2.5-micron pixel camera, high-resolution low-distortion double telecentric lens and optical system of high-resolution low-distortion double telecentric lens

Abstract

The invention relates to the technical field of machine vision lenses, and discloses a 2.5-micron pixel camera, a high-resolution low-distortion double telecentric lens and an optical system of the high-resolution low-distortion double telecentric lens. The optical system comprises a first lens G1 with positive focal power, a second lens G2 with positive focal power, a third lens with positive focal power, a fourth lens G4 with negative focal power, a fifth lens G5 with negative focal power, a sixth lens G6 with positive focal power and a seventh lens G7 with positive focal power which are sequentially arranged from the object space to the image space. The eighth lens G8 has positive focal power; and the ninth lens G9 has negative focal power. The optical axes of all the lenses coincide with a preset optical axis. According to the double telecentric lens, the high-resolution low-distortion double telecentric lens is realized, the full-field distortion is less than 0.02%, the resolution can reach 200lp / mm, and the measurement precision can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of machine vision lenses, and in particular to a 2.5-micron pixel camera and a high-resolution, low-distortion dual-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 cause problems such as different magnifications, parallax, and large distortion when the object distance changes, making it difficult to meet high detection requirements. Telecentric lenses can reduce or even eliminate the above problems. It can keep the image magnification constant within a certain object distance range. Its principle advantage makes it very suitable for the field of precision measurement and detection. Telecentric lenses are widely used in the field of machine vision precision detection, such as product measurement and judgment, and defect detection in the fields of semiconductors, 3C electronics, new energy, packaging and printing, smart logistics, automobile manufacturing, and medicine.

[0003] With the continuous development of the machine vision industry and the continuous improvement of camera chip resolution, the technical requirements for telecentric lenses are also increasing. Lower distortion and higher resolution are the development direction of telecentric lenses. In order to meet market demand, it is urgent to design a dual telecentric lens with high resolution and low distortion to improve measurement accuracy.

[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 2.5 micron pixel camera and a high-resolution, low-distortion bi-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 high-resolution and low-distortion double 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, a fifth lens G5 with negative focal power, a sixth lens G6 with positive focal power, a seventh lens G7 with positive focal power, an eighth lens G8 with positive focal power, and a ninth lens G9 with negative focal power, which are sequentially arranged from the object side to the image side, and the optical axes of all the lenses coincide with a predetermined optical axis;

[0008] The third lens G3 and the fourth lens G4 form a cemented lens U1, the fifth lens G5 and the sixth lens G6 form a cemented lens U2, and the eighth lens G8 and the ninth lens G9 form a cemented lens U3;

[0009] The aperture S is disposed between the fourth lens G4 and the fifth lens G5; the light rays incident in parallel to the first lens G1 converge at the aperture S after being refracted by the second lens G2 and the cemented lens U1.

[0010] Optionally, a center distance between the front surface of the first lens G1 and the aperture S is L1, and a center distance between the aperture S and the image plane is L2;

[0011] The focal length f1 of the first lens G1 satisfies the relationship: 0.9<|f1 / L1|<1.3;

[0012] The focal length f2 of the second lens G2 satisfies the relationship: 0.8<|f2 / L1|<1.3;

[0013] Focal length f of cemented lens group U1 U1 Satisfies the relationship: 0.3<|f U1 / L1|<0.6;

[0014] Focal length f of cemented lens group U2 U2 Satisfies the relationship: 0.5<|f U2 / L2|<0.8;

[0015] The focal length f7 of the seventh lens G7 satisfies the following relationship: 0.35<|f7 / L2|<0.62;

[0016] Focal length f of cemented lens group U3 U3 Satisfies the relationship: 0.75<|f U3 / L2|<1.05.

[0017] Optionally, the first lens G1 is a glass spherical lens with a biconvex structure, the second lens G2, the third lens G3, the fourth lens G4 and the ninth lens G9 are all glass spherical lenses with a meniscus structure, the fifth lens G5 is a glass spherical lens with a biconcave structure, and the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all glass spherical lenses with a biconvex structure.

