Object space telecentric imaging optical system and position alignment device

Abstract

The utility model discloses an object space telecentric imaging optical system and a position alignment device, the object space telecentric imaging optical system comprises an imaging system and an illumination system, the imaging system is provided with an object side and an image side which are oppositely arranged along an optical axis direction; the object space telecentric imaging optical system is composed of a first lens, a second lens, a third lens, a beam splitter prism, a fourth lens, a fifth lens and a sixth lens which are sequentially arranged from the object side to the image side. The illumination system comprises a light source, the light source is arranged corresponding to the beam splitter prism and is used for emitting an illumination light beam, the illumination light beam is reflected by the beam splitter prism and then illuminates the imaging system, through mutual combination of different lenses and reasonable distribution of positive and negative focal power, the magnification factor is increased, distortion is reduced, and high illumination uniformity and low cost are provided.

Description

TECHNICAL FIELD

[0001] The utility model relates to optical technology field especially relates to a object side telecentric imaging optical system and position alignment device. BACKGROUND

[0002] In semiconductor packaging photoetching equipment and flat panel display photoetching, position alignment device is one of very important devices, and from structure, position alignment device can be divided into coaxial position alignment device and off-axis position alignment device two big categories.Off-axis position alignment device can reduce the design, processing and adjustment requirements of optical projection system, and the alignment mode often adopts the measurement method based on machine vision technology, and the imaging lens is one of core components of machine vision system, and the advantages and disadvantages of its optical performance will directly determine the height of final alignment measurement precision.

[0003] Generally, the measuring optical system of high precision needs to ensure the image sharpness and the larger magnification, and the illumination uniformity needs to be less than 5% and the distortion is preferably less than 0.1%, and the products on the market are mostly 5X, and the number of lenses is more, and the cost is high. UTILITY MODEL CONTENTS

[0004] The main purpose of the utility model is to provide an object side telecentric imaging optical system, which aims at increasing magnification, reducing distortion, and providing high illumination uniformity and low cost.

[0005] To achieve the above object, the utility model provides an object side telecentric imaging optical system, comprising:

[0006] An imaging system, the object side telecentric imaging optical system has object side and image side in the direction of optical axis, the object side telecentric imaging optical system is sequentially arranged by first lens, second lens, third lens, light splitting prism, fourth lens, fifth lens and sixth lens from the object side to the image side;

[0007] An illumination system, comprising a light source, the light source is arranged corresponding to the light splitting prism, used to emit illumination beam, and after reflecting through the light splitting prism, illuminates the imaging system;

[0008] The first lens has positive focal power, the object side surface is convex, and the image side surface is convex.

[0009] The second lens has positive focal power, the object side surface is convex, and the image side surface is convex.

[0010] The third lens has negative focal power, the object side surface is concave, and the image side surface is concave.

[0011] The fourth lens has positive focal power, the object side surface is convex, and the image side surface is convex.

[0012] The fifth lens has positive refractive power, a concave object side surface, and a convex image side surface.

[0013] The sixth lens has positive refractive power, a concave object side surface, and a convex image side surface.

[0014] In an embodiment, the focal length of the object side telecentric imaging optical system is f, the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, and the following relationships are satisfied: 1.7 < |f1 / f| < 1.9, 1.9 < |f2 / f| < 2.1, 1.5 < |f3 / f| < 1.7, 4.5 < |f4 / f| < 4.7, 1.0 < |f5 / f| < 1.3, and 6.1 < |f6 / f| < 6.3.

[0015] In an embodiment, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are glass spherical lenses.

[0016] In an embodiment, the focal length of the object side telecentric imaging optical system is f, the total optical length of the object side telecentric imaging optical system is TTL, and the following conditions are satisfied:

[0017] 11.5 < TTL / f < 12, and 150 mm < TTL < 170 mm.

[0018] In an embodiment, the image side numerical aperture of the object side telecentric imaging optical system is NA, the F-number is F, and the following conditions are satisfied:

[0019] NA ≥ 0.12, and 33.1 ≤ F < 33.5.

