Large-view full-frame telecentric lens and optical system thereof

Abstract

The invention relates to the technical field of machine vision lenses, and discloses a large-view full-frame telecentric lens and an optical system thereof. The optical system is sequentially provided with a first lens G1 with positive focal power, a second lens G2 with positive focal power, a third lens G3 with positive focal power, a fourth lens G4 with negative focal power, a diaphragm S, a fifth lens G5 with negative focal power and a sixth lens G6 with positive focal power from an object side to an image side, and is characterized in that the first lens G1 with positive focal power, the second lens G2 with positive focal power, the third lens G3 with positive focal power, the fourth lens G4 with negative focal power, the diaphragm S, the fifth lens G5 with negative focal power and the sixth lens G6 with positive focal power are sequentially arranged from the object side to the image side; the seventh lens G7 has positive focal power; and the eighth lens G8 has positive focal power. According to the optical system of the double-telecentric structure, the resolution ratio is 145lp / mm, the visual field can reach phi 300mm, and the MTF value gt of the full visual field is achieved; the first lens and the second lens are integrated, the distortion is smaller than 0.02%, a full-frame camera is supported, the outer diameter size of the lens behind the first lens is greatly reduced, and the production and manufacturing cost is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of machine vision lenses, and in particular to a large-viewing-field full-frame telecentric lens and an optical system thereof. Background Art

[0002] In the machine vision precision optical measurement system, the use of ordinary industrial lenses will have the following problems: changes in object distance will cause different magnifications, parallax, large distortion and other problems, making it difficult to meet high detection requirements. Telecentric lenses can reduce or even eliminate the above problems. Within a certain object distance range, the image magnification will not change with the change of object distance. This advantage makes it very suitable for the field of precision measurement and detection.

[0003] With the rapid development of new energy, electric vehicle manufacturing and other industries, large field of view telecentric lenses are used in more and more application scenarios. At present, the field of view of most telecentric lenses on the market is concentrated below Φ150mm, which cannot meet the market demand. Therefore, this field is in urgent need of telecentric lenses with larger field of view, and at the same time with the characteristics of high telecentricity and low distortion, so as to meet the high detection requirements of today's market.

[0004] The above information is presented as background information only to assist with understanding the present disclosure and no determination or admission is made as to whether any of the above may be used as prior art with respect to the present disclosure. Summary of the invention

[0005] The object of the present invention is to provide a large-field-of-view full-frame telecentric lens and an optical system thereof, so as to solve or at least partially solve the technical problems existing in the prior art.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an optical system of a large-field full-frame telecentric lens, comprising a first lens G1 with positive focal power, a second lens G2 with positive focal power, a third lens G3 with positive focal power, a fourth lens G4 with negative focal power, an aperture S, a fifth lens G5 with negative focal power, a sixth lens G6 with positive focal power, a seventh lens G7 with positive focal power, and an eighth lens G8 with positive focal power, which are sequentially arranged from the object side to the image side; the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7, and the eighth lens G8 are all glass spherical lenses, which together form a double telecentric structure, wherein the outer diameter of the first lens G1 is the largest;

[0008] The third lens G3 and the fourth lens G4 form a cemented lens U1, and the fifth lens G5 and the sixth lens G6 form a cemented lens U2.

[0009] Optionally, the center distance between the first lens G1 and the second lens G2 is L1, and the focal length of the first lens G1 is f 1 , the focal length of the second lens G2 is f 2 , the focal length of the cemented lens group U1 is f U1 ;

[0010] f 1 Satisfies the relationship with L1: 0.9<|f 1 / L1|<1.5;

[0011] f U1 and f 2 Satisfies the relationship: 0.4<|f U1 / f 2 |<0.8.