[0018] Optionally, the refractive index of the third lens G3 is n3, the Abbe number is v3, and n3 and v3 respectively satisfy the relationship: 1.47 <n3<60,65<v3<82。

[0019] Optionally, the refractive index of the eighth lens G8 is smaller than the refractive index of the ninth lens G9.

[0020] Optionally, the aperture of the aperture S is a circular hole, and the center of the circular hole is on the predetermined optical axis;

[0021] The aperture adjustment range of the diaphragm is F4.8 to F32.

[0022] In a second aspect, the present invention provides a high-resolution, low-distortion bi-telecentric lens, comprising an optical system of a high-resolution, low-distortion bi-telecentric lens as described above.

[0023] In a third aspect, the present invention also provides a 2.5 micron pixel camera equipped with a high-resolution, low-distortion dual telecentric lens as described above.

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

[0025] The optical system provided by the present invention, which is composed of the first lens G1 to the ninth lens G9, realizes a high-resolution and low-distortion double telecentric lens. The distortion of the entire field of view is less than 0.02%, and the distortion is extremely low, so that objects can be measured with almost no deformation. The resolution can reach 200lp / mm, which can effectively improve the measurement accuracy.

[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 It is a structural schematic diagram of an optical system of a high-resolution and low-distortion double telecentric lens provided by an embodiment of the present invention.

[0029] Figure 2 It is a structural schematic diagram of an optical system of a high-resolution and low-distortion double telecentric lens provided by an embodiment of the present invention when the working distance is 306 mm.

[0030] Figure 3 The MTF curve diagram of an optical system of a high-resolution and low-distortion double telecentric lens provided by an embodiment of the present invention when the working distance is 306 mm.

[0031] Figure 4The optical distortion curve of an optical system of a high-resolution and low-distortion double telecentric lens provided by an embodiment of the present invention when the working distance is 306 mm.

[0032] Figure 5 It is a schematic structural diagram of an optical system of another high-resolution and low-distortion double telecentric lens provided by an embodiment of the present invention when the working distance is 312 mm.

[0033] Figure 6 This is an MTF curve diagram of another optical system of a high-resolution and low-distortion bi-telecentric lens provided by an embodiment of the present invention when the working distance is 312 mm.

[0034] Figure 7 This is an optical distortion curve of another optical system of a high-resolution and low-distortion double telecentric lens provided by an embodiment of the present invention when the working distance is 312 mm. DETAILED DESCRIPTION

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] Embodiment 1:

[0045] See also Figure 1 , Figure 1 It is a structural schematic diagram of an optical system of a high-resolution and low-distortion double telecentric lens provided by an embodiment of the present invention.

[0046] like Figure 1 As shown, the optical system includes 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 fifth lens G5 with negative focal power, a sixth lens G6 with positive focal power, a seventh lens G7 with positive focal power, an eighth lens G8 with positive focal power, and a ninth lens G9 with negative focal power, which are sequentially arranged from the object side to the image side, and the optical axes of all the lenses coincide with the predetermined optical axis;

[0047] The third lens G3 and the fourth lens G4 form a cemented lens U1, the fifth lens G5 and the sixth lens G6 form a cemented lens U2, and the eighth lens G8 and the ninth lens G9 form a cemented lens U3;

[0048] The aperture S is disposed between the fourth lens G4 and the fifth lens G5; the light rays incident in parallel to the first lens G1 converge at the aperture S after being refracted by the second lens G2 and the cemented lens U1.

[0049] Furthermore, the center distance between the front surface of the first lens G1 and the aperture S is L1, and the center distance between the aperture S and the image plane is L2;

[0050] The focal length f1 of the first lens G1 satisfies the relationship: 0.9<|f1 / L1|<1.3;

[0051] The first lens G1 converges parallel incident light to the aperture S. By satisfying the above relationship, on the one hand, the light height can be quickly reduced, which is beneficial to reducing the length of the system. On the other hand, it is beneficial for the subsequent lenses to move closer to the aperture position, thereby reducing the outer diameter of the lens.

