passes through the central axis CA. The multiple microstructures 140 are arranged into multiple rings adjacent to each other, and in the radial direction of the second optical element 110, the multiple microstructures 140 of two adjacent rings are staggered with each other. To put it another way, Figure 3 For example, the plurality of microstructures 140 include a first ring r1 and a second ring r2 arranged with the central axis CA as the axis of symmetry. The first ring r1 is adjacent to the second ring r2, and the first ring r1 is closer to the central axis CA than the second ring r2. The "staggered arrangement" may mean that the connection lines 143 of the microstructures 140 on the first ring r1 and the connection lines 143 of the microstructures 140 on the second ring r2 do not overlap with each other and each points to the central axis CA. And each microstructure 140 on the second ring r2 is arranged in the gap between each microstructure 140 on the first ring r1.

[0071] Please refer to Figure 4 When light enters the lens 10 along the central axis CA (i.e., the optical axis of the lens 10), part of the light will form stray light SL, and part of the stray light SL will irradiate the plurality of microstructures 140 on the surface 112 of the second optical element 110 along the radial direction of the lens 10. Since the extension line 140e of the connecting line 143 of the first reflecting surface 141 and the second reflecting surface 142 of the microstructure 140 passes through the central axis CA, when the stray light SL irradiates the second optical element 110, it is easily reflected, refracted, and absorbed by the first reflecting surface 141 and the second reflecting surface 142 of the microstructure 140, and is further split into a first sub-stray light SL1 and a second sub-stray light SL2.

[0072] Since the plurality of microstructures 140 form multiple rings (such as the first ring r1 and the second ring r2) adjacent to each other and arranged in an interlaced manner around the central axis CA, the first sub-stray light SL1 and the second sub-stray light SL2 are reflected by the microstructure 140 of the first ring r1 and leave the first ring r1, and then are refracted, reflected and absorbed by the first reflection surface 141 and the second reflection surface 142 of the multiple microstructures 140 arranged in an interlaced manner in the second ring r2, and continue to be split and attenuated. Similarly, after the stray light SL is reflected by the microstructure 140 of the second ring r2 and leaves the second ring r2, it will also be further refracted, reflected and absorbed by the microstructures 140 of the multiple rings (such as the third ring, the fourth ring, etc. not shown) that are adjacent to each other in sequence. Through the layout and arrangement of the microstructures 140 described above, the probability of the stray light SL leaving the multiple microstructures 140 after being reflected by the microstructure 140 only once can be greatly reduced, which is beneficial to the attenuation of the stray light SL.

[0073] In consideration of further optimizing the effect of attenuating stray light SL, appropriate materials can be selected to adjust the reflectivity of the microstructure 140. In some embodiments, the reflectivity of the microstructure 140 material can be less than 5%. That is, without considering refraction, the ratio of the total power of the first sub-stray light SL1 and the second sub-stray light SL2 to the power of the stray light SL can be less than 1 / 20. And through each reflection of the microstructure 140 of each ring, the power of the stray light SL will be reduced to 1 / 20 of the original after reflection, and the intensity of the stray light SL can be attenuated to the minimum through multiple reflections.

[0074] Figure 5 This is an enlarged schematic diagram of the microstructure of the first embodiment. Figure 5 In this embodiment, the microstructure 140 may be substantially a cone, for example Figure 5 The quadrangular pyramid shown in FIG. In addition to the aforementioned first reflection surface 141, second reflection surface 142 and connecting line 143, it also has a bottom surface 144, a vertex 145, a third reflection surface 147, a fourth reflection surface 148 and a connecting line 149. The bottom surface 144 can be connected to the first reflection surface 141 and the second reflection surface 142, and the connecting line 143 passes through the vertex 145 and is connected to another point on the bottom surface 144. The bottom surface 144 can be connected to the third reflection surface 147 and the fourth reflection surface 148, and the connecting line 149 passes through the vertex 145 and is connected to another point on the bottom surface 144. The connecting line 149 is the boundary line between the third reflection surface 147 and the fourth reflection surface 148. By each microstructure 140 being a cone with a vertex 145, it is helpful to increase the probability of multiple reflections of the stray light SL incident on the microstructure 140, but the present invention is not limited thereto.