[0012] Optionally, the center distance between the aperture S and the image plane is L2, and the focal length of the cemented lens group U2 is f U2 , the focal length of the seventh lens G7 is f 7 , the focal length of the eighth lens G8 is f 8 ;

[0013] f U2 Satisfies the relationship with L2: 0.24<|f U2 / L2|<0.65;

[0014] f 7 Satisfies the relationship with L2: 0.25<|f 7 / L2|<0.6;

[0015] f 8 Satisfies the relationship with L2: 0.5<|f 8 / L2|<0.9.

[0016] Optionally, the half image height of the optical system is y', and the half field of view is h;

[0017] y' and h satisfy the relationship: |y' / h|<0.5.

[0018] Optionally, the first lens G1 is a plano-convex lens, the second lens G2 is a meniscus lens, the third lens G3 is a meniscus lens, and the fourth lens G4 is a meniscus lens; the fifth lens G5 is a biconcave lens, the sixth lens G6 is a biconvex lens, the seventh lens G7 is a meniscus lens, and the eighth lens G8 is a biconvex lens.

[0019] Optionally, a ratio of an outer diameter of the first lens G1 to an outer diameter of the second lens G2 is greater than 3.85.

[0020] Optionally, the outer diameter of the cemented lens U1 and the outer diameter of the cemented lens U2 are both smaller than the outer diameter of the second lens G2.

[0021] Optionally, the optical axes of the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all on a predetermined optical axis;

[0022] Optionally, the aperture of the diaphragm S is a circular hole, and the center of the circular hole is on the predetermined optical axis.

[0023] In a second aspect, the present invention provides a large field of view full-frame telecentric lens, including an optical system of the large field of view full-frame telecentric lens as described above.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The optical system with a double telecentric structure provided by the present invention has a resolution of 145lp / mm, a field of view of up to Φ300mm, an MTF value of the full field of view>0.3, a distortion of less than 0.02%, supports full-frame cameras, and greatly reduces the outer diameter of the lens after the first lens, effectively reducing the production cost.

[0026] The present invention has other features and advantages, which will be apparent from or will be described in detail in the accompanying drawings and the following detailed description incorporated herein, which together serve to explain the specific principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 The present invention is a schematic structural diagram of an optical system of a large-field-of-view full-frame telecentric lens provided in an embodiment of the present invention.

[0029] Figure 2 An optical path diagram of an optical system of a large-field-of-view full-frame telecentric lens provided in an embodiment of the present invention.

[0030] Figure 3 This is an MTF curve diagram of an optical system of a large-field-of-view full-frame telecentric lens provided in Embodiment 1 of the present invention.

[0031] Figure 4This is a distortion diagram of an optical system of a large-field-of-view full-frame telecentric lens provided in Embodiment 1 of the present invention.

[0032] Figure 5 This is an MTF curve diagram of an optical system of a large-field-of-view full-frame telecentric lens provided in Embodiment 2 of the present invention.

[0033] Figure 6 This is a distortion diagram of an optical system of a large-field-of-view full-frame telecentric lens provided in Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0034] In order to explain in detail the possible application scenarios, technical principles, specific schemes that can be implemented, and the purposes and effects that can be achieved, the following is a detailed description of the specific embodiments listed in conjunction with the accompanying drawings. The embodiments described herein are only used to more clearly illustrate the technical solutions of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0035] Reference to "embodiment" herein means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or association with other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way to form a corresponding implementable technical solution.

[0036] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.

[0037] In the description of this application, the term "and / or" is an expression used to describe the logical relationship between objects, indicating that three relationships may exist, for example, A and / or B, which means: A exists, B exists, and A and B exist at the same time. In addition, the character " / " in this article generally indicates that the objects before and after are in an "or" logical relationship.

[0038] In the present application, terms such as “first” and “second” are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship of quantity, priority or sequence between these entities or operations.

[0039] Without further limitations, in this application, the words "include", "comprises", "has" or other similar expressions used in the sentences are intended to cover non-exclusive inclusion. These expressions do not exclude the presence of additional elements in the process, method or product including the elements, so that the process, method or product including a series of elements may include not only those limited elements, but also other elements not explicitly listed, or also include elements inherent to such process, method or product.