[0020] In an embodiment, the refractive index of the first lens is n1, the refractive index of the second lens is n2, the refractive index of the third lens is n3, the refractive index of the fourth lens is n4, the refractive index of the fifth lens is n5, and the refractive index of the sixth lens is n6, and the following conditions are satisfied: 1.44 < n1 < 1.56, 1.44 < n2 < 1.56, 1.55 < n3 < 1.7, 1.45 < n4 < 1.6, 1.45 < n5 < 1.6, and 1.5 < n6 < 1.65.

[0021] In an embodiment, the first lens has an Abbe number v1, the second lens has an Abbe number v2, the third lens has an Abbe number v3, the fourth lens has an Abbe number v4, the fifth lens has an Abbe number v5, and the sixth lens has an Abbe number v6, and the following conditions are satisfied: 63.0 < v1 < 64.0, 63.0 < v2 < 64.0, 36.0 < v3 < 37.0, 70.0 < v4 < 71.0, 81.0 < v5 < 82.0, and 40.0 < v6 < 41.0.

[0022] In an embodiment, the first lens has a thickness G1, the second lens has a thickness G2, the third lens has a thickness G3, the fourth lens has a thickness G4, the fifth lens has a thickness G5, and the sixth lens has a thickness G6, and the following conditions are satisfied:

[0023] 2 mm < G1 < 5 mm, 2 mm < G2 < 5 mm, 0.8 mm < G3 < 3 mm, 1 mm < G4 < 3 mm, 1 mm < G5 < 3 mm, and 2 mm < G6 < 4 mm.

[0024] In an embodiment, the first lens has a radius of curvature of an object side R2 and a radius of curvature of an image side R3, the second lens has a radius of curvature of an object side R4 and a radius of curvature of an image side R5, the third lens has a radius of curvature of an object side R6 and a radius of curvature of an image side R7, the fourth lens has a radius of curvature of an object side R9 and a radius of curvature of an image side R10, the fifth lens has a radius of curvature of an object side R11 and a radius of curvature of an image side R12, and the sixth lens has a radius of curvature of an object side R13 and a radius of curvature of an image side R14, and the following conditions are satisfied:

[0025] 110 mm < R2 < 130 mm, -25 mm < R3 < -10 mm, 15 mm < R4 < 40 mm, -45 mm < R5 < -28 mm, -30 mm < R6 < -15 mm, 45 mm < R7 < 65 mm, 35 mm < R9 < 55 mm, -145 mm < R10 < -125 mm, -20 mm < R11 < -8 mm, 45 mm < R12 < 65 mm, -40 mm < R13 < -25 mm, and -30 mm < R14 < -15 mm.

[0026] The utility model discloses still position alignment device, including object side telecentric imaging optical system, including:

[0027] An imaging system, the object side telecentric imaging optical system has opposite arrangement along the optical axis direction object side and image side, the object side telecentric imaging optical system is sequentially arranged by the first lens, the second lens, the third lens, the light splitting prism, the fourth lens, the fifth lens and the sixth lens from the object side to the image side;

[0028] An illumination system, comprising a light source, the light source is arranged corresponding to the light splitting prism, used to emit illumination light beam, and illuminates the imaging system after reflecting through the light splitting prism;

[0029] The first lens has positive focal power, the object side surface is convex, and the image side surface is convex.

[0030] The second lens has positive focal power, the object side surface is convex, and the image side surface is convex.

[0031] The third lens has negative focal power, the object side surface is concave, and the image side surface is concave.

[0032] The fourth lens has positive focal power, the object side surface is convex, and the image side surface is convex.

[0033] The fifth lens has positive focal power, the object side surface is concave, and the image side surface is concave.

[0034] The sixth lens has positive focal power, the object side surface is concave, and the image side surface is convex.