[0075] It is worth mentioning that the bottom surface 144 of the microstructure 140 includes an angle θ, and the value of the angle θ is less than 90 degrees. By designing the angle θ to be substantially an acute angle, the second optical element 110 can further increase the surface density of the microstructure 140 on the surface 111, the surface 112, and the surface 113 in the circumferential direction (i.e., the angular direction of the polar coordinates) relative to the obtuse angle, which is beneficial to increase the probability of the number of reflections of the radial stray light SL.

[0076] Furthermore, the extension line of the bisector 146 of the angle θ may pass through the central axis CA. In other words, the projection of the extension line 140e of the connecting line 143 on the bottom surface 144 may coincide with the extension line of the bisector 146 of the angle θ. The symmetrical design of the first reflecting surface 141 and the second reflecting surface 142 of the microstructure 140 may reduce the structural complexity of the microstructure 140, simplify the manufacturing difficulty of the microstructure 140 and the mold for manufacturing the microstructure 140. However, the present invention is not limited thereto. In some embodiments, the orthographic projections of the first reflecting surface 141 and the second reflecting surface 142 on the bottom surface 144 also form an angle θ, wherein the extension line of the bisector 146 of the angle θ passes through the central axis CA, and the connecting line 143 of the first reflecting surface 141 and the second reflecting surface 142 may not pass through the central axis CA but may have a slight deviation. The above design may also achieve the effect that the first reflecting surface 141 and the second reflecting surface 142 split the radial stray light SL. The orthographic projections of the third reflecting surface 147 and the fourth reflecting surface 148 on the bottom surface 144 also form an angle θ, wherein an extension line of the angle bisector 146 of the angle θ also passes through the central axis CA.

[0077] The microstructure 140 can be manufactured on the surface 111, the surface 112 and the surface 113 of the second optical element 110 by laser engraving, for example. Alternatively, the second optical element 110 and the plurality of microstructures 140 thereon can be manufactured by injection molding using a mold and injection molding of plastic material. Figure 2 In the embodiment, the second optical element 110 manufactured by injection molding may include a gate SG and have an appropriate gate depth G. Specifically, when the diameter of the second optical element 110 is substantially 6.89 millimeters (mm) and the thickness is substantially 0.325 mm, the gate depth G in the radial direction may be substantially 0.2 mm, the vertical height of the microstructure 140 is 0.060 mm, and the shortest side length of the bottom surface 144 of the microstructure 140 ranges from 0.051 mm to 0.077 mm, however, the present invention is not limited to the size of the optical element.

[0078] Please refer to Figure 1It is worth mentioning that the more the number of microstructures 140 is set, the more conducive it is to the attenuation of stray light SL, but it also leads to a further reduction in the size of the microstructure 140 and is difficult to demold during the manufacturing process. In order to strike a balance between the effectiveness of eliminating stray light SL and the difficulty of manufacturing, the microstructure 140 can satisfy the following relationship during manufacturing: α+β≦180 degrees, α≧90 degrees, β<90 degrees, where angle α is the angle between the bottom surface 112 and the central axis CA, and β is the angle between the bottom surface 112 and the connecting line 143. In other words, angle α is the obtuse angle between the bottom surface 112 and the central axis CA. From another perspective, on the cross-section of the lens 10, angle α is the supplementary angle of the acute angle between the central axis CA and the projection of the central axis CA on the surface 121. In this embodiment, angle α is the right angle between the bottom surface 112 and the central axis CA, and angle β is 50 degrees. Since the microstructure 140 is disposed on the surface 112 , the bottom surface 144 of the microstructure 140 may substantially coincide with the surface 112 .