[0040] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than", "less than", "exceed" and the like are understood to exclude the number itself; expressions such as "above", "below", "within" and the like are understood to include the number itself. In addition, in the description of the embodiments of this application, "multiple" means more than two (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups", "multiple times", etc., unless otherwise clearly and specifically limited.

[0041] In the description of the embodiments of the present application, space-related expressions used, such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or position relationship based on the orientation or position relationship shown in the specific embodiments or drawings, and are only for the convenience of describing the specific embodiments of the present application or facilitating the reader's understanding, and do not indicate or imply that the referred device or component must have a specific position, a specific orientation, or be constructed or operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0042] Unless otherwise expressly specified or limited, in the description of the embodiments of the present application, the terms such as "install", "connect", "connect", "fix", "set", etc. used should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integrated setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For technicians in the technical field to which the present application belongs, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0043] Embodiment 1:

[0044] See also Figure 1 and Figure 2 , Figure 1 is a schematic structural diagram of an optical system of a large-viewing-field full-frame telecentric lens provided by an embodiment of the present invention, Figure 2 An optical path diagram of an optical system of a large-field-of-view full-frame telecentric lens provided in an embodiment of the present invention.

[0045] like Figure 1 As shown, the optical system includes:

[0046] A first lens G1 with positive refractive power, a second lens G2 with positive refractive power, a third lens G3 with positive refractive power, a fourth lens G4 with negative refractive power, a stop S, a fifth lens G5 with negative refractive power, a sixth lens G6 with positive refractive power, a seventh lens G7 with positive refractive power, and an eighth lens G8 with positive refractive power are sequentially arranged from the object side to the image side;

[0047] In this embodiment, the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all glass spherical lenses. These lenses together form a Figure 1 The double telecentric structure shown;

[0048] The outer diameter of the first lens G1 is much larger than the outer diameters of all subsequent lenses; specifically, the ratio of the outer diameter of the first lens G1 to the outer diameter of the second lens G2 is greater than 3.85, and the outer diameter of the second lens G2 is larger than the outer diameters of other lenses; Figure 1 As shown, the outer diameter of the cemented lens U1 and the outer diameter of the cemented lens U2 are also smaller than the outer diameter of the second lens G2.

[0049] Furthermore, the third lens G3 and the fourth lens G4 form a cemented lens U1, and the fifth lens G5 and the sixth lens G6 form a cemented lens U2;

[0050] The first lens G1, the second lens G2 and the cemented lens U1 form a front group of the optical system, and the cemented lens U2, the seventh lens G7 and the eighth lens G8 form a rear group of the optical system;

[0051] like Figure 1 As shown, the center distance between the first lens G1 and the second lens G2 is L1, and the center distance between the aperture S and the image plane is L2;

[0052] Specifically, the focal length of the first lens G1 is f 1 , the focal length of the second lens G2 is f 2 , the focal length of the cemented lens group U1 is f U1 ;

[0053] f 1 Satisfies the relationship with L1: 0.9<|f 1 / L1|<1.5; By satisfying the above relationship, the outer diameters of the second lens G2 and the cemented lens group U1 can be greatly reduced, effectively reducing the production cost and system weight;

[0054] f U1 and f 2 Satisfies the relationship: 0.4<|f U1 / f 2 |<0.8.

[0055] Specifically, the focal length of the cemented lens group U2 is f U2 , the focal length of the seventh lens G7 is f 7 , the focal length of the eighth lens G8 is f 8 ;

[0056] f U2 Satisfies the relationship with L2: 0.24<|f U2 / L2|<0.65;

[0057] f 7 Satisfies the relationship with L2: 0.25<|f 7 / L2|<0.6;

[0058] f 8 Satisfies the relationship with L2: 0.5<|f 8 / L2|<0.9.

