CN114895441A - Liquid lens optical system and endoscope - Google Patents
Liquid lens optical system and endoscope Download PDFInfo
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- CN114895441A CN114895441A CN202210818436.6A CN202210818436A CN114895441A CN 114895441 A CN114895441 A CN 114895441A CN 202210818436 A CN202210818436 A CN 202210818436A CN 114895441 A CN114895441 A CN 114895441A
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/02—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective
- G02B15/04—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective by changing a part
- G02B15/06—Optical objectives with means for varying the magnification by changing, adding, or subtracting a part of the objective, e.g. convertible objective by changing a part by changing the front part
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/24—Instruments or systems for viewing the inside of hollow bodies, e.g. fibrescopes
- G02B23/2407—Optical details
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/24—Instruments or systems for viewing the inside of hollow bodies, e.g. fibrescopes
- G02B23/2407—Optical details
- G02B23/2423—Optical details of the distal end
- G02B23/243—Objectives for endoscopes
- G02B23/2438—Zoom objectives
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- 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
Abstract
The invention provides a liquid lens optical system, which comprises a liquid lens, a plurality of lens groups and a diaphragm, wherein the lens groups comprise a first lens group, a second lens group, a third lens group and a fourth lens group which are sequentially arranged from an object plane to an image plane along an optical axis; the fourth lens group comprises a field lens with negative focal power, and the surface of the field lens, facing the image surface, is a concave surface; the liquid lens optical system satisfies the following conditions: r +2d arctan (H/2 f) is less than or equal to R; wherein R represents the aperture of the diaphragm, R represents the clear aperture of the liquid lens, d represents the optical distance between the diaphragm and the liquid lens, H represents the image height of the liquid lens optical system, and f represents the equivalent focal length of the whole liquid lens optical system. The invention also provides an endoscope.
Description
Technical Field
The invention relates to the technical field of optical imaging systems, in particular to a liquid lens optical system and an endoscope.
Background
The lens can clearly collect images at different working distances through a focusing mode, the focusing mode of a traditional zoom lens (such as an endoscope lens) is realized based on mechanical movement, such as by a manual adjusting knob (which can also be driven by installing a motor), so that lenses or a lens group in the lens are driven to move transversely along an optical axis, and the deviation of the imaging focus of the lens caused by the change of the working distance is compensated by changing the optical interval between the lenses or between the lens and a camera chip.
In the conventional focusing manner, the focusing speed is slow because more time is required to control the lens or the lens group to move transversely along the optical axis; moreover, in some application scenarios (for example, a doctor performs an operation using an endoscope), the manual adjustment of the knob is required to focus, so that the operation is inconvenient, and the use experience of the user is affected. In addition, the existing partial zoom lens also has the problems of narrow working distance range, insufficient focusing definition and the like.
Meanwhile, in an endoscope system, the endoscope system generally comprises a tube lens system and an image pickup system, the image pickup system is often designed separately (that is, the tube lens system and the image pickup system are designed separately), and in order to better correct aberrations, a diaphragm of the image pickup system is generally placed in a lens group (because coma, astigmatism, distortion and vertical axis chromatic aberration are related to the position of the diaphragm in aberration correction). When the tube lens system and the camera system are connected, generally, the eyepiece group of the tube lens system is connected with the camera system, namely, the exit pupil position of the eyepiece is connected with the camera system, if the diaphragm of the camera system is in the middle of the lens group instead of the exit pupil position of the eyepiece, the matching effect of the camera system and the tube lens system is poor, and problems such as light blocking, stray light and the like can occur (the light-passing apertures (especially near the diaphragm) of some lenses can not be completely matched, and light overflows or is blocked on the surfaces of the lenses to cause the problems of stray light, light blocking and the like, further crosstalk is formed on images, and observation of users is seriously influenced).
Disclosure of Invention
The invention aims to provide a liquid lens optical system, which aims to solve or at least partially solve the defects of the background technology, can realize quick automatic focusing, has wide working distance range and high definition, has good matching performance with a tube lens system, and can avoid the problems of light blocking, stray light and the like.
The invention provides a liquid lens optical system, which comprises a liquid lens, a plurality of lens groups and a diaphragm, wherein the lens groups comprise a first lens group, a second lens group, a third lens group and a fourth lens group which are sequentially arranged from an object plane to an image plane along an optical axis, and each lens group comprises at least one lens; the liquid lens is positioned on one side of the first lens group facing the object surface, and the diaphragm is positioned on one side of the liquid lens facing the object surface; the liquid lens and the second lens group each have positive optical power, and the first lens group and the third lens group each have negative optical power; the surface of one side, facing the object plane, of the first lens group is a concave surface, and the surface of one side, facing the object plane, of the third lens group is a concave surface; the fourth lens group comprises a field lens with negative focal power, and the surface of the field lens, facing the image surface, is a concave surface;
the liquid lens optical system satisfies the following conditions: r +2d arctan (H/2 f) is less than or equal to R; wherein R represents the aperture of the diaphragm, R represents the clear aperture of the liquid lens, d represents the optical distance between the diaphragm and the liquid lens, H represents the image height of the liquid lens optical system, and f represents the equivalent focal length of the whole liquid lens optical system.