[0079] The above description is only based on the surface 112 of the second optical element 110 for exemplary description, and the arrangement of the plurality of microstructures 140 on the surface 111 and the surface 113 of the second optical element 110, and the arrangement of the plurality of microstructures 140 on the surface 101 of the first optical element 100 can refer to the above description, and will not be repeated here. Since the first optical element 100 can be a lens barrel as mentioned above, the microstructures 140 are arranged on the surface 101, so that the stray light SL transmitted to the image side surface IS but not absorbed by the second optical element 110 can be further absorbed by the surface 101 of the first optical element 100. The second optical element 110 can be a fixing ring, and the third optical element 120 can be a gasket, and the above-mentioned elements can also achieve the effect of reducing the stray light SL in the lens 10.

[0080] Some other embodiments will be listed below to explain the present invention in detail, wherein the same components will be marked with the same symbols, and the description of the same technical content will be omitted. For the omitted parts, please refer to the aforementioned embodiments and will not be repeated below.

[0081] Figure 6 4 is a schematic top view of the image side of the second optical element of the second embodiment. Figure 7 yes Figure 6 Please also refer to Figure 6 as well as Figure 7 The second optical element 110' of this embodiment is Figure 2Similar to the second optical element 110, each of the plurality of microstructures 140' includes a first reflective surface 141' and a second reflective surface 142' connected to each other. There is a connecting line 143' between the two reflective surfaces, and the connecting line 143' is the boundary line between the first reflective surface 141' and the second reflective surface 142'. The extension line 140'e of the connecting line 143' passes through the central axis CA. The plurality of microstructures 140' are arranged into a plurality of rings adjacent to each other, and in the radial direction of the second optical element 110', the plurality of microstructures 140' of two adjacent rings (for example, the first ring r1 and the second ring r2) are arranged alternately with each other. The difference between it and the second optical element 110 is that the shape of the microstructure is different. Specifically, the bottom surface 144' of the plurality of microstructures 140' of the second optical element 110' is substantially a triangle.

[0082] Figure 8 Schematic diagram of the light splitting principle of multiple microstructures in the second embodiment. Fig. 9 This is an enlarged schematic diagram of the microstructure of the second embodiment. Figures 8 to 9 Specifically, the plurality of microstructures 140' of the second optical element 110' can also achieve the above Figure 4 The light-splitting effect of the second optical element 110 is improved. For example, the first reflection surface 141' and the second reflection surface 142' of the microstructure 140' are also suitable for splitting the radial stray light SL into the first sub-stray light SL1 and the second sub-stray light SL2, and after passing through the microstructure 140' of the first ring r1, it continues to be split and reflected by the microstructures 140' on the adjacent second ring r2 and subsequent other adjacent rings. Furthermore, since the bottom surface 144' of the microstructure 140' is substantially triangular, more microstructures 140' can be set compared to quadrilaterals on the basis of the same area of ​​the surface 112. The total number of reflection surfaces of the multiple microstructures 140' on the second optical element 110' is further increased, and the number of times the stray light SL is reflected between the multiple microstructures 140' is increased. It is beneficial to further attenuate the stray light SL.

[0083] Similar to the extension line of the angle bisector 146 of the microstructure 140 passing through the central axis CA, the extension line of the bisector 146' of one of the angles θ of the bottom surface 144' of the microstructure 140' may also pass through the central axis CA, so as to further enhance the effect of splitting the stray light SL by the first reflective surface 141' and the second reflective surface 142'. The relevant contents can be referred to the above paragraphs, which will not be repeated here.

