CN114815187B - Telecentric optical system and telecentric optical lens - Google Patents
Telecentric optical system and telecentric optical lens Download PDFInfo
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- CN114815187B CN114815187B CN202210430160.4A CN202210430160A CN114815187B CN 114815187 B CN114815187 B CN 114815187B CN 202210430160 A CN202210430160 A CN 202210430160A CN 114815187 B CN114815187 B CN 114815187B
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- 230000003287 optical effect Effects 0.000 title claims abstract description 162
- 239000007788 liquid Substances 0.000 claims abstract description 58
- 229910052746 lanthanum Inorganic materials 0.000 claims description 9
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 9
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 4
- 229910052731 fluorine Inorganic materials 0.000 claims description 4
- 239000011737 fluorine Substances 0.000 claims description 4
- 239000011521 glass Substances 0.000 claims description 4
- 229910052788 barium Inorganic materials 0.000 claims description 3
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims 3
- 238000001514 detection method Methods 0.000 abstract description 6
- 230000000007 visual effect Effects 0.000 abstract description 4
- 239000006185 dispersion Substances 0.000 description 19
- 238000012546 transfer Methods 0.000 description 16
- 238000010586 diagram Methods 0.000 description 13
- 238000005286 illumination Methods 0.000 description 11
- 230000004075 alteration Effects 0.000 description 10
- 239000005308 flint glass Substances 0.000 description 9
- 239000005331 crown glasses (windows) Substances 0.000 description 6
- 230000008859 change Effects 0.000 description 5
- 238000003384 imaging method Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 230000005499 meniscus Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000011179 visual inspection Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/22—Telecentric objectives or lens systems
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
- G02B13/005—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having spherical lenses only
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B3/00—Simple or compound lenses
- G02B3/12—Fluid-filled or evacuated lenses
- G02B3/14—Fluid-filled or evacuated lenses of variable focal length
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/023—Mountings, adjusting means, or light-tight connections, for optical elements for lenses permitting adjustment
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/04—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B30/00—Camera modules comprising integrated lens units and imaging units, specially adapted for being embedded in other devices, e.g. mobile phones or vehicles
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
Abstract
The invention discloses a telecentric optical system and a telecentric optical lens, wherein a first lens group, a liquid lens and a second lens group are arranged at intervals along a main optical axis of the telecentric optical system from an object side to an image side, and the first lens group comprises M lenses which are sequentially arranged at intervals from the object side to the image side; the driving voltage or driving current of the liquid lens can be adjusted to adjust the focusing position of the telecentric optical system; the second lens group comprises N lenses which are sequentially arranged at intervals from the object side to the image side; wherein M is more than or equal to 5,N, and the values of M and N are the same or different. According to the invention, the original telecentric lens with fixed working distance focusing is expanded into the focusing lens with adjustable working distance within the range of 50mm, so that the application limit of the telecentric lens is greatly expanded, and the overall hardware cost and the working efficiency of a visual detection scheme are remarkably improved.
Description
Technical Field
The invention relates to the technical field of optical equipment, in particular to a telecentric optical system and a telecentric optical lens.
Background
With the continuous development of mechanical intelligence, the mechanical visual inspection is used in the fields of high-precision dimension measurement, tiny component identification, high-precision flaw detection and the like, and the telecentric lens is focused on due to excellent optical performances such as parallax free, small distortion, high resolution and the like. Although the telecentric lens has a larger depth of field than other lenses, the detection requirement of people still cannot be met, and when a sample with an ultra-large depth of field is tested, the test requirement can be met only by adopting a mode of moving an inner lens of the camera or integrally moving the camera, but the scheme has the problems of high cost, large volume, high subsequent maintenance cost and low focusing efficiency.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the present invention aims to provide a telecentric optical system and a telecentric optical lens, so as to obtain a telecentric optical system or optical lens with a large depth of field, and avoid the problems of high testing cost and low focusing efficiency caused by the test requirement realized by moving an inner lens of a camera or integrally moving the camera when testing an ultra-large depth of field.
To achieve the above and other related objects, the present invention provides a telecentric optical system, in which:
The first lens group comprises M lenses which are sequentially arranged at intervals from an object side to an image side;
The driving voltage or driving current of the liquid lens is adjustable to adjust the focusing position of the telecentric optical system;
The second lens group comprises N lenses which are sequentially arranged at intervals from the object side to the image side; wherein M is more than or equal to 5,N, and the values of M and N can be the same or different.