In an implementable manner, the fourth lens group includes at least two lenses, the field lens being located on a side of at least two of the fourth lens group facing the image plane.
In an implementable manner, the liquid lens optical system further satisfies the following condition: r is max -R < 2 mm; wherein R is max And the maximum light transmission aperture of a plurality of lens groups is represented.
In an implementable manner, the operating voltage of the liquid lens is between a lowest supply voltage and a highest supply voltage; when the liquid lens works between the lowest power supply voltage and the highest power supply voltage, the liquid lens has positive focal power, and the liquid lens optical system can enable an object plane to be clearly imaged within a distance range from infinity to 100 mm.
In an implementable manner, the radius of curvature of the layer of droplets within the liquid lens is-81 mm when the liquid lens is operated at the lowest supply voltage; when the liquid lens works under the highest power supply voltage, the curvature radius of the liquid drop layer in the liquid lens is-8 mm.
In one implementable manner, the lowest supply voltage is 43V and the highest supply voltage is 59V.
In one realisable form, the total length of the liquid lens optical system is < 50 mm.
In a realisable form, all of the lenses of the plurality of said lens groups having negative optical power have abbe numbers less than 40.
In an implementable manner, the liquid lens optical system further satisfies the following condition: h/2f is more than or equal to 0.14 and less than or equal to 0.212, and f is less than or equal to 25 mm.
In an implementable manner, the liquid lens has a minimum focal length f 1 The focal length of the first lens group is f 2 (ii) a The liquid lens optical system further satisfies the following conditions: f. of 1 ≥2|f 2 |。
In an implementable manner, the focal length of the second lens group is f 3 (ii) a The liquid lens optical system further satisfies the following conditions: f/2f 3 ＞1。
In an implementable manner, the liquid lens optical system further comprises a window plate located on the object plane-facing side of the liquid lens, the aperture being provided on the window plate.
The invention also provides an endoscope comprising the liquid lens optical system.
The liquid lens optical system provided by the invention is characterized in that the liquid lens, the first lens group, the second lens group, the third lens group and the fourth lens group are sequentially arranged, the liquid lens and the second lens group both have positive focal power, the first lens group and the third lens group both have negative focal power, and the first lens group and the third lens group both have concave surfaces towards the object plane side, so as to correct aberration generated by the positive focal power of the liquid lens and the second lens group; the fourth lens group comprises a field lens with negative focal power, and the surface of the field lens facing the image surface is a concave surface for the purpose of correcting curvature of field and vertical axis chromatic aberration; through the lens combination, the generated aberration can be matched and eliminated, and larger light deflection cannot be generated, so that the effective light transmission caliber of the lens group is basically consistent with that of the liquid lens; meanwhile, the focal length of the liquid lens can be quickly adjusted by adjusting the working voltage of the liquid lens, so that the focal length of a system can be quickly adjusted, manual driving or motor driving is not needed for focusing, quick automatic focusing is realized, the working distance range is wide, and the definition is high. Meanwhile, the diaphragm is positioned at the foremost end of the liquid lens optical system, and when the liquid lens optical system is connected with the tube lens system, the diaphragm is positioned at the exit pupil position of the ocular lens in the tube lens system, so that the liquid lens optical system can be completely matched with the tube lens system, and the problems of light blocking, stray light and the like are avoided.
Meanwhile, because of the limitation of the current process technology of the liquid lens, the clear aperture of the liquid lens is generally smaller, if the aperture of the light ray exceeds the clear aperture of the liquid lens, the imaging range of the edge light ray is changed, the view field light ray is shielded, and the edge light ray can not be seen completely, so that a dark edge appears; in order to avoid the problems, the liquid lens is arranged close to the diaphragm, parameters such as the aperture of the diaphragm, the clear aperture of the liquid lens, the optical distance between the diaphragm and the liquid lens are limited to meet the condition that R +2d arctan (H/2 f) is less than or equal to R, so that light can completely penetrate through the liquid lens without being blocked by the diaphragm, and the problems are avoided.
Drawings
Fig. 1 is a schematic diagram of an optical path structure of a liquid lens optical system according to a first embodiment of the present invention.
FIG. 2 is a MTF graph of a liquid lens optical system according to a first embodiment of the present invention.
FIG. 3 is a dot diagram of a liquid lens optical system according to a first embodiment of the present invention.
Fig. 4 is a schematic view showing the optical path structure of the endoscope in the first embodiment of the present invention.
Fig. 5 is a schematic diagram of an optical path structure of a liquid lens optical system according to a second embodiment of the present invention.