[0059] Furthermore, the half image height of the optical system is y', and the half field of view is h; y' and h satisfy the relationship: |y' / h|<0.5.

[0060] More specifically, in this embodiment, the first lens G1 is a plano-convex lens, the second lens G2 is a meniscus lens, the third lens G3 is a meniscus lens, and the fourth lens G4 is a meniscus lens; the fifth lens G5 is a biconcave lens, the sixth lens G6 is a biconvex lens, the seventh lens G7 is a meniscus lens, and the eighth lens G8 is a biconvex lens.

[0061] In this embodiment, the optical axes of the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all on a predetermined optical axis;

[0062] The aperture of the diaphragm S is a circular hole, and the center of the circular hole is on the predetermined optical axis.

[0063] It is understandable that the aperture value of the aperture S needs to be adjusted accordingly according to the specific application scenario.

[0064] In order to verify whether the above optical system meets the design purpose, the following is a specific test example given according to the above settings of this embodiment:

[0065] In this test example, the lens data of the optical system are shown in Table 1 below:

[0066] Table 1

[0067] surface Radius(mm) Thickness(mm) Refractive Index Abbe number Outer diameter(mm) G1 front surface 711.87 35.0 1.90 30 330 G1 rear surface ∞ 599.7 330 G2 front surface 117.02 11.9 1.75 30 84 G2 rear surface 243.03 34.4 75 G3 front surface 30.60 11.4 1.50 80 47 G3, G4 glued surface 78.76 5.8 1.80 - 47 G4 rear surface 25.66 36.6 32 Aperture S ∞ 15.7 G5 front surface -29.43 5.3 1.85 - 21 G5, G6 bonding surface 144.88 14.5 1.60 65 37 G6 rear surface -40.83 6.5 37 G7 front surface -577.42 11.1 1.70 - 50 G7 rear surface -59.96 45.5 50 G8 front surface 342.42 14.7 1.90 20 66 G8 rear surface -214.93 96.8 66 Image plane /

[0068] It should be noted that in Table 1, the “front surface” corresponds to Figure 1 The left side surface of the lens or lens group corresponds to the "back surface" Figure 1 The corresponding lens or lens group on the right side surface; or can be understood as: the object side is Figure 1 On the left, the image side (or image plane) is Figure 1 On the right side, the surface close to the object side is the "front surface", and the surface close to the image side is the "back surface".

[0069] In this test example, the telecentric lens optical system has a distance L1 = 599.7 mm, a distance L2 = 210 mm, and a focal length f of the first lens G1. 1 =785mm, the focal length of the second lens G2 is f 2 =287mm, focal length f of cemented lens group U1 U1 =-175mm, focal length f of cemented lens group U2 U2 =-91mm, the focal length of the seventh lens G7 is f 7 =94mm, the focal length of the eighth lens G8 is f 8 =147mm;

[0070] Substituting the above values ​​into each relational expression, we obtain:

[0071] |f 1 / L1|=1.309,|f U1 / f 2 |=0.610,|f U2 / L2|=0.433,|f 7 / L2|=0.448,|f 8 / L2|=0.7.

[0072] Therefore, the relevant relationship of this embodiment is satisfied, namely:

[0073] 0.9<|f 1 / L1|<1.5, 0.4<|f U1 / f 2 |<0.8, 0.24<|f U2 / L2|<0.65, 0.25<|f 7 / L2|<0.6,0.5<|f 8 / L2|<0.9.

[0074] As can be seen from Table 1, the outer diameter of the second lens G2 and the cemented lens group U1 is much smaller than the outer diameter of the first lens G1, which can effectively reduce the production cost and system weight;

[0075] The optical system is a double telecentric structure with a working distance of 500mm, an object field of view of Φ300mm, a half-image height y'=22mm, and supports full-frame high-resolution cameras.