[0035] In the technical scheme of the utility model, the imaging system constitutes an object side telecentric system, can provide stable imaging quality in a wider working distance range, ensures constant magnification, meets the requirement of precision detection, improves the collection effect of light through the first lens with positive focal power, thereby providing a large field of view, well corrects the spherical aberration and chromatic aberration of the system through the first lens with positive focal power, the second lens with positive focal power and the third lens with negative focal power; when the parallel light transmission passes through the light splitting prism, further converges the parallel light through the fourth lens with positive focal power, corrects the system curvature of field and astigmatism through the fifth lens with double concave and positive focal power and the sixth lens with concave-convex and positive focal power, improves the imaging quality; through the comprehensive arrangement of the focal power of each lens, the object side telecentric imaging optical system can well control the light trend, reduce distortion while introducing more light, correct spherical aberration and chromatic aberration, and through the mutual combination of different lenses and the reasonable distribution of the positive and negative focal power, increase the magnification, reduce distortion, and provide high illumination uniformity and low cost. BRIEF DESCRIPTION OF DRAWINGS

[0036] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0037] Figure 1 A schematic diagram of the structure of an embodiment of the object-side telecentric imaging optical system provided by this utility model;

[0038] Figure 2 for Figure 1 A schematic diagram of the MTF curve of an embodiment of the telecentric imaging optical system of China Physics Group.

[0039] Figure 3 for Figure 1 A schematic diagram of a TFM (Transient Micrometer) system according to an embodiment of the telecentric imaging optical system of China Physics Group.

[0040] Figure 4 for Figure 1 A dot diagram of an embodiment of the telecentric imaging optical system of China Physics Group.

[0041] Figure 5 for Figure 1 A schematic diagram of field curvature / distortion in an embodiment of the telecentric imaging optical system of China Physics Group.

[0042] Figure 6 for Figure 1 Uniformity simulation diagram of an embodiment of the telecentric imaging optical system of China Physics.

[0043] Explanation of icon numbers:

[0044] 100. Object-side telecentric imaging optical system; 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Object plane; 8. Beam splitter; 9. Image plane; 10. Light source.

[0045] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0046] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0047] It should be noted that if the embodiment of the utility model has the directionality indication (such as up, down, left, right, front, back, etc.), the directionality indication is only used to explain the relative position relationship, movement condition, etc. between the components in a certain specific posture, if the specific posture changes, the directionality indication also changes accordingly.

[0048] In addition, if the embodiment of the utility model has the description of "first", "second" and the like, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one feature. In addition, if "and / or" or "and / or" appears in the whole text, its meaning includes three parallel schemes, for example, "A and / or B" includes A scheme, or B scheme, or A and B scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, also not within the protection scope required by the utility model.

[0049] The utility model provides a kind of object side telecentric imaging optical system 100.

[0050] First, it needs to be understood that optical power is equal to the difference between image side beam convergence and object side beam convergence, which represents the ability of optical system to bend light. The greater the absolute value of optical power, the stronger the bending ability of light, and the smaller the absolute value of optical power, the weaker the bending ability of light. When optical power is positive, the refraction of light is convergent; When optical power is negative, the refraction of light is divergent. Optical power can be used to represent a certain refractive surface of a lens, can be used to represent a certain lens, and can be used to represent a system formed by multiple lenses.

[0051] Please refer to Figure 1In an embodiment of the present application, the object-side telecentric imaging optical system 100 comprises an imaging system and an illumination system, the imaging system has an object side and an image side arranged oppositely along the optical axis direction, the object-side telecentric imaging optical system 100 is composed of the first lens 1, the second lens 2, the third lens 3, the light splitting prism 8, the fourth lens 4, the fifth lens 5 and the sixth lens 6 arranged in sequence from the object side to the image side; the illumination system comprises a light source 10, the light source 10 is arranged corresponding to the light splitting prism 8, used to emit an illumination beam, and after reflection by the light splitting prism 8, the imaging system is illuminated, wherein the first lens 1 has positive focal power, the object side is a convex surface, and the image side is a convex surface; the second lens 2 has positive focal power, the object side is a convex surface, and the image side is a convex surface; the third lens 3 has negative focal power, the object side is a concave surface, and the image side is a concave surface; the fourth lens 4 has positive focal power, the object side is a convex surface, and the image side is a convex surface; the fifth lens 5 has positive focal power, the object side is a concave surface, and the image side is a concave surface; the sixth lens 6 has positive focal power, the object side is a concave surface, and the image side is a convex surface.