FIG. 6 is a MTF graph of a liquid lens optical system according to a second embodiment of the present invention.
FIG. 7 is a dot diagram of a liquid lens optical system according to a second embodiment of the present invention.
Fig. 8 is a schematic view showing the optical path structure of an endoscope in a second embodiment of the present invention.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
The terms "first," "second," "third," "fourth," and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
The terms of orientation, up, down, left, right, front, back, top, bottom, and the like (if any) referred to in the specification and claims of the present invention are defined by the positions of structures in the drawings and the positions of the structures relative to each other, only for the sake of clarity and convenience in describing the technical solutions. It is to be understood that the use of the directional terms should not be taken to limit the scope of the invention as claimed.
As shown in fig. 1, a liquid lens optical system 1 according to an embodiment of the present invention includes a liquid lens 12, a plurality of lens groups, and a stop 111. The plurality of lens groups include a first lens group 13, a second lens group 14, a third lens group 15, and a fourth lens group 16, each including at least one lens, which are arranged in order from an object plane to an image plane (i.e., in a left-to-right direction as viewed in fig. 1) along an optical axis; the liquid lens 12 is located on the side of the first lens group 13 facing the object plane, and the diaphragm 111 is located on the side of the liquid lens 12 facing the object plane; the liquid lens 12 and the second lens group 14 each have positive power, and the first lens group 13 and the third lens group 15 each have negative power; the surface of the first lens group 13 facing the object plane is a concave surface, and the surface of the third lens group 15 facing the object plane is a concave surface; the fourth lens group 16 includes a field lens 161 having negative power, the surface of the field lens 161 facing the image plane side is a concave surface, and the fourth lens group 16 may be a positive lens (i.e., having positive power) or a negative lens (i.e., having negative power);
the liquid lens optical system 1 satisfies the following conditions: r +2d arctan (H/2 f) is less than or equal to R; where R denotes the aperture of the stop 111, R denotes the clear aperture of the liquid lens 12, d denotes the optical distance between the stop 111 and the liquid lens 12, H denotes the image height of the liquid lens optical system 1, and f denotes the equivalent focal length of the entire liquid lens optical system 1.
Specifically, in the present embodiment, when the light beam propagates from the image plane, the light beam starts to diverge at a certain angle after passing through the stop 111, and therefore, a lens with positive power is required to reduce the divergence of the light beam, which is equivalent to reducing the aperture of the light beam, and is beneficial to the correction of the back aberration, so that the liquid lens 12 is configured to have positive power. The first lens group 13 is mainly used for balancing the aberration generated by the liquid lens 12 with positive focal power, the second lens group 14 is used for bearing the main light-gathering effect of an optical path, the third lens group 15 is mainly used for balancing the aberration generated by the second lens group 14, and the surface of the fourth lens group 16 facing to the image surface is concave to the image surface, and the purpose of the fourth lens group is mainly to correct curvature of field and vertical axis chromatic aberration.
Specifically, the present embodiment provides a liquid lens 12, a first lens group 13, a second lens group 14, a third lens group 15 and a fourth lens group 16 in sequence, wherein the liquid lens 12 and the second lens group 14 both have positive focal power, the first lens group 13 and the third lens group 15 both have negative focal power, and the first lens group 13 and the third lens group 15 both have concave surfaces on the sides facing the object plane, for the purpose of correcting aberrations caused by the positive focal power of the liquid lens 12 and the second lens group 14, respectively; the fourth lens group 16 includes a field lens 161 having negative power, and the surface of the field lens 161 on the image plane side is concave for the purpose of correcting curvature of field and vertical axis chromatic aberration; through the lens combination, the generated aberration can be matched and eliminated, and larger light deflection cannot be generated, so that the effective light transmission caliber of the lens group is basically consistent with the light transmission caliber of the liquid lens 12; meanwhile, the focal length of the liquid lens 12 can be quickly adjusted by adjusting the working voltage of the liquid lens 12, so that the focal length of the system can be quickly adjusted, manual driving or motor driving focusing is not needed, quick automatic focusing is realized, the working distance range is wide, and the definition is high. Meanwhile, since the diaphragm 111 is located at the foremost end of the liquid lens optical system 1, when the liquid lens optical system 1 is connected to the tube lens system 2 (please refer to fig. 4 for the specific structure of the tube lens system 2), the diaphragm 111 is located at the exit pupil position of the eyepiece 23 in the tube lens system 2, so that the liquid lens optical system 1 can be completely matched with the tube lens system 2, thereby avoiding the problems of light blocking, stray light, and the like.