Optionally, the telecentric optical system further comprises a diaphragm, and the diaphragm is located between the liquid lens and the second lens group and is disposed at one side of the liquid lens close to the second lens group.
Optionally, the first lens group includes a first lens, a second lens, a third lens, a fourth lens and a fifth lens sequentially arranged at intervals from the object side to the image side; the second lens group comprises a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens which are sequentially arranged at intervals from the object side to the image side.
Optionally, the optical interval between the fifth lens and the diaphragm is 5.137 mm-5.337 mm; the optical interval between the liquid lens and the sixth lens is 3.246 mm-3.546 mm.
Optionally, the optical interval between the first lens and the second lens is 13.681 mm-14.481 mm; the optical interval between the second lens and the third lens is 6.001 mm-6.121 mm; the optical interval between the third lens and the fourth lens is 11.126 mm-11.186 mm; the optical interval between the fourth lens and the fifth lens is between 1.963mm and 1.983 mm.
Optionally, the first lens is a biconvex lens, the second lens is a convex-concave lens, the third lens is a convex-concave lens, the fourth lens is a convex-concave lens, and the fifth lens is a biconcave lens.
Optionally, the first lens and the second lens are both fluorine crown lenses, the third lens is a heavy crown lens, the fourth lens is a lanthanum crown lens, and the fifth lens is a heavy flint lens.
Optionally, the optical interval between the sixth lens and the seventh lens is between 1.971mm and 2.171 mm; the optical interval between the seventh lens and the eighth lens is 13.245 mm-13.845 mm; the optical interval between the eighth lens and the ninth lens is between 1.370mm and 1.570 mm; the optical interval between the ninth lens and the tenth lens is 11.264 mm-11.324 mm; the optical interval between the sixth lens and the image surface of the telecentric optical system is 78.45 mm-78.49 mm.
Optionally, the sixth lens is a meniscus lens, the seventh lens is a meniscus lens, the eighth lens is a meniscus lens, the ninth lens is a biconvex lens, and the tenth lens is a biconvex lens.
Optionally, the sixth lens is a heavy barium flint glass lens, the seventh lens is a crown glass lens, the eighth lens is a heavy flint glass lens, the ninth lens is a heavy lanthanum flint glass lens, and the tenth lens is a heavy lanthanum flint glass lens.
Optionally, the working distance of the telecentric optical system is between 133mm and 183mm.
Optionally, in the telecentric optical system, each lens in the first lens group and the second lens group is a glass lens.
Optionally, the liquid lens comprises a drive circuit assembly for applying a drive voltage or drive current to the liquid lens.
Optionally, the working distance of the telecentric optical system is between 133mm and 183 mm.
The invention also provides a telecentric optical lens, which comprises the telecentric optical system of any one of the schemes.
Compared with the prior art, the telecentric optical system and the telecentric optical lens have at least the following beneficial effects:
The telecentric optical system is provided with a first lens group, a liquid lens and a second lens group at intervals along a main optical axis of the telecentric optical system from an object side to an image side. The first lens group comprises M lenses which are sequentially arranged at intervals from an object side to an image side; the driving voltage or driving current of the liquid lens can be adjusted to adjust the focusing position of the telecentric optical system; the second lens group comprises N lenses which are sequentially arranged at intervals from the object side to the image side; wherein M is more than or equal to 5,N, and the values of M and N can be the same or different. Therefore, the invention utilizes the combination of the liquid lens and the telecentric light path, realizes the variable compensation of the working distance through the front and back curvature variable of the liquid lens, eliminates curvature change of the liquid lens in a large depth-of-field state by controlling the number and the shape of the lenses positioned at two sides of the liquid lens and the distance between the lenses, eliminates aberration, expands the original telecentric lens focusing at a fixed working distance into a focusing lens with adjustable working distance within a range of 50mm, greatly expands the application limit of the telecentric lens, and obviously improves the whole hardware cost and the working efficiency of a visual detection scheme.
Further, the invention can adjust the focusing position of the whole telecentric optical system in real time by controlling the liquid lens driving voltage, thereby completing the purpose of quick focusing at different working distances; because the liquid lens is adopted to realize focusing, the lens has no displacement in the focusing process, the stability is better, and the focusing speed is faster;
in addition, the telecentric optical system and the telecentric lens of the invention do not need to be provided with a driving motor, so that the whole volume is smaller, the structure is more compact, and the cost is lower.
