Low-distortion anti-seismic lens and optical system thereof

Abstract

The invention relates to the technical field of machine vision lenses, and discloses a low-distortion anti-seismic lens and an optical system thereof. The optical system comprises a front group S1 with negative focal power, a middle group S2 with positive focal power, a diaphragm A0 and a rear group S3 with positive focal power, wherein the front group S1, the middle group S2, the diaphragm A0 and the rear group S3 are sequentially arranged from an object side to an image side; the positions of the front group S1, the middle group S2, the diaphragm A0 and the rear group S3 are relatively fixed; the focal length f of the optical system, the focal length fS1 of the front group S1, the focal length fS2 of the middle group S2 and the focal length fS3 of the rear group S3 respectively meet the following relational expressions: 2.00 lt; fS1 / flt; 3.00, 1.90 lt, 3.00, 1.90 lt; fS2 / flt; 2.50, 0.75 lt, 2.50, 0.75 lt; fS3 / flt; and 1.30. According to the invention, the focal length of the low-distortion anti-seismic lens is 16 mm, the resolution can reach 185lp / mm, and the maximum optical distortion of the full view field is lower than 0.12%.

Description

Technical Field

[0001] The present invention relates to the technical field of machine vision lenses, and in particular to a low-distortion, anti-vibration lens and an optical system thereof. Background Art

[0002] The imaging quality of the lens directly affects the picture effect of the shooting, and "lens distortion" is a key point that affects the imaging quality of the lens. Lens distortion mainly refers to the inability of the lens to accurately transmit the shooting scene to the sensor, resulting in unnatural distortion of the geometric shapes in the picture. With the advent of Industry 4.0 and the promotion of intelligent manufacturing, the demand for low-distortion lenses is increasing. Some automation industries have very high requirements for shooting quality, such as automated assembly, robotic arms, high-speed reciprocating production lines, etc. Since the equipment is always running at high speed, the lens is required to obtain clear, high-resolution images in a vibrating environment, so it has high requirements for lens distortion and good anti-vibration performance.

[0003] At present, the existing anti-vibration lenses in China have varying degrees of deficiencies in terms of resolution and distortion, and the specification distribution is incomplete; especially in the semiconductor and electronics industries, such as in semiconductor manufacturing and electronic assembly processes, anti-vibration lenses are used for precise detection or measurement, which requires the distortion of the anti-vibration lenses to be as low as possible; therefore, the research and development of low-distortion anti-vibration lenses is more urgent.

[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 low-distortion anti-vibration 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 low-distortion anti-vibration lens, characterized in that it comprises a front group S1 with negative optical power, a middle group S2 with positive optical power, an aperture A0 and a rear group S3 with positive optical power, which are arranged in sequence from the object side to the image side, and the positions of the front group S1, the middle group S2, the aperture A0 and the rear group S3 are relatively fixed to each other; the front group S1, the middle group S2 and the rear group S3 are respectively composed of a plurality of spherical lenses, and the optical axes of all the spherical lenses coincide with a predetermined optical axis;

[0008] The focal length f of the optical system and the focal length f of the front group S1 S1 , focal length f of middle group S2 S2 And the focal length f of the rear group S3 S3They satisfy the following relationships respectively:

[0009] 2.00<|f S1 / f|<3.00; 1.90<|f S2 / f|<2.50; 0.75<|f S3 / f|<1.30.

[0010] Optionally, the front group S1 includes a first lens G1 having negative refractive power.

[0011] The middle group S2 includes a second lens G2 having positive power, a third lens G3 having negative power, a fourth lens G4 having positive power, and a fifth lens G5 having negative power;

[0012] The rear group S3 includes a sixth lens G6 with positive power, a seventh lens G7 with negative power, an eighth lens G8 with positive power, and a ninth lens G9 with positive power;

[0013] Among them, the first lens G1, the third lens G3, the fourth lens G4, the fifth lens G5 and the eighth lens G8 are meniscus lenses, the second lens G2 is a biconvex lens, the sixth lens G6 is a plano-convex lens or a biconvex lens, the seventh lens G7 is a biconcave lens, and the ninth lens G9 is a biconvex lens or a meniscus lens.