Meanwhile, because of the limitation of the current process technology of the liquid lens 12, the clear aperture of the liquid lens 12 is generally small, if the aperture of the light ray exceeds the clear aperture of the liquid lens 12, the imaging range of the edge light ray is changed, the view field light ray is shielded, and the edge light ray can not be seen completely, so that a dark edge appears; in order to avoid the above problem, the liquid lens 12 is disposed immediately behind the diaphragm 111, and parameters such as the aperture of the diaphragm 111, the aperture of the light transmission of the liquid lens 12, and the optical distance between the diaphragm 111 and the liquid lens 12 are defined so as to satisfy R +2d arctan (H/2 f) R or less, so that all light can pass through the liquid lens 12 from the diaphragm 111 without being blocked, thereby avoiding the above problem.
As an embodiment, the liquid lens 12 has a minimum focal length f 1 (i.e., the minimum focal length of the liquid lens 12 upon zooming), the focal length of the first lens group 13 is f 2 (ii) a The liquid lens optical system 1 also satisfies the following conditions: f. of 1 ≥2|f 2 L. The purpose of this arrangement is to let the liquid throughThe lens 12 ensures that the angle change of the light is small as much as possible during zooming, and meanwhile, the first lens group 13 with larger focal power (i.e., smaller focal length) is used for correcting the aberration of the liquid lens 12.
In one embodiment, since second lens group 14 is used to bear the main light-gathering effect of the optical path, second lens group 14 needs to have larger focal power (i.e. smaller focal length), and focal length f of second lens group 14 is 3 (ii) a The liquid lens optical system 1 therefore also satisfies the following condition: f/2f 3 > 1 (i.e., f > 2 f) 3 ）。
Specifically, when the focal length of the liquid lens 12 is changed, the equivalent focal length of the entire liquid lens optical system 1 is also changed, so that the equivalent focal length of the entire liquid lens optical system 1 can be maintained within the design range by adjusting the focal length combination of each lens group, and therefore, the present embodiment does not limit the specific focal length value of each lens group, but limits the range of the focal length ratio of the liquid lens 12, the first lens group 13, and the second lens group 14, thereby facilitating the selection of the lens groups and maintaining the equivalent focal length of the entire liquid lens optical system 1 within the design range.
As an embodiment, in order to make the liquid lens optical system 1 better fit to the tube lens system 2, the liquid lens optical system 1 further satisfies the following condition: h/2f is more than or equal to 0.14 and less than or equal to 0.212, and f is less than or equal to 25 mm. Preferably, f is between 16mm and 18 mm.
As shown in fig. 1, as an embodiment, the fourth lens group 16 includes at least two lenses, and the field lens 161 is located on the side of at least two lenses of the fourth lens group 16 facing the image plane (i.e. the field lens 161 is located on the rightmost side of the fourth lens group 16) to ensure that the surface of the fourth lens group 16 facing the image plane side is a concave surface.
As shown in fig. 1, as an embodiment, the liquid lens optical system 1 further satisfies the following conditions: r max -R < 2 mm; wherein R is max And represents the maximum clear aperture of the plurality of lens groups. By further limiting the light transmission apertures of the liquid lens 12 and each lens group, the deflection of light rays can be further reduced, and the effectiveness of the lens groups is ensuredThe light transmission aperture is consistent with the light transmission aperture of the liquid lens 12.
As shown in fig. 1, as an embodiment, the operating voltage of the liquid lens 12 is between the lowest supply voltage and the highest supply voltage; when the liquid lens 12 operates between the lowest power supply voltage and the highest power supply voltage, the liquid lens 12 has positive power, and the liquid lens optical system 1 can image the object plane clearly in a distance range of infinity to 100mm (i.e., the distance between the object to be observed and the liquid lens optical system).
In one embodiment, when the liquid lens 12 is operated at the lowest power supply voltage, the radius of curvature of the liquid drop layer (not shown) in the liquid lens 12 is-81 mm; when the liquid lens 12 works under the highest power supply voltage, the curvature radius of the liquid drop layer in the liquid lens 12 is-8 mm, namely the change value of the curvature radius of the liquid drop layer in the liquid lens 12 is-81 mm-8 mm, and the corresponding focusing distance of the system is infinity-100 mm at the moment.
In one embodiment, the minimum power supply voltage is 43V, and the maximum power supply voltage is 59V, i.e. the operating voltage range of the liquid lens 12 is 43-59V. By selecting the liquid lens 12 with a low voltage value, the risk of electric leakage due to an excessively high supply voltage (especially the highest supply voltage) during operation can be avoided. Meanwhile, in the embodiment, a variation value of 0.2V is set between the lowest power supply voltage and the highest power supply voltage (i.e., the variation value is incremented by 0.2V as a tolerance on the basis of the lowest power supply voltage, or the variation value is decremented by 0.2V as a tolerance on the basis of the highest power supply voltage, and data sampling is performed at each point), and by adding sampling data points, it is ensured that the lens does not generate virtual focus (i.e., the distance between the object and the system is prevented from being exactly not at the focused data point) as much as possible.
As an embodiment, the total length of the liquid lens optical system 1 is < 50mm in order to ensure a reasonable overall size of the system and avoid excessive length. Further, the total length of the liquid lens optical system 1 is < 45 mm.