Drawings
FIG. 1 is a schematic diagram of a telecentric optical system according to an embodiment of the invention;
FIG. 2 is a graph of field curves (Field Curvature) of a telecentric optical system with a working distance of 133mm in an embodiment of the invention, wherein the solid lines correspond to sagittal curves with wavelength bands of 465nm, 470nm and 475nm, respectively, the abscissa is in millimeters, and the ordinate corresponds to a (semi) field of view interval Y+ of the telecentric optical system;
FIG. 3 is a graph of Distortion (dispersion) of a telecentric optical system with a working distance of 133mm in an embodiment of the invention, wherein the solid lines correspond to sagittal curves with wavelength bands of 465nm, 470nm and 475nm, respectively, the abscissa is in millimeters, and the ordinate corresponds to a (semi) field of view interval Y+ of the telecentric optical system;
FIG. 4 is a plot of the modulation transfer function (OTF) of the Fourier transform of a telecentric optical system with a working distance of 133mm, wherein the abscissa is the spatial frequency, the ordinate is the optical transfer function modulus (Modulus of the OTF), the solid line represents the meridian (changing) curve, and the dashed line represents the sagittal (Sagittal) curve, according to an embodiment of the invention;
FIG. 5 is a graph of the relative illuminance of an image plane of a telecentric optical system with a working distance of 133mm, according to an embodiment of the invention, wherein the abscissa is the (half) field of view interval and the ordinate is the relative illuminance (Relative Illumination);
FIG. 6 is a graph of dispersion circles for telecentric optics with working distances of 133mm at wavelengths of 465nm, 470nm, and 475nm in an embodiment of the invention;
FIG. 7 is a graph of field curves (Field Curvature) of a telecentric optical system with a working distance of 150mm in an embodiment of the invention, wherein the solid lines correspond to sagittal curves with wavelength bands of 465nm, 470nm and 475nm, respectively, the abscissa is in millimeters, and the ordinate corresponds to the (semi) field of view interval Y+;
FIG. 8 is a graph of Distortion (dispersion) of a telecentric optical system with a working distance of 150mm in an embodiment of the invention, wherein the solid lines correspond to sagittal curves with wavelength bands of 465nm, 470nm and 475nm, respectively, the abscissa is in millimeters, and the ordinate corresponds to the (semi) field of view interval Y+ of the telecentric optical system;
FIG. 9 is a plot of the modulation transfer function (OTF) of the Fourier transform of a telecentric optical system with a working distance of 150mm, wherein the abscissa is the spatial frequency, the ordinate is the optical transfer function modulus (Modulus of the OTF), the solid line represents the meridian (changing) curve, and the dashed line represents the sagittal (Sagittal) curve, in an embodiment of the invention;
FIG. 10 is a graph of the relative illuminance of an image plane of a telecentric optical system with a working distance of 150mm, according to an embodiment of the invention, wherein the abscissa is the (half) field of view interval and the ordinate is the relative illuminance (Relative Illumination);
FIG. 11 is a graph of dispersion circles for telecentric optics with working distances of 150mm at wavelengths of 465nm, 470nm, and 475nm in an embodiment of the invention;
FIG. 12 is a graph of field curves (Field Curvature) of a telecentric optical system with a working distance of 183mm in an embodiment of the invention, wherein the solid lines correspond to sagittal curves with wavelength bands of 465nm, 470nm and 475nm, respectively, the abscissa is in millimeters, and the ordinate corresponds to the (semi) field of view interval Y+;
FIG. 13 is a graph of Distortion (dispersion) of a telecentric optical system with a working distance of 183mm in an embodiment of the invention, wherein the solid lines correspond to sagittal curves with wavelength bands of 465nm, 470nm and 475nm, respectively, the abscissa is in millimeters, and the ordinate corresponds to the (semi) field of view interval Y+ of the telecentric optical system;
FIG. 14 is a plot of the modulation transfer function (OTF) of the Fourier transform of a telecentric optical system with a working distance of 183mm, wherein the abscissa is the spatial frequency, the ordinate is the optical transfer function modulus (Modulus of the OTF), the solid line represents the meridian (changing) curve, and the dashed line represents the sagittal (Sagittal) curve, in an embodiment of the invention;
FIG. 15 is a graph of the relative illuminance of an image plane of a telecentric optical system with a working distance of 183mm, according to an embodiment of the invention, wherein the abscissa is the (half) field of view interval and the ordinate is the relative illuminance (Relative Illumination);
FIG. 16 is a graph of dispersion circles for telecentric optics with working distances of 183mm at wavelengths of 465nm, 470nm, and 475nm in an embodiment of the invention.