[0052] Furthermore, the focal length f2 of the second lens G2 satisfies the relationship: 0.8<|f2 / L1|<1.3; the second lens G2 is far away from the first lens G1 and close to the aperture S side, so that a small outer diameter can be maintained; Figure 1 As shown, the second lens G2 is a meniscus structure bent toward the aperture, which can relax the angle of incident light and balance spherical aberration and coma;

[0053] Focal length f of cemented lens group U1 U1 Satisfies the relationship: 0.3<|f U1 / L1 < 0.6; In this embodiment, the third lens G3 is made of a low-dispersion material, which can better correct chromatic aberration. Specifically, the refractive index of the third lens G3 is n3, and the Abbe number is v3. n3 and v3 respectively satisfy the relational expressions: 1.47 < n3 < 60, 65 < v3 < 82.

[0054] The focal length f of the cemented lens group U2 U2 Satisfies the relational expression: 0.5 < |f U2 / L2 < 0.8; In this embodiment, both lenses of the cemented lens group U2, namely the fifth lens G5 and the sixth lens G6, are made of materials with relatively high refractive indices, which can bear a large incident angle, maintain a proper shape at the same time, and form small field curvature and spherical aberration.

[0055] The focal length f7 of the seventh lens G7 satisfies the following relational expression: 0.35 < |f7 / L2| < 0.62;

[0056] The focal length f of the cemented lens group U3 U3 Satisfies the relational expression: 0.75 < |f U3 / L2 < 1.05. In this embodiment, the refractive index of the eighth lens G8 is n8, and the refractive index of the ninth lens G9 is n9, which satisfy the relational expression: n8 < n9. By satisfying the above relational expressions, the cemented surface of the cemented lens has a negative optical power, which can balance the remaining spherical aberration and coma of the front lenses, and is also beneficial to the correction of distortion.

[0057] In this embodiment, the first lens G1 to the ninth lens G9 are all glass spherical lenses. Specifically, the first lens G1 is a glass spherical lens with a biconvex structure, and the second lens G2, the third lens G3, the fourth lens G4 and the ninth lens G9 are all glass spherical lenses with a meniscus structure. The fifth lens G5 is a glass spherical lens with a biconcave structure, and the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all glass spherical lenses with a biconvex structure.

[0058] In this embodiment, the aperture of the aperture stop S is set as a circular hole, and the center of the circular hole is on the predetermined optical axis;

[0059] The aperture adjustment range of the aperture stop is F4.8~F32.

[0060] Exemplarily, based on the above design concept, an optical system is designed in this embodiment, as Figure 2 shown. The relevant data of this optical system are specifically shown in Table 1:

[0061] Table 1

[0062] surface Radius(mm) Thickness(mm) Refractive Index Abbe number G1 front surface 409.8 24.4 1.70 25 G1 rear surface -827.0 247.9 G2 front surface 79.2 10.6 1.65 G2 rear surface 118.1 18.5 G3 front surface 28.5 13.9 1.50 80 G3, G4 glued surface 95.4 10.3 1.80 G4 rear surface 21.9 25.9 Aperture S ∞ 6.5 G5 front surface -8.2 1.3 1.95 G5, G6 bonding surface 75.9 5.5 1.80 G6 rear surface -12.3 0.1 G7 front surface 286.1 5.7 1μ90 G7 back surface -27.0 3.2 G8 front surface 56.3 7.7 1μ95 G8, G9 bonding surface -19.3 8.5 2.0 25 G9 rear surface -188.6 18.9 Image plane /

[0063] It should be noted that in Table 1, "front surface" corresponds to Figure 2The left side surface of the lens or lens group corresponds to the "back surface" Figure 2 The corresponding lens or lens group on the right side surface; or can be understood as: the object side is Figure 2 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".

[0064] In the optical system shown in the table above, the distance L1 = 351 mm, the distance L2 = 57 mm, the focal length f1 of the first lens G1 = 391 mm, the focal length f2 of the second lens G2 = 332 mm, and the focal length f U1 =-158mm, focal length f of cemented lens group U2 U2 =-38mm, focal length f of cemented lens group U3 U3 =51mm, the focal length f7 of the seventh lens G7=27mm;

[0065] The optical system has a double telecentric structure, a working distance of 306mm, an object field of view of Φ150mm, a maximum aperture of F4.8, and a maximum imaging surface of Φ11mm.