[0014] Optionally, the second lens G2 and the third lens G3 are cemented into a first cemented lens group U1 with positive power; the fourth lens G4 and the fifth lens G5 are cemented into a second cemented lens group U2 with negative power; the sixth lens G6 and the seventh lens G7 are cemented into a third cemented lens group U3 with negative power;

[0015] The focal length of the first cemented lens group U1 is f U1 , f U1 The ratio of the focal length f of the optical system satisfies the relationship: 1.20<|f U1 / f|<2.00; the focal length of the second cemented lens group is f U2 , f U2 The ratio of f satisfies the relationship: 1.90<|f U2 / f|<3.00; the focal length of the third cemented lens group is f U3 , f U3 The ratio of f satisfies the relationship: 3.00<|f U3 / f|<4.50.

[0016] Optionally, a distance L between a front surface vertex of the first lens G1 and a back surface vertex of the ninth lens G9 satisfies the relationship:

[0017] |L / f|>2.90;

[0018] The front surface of the first lens G1 is a side surface of the first lens G1 away from the second lens G2, and the rear surface of the ninth lens G9 is a side surface of the ninth lens G9 away from the eighth lens G8; the vertex of the front surface of the first lens G1 and the vertex of the rear surface of the ninth lens G9 are both on the predetermined optical axis.

[0019] Optionally, a ratio of an optical back focal length BFL of the optical system to f satisfies the relationship: |BFL / f|<1.20.

[0020] Optionally, the ratio of the half-image height y' to f of the optical system satisfies the relationship: |y' / f|<0.50.

[0021] Optionally, the focal length of the eighth lens G8 is f G8 , f G8 The ratio to f satisfies the relationship: 1.40<|f G8 / f|<2.50;

[0022] The focal length of the ninth lens G9 is f G9 , f G9 The ratio to f satisfies the relationship: 0.85<|f G9 / f|<1.60.

[0023] Optionally, when the object distance changes, all the spherical lenses move together as a whole, and focusing is performed by changing the optical back focal length BFL of the optical system. This method ensures structural stability and achieves an anti-vibration effect.

[0024] Optionally, the aperture of the aperture A0 is a circular hole, and the center of the circular hole is on the predetermined optical axis;

[0025] The aperture value of the diaphragm is F2.8 to F16.

[0026] In a second aspect, the present invention provides a low-distortion anti-vibration lens, comprising a focusing structure and an optical system of the low-distortion anti-vibration lens as described above;

[0027] The focusing structure can drive the front group S1, the middle group S2, the aperture A0 and the rear group S3 as a whole to move closer to or farther away from the image plane along a predetermined optical axis to achieve focusing.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The optical system provided by the present invention adopts a whole-group focusing method, realizes a low-distortion and anti-vibration lens with a focal length of 16 mm, an image side F number of 2.8, a maximum imaging surface of φ11 mm, and a resolution of up to 185 lp / mm, that is, when the corresponding maximum imaging chip is used, its pixels can reach 7.9 million pixels, and the maximum optical distortion of the full field of view is less than 0.12%.

[0030] 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

[0031] 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.

[0032] Figure 1 The diagram is a schematic structural diagram of an optical system of a low-distortion, anti-vibration lens provided by an embodiment of the present invention.

[0033] Figure 2 This is an optical distortion curve of an optical system of a low-distortion anti-vibration lens provided by an embodiment 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 , Figure 1 The diagram is a schematic structural diagram of an optical system of a low-distortion, anti-vibration lens provided by an embodiment of the present invention.