As an embodiment, the abbe numbers vd of all the lenses having negative power (including the negative lenses in the first lens group 13, the third lens group 15 and the fourth lens group 16) in the plurality of lens groups are less than 40, that is, the lenses having negative power are made of high dispersion materials (i.e., materials having low abbe numbers), thereby effectively reducing the vertical chromatic aberration caused by the positive lenses. Preferably, all lenses with negative power have an abbe number vd smaller than 30.
As shown in fig. 1, in one embodiment, the liquid lens optical system 1 further includes an optical filter 17, and the optical filter 17 is disposed on a side of the fourth lens group 16 facing the image plane. The filter 17 is an infrared filter, the filter 17 can pass light with a wavelength of 400-.
As shown in fig. 1, as an embodiment, the liquid lens optical system 1 further includes an image sensor 19 (sensor), the image sensor 19 is located on a side of the fourth lens group 16 facing the image plane, and the optical filter 17 is located between the fourth lens group 16 and the image sensor 19. The image sensor 19 has a diagonal dimension L, and the meaning and numerical value of the image height H of the liquid lens optical system 1 and the diagonal dimension L of the image sensor 19 are equivalent.
As shown in fig. 1, as an embodiment, the liquid lens optical system 1 further includes a prism unit 18, and the prism unit 18 is used for splitting the color of the white light into three primary colors of RGB for the image sensor 19 to collect the light signal. The prism unit 18 is disposed on a side of the filter 17 facing the image plane, and the prism unit 18 is located between the filter 17 and the image sensor 19.
As shown in fig. 1, as an embodiment, the liquid lens optical system 1 further includes a window sheet 11, the window sheet 11 performs a sealing function (seals a light entrance of the lens barrel), the window sheet 11 is located on a side of the liquid lens 12 facing the object plane, and a diaphragm 111 is disposed on the window sheet 11.
Specifically, the arrangement of the diaphragm 111 on the window sheet 11 is beneficial to reducing the overall size of the system, facilitates the arrangement of components, and can further reduce the distance between the diaphragm 111 and the exit pupil position of the ocular 23. In the present embodiment, the diaphragm 111 is disposed on the side of the window sheet 11 facing the object plane (i.e., the left side surface of the window sheet 11), so that the diaphragm 111 is closer to the exit pupil position of the eyepiece 23 in the tube lens system 2, but the diaphragm 111 is easily scratched to cause generation of stray light; of course, the diaphragm 111 may be disposed on the side of the window sheet 11 facing the image plane (i.e. the right side of the window sheet 11) to avoid the diaphragm 111 from being scratched, but the disadvantage is that the distance between the diaphragm 111 and the exit pupil position of the ocular lens 23 is longer than that of the above structure. Of course, in other embodiments, the diaphragm 111 may be disposed not on the window plate 11, but between the window plate 11 and the liquid lens 12.
As shown in fig. 4, an endoscope is further provided in the embodiment of the present invention, which includes the above-described liquid lens optical system 1. The endoscope also comprises a tube lens system 2, the tube lens system 2 comprises an objective lens 21, an image rotating system 22 and an ocular lens 23 which are sequentially arranged from an object plane to an image plane along an optical axis, and the image rotating system 22 comprises three groups of image rotating rod lens groups. The eyepiece 23 of the tube lens system 2 is connected to the liquid lens optical system 1, and the stop 111 of the liquid lens optical system 1 is located at the exit pupil position of the eyepiece 23.
In the liquid lens optical system 1 provided by the embodiment of the present invention, the liquid lens 12, the first lens group 13, the second lens group 14, the third lens group 15 and the fourth lens group 16 are sequentially disposed, and the liquid lens 12 and the second lens group 14 both have positive focal power, the first lens group 13 and the third lens group 15 both have negative focal power, the fourth lens group 16 includes a field lens 161 having negative focal power, a surface of the field lens 161 facing an image plane side is a concave surface, through the above lens combination, generated aberrations can be matched and eliminated, and large light deflection is not generated, so that an effective clear aperture of the lens group is substantially consistent with a clear aperture of the liquid lens 12; meanwhile, the focal length of the liquid lens 12 can be quickly adjusted by adjusting the working voltage of the liquid lens 12, so that the focal length of the system can be quickly adjusted, manual driving or motor driving focusing is not needed, quick automatic focusing is realized, the working distance range is wide, and the definition is high. Meanwhile, since the diaphragm 111 is located at the foremost end of the liquid lens optical system 1, when the liquid lens optical system 1 is connected to the tube lens system 2 (please refer to fig. 4 for the specific structure of the tube lens system 2), the diaphragm 111 is located at the exit pupil position of the eyepiece 23 in the tube lens system 2, so that the liquid lens optical system 1 can be completely matched with the tube lens system 2, thereby avoiding the problems of light blocking, stray light, and the like.