[0066] Please refer to Figure 3 and Figure 4 , Figure 3 : is an MTF curve diagram of an optical system of a high-resolution and low-distortion double telecentric lens provided by an embodiment of the present invention, Figure 4 is an optical distortion curve of an optical system of a high-resolution, low-distortion bi-telecentric lens provided by an embodiment of the present invention;

[0067] like Figure 3 As shown, the MTF value of the optical system at the full field of view of 200lp / mm is >0.3, which can achieve high-resolution imaging of the optical system.

[0068] like Figure 4 As shown, it can be seen that the distortion of the optical system is less than 0.02%, which is very small and can meet the requirements of high-precision measurement.

[0069] This embodiment realizes a high-resolution and low-distortion bi-telecentric lens through the structural design of the above optical system. The distortion of the whole field of view is less than 0.02%, the resolution can reach 200lp / mm, and it can support high-resolution cameras with 2.5 micron pixels.

[0070] Embodiment 2:

[0071] See also Figure 1 , Figure 1 It is a structural schematic diagram of an optical system of a high-resolution and low-distortion double telecentric lens provided by an embodiment of the present invention.

[0072] like Figure 1 As shown, the optical system includes 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 fifth lens G5 with negative focal power, a sixth lens G6 with positive focal power, a seventh lens G7 with positive focal power, an eighth lens G8 with positive focal power, and a ninth lens G9 with negative focal power, which are sequentially arranged from the object side to the image side, and the optical axes of all the lenses coincide with the predetermined optical axis;

[0073] The third lens G3 and the fourth lens G4 form a cemented lens U1, the fifth lens G5 and the sixth lens G6 form a cemented lens U2, and the eighth lens G8 and the ninth lens G9 form a cemented lens U3;

[0074] The aperture S is disposed between the fourth lens G4 and the fifth lens G5; the light rays incident in parallel to the first lens G1 converge at the aperture S after being refracted by the second lens G2 and the cemented lens U1.

[0075] Furthermore, the center distance between the front surface of the first lens G1 and the aperture S is L1, and the center distance between the aperture S and the image plane is L2;

[0076] The focal length f1 of the first lens G1 satisfies the relationship: 0.9<|f1 / L1|<1.3;

[0077] The first lens G1 converges parallel incident light to the aperture S. By satisfying the above relationship, on the one hand, the light height can be quickly reduced, which is beneficial to reducing the length of the system. On the other hand, it is beneficial for the subsequent lenses to move closer to the aperture position, thereby reducing the outer diameter of the lens.

[0078] Furthermore, the focal length f2 of the second lens G2 satisfies the relationship: 0.8<|f2 / L1|<1.3; the second lens G2 is far away from the first lens G1 and close to the aperture S side, so that a small outer diameter can be maintained; Figure 1 As shown, the second lens G2 is a meniscus structure bent toward the aperture, which can relax the angle of incident light and balance spherical aberration and coma;

[0079] Focal length f of cemented lens group U1 U1 Satisfies the relationship: 0.3<|f U1 / L1|<0.6; In this embodiment, the third lens G3 is made of low dispersion material, which can better correct chromatic aberration. Specifically, the refractive index of the third lens G3 is n3, the Abbe number is v3, and n3 and v3 respectively satisfy the relationship: 1.47 <n3<60,65<v3<82。

[0080] Focal length f of cemented lens group U2 U2 Satisfies the relationship: 0.5<|f U2 / L2 < 0.8; In this embodiment, both lenses of the cemented lens group U2, namely the fifth lens G5 and the sixth lens G6, are made of materials with relatively high refractive indices, which can bear a relatively large incident angle, while maintaining a suitable shape to form a relatively small field curvature and spherical aberration.