[0052] It should be noted that the object-side telecentric system means that the light on the object side enters the system almost parallel to the optical axis, that is, the incident angle is close to zero, which means that even if the position of the object changes, the size of the image will not be affected. This design ensures that no matter how the object moves along the optical axis within a certain range, the size of the image remains unchanged, thereby realizing constant magnification. For the imaging system, by so arranging, the imaging system constitutes an object-side telecentric system, which can provide stable imaging quality within a wider working distance range, ensures a larger and constant magnification, and meets the requirements of precision detection.

[0053] In addition, the light splitting prism 8 can be a non-polarization light splitting prism 8, the reflection transmission ratio is 1:1, the light source 10 is located above the light splitting prism 8, and the line connecting the light splitting prism 8 is perpendicular to the optical axis, for emitting an illumination beam; the illumination beam is a parallel light source 10 after passing through a spot homogenizer, and forms a Kohler illumination after being reflected by the light splitting prism 8, thereby improving the illumination uniformity. The illuminated object plane 7 reflects parallel light, and the parallel light sequentially passes through the first lens 1, the second lens 2, the third lens 3, the light splitting prism 8, the fourth lens 4, the fifth lens 5 and the sixth lens 6 in the direction parallel to the optical axis, and finally forms an image on the image plane 9. By arranging the first lens 1 with positive focal power, the second lens 2 with positive focal power and the third lens 3 with negative focal power, the spherical aberration and chromatic aberration of the system are well corrected; when the parallel light transmits through the light splitting prism 8, the fourth lens 4 with positive focal power is arranged to further converge the parallel light, the fifth lens 5 with double concave and positive focal power and the sixth lens 6 with concave-convex and positive focal power are used to jointly correct the field curvature and astigmatism of the system, thereby improving the imaging quality; on the other hand, only six lenses are used, thereby saving the cost.

[0054] In the technical scheme of the utility model, the imaging system constitutes a telecentric system, which can provide stable imaging quality in a wide working distance range, ensure constant magnification, meet the requirements of precision detection, improve the collection of light through the first lens 11 with positive focal power, thereby providing a large field of view, correct the spherical aberration and chromatic aberration of the system through the first lens 1 with positive focal power, the second lens 2 with positive focal power and the third lens 3 with negative focal power, further converge the parallel light through the fourth lens 4 with positive focal power after the parallel light transmits through the light splitting prism 8, correct the field curvature and astigmatism of the system through the fifth lens 5 with double concave and positive focal power and the sixth lens 6 with concave-convex and positive focal power, thereby improving the imaging quality, and control the light trend through the comprehensive arrangement of the focal power of each lens, introduce more light while reducing distortion, correct spherical aberration and chromatic aberration, increase the magnification through the combination of different lenses and reasonable distribution of the positive and negative focal power, reduce distortion, and provide high illumination uniformity and low cost.

[0055] In an embodiment of the utility model, need to understand, focal length refers to the distance from the rear surface of lens to image plane 9 in optical system, focal length determines the magnification and angle of view of image, optical power is the reciprocal of focal length, the focal length of object far -centered imaging optical system 100 is f, the focal length of first lens 1 is f1, the focal length of second lens 2 is f2, the focal length of third lens 3 is f3, the focal length of fourth lens 4 is f4, the focal length of fifth lens 5 is f5, the focal length of sixth lens 6 is f6, and satisfy the following relations: 1.7<|f1 / f|<1.9, 1.9<|f2 / f|<2.1, 1.5<|f3 / f|<1.7, 4.5<|f4 / f|<4.7, 1.0<|f5 / f|<1.3, 6.1<|f6 / f|<6.3;Through the mutual combination of different lenses and the reasonable distribution of optical power, the resolution of the object far -centered imaging optical system 100 is improved.