List of reference numerals:
1. First lens
2. Second lens
3. Third lens
4. Fourth lens
5. Fifth lens
6. Liquid lens
7. Diaphragm
8. Sixth lens
9. Seventh lens
10. Eighth lens
11. Ninth lens
12. Tenth lens
13. Image side
14. Object side
Detailed Description
Further advantages and effects of the present application will become apparent to those skilled in the art from the disclosure of the present application, which is described by the following specific examples. The application may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present application. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict.
It should be noted that the illustrations provided in the embodiments of the application are merely schematic illustrations of the basic concepts of the application, and only the components related to the application are shown in the illustrations, rather than being drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of each component in actual implementation may be arbitrarily changed, and the layout of the components may be more complicated. The structures, proportions, sizes, etc. shown in the drawings are shown only in connection with the present disclosure for understanding and reading by those skilled in the art, and are not intended to limit the scope of the application, which is defined by the claims, so that any structural modifications, proportional changes, or dimensional adjustments should be made without affecting the efficacy or achievement of the present application.
Example 1
In order to solve the problem that a telecentric lens is only suitable for narrow working scene azimuth caused by a fixed working distance, the embodiment provides a telecentric optical system and a telecentric optical lens, which can focus for a plurality of times within a range of 50mm, thereby improving the detection efficiency and greatly reducing the hardware cost of mechanical vision.
The present embodiment utilizes the rapid and stable deformation characteristics of a liquid lens to achieve rapid focusing by adding the liquid lens (also referred to as a liquid lens) to a telecentric optical system (e.g., telecentric lens). However, the curvature of the liquid lens at a large depth of field becomes large, new aberrations (e.g., spherical aberration and curvature of field) are easily brought about, and a clear phase is not easily obtained. In order to eliminate curvature change of the liquid lens under a large depth of field, the telecentric optical system in the embodiment is provided with a first lens group, a liquid lens and a second lens group at intervals along a main optical axis of the telecentric optical system from an object side to an image side. The first lens group comprises M lenses which are sequentially arranged at intervals from an object side to an image side; the driving voltage or driving current of the liquid lens can be adjusted to adjust the focusing position of the telecentric optical system; the second lens group comprises N lenses which are sequentially arranged at intervals from the object side to the image side; wherein M is more than or equal to 5,N, and the values of M and N can be the same or different; m, N is a positive integer. According to the embodiment, the combination of the liquid lens and the telecentric light path is utilized, the variable compensation of the working distance is realized through the front-back curvature variable of the liquid lens, the curvature change of the liquid lens in a large depth-of-field state is eliminated through controlling the number and the shape of lenses positioned at two sides of the liquid lens and the distance between the lenses, the aberration is eliminated, and the original telecentric lens focusing at a fixed working distance is expanded into a focusing lens with an adjustable working distance within a 50mm range.
Specifically, fig. 1 shows a schematic configuration of the telecentric optical system of the present invention. As shown in fig. 1, a first lens group, a liquid lens 6, and a second lens group are disposed in order from an object side 14 to an image side 13 along a main optical axis of the telecentric optical system; the first lens group comprises a first lens 1, a second lens 2, a third lens 3, a fourth lens 4 and a fifth lens 5 in sequence from the object side to the image side; the second lens group includes, in order from the object side to the image side, a sixth lens 8, a seventh lens 9, an eighth lens 10, a ninth lens 11, and a tenth lens 12. And adjusting the focusing position of the telecentric optical system by controlling the driving voltage or the driving current of the liquid lens so as to finish focusing of the telecentric optical system under different working distances.
In this embodiment, as shown in fig. 1, in order to apply a driving voltage or a driving current to the liquid lens, the liquid lens includes a driving circuit assembly (not shown in the figure), and the driving circuit assembly applies the driving voltage or the driving current to the electrode of the liquid lens, and the curvature of the liquid in the liquid lens is changed to change the focal length, so as to accomplish the focusing purpose under different working distances.