[0076] Please refer to Figure 3 and Figure 4 , Figure 3 The MTF (Modulation Transfer Function) curve of the optical system of a large field of view full-frame telecentric lens provided in the first embodiment of the present invention is as follows: Figure 4 A distortion diagram of an optical system of a large-field-of-view full-frame telecentric lens provided in Embodiment 1 of the present invention;

[0077] like Figure 3 and Figure 4 As shown, the optical system of this test example has an MTF value of >0.3 at 145lp / mm in the full field of view and a distortion of less than 0.01%.

[0078] In summary, the optical system of a large-field full-frame telecentric lens provided in this embodiment realizes a telecentric optical system with a field of view of Φ300 mm through reasonable lens combination design and focal length matching, with a full-field distortion of less than 0.02%, a resolution of 145lp / mm, and supports full-frame cameras; the optical system can greatly reduce the outer diameter of the lens after the first lens G1, effectively reducing the production cost.

[0079] Embodiment 2:

[0080] See also Figure 1 and Figure 2 , Figure 1 is a schematic structural diagram of an optical system of a large-viewing-field full-frame telecentric lens provided by an embodiment of the present invention, Figure 2 An optical path diagram of an optical system of a large-field-of-view full-frame telecentric lens provided in an embodiment of the present invention.

[0081] like Figure 1 As shown, the optical system includes:

[0082] A first lens G1 with positive refractive power, a second lens G2 with positive refractive power, a third lens G3 with positive refractive power, a fourth lens G4 with negative refractive power, a stop S, a fifth lens G5 with negative refractive power, a sixth lens G6 with positive refractive power, a seventh lens G7 with positive refractive power, and an eighth lens G8 with positive refractive power are sequentially arranged from the object side to the image side;

[0083] In this embodiment, the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all glass spherical lenses. These lenses together form a Figure 1 The double telecentric structure shown;

[0084] The outer diameter of the first lens G1 is much larger than the outer diameters of all subsequent lenses; specifically, the ratio of the outer diameter of the first lens G1 to the outer diameter of the second lens G2 is greater than 3.85, and the outer diameter of the second lens G2 is larger than the outer diameters of other lenses; Figure 1 As shown, the outer diameter of the cemented lens U1 and the outer diameter of the cemented lens U2 are also smaller than the outer diameter of the second lens G2.

[0085] Furthermore, the third lens G3 and the fourth lens G4 form a cemented lens U1, and the fifth lens G5 and the sixth lens G6 form a cemented lens U2;

[0086] The first lens G1, the second lens G2 and the cemented lens U1 form a front group of the optical system, and the cemented lens U2, the seventh lens G7 and the eighth lens G8 form a rear group of the optical system;

[0087] like Figure 1 As shown, the center distance between the first lens G1 and the second lens G2 is L1, and the center distance between the aperture S and the image plane is L2;

[0088] Specifically, the focal length of the first lens G1 is f 1 , the focal length of the second lens G2 is f 2 , the focal length of the cemented lens group U1 is f U1 ;

[0089] f 1 Satisfies the relationship with L1: 0.9<|f 1 / L1|<1.5; By satisfying the above relationship, the outer diameters of the second lens G2 and the cemented lens group U1 can be greatly reduced, effectively reducing the production cost and system weight;

[0090] f U1 and f 2 Satisfies the relationship: 0.4<|f U1 / f 2 |<0.8.

[0091] Specifically, the focal length of the cemented lens group U2 is f U2 , the focal length of the seventh lens G7 is f 7 , the focal length of the eighth lens G8 is f 8 ;

[0092] f U2 Satisfies the relationship with L2: 0.24<|f U2 / L2|<0.65;

[0093] f 7 Satisfies the relationship with L2: 0.25<|f 7 / L2|<0.6;

[0094] f 8 Satisfies the relationship with L2: 0.5<|f 8 / L2|<0.9.