[0084] Fig.10 FIG. 4 is a schematic top view of the object side of the third optical element of the third embodiment. Fig.11 yes Fig.10 Schematic diagram of the enlarged surface of the third optical element. Fig.12 yes Fig.10A schematic cross-sectional view of a third optical element. Fig.13 yes Fig.12 Please also refer to Figures 10 to 13 , the surface 121 and the surface 122 of the third optical element 120 may both be provided with a plurality of microstructures 140. Similarly, the plurality of microstructures 140 on the surface 121 and the surface 122 may also be arranged alternately to form a plurality of rings, and the adjacent two rings (eg Fig.11 The microstructures 140 of the first ring r1 and the second ring r2 can be arranged alternately. Fig.11 and Fig.13 As shown, each of the plurality of microstructures 140 includes a first reflective surface 141 and a second reflective surface 142, and a connecting line 143 between the first reflective surface 141 and the second reflective surface 142, wherein an extension line 140e of the connecting line 143 passes through the central axis CA. In order to conveniently present the relationship between the extension line 140e and the central axis CA, Fig.13 In the cross-sectional enlarged schematic diagram of FIG. 1 , the auxiliary line CA' is used to replace the central axis CA. The auxiliary line CA' is an axis substantially parallel to the central axis CA. Therefore, the angle between the surface 121 and the surface 122 and the auxiliary line CA' is equal to the angle between the surface 121 and the surface 122 and the central axis CA. The principle of eliminating stray light SL by the microstructure 140 on the third optical element 120 can be referred to the aforementioned Figure 4 The second optical element 110 and Figure 8 The second optical element 110' is not described in detail here.

[0085] Please refer to Fig.13 It is worth mentioning that the more the number of microstructures 140 is set, the more conducive it is to the attenuation of stray light SL, but it also leads to a further reduction in the size of the microstructure 140 and is difficult to demold during the manufacturing process. In order to strike a balance between the effectiveness of eliminating stray light SL and the difficulty of manufacturing, the microstructure 140 can satisfy the following relationship during manufacturing: α+β≦180 degrees, α≧90 degrees, β<90 degrees, where angle α is the angle between the bottom surface 144 and the central axis CA, and β is the angle between the bottom surface 144 and the connecting line 143. In other words, angle α is the obtuse angle between the bottom surface 144 and the central axis CA. From another perspective, on the cross-section of the lens 10, angle α is the supplementary angle of the acute angle between the central axis CA and the projection of the central axis CA on the surface 121. In this embodiment, angle α is 160 degrees and angle β is 20 degrees. Since the microstructure 140 is disposed on the surface 121 and the surface 122 , the bottom surface 144 of the microstructure 140 may substantially coincide with the surface 121 or the surface 122 .

[0086] It should be noted that since the bottom surface 144 of the microstructure 140 is a quadrilateral, the lengths L of the sides are not necessarily the same. Fig.11 In the enlarged view of the surface 121 of the microstructure 140, the bottom surface 144 of the microstructure 140 can be substantially kite-shaped. The connecting line 143 refers to one of the longest connecting lines in the bottom surface 144. Taking the bottom surface 144 as a kite as an example, the connecting line 143 refers to the long axis of the kite. The extension line 140e of the connecting line 143 is the extension of the long axis of the kite.

[0087] In other embodiments, in order to make the multiple microstructures 140 consistent and make the spacing tolerance between adjacent microstructures 140 less than the shortest side length L of the microstructure 140, which is beneficial to reduce the probability of stray light SL incident on the microstructure 140 and being reflected once, the microstructure 140 can further satisfy the following relationship: 90 degrees ≦ α ≦ 135 degrees, and the difference in angle θ of the bottom surface 144 of each of the multiple microstructures 140 is less than or equal to 5 degrees. However, the present invention is not limited to this. In other embodiments, the microstructure 140 can also further satisfy the following relationship: 90 degrees ≦ α ≦ 135 degrees, and the difference between the maximum side lengths L of the bottom surface 144 of each of the multiple microstructures 140 is less than or equal to 5%.