In this example, as shown in FIG. 1, the narrow-band antireflection film for blue light (465-475 nm) was used on all the lens surfaces except the liquid lens. Based on the light path design consideration, the first lens 1 is a biconvex lens, the second lens 2 is a convex-concave lens, the third lens 3 is a convex-concave lens, the fourth lens 4 is a convex-concave lens, the fifth lens 5 is a biconcave lens, the sixth lens 8 is a concave-convex lens, the seventh lens 9 is a concave-convex lens, the eighth lens 10 is a convex-concave lens, the ninth lens 11 is a biconvex lens, and the tenth lens 12 is a biconvex lens. It should be noted that, the main function of the first lens group is to converge the angles of the principal rays and the optical axis of the object-side luminous point corresponding to the object-side field telecentric optical path; the liquid lens is mainly used for adjusting the position of the compensation image plane; the second lens group corresponds to a telecentric light path of the image space visual field, converges to angles of all principal rays and an optical axis of the image space, and ensures the image plane size and the optical multiplying power of the whole system; the curvature and the materials of the lenses are optimized through aberration correction, and the positions of the lenses are not changed, so that the stability of the whole telecentric optical system can be improved.
As shown in fig. 1, in order to limit the size of the light beam or the field of view (imaging range), a diaphragm 7 may be further disposed in the telecentric optical system of the present embodiment, where the diaphragm 7 is disposed on the right side of the liquid lens 6, and in addition, the diaphragm 7 may be further used to shape and optimize the light beam, so as to improve the light beam quality; as an example, the diaphragm 7 may be, for example, an edge of a liquid lens, a frame or a specially provided screen with holes, that is, in other embodiments, the telecentric optical system may be used as the diaphragm 7 without providing the diaphragm 7 exclusively, using an edge of a liquid lens, a frame or the like.
As shown in fig. 1, the telecentric optical system employs a 10-piece optical model, the object plane of a lens refers to the surface of the lens facing the object side 14, and the image plane refers to the surface of the lens facing the image side 13. In the present embodiment, the shape and curvature parameters of each lens of the telecentric optical system are as follows: the object plane of the first lens 1 is a convex spherical surface, the curvature radius is 68.3mm, the image plane is a convex spherical surface, and the curvature radius is-613.2 mm; the object plane of the second lens 2 is a convex spherical surface, the curvature radius is 47mm, the image plane is a concave spherical surface, and the curvature radius is 99.7mm; the object plane of the third lens 3 is a convex spherical surface, the curvature radius is 49.9mm, the image plane is a concave spherical surface, and the curvature radius is 76.3mm; the object plane of the fourth lens 4 is a convex spherical surface, the curvature radius is 28.7mm, the image plane is a concave spherical surface, and the curvature radius is 92.4mm; the object plane of the fifth lens 5 is a concave spherical surface, the curvature radius is-227.1 mm, the image plane is a concave spherical surface, and the curvature radius is 12.6mm; the object plane of the sixth lens 8 is a concave spherical surface, the curvature radius is-10.8 mm, the image plane is a convex spherical surface, and the curvature radius is-13.8 mm; the object plane of the seventh lens 9 is a concave spherical surface, the curvature radius is-51.2 mm, the image plane is a convex spherical surface, and the curvature radius is-19.6 mm; the object plane of the eighth lens 10 is a convex spherical surface, the curvature radius is 201.9mm, the image plane is a concave spherical surface, and the curvature radius is 58.5mm; the object plane of the ninth lens 11 is a convex spherical surface, the curvature radius is 64.2mm, the image plane is a convex spherical surface, and the curvature radius is-57.5 mm; the object plane of the tenth lens 12 is a convex spherical surface, the curvature radius is 293.2mm, the image plane is a convex spherical surface, and the curvature radius is-141.2 mm; in order to ensure imaging quality, the aperture deviation of each lens is not large, and the tolerance of the curvature radius of each lens is limited in the range of 3 apertures of Newton rings. The shape parameters of the lenses may be flexibly adjusted as needed, and are not limited to the above-listed parameters.