[0045] like Figure 1 As shown, the optical system comprises a front group S1 with negative optical power, a middle group S2 with positive optical power, an aperture A0 and a rear group S3 with positive optical power, which are arranged in sequence from the object side to the image side, and the positions of the front group S1, the middle group S2, the aperture A0 and the rear group S3 are relatively fixed to each other; the front group S1, the middle group S2 and the rear group S3 are respectively composed of a plurality of spherical lenses, and the optical axes of all the spherical lenses coincide with the predetermined optical axis;

[0046] The focal length f of the optical system and the focal length f of the front group S1 S1 , focal length f of middle group S2 S2 And the focal length f of the rear group S3 S3 They satisfy the following relationships respectively:

[0047] 2.00<|f S1 / f|<3.00; 1.90<|f S2 / f|<2.50; 0.75<|f S3 / f|<1.30.

[0048] Exemplarily, as an optional implementation, the front group S1 includes a first lens G1 having negative refractive power.

[0049] The middle group S2 includes a second lens G2 having positive power, a third lens G3 having negative power, a fourth lens G4 having positive power, and a fifth lens G5 having negative power;

[0050] The rear group S3 includes a sixth lens G6 with positive power, a seventh lens G7 with negative power, an eighth lens G8 with positive power, and a ninth lens G9 with positive power;

[0051] Among them, the first lens G1, the third lens G3, the fourth lens G4, the fifth lens G5 and the eighth lens G8 are meniscus lenses, the second lens G2 is a biconvex lens, the sixth lens G6 is a plano-convex lens or a biconvex lens, the seventh lens G7 is a biconcave lens, and the ninth lens G9 is a biconvex lens or a meniscus lens.

[0052] Further, the second lens G2 and the third lens G3 are cemented into a first cemented lens group U1 with positive power; the fourth lens G4 and the fifth lens G5 are cemented into a second cemented lens group U2 with negative power; the sixth lens G6 and the seventh lens G7 are cemented into a third cemented lens group U3 with negative power;

[0053] The focal length of the first cemented lens group U1 is f U1 , f U1 The ratio of the focal length f of the optical system satisfies the relationship: 1.20<|f U1 / f|<2.00; the focal length of the second cemented lens group is f U2 , f U2 The ratio of f satisfies the relationship: 1.90<|f U2 / f|<3.00; the focal length of the third cemented lens group is f U3 , f U3 The ratio of f satisfies the relationship: 3.00<|f U3 / f|<4.50.

[0054] Specifically, the distance L between the front surface vertex of the first lens G1 and the back surface vertex of the ninth lens G9 satisfies the relationship:

[0055] |L / f|>2.90;

[0056] The front surface of the first lens G1 is a side surface of the first lens G1 away from the second lens G2, and the rear surface of the ninth lens G9 is a side surface of the ninth lens G9 away from the eighth lens G8; the vertex of the front surface of the first lens G1 and the vertex of the rear surface of the ninth lens G9 are both on the predetermined optical axis.

[0057] Furthermore, the focal length of the eighth lens G8 is f G8 , f G8 The ratio to f satisfies the relationship: 1.40<|f G8 / f|<2.50;

[0058] The focal length of the ninth lens G9 is f G9 , f G9 The ratio to f satisfies the relationship: 0.85<|f G9 / f|<1.60.

[0059] In this embodiment, the ratio of the optical back focal length BFL of the optical system to f satisfies the relationship: |BFL / f|<1.20;

[0060] In this embodiment, the ratio of the half-image height y' to f of the optical system satisfies the relationship: |y' / f|<0.50.

[0061] It should be noted that, in this embodiment, when the object distance changes, all the spherical lenses move together as a whole, that is, in this embodiment, focusing is performed by changing the optical back focal length BFL of the optical system.

[0062] Further, the aperture of the aperture A0 is a circular hole, and the center of the circular hole is on the predetermined optical axis;

[0063] The aperture value of the aperture A0 ranges from F2.8 to F16. It is understandable that the aperture value of the aperture A0 needs to be adjusted accordingly according to the specific application scenario.