[0095] Furthermore, the half image height of the optical system is y', and the half field of view is h; y' and h satisfy the relationship: |y' / h|<0.5.

[0096] More specifically, in this embodiment, the first lens G1 is a plano-convex lens, the second lens G2 is a meniscus lens, the third lens G3 is a meniscus lens, and the fourth lens G4 is a meniscus lens; the fifth lens G5 is a biconcave lens, the sixth lens G6 is a biconvex lens, the seventh lens G7 is a meniscus lens, and the eighth lens G8 is a biconvex lens.

[0097] In this embodiment, the optical axes of the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all on a predetermined optical axis;

[0098] The aperture of the diaphragm S is a circular hole, and the center of the circular hole is on the predetermined optical axis.

[0099] It is understandable that the aperture value of the aperture S needs to be adjusted accordingly according to the specific application scenario.

[0100] In order to verify whether the above optical system meets the design purpose, the following is a specific test example given according to the above settings of this embodiment:

[0101] In this test example, the lens data of the optical system are shown in Table 2 below:

[0102] Table 2

[0103]

[0104]

[0105] It should be noted that in Table 2, the “front surface” corresponds to Figure 1 The left side surface of the lens or lens group corresponds to the "back surface" Figure 1 The corresponding lens or lens group on the right side surface; or can be understood as: the object side is Figure 1 On the left, the image side (or image plane) is Figure 1 On the right side, the surface close to the object side is the "front surface", and the surface close to the image side is the "back surface".

[0106] In this test example, the telecentric lens optical system has a distance L1 = 716.7 mm, a distance L2 = 215 mm, and a focal length f of the first lens G1. 1 =938mm, the focal length of the second lens G2 is f 2 =290mm, focal length f of cemented lens group U1 U1 =-165mm, focal length f of cemented lens group U2 U2 =-97mm, the focal length of the seventh lens G7 is f 7 =99mm, the focal length of the eighth lens G8 is f 8 =153mm;

[0107] Substituting the above values ​​into each relational expression, we obtain:

[0108] |f 1 / L1|=1.309,|f U1 / f 2 |=0.569,|f U2 / L2|=0.451,|f 7 / L2|=0.460,|f 8 / L2|=0.712.

[0109] Therefore, the relevant relationship of this embodiment is satisfied, namely:

[0110] 0.9<|f 1 / L1|<1.5, 0.4<|f U1 / f 2 |<0.8, 0.24<|f U2 / L2|<0.65, 0.25<|f 7 / L2|<0.6,0.5<|f 8 / L2|<0.9.

[0111] As can be seen from Table 2, the outer diameter of the second lens G2 and the cemented lens group U1 is much smaller than the outer diameter of the first lens G1, which can effectively reduce the production cost and system weight;

[0112] In this test example, the optical system has a double telecentric structure, a working distance of 550 mm, an object field of view of Φ350 mm, a half-image height y'=22 mm, and supports full-frame high-resolution cameras.

[0113] Please refer to Figure 5 and Figure 6 , Figure 5The MTF curve diagram of the optical system of a large field of view full-frame telecentric lens provided in the second embodiment of the present invention is as follows: Figure 6 A distortion diagram of an optical system of a large-viewing-field full-frame telecentric lens provided in the second embodiment of the present invention;

[0114] like Figure 5 and Figure 6 As shown, the optical system of this test example has an MTF value of >0.3 at 145lp / mm in the full field of view, and a distortion of less than 0.02%.

[0115] In summary, the optical system of a large-field full-frame telecentric lens provided in this embodiment realizes a telecentric optical system with a field of view of Φ300mm through reasonable lens combination design and focal length matching, with a full-field distortion of less than 0.02%, a resolution of 145lp / mm, and supports full-frame cameras; the optical system can greatly reduce the outer diameter of the lens after the first lens G1, effectively reducing the production cost.

[0116] Embodiment three:

[0117] This embodiment provides a large-field-of-view full-frame telecentric lens, including an optical system of a large-field-of-view full-frame telecentric lens as described in Embodiment 1 or Embodiment 2.