In this embodiment, the optical interval parameters between each lens and the liquid lens of the telecentric optical system are as follows: the first lens 1 to the second lens 2 are spaced 14.081mm apart, with a tolerance +/-0.4mm; the second lens 2 to the third lens 3 are spaced 6.061mm apart by a tolerance +/-0.1mm; the third lens 3 to the fourth lens 4 are spaced by 11.156mm with a tolerance +/-0.03mm; the fourth lens 4 to the fifth lens 5 are spaced 1.973mm with a tolerance +/-0.01mm; the interval from the fifth lens 5 to the liquid lens 6 is 5.237mm, and the tolerance is +/-0.1mm; the liquid lens to sixth lens 8 spacing is 3.396, tolerance +/-0.15mm; the sixth lens 8 to seventh lens 9 are spaced 2.071 apart by a tolerance +/-0.1mm; the seventh lens 9 to the eighth lens 10 are spaced 13.545mm apart by a tolerance +/-0.3mm; the eighth lens 10 to the ninth lens 11 are spaced 1.47mm apart by a tolerance +/-0.1mm; the ninth lens 11 to tenth lens 12 are spaced 11.294mm apart by a tolerance +/-0.3mm; the sixth lens 8-to-image plane spacing is 78.47mm with a tolerance of +/-0.02mm. It should be noted that the optical interval may be flexibly adjusted according to the need, and is not limited to the above-listed dimensions.
In the present embodiment, in the telecentric optical system, the lenses other than the liquid lens are glass lenses. Specifically, for example, a-39N (of course, other types of liquid lenses capable of meeting the optical path requirements can be adopted) of corning company can be adopted as the liquid lens, and the liquid lens has different curvature forms according to different driving voltages so as to correspond to different working distances; in a specific example, the curvature forms of the optical lens under the driving of three voltages of 36V/47V/52V (of course, other suitable driving voltages can be adopted) can be utilized, and the optical lens corresponds to a telecentric optical system with a working distance of 133 mm/150 mm/183mm respectively; the materials of the lenses except the liquid lenses are as follows: in an alternative embodiment, the first lens 1 is a fluorine crown glass. The second lens 2 may be a fluorine crown glass. The third lens 3 may be made of dense phosphorus crown glass. The fourth lens 4 may be lanthanum crown glass. The fifth lens 5 may be made of heavy flint glass. The sixth lens 8 may be a heavy barium flint glass. The seventh lens 9 may be crown glass. The eighth lens 10 may employ heavy flint glass. The ninth lens 11 may be made of heavy lanthanum flint glass. The tenth lens 12 may be a heavy lanthanum flint glass. It should be noted that the materials of the telecentric optical system of this example can be adjusted according to the actual situation, and are not limited to the above-described shape and size; it will be appreciated that in other embodiments, each lens of the telecentric optical system other than the liquid lens may also employ a combination of glass and plastic lenses, or all plastic lenses.
In the embodiment, the working wavelength of the telecentric optical system is between 465nm and 675nm, and the axial chromatic aberration and vertical chromatic aberration of the whole system are compensated and corrected by lenses with different refractive indexes and chromatic dispersion coefficients; the maximum half field of view of the telecentric optical system is 19.2mm; the working distance of the telecentric optical system is between 133mm and 183mm, such as 133mm,150mm,183mm or other suitable values.
FIGS. 2-6 show performance plots of a field curvature (Field Curvature) plot, a Distortion (dispersion) plot, a Fourier transform modulation transfer function (OTF) plot, an image plane relative illuminance plot, and a dispersion plot, respectively, for a telecentric optical system having a working distance of 133 mm; FIGS. 7-11 show performance plots of a field curvature (Field Curvature) plot, a Distortion (dispersion) plot, a Fourier transform modulation transfer function (OTF) plot, an image plane relative illuminance plot, and a dispersion plot, respectively, for a telecentric optical system having a working distance of 150 mm; fig. 12-16 show performance plots of field curvature (Field Curvature) plot, distortion (dispersion) plot, fourier transform modulation transfer function (OTF) plot, image plane relative illuminance plot, and dispersion plot, respectively, for a 183mm working distance telecentric optical system.