[0056] In order to reduce the cost, in an embodiment of the utility model, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5 and the sixth lens 6 are glass spherical lenses, on the basis of ensuring the effect, reducing various optical aberrations, effectively inhibiting the chromatic aberration of the system, and because the glass lens is not easy to be affected by thermal expansion and cold shrinkage, the glass lens can well resist the problem of lens thermal deformation, and long-time high precision of the lens is maintained, in addition, compared with aspherical lens, it is easier to manufacture and the cost is lower.

[0057] In an embodiment of the utility model, the optical total length of the object far -centered imaging optical system 100, that is, the distance from the object side of the first lens 1 to the image side of the sixth lens 6 is TTL, the focal length of the object far -centered imaging optical system 100 is f, and satisfy: 11.5<TTL / f<12, 150mm<TTL<170mm;By limiting the optical total length of the object far -centered imaging optical system 100, it is helpful to better match with other detection components, ensure the coordinated operation of the whole system, and in the limited space, the limited optical total length is helpful to optimize the system layout and form the object far -centered system.

[0058] In an embodiment of the utility model, the image side numerical aperture of the object side telecentric imaging optical system 100 is NA, the aperture value is F, and the following conditions are met: NA is 0.12, 33.1 is less than F less than 33.5.When the aperture value F of the object side telecentric imaging optical system 100 is in the range, the resolution and contrast of the lens are optimal, and the lens light throughput is large, and it is easier to realize a large target surface, in addition, it can be understood that the image side numerical aperture is used to describe an important parameter of the light collecting ability of the objective lens, the larger the image side numerical aperture is, the stronger the light collecting ability of the objective lens is, thereby higher resolution and contrast can be realized, and by limiting the image side numerical aperture, the resolution of the object side telecentric imaging optical system 100 is improved.

[0059] In an embodiment of the utility model, the refractive index of the first lens 1 is n1, the refractive index of the second lens 2 is n2, the refractive index of the third lens 3 is n3, the refractive index of the fourth lens 4 is n4, the refractive index of the fifth lens 5 is n5, and the refractive index of the sixth lens 6 is n6, and the following conditions are met: 1.44 is less than n1 less than 1.56, 1.44 is less than n2 less than 1.56, 1.55 is less than n3 less than 1.7, 1.45 is less than n4 less than 1.6, 1.45 is less than n5 less than 1.6, and 1.5 is less than n6 less than 1.65.By controlling the refractive index value range of the lenses, the refractive angle and path of light can be more finely controlled, thereby ensuring that light converges to the correct position, improving clarity and reducing distortion, and improving detection effect.

[0060] In an embodiment of the utility model, the Abbe number of the first lens 1 is v1, the Abbe number of the second lens 2 is v2, the Abbe number of the third lens 3 is v3, the Abbe number of the fourth lens 4 is v4, the Abbe number of the fifth lens 5 is v5, and the Abbe number of the sixth lens 6 is v6, and the following conditions are met: 63.0 is less than v1 less than 64.0, 63.0 is less than v2 less than 64.0, 36.0 is less than v3 less than 37.0, 70.0 is less than v4 less than 71.0, 81.0 is less than v5 less than 82.0, and 40.0 is less than v6 less than 41.0.By controlling the Abbe number value range of the lenses, the refractive index difference of various wavelength light can be effectively balanced by the corresponding dispersion coefficient, chromatic aberration is reduced, the image edge is clearer, color transition is natural, and a clear, distortion-free image is formed.