[0088] On the other hand, the above Figure 5 Microstructure 140 (or Fig. 9 The lengths L of the multiple sides of the microstructure 140') may be substantially equal, or the lengths L of two adjacent sides may be substantially equal, or the lengths L of the sides may be substantially unequal, and the present invention is not limited thereto. It should be noted that: Figure 1 The first optical element 100, Figure 2 The second optical element 110, Figure 6 The second optical element 110' and Fig.10 In the third optical element 120 in the ring, the spacing between the bottom surfaces 144 of the multiple microstructures 140 located in the same ring, or the spacing between the bottom surfaces 144' of the multiple microstructures 140', can be smaller than the shortest side length L in the microstructure 140 (or microstructure 140'). Here, "spacing" refers to the minimum distance between the edge of the bottom surface 144 and the edge of another bottom surface 144 adjacent to the same ring. As described above, the actual spacing tolerance of adjacent microstructures 140 can be smaller than the side length L of the shortest side of the microstructure 140, which is beneficial to reduce the probability of the stray light SL being reflected only once after being incident on the microstructure 140.

[0089] Fig.14 It is a schematic diagram for deducing the theoretical maximum reflection number range and the theoretical minimum reflection number range between the two microstructures of the present invention. Fig.15The conditions of various parameters between the microstructure 140 (or microstructure 140') will now be further described. Fig.14 and Fig.15 , assuming that the incident angle of the stray light SL is 90 degrees, that is, it is parallel to the bottom surface 144 of the microstructure 140 and irradiates the point E or point F of the microstructure 140, and is reflected to the point B and point D of the microstructure 140, and the vertical height between the point B and the point D and the bottom surface 144 is K, and the bottom surface 144 of the microstructure 140 is a rhombus, so the lengths L of the sides of the bottom surface 144 are all equal. The vertical height from the vertex 145 of the microstructure 140 to the bottom surface 144 is the height H, the angle in the bottom surface 144 facing the incident direction of the stray light SL is the angle θ, and the horizontal distance AB from the irradiation point at the height K to the height H is the length b, the half distance AC of the shorter diagonal line in the bottom surface 144 is the length a, and the distance BD is the length c. When the stray light SL is incident on a plurality of microstructures 140 and the range falls within T, it can be reflected by the microstructures 140 in the first row (e.g., the first ring r1 mentioned above) and transmitted to the microstructures 140 in the second row (e.g., the second ring r2 mentioned above) and continuously reflected, so T is the range with the maximum number of reflections. Conversely, when the stray light SL is incident on the microstructure 140 and the range falls within T', the stray light SL is reflected by the microstructure 140 and will be reflected to the microstructures 140 in the same row (and the first ring r1) and will not be transmitted to the microstructures 140 in the next row (i.e., the second ring r2), so T' is the range with the minimum number of reflections.

[0090] From the trigonometric relationship, we know that a = L*cos(90°-θ / 2), and Fig.15 From the ratio of similar shapes in: (HK) / H=AB / AC=b / a, we can know that b=a*(HK) / H. And through geometric relationships, we get c=2(ab)+δ, where δ is the spacing between the two microstructures 140. On the other hand, BDE is an isosceles triangle, so BD=DE=c. And DEF is a right triangle of cosθ, so T=c / cosθ. Substituting the above a, b, and c respectively, we can get T=2*K*L*cos(90°-θ / 2) / H*cosθ+δ / cosθ. And T'=(aT / 2)*2. For example, when θ is 60 degrees and H and L are equal, T=2K+2δ, T'=L-2K-2δ.