FIGS. 2 and 3 show field curvature (Field Curvature) and Distortion (dispersion) diagrams of a telecentric optical system having a working distance of 133 mm; FIGS. 7 and 8 show field curvature (Field Curvature) and Distortion (dispersion) diagrams of a telecentric optical system having a working distance of 150 mm; FIGS. 12 and 13 show field curvature (Field Curvature) and Distortion (dispersion) diagrams of a telecentric optical system having a working distance of 183 mm; in the field curve (Field Curvature) diagram, the solid line represents a meridian (changing) curve, the dashed line represents a sagittal (Sagittal) curve, the abscissa is in millimeters, the ordinate corresponds to the (half) field interval y+ of the optical system, in the Distortion (dispersion) diagram, the abscissa is in percent Distortion, and the ordinate corresponds to the (half) field interval y+ of the fixed-focus optical system, and the 3 curves represent Distortion (dispersion) diagrams of the fixed-focus optical system at wavelengths of 465nm, 470nm and 475nm, respectively, it is to be noted that fig. 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15 and 16 only study the performance of half fields of view because the telecentric optical system of the present invention is rotationally symmetrical. It can be seen from the field diagrams and distortion diagrams of the telecentric optical systems with different working distances that the maximum distortion generally occurs at the whole edge position of the field, the distortion is distributed according to the rule that the field gradually increases from small to large, and the maximum distortion is 0.112%.
FIG. 4 shows a modulation transfer function (OTF) plot of the Fourier transform of a telecentric optical system with a working distance of 133 mm; FIG. 9 shows a modulation transfer function (OTF) plot of the Fourier transform of a telecentric optical system with a working distance of 150 mm; FIG. 14 shows a modulation transfer function (OTF) plot of the Fourier transform of a telecentric optical system with a working distance of 183 mm; in the above-mentioned modulation transfer function (OTF) diagrams of each fourier transform, the abscissa is the spatial frequency, the ordinate is the optical transfer function modulus (Modulus of the OTF), the solid line represents the meridian (changed) curve, and the broken line represents the sagittal (Sagittal) curve, it can be seen from the figure that in the operating band, the spatial transfer function of the whole optical system is one of the performance parameters of the whole optical system operating in this band, which is a way of evaluating the resolution of the whole system, and the corresponding meridian and sagittal curves of different fields of view are shown in the above-mentioned modulation transfer function (OTF) diagrams of each fourier transform.
FIG. 5 shows an image plane illumination map of a telecentric optical system having a working distance of 133 mm; FIG. 10 shows an image plane illumination map of a telecentric optical system with a working distance of 150 mm; FIG. 15 shows an image plane illumination map of a telecentric optical system with a working distance of 183 mm; in each of the above-described image plane illuminance diagrams, the abscissa represents a (half) field of view section, and the ordinate represents relative illuminance (Relative Illumination). The relative illumination mainly shows the illumination distribution condition in different areas of the image surface after the light passes through the optical system, shows the attenuation condition of the illumination of different fields of view, and is an important index for evaluating the illumination of the image surface of the whole optical system. The image plane illuminance curves in the image plane illuminance diagrams are between 0.98 and 1.0, which shows that the uniformity of the illuminance changes correspondingly with the change of the size of the field of view, and the image plane illuminance gradually decreases with the increase of the field of view.
FIG. 6 shows the circle of confusion of a telecentric optical system with a working distance of 133mm at wavelengths 465nm, 470nm and 475 nm; FIG. 11 shows the circle of confusion of a telecentric optical system with a working distance of 60mm at wavelengths 465nm, 470nm and 475 nm; FIG. 16 shows dispersion circles for a telecentric optical system with a working distance of 183mm at wavelengths 465nm, 470nm and 475 nm; the above-mentioned respective circles represent the cases of imaging aberrations of the telecentric optical systems having working distances of 133mm, 150mm and 183mm in different fields of view, and the distribution of aberrations in different fields of view is also an important way to evaluate the overall imaging characteristics of one optical system, and from fig. 6, 11 and 16, it is possible to observe the limits to which the aberrations of the respective fields of view have been corrected.
Example two
The present embodiment provides a telecentric optical lens including the telecentric optical system of the above embodiment. In the embodiment, the telecentric optical system in the first embodiment is applied to the telecentric optical lens, and similarly, the original telecentric lens focusing with fixed working distance can be expanded to the focusing lens with adjustable working distance within 50mm, so that the application limit of the telecentric lens is greatly expanded, and the overall hardware cost and the working efficiency of the visual detection scheme are obviously improved.