[0064] Exemplarily, in this example, the relevant data of the optical system are specifically shown in Table 1:

[0065] Table 1

[0066]

[0067]

[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 example, the focal length f of the optical system is 16mm, the maximum aperture is F2.8, and the focal length f of the front group S1 is S1 =-40.40mm, focal length f of center group S2 S2 =36.00mm, focal length f of rear group S3 S3 =14.60mm, the distance L from the front surface vertex of the first lens G1 to the back surface vertex of the ninth lens G9 =53.70mm, the optical back focal length BFL =13.90mm, the half image height y' =5.5mm, the focal length f of the first cemented lens group U1 U1 =25.60mm, the focal length of the second cemented lens group U2 is f U2 =-35.60mm, the focal length of the third cemented lens group U3U3 =-58.40mm, the focal length of the eighth lens G8 is f G8 =31.00mm, the focal length of the ninth lens G9 is f G9 =20.90mm.

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

[0071] |f S1 / f|=2.53,|f S2 / f|=2.25,|f S3 / f|=0.91,|L / f|=3.36,|BFL / f|=0.87,|y' / f|=0.34,|f U1 / f|=1.60,

[0072] |f U2 / f|=2.23;|f U3 / f|=3.65;|f G8 / f|=1.94;|f G9 / f|=1.31.

[0073] Therefore, the relevant relationship of this embodiment is satisfied, namely:

[0074] 2.00<|f S1 / f|<3.00; 1.90<|f S2 / f|<2.50; 0.75<|f S3 / f|<1.30;

[0075] |L / f|>2.90; |BFL / f|<1.20; |y' / f|<0.50;

[0076] 1.20<|f U1 / f|<2.00;1.90<|f U2 / f|<3.00;

[0077] 3.00<|f U3 / f|<4.50;1.40<|f G8 / f|<2.50;

[0078] 0.85<|f G9 / f|<1.60.

[0079] Please continue to refer to Figure 2 , Figure 2 is an optical distortion curve of an optical system of a low-distortion anti-vibration lens provided by an embodiment of the present invention; Figure 2 As shown, according to experimental verification, the maximum optical distortion of the optical system within the full field of view is less than 0.12%.

[0080] Through the structural design of the above-mentioned optical system, this embodiment realizes a low-distortion and anti-vibration lens with a focal length of 16 mm, and the maximum optical distortion of the whole field of view is less than 0.12%; and, this embodiment adopts a whole-group focusing method, which ensures structural stability and achieves anti-vibration effect; in addition, its light aperture can be flexibly adjusted and can be suitable for a variety of application scenarios.

[0081] Embodiment 2:

[0082] This embodiment provides a low-distortion anti-vibration lens, comprising a focusing structure and an optical system of the low-distortion anti-vibration lens as described in the first embodiment;

[0083] The focusing structure is used to drive the front group S1, the middle group S2, the aperture A0 and the rear group S3 as a whole to approach or move away from the image plane along a predetermined optical axis to achieve focusing.

[0084] Since the optical system has been described in detail in the first embodiment, it will not be described in detail in this embodiment.

[0085] In summary, the embodiment of the present invention realizes a low distortion and anti-vibration lens with a focal length of 16mm, an image side F number of 2.8, a maximum imaging surface of φ11mm, and a resolution of up to 185lp / mm, that is, when the corresponding maximum imaging chip is used, its pixels can reach 7.9 million pixels, and the maximum optical distortion of the full field of view is less than 0.12%. It has both high resolution and low distortion, and has good anti-vibration performance, which can meet the application requirements of precise detection or measurement.