Meanwhile, the liquid lens 12 is arranged close to the diaphragm 111, and parameters such as the aperture of the diaphragm 111, the light-transmitting aperture of the liquid lens 12, the optical distance between the diaphragm 111 and the liquid lens 12 and the like are limited, so that the parameters meet the condition that R +2d arctan (H/2 f) is less than or equal to R, light rays can completely penetrate through the liquid lens 12 without being shielded by the diaphragm 111, and the defects such as dark edges and the like are avoided.
The liquid lens optical system 1 according to the present invention will be described in detail with reference to specific examples.
First embodiment
As shown in fig. 1 to 4, a liquid lens optical system 1 according to a first embodiment of the present invention includes a window sheet 11, a liquid lens 12, a first lens group 13, a second lens group 14, a third lens group 15, a fourth lens group 16, an optical filter 17, a prism unit 18, and an image sensor 19, which are sequentially disposed along an optical axis from an object plane to an image plane. The aperture 111 is disposed on the window plate 11 and located on a side of the window plate 11 facing the object plane.
The liquid lens 12 has positive focal power, and the liquid lens optical system 1 can clearly image within a distance range from infinity to 100mm from the object plane by changing the focal length of the liquid lens 12. When the focal length of the liquid lens 12 is adjusted, the liquid lens 12 always has the characteristic of positive focal power, the voltage adjustment range of the liquid lens 12 is 43V-54V, the curvature radius of the corresponding liquid drop layer is-81 mm-14.513 mm, and the corresponding focal length variation range is 490 mm-121 mm.
The first lens group 13 is a double cemented lens, the surface of the first lens group 13 facing the object plane is a concave surface, the surface of the first lens group 13 facing the image plane is a convex surface, the first lens group 13 has negative focal power, and the focal length thereof is about-28 mm.
The second lens group 14 is a cemented doublet, the surface of the second lens group 14 facing the object plane is a plane, the surface of the second lens group 14 facing the image plane is a convex surface, and the second lens group 14 has positive focal power and has a focal length of about 7.4 mm.
The third lens group 15 is a double cemented lens, the surface of the third lens group 15 facing the object plane is a concave surface, the surface of the third lens group 15 facing the image plane is a convex surface, the third lens group 15 has negative focal power, and the focal length thereof is about-34 mm.
The fourth lens group 16 is a double cemented lens, the surface of the fourth lens group 16 facing the object plane is a convex surface, the surface of the fourth lens group 16 facing the image plane is a concave surface, and the fourth lens group 16 has negative power and has a focal length of about-24 mm. The fourth lens group 16 includes a field lens 161 having negative power, the surface of the field lens 161 on the image plane side is a concave surface, and the field lens 161 is located on the side of the two lenses of the fourth lens group 16 facing the image plane (i.e., the field lens 161 is located on the rightmost side of the fourth lens group 16).
The liquid lens optical system 1 satisfies the following conditions: r +2d arctan (H/2 f) is less than or equal to R; where R denotes the aperture of the stop 111, R denotes the clear aperture of the liquid lens 12, d denotes the optical distance between the stop 111 and the liquid lens 12, H denotes the image height of the liquid lens optical system 1, and f denotes the equivalent focal length of the entire liquid lens optical system 1.
The liquid lens optical system 1 also satisfies the following conditions: r max -R < 2 mm; wherein R is max And represents the maximum clear aperture of the plurality of lens groups.
Fig. 2 and fig. 3 are simulation results of the liquid lens optical system, and it can be seen from the modulation Transfer function mtf (modulation Transfer function) curve of fig. 2 that the Transfer function of each field has reached the diffraction limit, and the imaging effect is excellent. As can be seen from the dot-matrix diagram of FIG. 3, the size of the Airy spots is 3.58um, and the RMS of each field is much smaller than that of the Airy spots, so that the lens has good imaging quality.
As shown in fig. 4, the present embodiment also provides an endoscope including the liquid lens optical system 1 described above. The endoscope also comprises a tube lens system 2, the tube lens system 2 comprises an objective lens 21, an image rotating system 22 and an ocular lens 23 which are sequentially arranged from an object plane to an image plane along an optical axis, and the image rotating system 22 comprises three groups of image rotating rod lens groups. The eyepiece 23 of the tube lens system 2 is connected to the liquid lens optical system 1, and the stop 111 of the liquid lens optical system 1 is located at the exit pupil position of the eyepiece 23.
In order to better fit the liquid lens optical system 1 to the tube lens system 2, the liquid lens optical system 1 further satisfies the following conditions: h/2f is more than or equal to 0.14 and less than or equal to 0.212, and f is less than or equal to 25 mm. Preferably, f is between 16mm and 18 mm. In the present embodiment, the equivalent focal length f of the liquid lens optical system 1 is 18mm, the image height H of the liquid lens optical system 1 is 6.4mm, and the total length of the liquid lens optical system 1 is about 43.2 mm.