[0061] It can be understood that the radius of curvature refers to the degree of bending of the lens surface, which determines how light is focused or scattered. Smaller radius of curvature (larger curvature) generally means stronger focusing ability, while larger radius of curvature (smaller curvature) provides longer working distance and greater depth of field. In the position alignment device, selecting the appropriate radius of curvature is crucial to achieve precise alignment, and in the lithography process, the objective lens needs to be precisely focused on the wafer surface to ensure that the pattern can be accurately transferred to the photoresist. If the radius of curvature range is too large or too small, it may cause inaccurate focusing, thereby affecting the quality and yield of the final product. For example, if the radius of curvature is too small, it may increase the spherical aberration; if the radius of curvature is too large, it may not be able to achieve the required high resolution, therefore, in an embodiment of the present application, the radius of curvature of the object side of the first lens 1 is R2, the radius of curvature of the image side is R3, the radius of curvature of the object side of the second lens 2 is R4, the radius of curvature of the image side is R5, the radius of curvature of the object side of the third lens 3 is R6, the radius of curvature of the image side is R7, the radius of curvature of the object side of the fourth lens 4 is R9, the radius of curvature of the image side is R10, the radius of curvature of the object side of the fifth lens 5 is R11, the radius of curvature of the image side is R12, the radius of curvature of the object side of the sixth lens 6 is R13, the radius of curvature of the image side is R14, and satisfy the following conditions: 110mm < R2 < 130mm, -25mm < R3 < -10mm, 15mm < R4 < 40mm, -45mm < R5 < -28mm, -30mm < R6 < -15mm, 45mm < R7 < 65mm, 35mm < R9 < 55mm, -145mm < R10 < -125mm, -20mm < R11 < -8mm, 45mm < R12 < 65mm, -40mm < R13 < -25mm, -30mm < R14 < -15mm; by limiting the radius of curvature range, spherical aberration can be reduced, lithography quality can be improved, and an appropriate radius of curvature range helps to control chromatic aberration, ensuring that light of different wavelengths is focused at the same position to adjust the focusing effect.

[0062] In addition, it can be understood that if the lens thickness range is not appropriate, it can cause inaccurate focusing, thereby affecting the quality and yield of the final product. For example, if the lens is too thick, it can increase the chromatic aberration; if the lens is too thin, it can not achieve the required high resolution, therefore, in an embodiment of the utility model, the thickness of the first lens 1 is G1, the thickness of the second lens 2 is G2, the thickness of the third lens 3 is G3, the thickness of the fourth lens 4 is G4, the thickness of the fifth lens 5 is G5, the thickness of the sixth lens 6 is G6, and the following conditions are met: 2mm < G1 < 5mm, 2mm < G2 < 5mm, 0.8mm < G3 < 3mm, 1mm < G4 < 3mm, 1mm < G5 < 3mm, 2mm < G6 < 4mm; by limiting the thickness of each lens, it is better matched with other position alignment device components (such as mask table, wafer table, etc.), and the coordinated operation of the whole system is ensured.

[0063] Table 1

[0064]

[0065]

[0066] Specifically, in the embodiment, Figure 2 the MTF curve of the example at 50lp / mm, Figure 3 the TFM curve of the example at 40lp / mm, Figure 4 the point column diagram of the example, Figure 5 the field curvature / distortion diagram of the example, Figure 6 the uniformity simulation diagram of the example, by Figures 2-6 It can be known that the fixed focus lens provided by the embodiment has good imaging capability.

[0067] The utility model also proposes a position alignment device, the security lens includes object side telecentric imaging optical system, the specific structure of object side telecentric imaging optical system refers to the above-mentioned embodiment, because the position alignment device adopts all the technical schemes of the above-mentioned all embodiments, therefore at least has all the beneficial effects brought by the technical scheme of the above-mentioned embodiment, here will not repeat.

[0068] The above-mentioned is only the exemplary implementation of the utility model, and does not limit the patent range of the utility model, and all equivalent structural transformations made by using the utility model specification and drawing contents, or direct / indirect application in other related technical fields are included in the patent protection range of the utility model.

Claims

1. An object-side telecentric imaging optical system characterized by comprising: The application relates to an imaging system, and relates to a kind of object side telecentric imaging optical system and illumination system. The object side telecentric imaging optical system is sequentially arranged by first lens, second lens, third lens, light splitting prism, fourth lens, fifth lens and sixth lens from the object side to the image side. The first lens has positive focal power, and the object side surface is convex, and the image side surface is convex. The second lens has positive focal power, and the object side surface is convex, and the image side surface is convex. The third lens has negative focal power, and the object side surface is concave, and the image side surface is concave. The fourth lens has positive focal power, and the object side surface is convex, and the image side surface is convex. The fifth lens has positive focal power, and the object side surface is concave, and the image side surface is concave. The sixth lens has positive focal power, and the object side surface is concave, and the image side surface is convex. The focal length of the object side telecentric imaging optical system is f, the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, and the focal length of the sixth lens is f6, and the following relationships are met: 1.7<|f1 / f|<1.9, 1.9<|f2 / f|<2.1, 1.5<|f3 / f|<1.7, 4.5<|f4 / f|<4.7, 1.0<|f5 / f|<1.3, and 6.1<|f6 / f|<6.