[0081] The focal length f7 of the seventh lens G7 satisfies the following relationship: 0.35 < |f7 / L2| < 0.62;

[0082] The focal length f of the cemented lens group U3 U3 satisfies the relationship: 0.75 < |f U3 / L2| < 1.05. In this embodiment, the refractive index of the eighth lens G8 is n8, and the refractive index of the ninth lens G9 is n9, which satisfies the relationship: n8 < n9. By satisfying the above relationship, the cemented surface of the cemented lens has a negative optical power, which can balance the remaining spherical aberration and coma of the front lenses, and is also beneficial to the correction of distortion.

[0083] In this embodiment, the first lens G1 to the ninth lens G9 are all glass spherical lenses. Specifically, the first lens G1 is a glass spherical lens with a biconvex structure, the second lens G2, the third lens G3, the fourth lens G4, and the ninth lens G9 are all glass spherical lenses with a meniscus structure, the fifth lens G5 is a glass spherical lens with a biconcave structure, and the sixth lens G6, the seventh lens G7, and the eighth lens G8 are all glass spherical lenses with a biconvex structure.

[0084] In this embodiment, the aperture of the aperture stop S is set as a circular hole, and the center of the circular hole is on the predetermined optical axis;

[0085] The aperture adjustment range of the aperture stop is F4.8 to F32.

[0086] Exemplarily, based on the above design concept, an optical system is designed in this embodiment, as Figure 5 shown. The relevant data of this optical system are specifically shown in Table 2:

[0087] Table 2

[0088] surface Radius(mm) Thickness(mm) Refractive Index Abbe number G1 front surface 394.4 19.1 1.85 24 G1 rear surface -779.5 191.4 G2 front surface 80.9 12.5 1.50 G2 rear surface 133.9 3.3 G3 front surface 27.2 14.7 1.50 80 G3, G4 glued surface 162.5 14.2 1.75 G4 rear surface 17.1 22.0 Aperture S ∞ 3.3 G5 front surface -8.9 1.6 1.92 G5, G6 bonding surface 32.0 <![CDATA[5 . 4]]> 1.75 G6 rear surface -12.3 0.9 G7 front surface 99.4 8.0 1μ80 G7 back surface -30.1 10.2 G8 front surface 56.6 8.0 1μ94 G8, G9 bonding surface -37.8 7.8 1.95 30 G9 rear surface -143.8 16.7 Image plane /

[0089] It should be noted that in Table 2, "front surface" corresponds to Figure 5 the left surface of the corresponding lens or lens group in Figure 5 , and "rear surface" corresponds to Figure 5 the right surface of the corresponding lens or lens group in Figure 1 ; or it can be understood that: the object side is on the

[0090] In the optical system shown in the table above, the distance L1 = 280 mm, the distance L2 = 62 mm, the focal length f1 of the first lens G1 = 304 mm, the focal length f2 of the second lens G2 = 338 mm, and the focal length f U1 =-93mm, focal length f of cemented lens group U2 U2 =-48mm, focal length f of cemented lens group U3 U3 =49mm, and the focal length f7 of the seventh lens G7 =29mm.

[0091] In the second embodiment, the lens optical system is a double telecentric structure, with a working distance of 312 mm, an object field of view of Φ120 mm, a maximum aperture of F4.2, and a maximum imaging surface of φ11 mm.

[0092] Please refer to Figure 6 and Figure 7 , Figure 6 : is an MTF curve diagram of another optical system of a high-resolution and low-distortion bi-telecentric lens provided by an embodiment of the present invention when the working distance is 312 mm. Figure 7 is an optical distortion curve of another optical system of a high-resolution and low-distortion bi-telecentric lens provided by an embodiment of the present invention when the working distance is 312 mm;

[0093] like Figure 6 As shown, the MTF value of the optical system at the full field of view of 230lp / mm is >0.3, and it can support up to 2.2-micron pixel cameras, enabling high-resolution imaging of the optical system.

[0094] like Figure 7 As shown, it can be seen that the distortion of the optical system is less than 0.012%, which is very small and can measure objects with almost no deformation.

[0095] This embodiment realizes a high-resolution and low-distortion bi-telecentric lens through the structural design of the above optical system. The distortion of the whole field of view is less than 0.012%, the resolution can reach 230lp / mm, and it can support high-resolution cameras with 2.5 micron pixels.