[0086] 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 low-distortion, anti-vibration lens, characterized in that: The optical system comprises a front group S1 with negative optical power, a middle group S2 with positive optical power, an aperture A0 and a rear group S3 with positive optical power, which are arranged in sequence from the object side to the image side, and the positions of the front group S1, the middle group S2, the aperture A0 and the rear group S3 are relatively fixed to each other; the front group S1, the middle group S2 and the rear group S3 are respectively composed of a plurality of spherical lenses, and the optical axes of all the spherical lenses coincide with the predetermined optical axis; The focal length f of the optical system and the focal length f of the front group S1 S1 , focal length f of middle group S2 S2 And the focal length f of the rear group S3 S3 They satisfy the following relationships respectively: 2.00<|f S1 / f|<3.00;1.90<|f S2 / f|<2.50;0.75<|f S3 / f|<1.30。 2. The optical system of a low-distortion anti-vibration lens according to claim 1, characterized in that: The front group S1 includes a first lens G1 having negative refractive power. The middle group S2 includes a second lens G2 having positive power, a third lens G3 having negative power, a fourth lens G4 having positive power, and a fifth lens G5 having negative power; The rear group S3 includes a sixth lens G6 with positive power, a seventh lens G7 with negative power, an eighth lens G8 with positive power, and a ninth lens G9 with positive power; Among them, the first lens G1, the third lens G3, the fourth lens G4, the fifth lens G5 and the eighth lens G8 are meniscus lenses, the second lens G2 is a biconvex lens, the sixth lens G6 is a plano-convex lens or a biconvex lens, the seventh lens G7 is a biconcave lens, and the ninth lens G9 is a biconvex lens or a meniscus lens.

3. The optical system of a low-distortion anti-vibration lens according to claim 2, characterized in that: The second lens G2 and the third lens G3 are cemented into a first cemented lens group U1 having positive refractive power; The fourth lens G4 and the fifth lens G5 are cemented into a second cemented lens group U2 with negative power; the sixth lens G6 and the seventh lens G7 are cemented into a third cemented lens group U3 with negative power; The focal length of the first cemented lens group U1 is f U1 , f U1 The ratio of the focal length f of the optical system satisfies the relationship: 1.20<|f U1 / f|<2.00; the focal length of the second cemented lens group is f U2 , f U2 The ratio of f satisfies the relationship: 1.90<|f U2 / f|<3.00; the focal length of the third cemented lens group is f U3 , f U3 The ratio of f satisfies the relationship: 3.00<|f U3 / f|<4.

50.

4. The optical system of a low-distortion anti-vibration lens according to claim 3, characterized in that: The distance L between the front surface vertex of the first lens G1 and the back surface vertex of the ninth lens G9 satisfies the relationship: |L / f|>2.90; The front surface of the first lens G1 is a side surface of the first lens G1 away from the second lens G2, and the rear surface of the ninth lens G9 is a side surface of the ninth lens G9 away from the eighth lens G8; the vertex of the front surface of the first lens G1 and the vertex of the rear surface of the ninth lens G9 are both on the predetermined optical axis.

5. The optical system of a low-distortion anti-vibration lens according to claim 3, characterized in that: The ratio of the optical back focal length BFL of the optical system to f satisfies the relationship: |BFL / f|<1.

20.

6. The optical system of a low-distortion anti-vibration lens according to claim 3, characterized in that: The ratio of the half-image height y' to f of the optical system satisfies the relationship: |y' / f|<0.

50.

7. The optical system of a low-distortion anti-vibration lens according to claim 3, characterized in that: The focal length of the eighth lens G8 is f G8 , f G8 The ratio to f satisfies the relationship: 1.40<|f G8 / f|<2.50; The focal length of the ninth lens G9 is f G9 , f G9 The ratio to f satisfies the relationship: 0.85<|f G9 / f|<1.

60.

8. The optical system of a low-distortion anti-vibration lens according to claim 5, characterized in that: When the object distance changes, all the spherical lenses move together as a whole, and focusing is performed by changing the optical back focal length BFL of the optical system.

9. The optical system of a low-distortion anti-vibration lens according to claim 1, characterized in that: The aperture of the aperture A0 is a circular hole, and the center of the circular hole is on the predetermined optical axis; The aperture value of the diaphragm is F2.8 to F16.

10. A low-distortion, anti-vibration lens, characterized in that: An optical system comprising a focusing structure and a low-distortion, anti-vibration lens as claimed in any one of claims 1 to 9; The focusing structure can drive the front group S1, the middle group S2, the aperture A0 and the rear group S3 as a whole to approach or move away from the image plane along a predetermined optical axis.

Images