[0091] Through the above, the angle θ of the bottom surface 144 of the microstructure 140 can satisfy the following relationship: 55 degrees ≦θ ≦ 65 degrees. For the stray light SL with an incident angle of 90 degrees (i.e., when the incident direction of the stray light SL is substantially parallel to the bottom surface 144), the theoretical maximum number of reflections can reach the maximum value. However, the present invention is not limited to this. In other embodiments, the angle θ of the bottom surface 144 of the microstructure 140 can satisfy the following relationship: 35 degrees ≦θ ≦ 45 degrees. For the stray light SL with an incident angle of 90 degrees, the theoretical minimum number of reflections is greater than 55 degrees ≦θ ≦ 65 degrees. In some embodiments, in order to meet the above-mentioned range of the maximum number of reflections T, the range of the minimum number of reflections T', and to cooperate with the lens 10 with a length of 3 mm to 50 mm in the direction of the central axis CA, the microstructure 140 can satisfy the following relationship: 0.45 micrometers / degree ≦ H / θ ≦ 9.1 micrometers / degree. In some embodiments, the microstructure 140 may also satisfy the following relationship: 0.45 micrometers / degree ≦ L / θ ≦ 9.1 micrometers / degree, where L is the shortest side length L of the bottom surface 144. In other embodiments, the microstructure 140 may also satisfy the following relationship: 0.6 ≦ H / L ≦ 1.0. The definition of the relevant parameters can refer to the above paragraphs and will not be repeated here. Through the above parameter range, the microstructure 140 can theoretically meet the range T of the maximum number of reflections and the range T' of the minimum number of reflections.

[0092] Figures 16 to 18 This is an optical simulation diagram of the number of stray light reflections at different angles on the bottom surface of the microstructure of the present invention. Figures 16 to 18 The control variable is that 30 microstructures 140 are arranged in a 6*5 array; the side length of each microstructure 140 is 0.06 mm; the stray light SL is irradiated to a height of 0.02 mm from the bottom surface 144. The difference is Fig.16 An extension line of the bisector 146 of the middle angle θ passes through the central axis CA, and the angle θ=90 degrees. Fig.17 The bisector 146 of the middle angle θ passes through the central axis CA, and the angle θ=60 degrees. Fig.18 The bisector 146 of the angle θ passes through the central axis CA, and the angle θ = 40 degrees. Fig.16 When θ = 90 degrees, the maximum number of reflections is 10 and the minimum number of reflections is 2. Fig.17 When θ = 60 degrees, the maximum number of reflections is 12 times and the minimum number of reflections is 2 times. Fig.18 When θ=40 degrees, the maximum number of reflections is 10 and the minimum number of reflections is 5. From the above preliminary analysis, it can be seen that the smaller the angle θ is, the more conducive it is for the stray light SL to be reflected multiple times between the interfaces, but too small an angle will also lead to problems such as difficulty in processing and forming the multiple microstructures 140.

[0093] In summary, in the optical element of the present invention, since the extension line of the connection line of the reflective surface of each microstructure passes through the central axis, it is suitable for splitting the stray light from the radial direction. And by forming multiple rings around the central axis and staggered arrangement of the microstructures, the stray light incident on the microstructures will be reflected multiple times by the reflective surfaces of the staggered microstructures. Each time the stray light is reflected, the stray light will be greatly attenuated. By splitting and reflecting the reflective surface of the microstructure multiple times, the stray light with different incident angles can be effectively suppressed. When the incident angle of the stray light is 90 degrees, that is, the incident direction of the stray light is parallel to the bottom surface of the microstructure, the stray light reflected by the first ring and entering the second ring can reach the maximum number of reflections, reducing the chance of the stray light leaving the multiple microstructures with only a single reflection, and further attenuating the stray light to a minimum.

[0094] The ranges covered by the above optical parameters, the comparison relationship between the optical parameters, and the maximum and minimum values ​​of the conditional expressions, as well as the numerical ranges within the maximum and minimum values, are all features that can be implemented by the present invention and are within the scope disclosed by the present invention. The above is only an example and should not be limited to this.

[0095] All embodiments of the present invention can be implemented, and some feature combinations can be extracted from the same embodiment. Compared with the prior art, the feature combination can also achieve unexpected effects of the present case. The feature combination includes but is not limited to the combination of features such as face shape, angle and conditional formula. The disclosure of the implementation mode of the present invention is a specific embodiment to illustrate the principle of the present invention, and the present invention should not be limited to the disclosed embodiment. In other words, the embodiment and its drawings are only for demonstration of the present invention and are not limited thereto.