Further, the embodiment can adjust the focusing position of the whole telecentric optical system or telecentric lens in real time by controlling the driving voltage of the liquid lens, thereby completing the purpose of quick focusing at different working distances; because the liquid lens is adopted to realize focusing, the lens has no displacement in the focusing process, the stability is better, and the focusing speed is faster;
in addition, the telecentric optical system or the telecentric lens in the embodiment does not need to be provided with a driving motor, so that the whole volume is smaller, the structure is more compact, and the cost is lower.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (10)
1. A telecentric optical system, characterized in that, in a direction from an object side to an image side along a main optical axis of the telecentric optical system, the telecentric optical system is composed of a first lens group, a liquid lens, a diaphragm, and a second lens group in order, wherein:
The first lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens from the object side to the image side in sequence, and the lenses are arranged at intervals; the first lens is a biconvex lens, the second lens is a convex-concave lens, the third lens is a convex-concave lens, the fourth lens is a convex-concave lens, and the fifth lens is a biconcave lens;
A liquid lens whose driving voltage or driving current is adjustable to adjust a focusing position of the telecentric optical system;
the diaphragm is positioned between the liquid lens and the second lens group and is arranged at one side of the liquid lens, which is close to the second lens group;
The second lens group comprises a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens from the object side to the image side in sequence, and the lenses are arranged at intervals; the sixth lens is a concave-convex lens, the seventh lens is a concave-convex lens, the eighth lens is a convex-concave lens, the ninth lens is a biconvex lens, and the tenth lens is a biconvex lens.
2. The telecentric optical system of claim 1 wherein the optical separation between said fifth lens and said stop is between 5.137mm and 5.337 mm; the optical interval between the liquid lens and the sixth lens is 3.246 mm-3.546 mm.
3. The telecentric optical system of claim 1 wherein the optical separation between said first and second lenses is between 13.681mm and 14.481 mm; the optical interval between the second lens and the third lens is 6.001-6.121 mm; the optical interval between the third lens and the fourth lens is 11.126-11.186 mm; the optical interval between the fourth lens and the fifth lens is between 1.963mm and 1.983 mm.
4. The telecentric optical system of claim 1 wherein said first lens and said second lens are both fluorine crown lenses, said third lens is a heavy crown lens, said fourth lens is a lanthanum crown lens, and said fifth lens is a heavy flint lens.
5. The telecentric optical system of claim 1 wherein the optical separation between said sixth and seventh lenses is between 1.971mm and 2.171 mm; the optical interval between the seventh lens and the eighth lens is 13.245 mm-13.845 mm; the optical interval between the eighth lens and the ninth lens is between 1.370mm and 1.570 mm; the optical interval between the ninth lens and the tenth lens is 11.264 mm-11.324 mm; the optical interval between the sixth lens and the image surface of the telecentric optical system is 78.45 mm-78.49 mm.
6. The telecentric optical system of claim 1 wherein said sixth lens is a barium flint lens, said seventh lens is a crown lens, said eighth lens is a flint lens, said ninth lens is a lanthanum flint lens, said tenth lens is a lanthanum flint lens.
7. The telecentric optical system of claim 1 wherein the working distance of the telecentric optical system is between 133mm and 183mm.
8. The telecentric optical system of claim 1 wherein each lens within said first and second lens groups is a glass lens in said telecentric optical system.
9. The telecentric optical system of claim 1, wherein the liquid lens comprises a drive circuit assembly for applying a drive voltage or drive current to the liquid lens.
10. A telecentric optical lens comprising the telecentric optical system of any one of claims 1 to 9.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5905596A (en) * | 1997-02-25 | 1999-05-18 | Fuji Photo Optical Co., Ltd. | Telecentric projection lens system |
| CN110927941A (en) * | 2018-09-19 | 2020-03-27 | 精工爱普生株式会社 | Projection optical system and projection type image display device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| EP3958024A1 (en) * | 2020-08-21 | 2022-02-23 | Qioptiq Photonics GmbH & Co. KG | Autofocusing microscope lens comprising a liquid lens |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5905596A (en) * | 1997-02-25 | 1999-05-18 | Fuji Photo Optical Co., Ltd. | Telecentric projection lens system |
| CN110927941A (en) * | 2018-09-19 | 2020-03-27 | 精工爱普生株式会社 | Projection optical system and projection type image display device |
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