3.

2. The object telecentric imaging optical system according to claim 1, wherein The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are glass spherical lenses.

3. The object telecentric imaging optical system according to claim 1, wherein The focal length of the object side telecentric imaging optical system is f, the total optical length of the object side telecentric imaging optical system is TTL, and the following conditions are met: 11.5<TTL / f<12, and 150mm<TTL<170mm.

4. The object telecentric imaging optical system according to claim 1, wherein The image side numerical aperture of the object side telecentric imaging optical system is NA, the aperture value is F, and the following conditions are met: NA>=0.12, and 33.1<=F<33.

5.

5. The object telecentric imaging optical system according to claim 1, wherein The refractive index of the first lens is n1, the refractive index of the second lens is n2, the refractive index of the third lens is n3, the refractive index of the fourth lens is n4, the refractive index of the fifth lens is n5, and the refractive index of the sixth lens is n6, and the following conditions are met: 1.44<n1<1.56, 1.44<n2<1.56, 1.55<n3<1.7, 1.45<n4<1.6, 1.45<n5<1.6, and 1.5<n6<1.

65. ​ 6. The object telecentric imaging optical system according to claim 1, wherein ​ 7. The object telecentric imaging optical system according to claim 1, wherein An Abbe number of the first lens is v1, an Abbe number of the second lens is v2, an Abbe number of the third lens is v3, an Abbe number of the fourth lens is v4, an Abbe number of the fifth lens is v5, an Abbe number of the sixth lens is v6, and the following conditions are satisfied: 63.0 < v1 < 64.0, 63.0 < v2 < 64.0, 36.0 < v3 < 37.0, 70.0 < v4 < 71.0, 81.0 < v5 < 82.0, 40.0 < v6 < 41.

0.

8. The object telecentric imaging optical system according to claim 1, wherein A thickness of the first lens is G1, a thickness of the second lens is G2, a thickness of the third lens is G3, a thickness of the fourth lens is G4, a thickness of the fifth lens is G5, a thickness of the sixth lens is G6, and the following conditions are satisfied: 2 mm < G1 < 5 mm, 2 mm < G2 < 5 mm, 0.8 mm < G3 < 3 mm, 1 mm < G4 < 3 mm, 1 mm < G5 < 3 mm, 2 mm < G6 < 4 mm.

9. The object telecentric imaging optical system according to claim 1, wherein A radius of curvature of an object side surface of the first lens is R2, a radius of curvature of an image side surface is R3, a radius of curvature of an object side surface of the second lens is R4, a radius of curvature of an image side surface is R5, a radius of curvature of an object side surface of the third lens is R6, a radius of curvature of an image side surface is R7, a radius of curvature of an object side surface of the fourth lens is R9, a radius of curvature of an image side surface is R10, a radius of curvature of an object side surface of the fifth lens is R11, a radius of curvature of an image side surface is R12, a radius of curvature of an object side surface of the sixth lens is R13, a radius of curvature of an image side surface is R14, and the following conditions are satisfied: 110 mm < R2 < 130 mm, -25 mm < R3 < -10 mm, 15 mm < R4 < 40 mm, -45 mm < R5 < -28 mm, -30 mm < R6 < -15 mm, 45 mm < R7 < 65 mm, 35 mm < R9 < 55 mm, -145 mm < R10 < -125 mm, -20 mm < R11 < -8 mm, 45 mm < R12 < 65 mm, -40 mm < R13 < -25 mm, -30 mm < R14 < -15 mm.

10. A position alignment apparatus characterized by comprising: An object side telecentric imaging optical system according to any one of claims 1 to 9.

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