Claims

1. An optical element that causes stray light to be reflected multiple times, characterized in that: include: A plurality of microstructures are arranged around the central axis of the optical element, and each microstructure includes a first reflective surface and a second reflective surface connected to each other, and has a connecting line, which is a boundary line between the first reflective surface and the second reflective surface, and an extension line of the connecting line passes through the central axis. The microstructures are arranged into a plurality of adjacent rings, and the microstructures of two adjacent rings in the rings are arranged alternately.

2. The optical element according to claim 1, wherein The microstructure is substantially a cone, and further comprises: a bottom surface connected to the first reflecting surface and the second reflecting surface, and The vertex through which the connecting line passes.

3. The optical element according to claim 2, wherein: The bottom surface includes an angle which is less than 90 degrees, and an extension line of the bisector of the angle passes through the central axis.

4. An optical element that causes multiple reflections of stray light, characterized in that: include: A plurality of microstructures are arranged around the central axis of the optical element, and each microstructure comprises: bottom surface; Vertex; and A first reflecting surface and a second reflecting surface connected to each other are formed from the bottom surface to the vertex, and a connecting line is provided. The connecting line is a boundary line between the first reflecting surface and the second reflecting surface, and the orthographic projections of the first reflecting surface and the second reflecting surface on the bottom surface form an angle. wherein the extension line of the angle bisector of the angle passes through the central axis, The microstructures are arranged into a plurality of adjacent rings, and the microstructures of two adjacent rings in the rings are arranged alternately.

5. The optical element according to claim 1 or 4, characterized in that: The spacing between the bottom surfaces of the microstructures in the same ring is smaller than the shortest side length of the bottom.

6. The optical element according to claim 1 or 4, characterized in that: The reflectivity of the microstructure is less than 5%.

7. The optical element according to claim 1 or 4, characterized in that: The optical element is a lens barrel.

8. The optical element according to claim 1 or 4, characterized in that: The optical element is a ring-shaped optical element.

9. The optical element according to claim 3 or 4, characterized in that: The microstructure satisfies the following relationship: α+β≦180 degrees, α≧90 degrees, β<90 degrees, wherein α is the angle between the bottom surface and the central axis, and β is the angle between the bottom surface and the connecting line.

10. The optical element according to claim 3 or 4, characterized in that: The microstructure satisfies the following relationship: 90 degrees≦α≦135 degrees, wherein α is an angle between the bottom surface and the central axis, and the difference in the angles of the bottom surfaces of the microstructures is less than or equal to 5 degrees.

11. The optical element according to claim 3 or 4, characterized in that: The microstructure satisfies the following relationship: 90 degrees≦α≦135 degrees, wherein α is an angle between the bottom surface and the central axis, and a difference between the maximum lengths of the bottom surfaces of the microstructures is less than or equal to 5%.

12. The optical element according to claim 3 or 4, characterized in that The shape of the bottom surface is substantially a triangle.

13. The optical element according to claim 3 or 4, characterized in that: The microstructure satisfies the following relationship: 55 degrees ≦θ ≦ 65 degrees, where θ is the angle of the bottom surface.

14. The optical element according to claim 3 or 4, characterized in that: The microstructure satisfies the following relationship: 35 degrees ≦θ ≦ 45 degrees, where θ is the angle of the bottom surface.

15. The optical element according to claim 3 or 4, characterized in that: The microstructure satisfies the following relationship: 0.45 micrometers / degree ≦ H / θ ≦ 9.1 micrometers / degree, wherein H is the vertical height from the bottom surface to the vertex, and θ is the angle of the bottom surface.

16. The optical element according to claim 3 or 4, characterized in that: The microstructure satisfies the following relationship: 0.45 micrometers / degree ≦ L / θ ≦ 9.1 micrometers / degree, wherein L is the shortest side length of the bottom surface, and θ is the angle of the bottom surface.

17. The optical element according to claim 3 or 4, characterized in that: The microstructure satisfies the following relationship: 0.6≦H / L≦1.0, wherein H is the vertical height from the base to the vertex, and L is the shortest side length of the base.

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