Specific parameters of each optical component in this embodiment are shown in the following table:
second embodiment
As shown in fig. 5 to 8, a liquid lens optical system 1 according to a second embodiment of the present invention includes a window sheet 11, a liquid lens 12, a first lens group 13, a second lens group 14, a third lens group 15, a fourth lens group 16, a filter 17, a prism unit 18, and an image sensor 19, which are sequentially disposed along an optical axis from an object plane to an image plane. The aperture 111 is disposed on the window plate 11 and located on a side of the window plate 11 facing the object plane.
The liquid lens 12 has positive focal power, and the liquid lens optical system 1 can clearly image within a distance range from infinity to 100mm from the object plane by changing the focal length of the liquid lens 12. When the focal length of the liquid lens 12 is adjusted, the liquid lens 12 always has the characteristic of positive focal power, the voltage adjusting range of the liquid lens 12 is 49V-56V, the curvature radius of the corresponding liquid drop layer is-26.9 mm-10.7 mm, and the corresponding focal length variation range is 245 mm-97 mm.
The first lens group 13 is a double cemented lens, the surface of the first lens group 13 facing the object plane is a concave surface, the surface of the first lens group 13 facing the image plane is a concave surface, the first lens group 13 has negative focal power, and the focal length thereof is about-8.17 mm.
The second lens group 14 is composed of two single positive lenses, and the second lens group 14 has positive power and a focal length of about 5.73 mm.
The third lens group 15 is a double cemented lens, the surface of the third lens group 15 facing the object plane is a concave surface, the surface of the third lens group 15 facing the image plane is a concave surface, the third lens group 15 has negative focal power, and the focal length of the third lens group 15 is about-7.6 mm.
The fourth lens group 16 is composed of two single positive lenses and a field lens 161 having negative power, the field lens 161 is located on the side of the three lenses of the fourth lens group 16 toward the image plane (i.e., the field lens 161 is located on the rightmost side of the fourth lens group 16), and the fourth lens group 16 has positive power and has a focal length of about 13.644 mm.
Specifically, by disposing the second lens group 14 to be composed of two single positive lenses and the fourth lens group 16 to be composed of two single positive lenses and a field lens 161 having negative focal power, the arrangement is advantageous in that the focal power of each lens can be reduced, the deflection angle of light can be made smaller, and the small deflection angle can make the tolerance sensitivity of the lens as a whole lower, which is advantageous in improving the production yield.
The liquid lens optical system 1 satisfies the following conditions: r +2d arctan (H/2 f) is less than or equal to R; where R denotes the aperture of the stop 111, R denotes the clear aperture of the liquid lens 12, d denotes the optical distance between the stop 111 and the liquid lens 12, H denotes the image height of the liquid lens optical system 1, and f denotes the equivalent focal length of the entire liquid lens optical system 1.
The liquid lens optical system 1 also satisfies the following conditions: r max -R < 2 mm; wherein R is max And represents the maximum clear aperture of the plurality of lens groups. In this embodiment, R max -R=0.6mm。
Fig. 6 and 7 show simulation results of the liquid lens optical system, and it can be seen from the modulation Transfer function mtf (modulation Transfer function) curve of fig. 6 that the Transfer function of each field has reached the diffraction limit, and the imaging effect is excellent. As can be seen from the dot-matrix diagram of FIG. 7, the size of the Airy spots is 3.58um, and the RMS of each field is much smaller than that of the Airy spots, and the lens has good imaging quality.
As shown in fig. 8, the present embodiment also provides an endoscope including the liquid lens optical system 1 described above. The endoscope also comprises a tube lens system 2, the tube lens system 2 comprises an objective lens 21, an image rotating system 22 and an ocular lens 23 which are sequentially arranged from an object plane to an image plane along an optical axis, and the image rotating system 22 comprises three groups of image rotating rod lens groups. The eyepiece 23 of the tube lens system 2 is connected to the liquid lens optical system 1, and the stop 111 of the liquid lens optical system 1 is located at the exit pupil position of the eyepiece 23.
In order to better fit the liquid lens optical system 1 to the tube lens system 2, the liquid lens optical system 1 further satisfies the following conditions: h/2f is more than or equal to 0.14 and less than or equal to 0.212, and f is less than or equal to 25 mm. Preferably, f is between 16mm and 18 mm. In the present embodiment, the equivalent focal length f of the liquid lens optical system 1 is 16.3mm, the image height H of the liquid lens optical system 1 is 6.4mm, H/2f =0.196, and the total length of the liquid lens optical system 1 is about 43.7 mm.