[0096] Embodiment three:

[0097] This embodiment provides a high-resolution and low-distortion bi-telecentric lens, including an optical system of a high-resolution and low-distortion bi-telecentric lens as described in Embodiment 1 or Embodiment 2.

[0098] Since the optical system has been described in detail in the above embodiments, it will not be described in detail in this embodiment.

[0099] Furthermore, this embodiment also provides a 2.5-micron pixel camera equipped with a high-resolution, low-distortion dual-telecentric lens as described above.

[0100] In summary, the embodiment of the present invention realizes a high-resolution and low-distortion bi-telecentric lens with a full field of view distortion of less than 0.02% and a resolution of up to 200lp / mm. It can be adapted to a high-resolution camera with 2.5-micron pixels, effectively improving the measurement accuracy.

[0101] 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 high-resolution and low-distortion double telecentric lens, characterized in that: The optical lens comprises a first lens G1 with positive power, a second lens G2 with positive power, a third lens G3 with positive power, a fourth lens G4 with negative power, a fifth lens G5 with negative power, a sixth lens G6 with positive power, a seventh lens G7 with positive power, an eighth lens G8 with positive power and a ninth lens G9 with negative power, which are sequentially arranged from the object side to the image side, and the optical axes of all the lenses coincide with the predetermined optical axis; The third lens G3 and the fourth lens G4 form a cemented lens U1, the fifth lens G5 and the sixth lens G6 form a cemented lens U2, and the eighth lens G8 and the ninth lens G9 form a cemented lens U3; The aperture S is disposed between the fourth lens G4 and the fifth lens G5; the light rays incident in parallel to the first lens G1 converge at the aperture S after being refracted by the second lens G2 and the cemented lens U1.

2. The optical system of a high-resolution and low-distortion double telecentric lens according to claim 1, characterized in that: The center distance between the front surface of the first lens G1 and the aperture S is L1, and the center distance between the aperture S and the image plane is L2; The focal length f1 of the first lens G1 satisfies the relationship: 0.9<|f1 / L1|<1.3; The focal length f2 of the second lens G2 satisfies the relationship: 0.8<|f2 / L1|<1.3; Focal length f of cemented lens group U1 U1 Satisfies the relationship: 0.3<|f U1 / L1|<0.6; Focal length f of cemented lens group U2 U2 Satisfies the relationship: 0.5<|f U2 / L2|<0.8; The focal length f7 of the seventh lens G7 satisfies the following relationship: 0.35<|f7 / L2|<0.62; Focal length f of cemented lens group U3 U3 Satisfies the relationship: 0.75<|f U3 / L2|<1.

05.

3. The optical system of a high-resolution and low-distortion bi-telecentric lens according to claim 1, characterized in that: The first lens G1 is a glass spherical lens with a biconvex structure, the second lens G2, the third lens G3, the fourth lens G4 and the ninth lens G9 are all glass spherical lenses with a meniscus structure, the fifth lens G5 is a glass spherical lens with a biconcave structure, the sixth lens G6, the seventh lens G7 and the eighth lens G8 are all glass spherical lenses with a biconvex structure.

4. The optical system of a high-resolution and low-distortion double telecentric lens according to claim 2, characterized in that: The refractive index of the third lens G3 is n3, and the Abbe number is v3. n3 and v3 respectively satisfy the relationship: 1.47 <n3<60,65<v3<82。 5. The optical system of a high-resolution and low-distortion double telecentric lens according to claim 2, characterized in that: The refractive index of the eighth lens G8 is smaller than the refractive index of the ninth lens G9.

6. The optical system of a high-resolution and low-distortion bi-telecentric lens according to claim 1, characterized in that: The aperture of the aperture S is a circular hole, and the center of the circular hole is on the predetermined optical axis; The aperture adjustment range of the diaphragm is F4.8 to F32.

7. A high-resolution, low-distortion bi-telecentric lens, characterized in that: An optical system comprising a high-resolution, low-distortion, double-telecentric lens as described in any one of claims 1-6.

8. A 2.5 micron pixel camera, characterized in that: Equipped with a high-resolution, low-distortion bi-telecentric lens as claimed in claim 7.

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