[0118] Since the optical system has been described in detail in the above embodiments, it will not be described in detail in this embodiment.

[0119] In summary, the embodiment of the present invention realizes a telecentric lens with a resolution of 145lp / mm and a field of view of Φ300mm or more, with a full field of view distortion of less than 0.02%, and supports full-frame cameras; the telecentric lens can greatly reduce the outer diameter of the lens after the first lens G1, effectively reducing the production cost and meeting the application requirements of precise detection or measurement.

[0120] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical system of a large field of view full-frame telecentric lens, characterized in that: The invention comprises a first lens G1 with positive focal power, a second lens G2 with positive focal power, a third lens G3 with positive focal power, a fourth lens G4 with negative focal power, an aperture S, a fifth lens G5 with negative focal power, a sixth lens G6 with positive focal power, a seventh lens G7 with positive focal power and an eighth lens G8 with positive focal power, which are arranged in sequence from the object side to the image side; the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all glass spherical lenses, which together form a double telecentric structure, wherein the outer diameter of the first lens G1 is the largest; The third lens G3 and the fourth lens G4 form a cemented lens U1, and the fifth lens G5 and the sixth lens G6 form a cemented lens U2.

2. The optical system of a large field of view full-frame telecentric lens according to claim 1, characterized in that: The center distance between the first lens G1 and the second lens G2 is L1, the focal length of the first lens G1 is f1, the focal length of the second lens G2 is f2, and the focal length of the cemented lens group U1 is f U1 ; f1 and L1 satisfy the relationship: 0.9<|f1 / L1|<1.5; f U1 and f2 satisfy the relationship: 0.4<|f U1 / f2|<0.

8.

3. The optical system of a large field of view full-frame telecentric lens according to claim 2, characterized in that: The center distance between the aperture S and the image plane is L2, and the focal length of the cemented lens group U2 is f U2 , the focal length of the seventh lens G7 is f7, and the focal length of the eighth lens G8 is f8; f U2 Satisfies the relationship with L2: 0.24<|f U2 / L2|<0.65; f7 and L2 satisfy the relationship: 0.25<|f7 / L2|<0.6; f8 and L2 satisfy the relationship: 0.5<|f8 / L2|<0.

9.

4. The optical system of a large field of view full-frame telecentric lens according to claim 3, characterized in that: The half image height of the optical system is y', and the half field of view is h; y' and h satisfy the relationship: |y' / h|<0.

5.

5. The optical system of a large field of view full-frame telecentric lens according to claim 1, characterized in that: The first lens G1 is a plano-convex lens, the second lens G2 is a meniscus lens, the third lens G3 is a meniscus lens, and the fourth lens G4 is a meniscus lens; the fifth lens G5 is a biconcave lens, the sixth lens G6 is a biconvex lens, the seventh lens G7 is a meniscus lens, and the eighth lens G8 is a biconvex lens.

6. The optical system of a large field of view full-frame telecentric lens according to claim 1, characterized in that: The ratio of the outer diameter of the first lens G1 to the outer diameter of the second lens G2 is greater than 3.

85.

7. The optical system of a large field of view full-frame telecentric lens according to claim 6, characterized in that: The outer diameters of the cemented lens U1 and the cemented lens U2 are both smaller than the outer diameter of the second lens G2.

8. The optical system of a large field of view full-frame telecentric lens according to claim 1, characterized in that: The optical axes of the first lens G1, the second lens G2, the third lens G3, the fourth lens G4, the fifth lens G5, the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all on a predetermined optical axis; The aperture of the diaphragm S is a circular hole, and the center of the circular hole is on the predetermined optical axis.

9. A full-frame telecentric lens with a large field of view, characterized in that: An optical system comprising a large field of view full-frame telecentric lens as described in any one of claims 1 to 8.

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