Specific parameters of each optical component in this embodiment are shown in the following table:
the above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (13)
1. A liquid lens optical system comprising a liquid lens (12), a plurality of lens groups, and a stop (111), characterized in that the plurality of lens groups comprises a first lens group (13), a second lens group (14), a third lens group (15), and a fourth lens group (16) arranged in this order along an optical axis from an object surface to an image surface, each of the lens groups comprising at least one lens; the liquid lens (12) is positioned on one side, facing the object plane, of the first lens group (13), and the diaphragm (111) is positioned on one side, facing the object plane, of the liquid lens (12); the liquid lens (12) and the second lens group (14) each have positive optical power, and the first lens group (13) and the third lens group (15) each have negative optical power; the surface of one side, facing the object plane, of the first lens group (13) is a concave surface, and the surface of one side, facing the object plane, of the third lens group (15) is a concave surface; the fourth lens group (16) comprises a field lens (161) with negative focal power, and the surface of the field lens (161) facing the image surface side is a concave surface;
the liquid lens optical system (1) satisfies the following conditions: r +2d arctan (H/2 f) is less than or equal to R; wherein R represents the aperture of the diaphragm (111), R represents the clear aperture of the liquid lens (12), d represents the optical distance between the diaphragm (111) and the liquid lens (12), H represents the image height of the liquid lens optical system (1), and f represents the equivalent focal length of the entire liquid lens optical system (1).
2. A liquid lens optical system as claimed in claim 1, characterized in that the liquid lens (12) has a minimum focal length f 1 The focal length of the first lens group (13) is f 2 (ii) a The liquid lens optical system (1) further satisfies the following condition: f. of 1 ≥2|f 2 |。
3. A liquid lens optical system as claimed in claim 1, characterized in that said second lens group (14) has a focal length f 3 (ii) a The liquid lens optical system (1) further satisfies the following condition: f/2f 3 ＞1。
4. A liquid lens optical system as claimed in claim 1, characterized in that the liquid lens optical system (1) further satisfies the following condition: h/2f is more than or equal to 0.14 and less than or equal to 0.212, and f is less than or equal to 25 mm.
5. The liquid lens optical system of claim 1, wherein the fourth lens group (16) comprises at least two lenses, and the field lens (161) is located on a side of the at least two lenses of the fourth lens group (16) facing an image plane.
6. A liquid lens optical system as claimed in claim 1, characterized in that the liquid lens optical system (1) further satisfies the following condition: r max -R < 2 mm; wherein R is max And the maximum light transmission aperture of a plurality of lens groups is represented.
7. A liquid lens optical system as claimed in claim 1, characterized in that the operating voltage of the liquid lens (12) is between a minimum supply voltage and a maximum supply voltage; when the liquid lens (12) is operated between the lowest power supply voltage and the highest power supply voltage, the liquid lens (12) has positive focal power, and the liquid lens optical system (1) can enable an object plane to be clearly imaged in a distance range from infinity to 100 mm.
8. The liquid lens optical system of claim 7, wherein a radius of curvature of a layer of droplets within the liquid lens (12) is-81 mm when the liquid lens (12) is operated at the lowest supply voltage; when the liquid lens (12) works under the highest power supply voltage, the curvature radius of the liquid drop layer in the liquid lens (12) is-8 mm.
9. A liquid lens optical system as claimed in claim 7 wherein the minimum supply voltage is 43V and the maximum supply voltage is 59V.
10. A liquid lens optical system as claimed in claim 1, characterized in that the total length of the liquid lens optical system (1) is < 50 mm.
11. A liquid lens optical system as claimed in claim 1 wherein all of the lenses of the plurality of lens groups having negative optical power have abbe numbers less than 40.
12. Liquid lens optical system according to claim 1, characterized in that the liquid lens optical system (1) further comprises a window plate (11), the window plate (11) being located on the object plane-facing side of the liquid lens (12), the diaphragm (111) being arranged on the window plate (11).
13. An endoscope comprising a liquid lens optical system as claimed in any one of claims 1 to 12.
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| CN202210818436.6A CN114895441B (en) | 2022-07-13 | 2022-07-13 | Liquid lens optical system and endoscope |
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| CN202210818436.6A CN114895441B (en) | 2022-07-13 | 2022-07-13 | Liquid lens optical system and endoscope |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110273611A1 (en) * | 2009-09-02 | 2011-11-10 | Konica Minolta Opto, Inc | Single-Focus Optical System, Image Pickup Device, and Digital Apparatus |
| CN103969803A (en) * | 2013-02-04 | 2014-08-06 | 大立光电股份有限公司 | Moving focusing optical lens group |
| CN114488368A (en) * | 2022-04-15 | 2022-05-13 | 深圳术为科技有限公司 | Liquid lens optical system and camera lens |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110273611A1 (en) * | 2009-09-02 | 2011-11-10 | Konica Minolta Opto, Inc | Single-Focus Optical System, Image Pickup Device, and Digital Apparatus |
| CN103969803A (en) * | 2013-02-04 | 2014-08-06 | 大立光电股份有限公司 | Moving focusing optical lens group |
| CN114488368A (en) * | 2022-04-15 | 2022-05-13 | 深圳术为科技有限公司 | Liquid lens optical system and camera lens |
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