CN218272922U - Optical adapter, camera and polarized light endoscope - Google Patents

Abstract

The utility model relates to an optics adapter, camera and polarized light endoscope. The optical adapter includes: a first lens having a positive refractive power, the object side surface being convex; the second lens with positive focal power, the object side surface is a convex surface, and the image side surface is a concave surface; a third lens with negative focal power, wherein the image side surface is a concave surface; the fourth lens with negative focal power, the object side surface is a convex surface, and the image side surface is a concave surface; the fifth lens with negative focal power, the object side surface is a concave surface, and the image side surface is a convex surface; the sixth lens with negative focal power, the object side surface is a concave surface, and the image side surface is a convex surface; a seventh lens element with positive refractive power having a concave object-side surface and a convex image-side surface; and the object side surface of the eighth lens is a convex surface. The optical adapter can effectively correct aberration such as distortion, coma aberration, field curvature and the like, so that the optical adapter has good imaging quality and is favorable for smooth diagnosis or treatment when being applied to a polarized light endoscope.

Description

Optical adapter, camera and polarized light endoscope

Technical Field

The utility model relates to a polarized light endoscope imaging technology field especially relates to an optics adapter, camera and polarized light endoscope.

Background

The endoscope is a medical device which can enter a human body to observe, diagnose or treat and generally comprises a camera host, a camera and an endoscope mirror, wherein the camera comprises an optical adapter and a camera main body, the camera main body is communicated with the endoscope mirror through the optical adapter, and the imaging definition of the endoscope has very important influence on the efficiency and accuracy of diagnosis and treatment. However, the current endoscope has poor imaging quality, and is difficult to obtain a clear image of a subject, thereby affecting smooth progress of diagnosis or treatment.

SUMMERY OF THE UTILITY MODEL

Based on this, it is necessary to provide an optical adapter, a camera and a polarized light endoscope to improve the imaging definition of the endoscope.

An optical adapter in which the number of lenses having optical power is eight, the optical adapter comprising, in order from an object side to an image side along an optical axis:

a first lens having a positive optical power, an object side surface of the first lens being convex;

the second lens with positive focal power is characterized in that the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

a third lens with negative focal power, wherein the image side surface of the third lens is a concave surface;

the fourth lens with negative focal power is provided with a convex object-side surface and a concave image-side surface;

the fifth lens is provided with negative focal power, the object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a convex surface;

the sixth lens with negative focal power is characterized in that the object side surface of the sixth lens is a concave surface, and the image side surface of the sixth lens is a convex surface;

the seventh lens with positive focal power is characterized in that the object side surface of the seventh lens is a concave surface, and the image side surface of the seventh lens is a convex surface;

and the object side surface of the eighth lens is a convex surface.

In one embodiment, the optical adapter further includes a first protection element disposed on an object side of the first lens, and the optical adapter satisfies the following conditional expression:

0.4≤CT2/T12≤0.6；

wherein, CT2 is the thickness of the first lens element on the optical axis, and T12 is the distance from the image-side surface of the first protection element to the object-side surface of the first lens element on the optical axis.

In one embodiment, the optical adapter satisfies the following conditional expression:

0.8≤CT3/CT2≤1.1；

wherein CT3 is the thickness of the second lens element on the optical axis, and CT2 is the thickness of the first lens element on the optical axis.

In one embodiment, the optical adapter satisfies the following conditional expression:

-8.5≤f4/f3≤-6.5；

wherein f4 is an effective focal length of the third lens, and f3 is an effective focal length of the second lens.

In one embodiment, the optical adapter satisfies the following conditional expression:

CT5/T45 is more than or equal to 1.1 and less than or equal to 1.3; and/or the presence of a gas in the gas,

CT7/T78 is more than or equal to 1.8 and less than or equal to 2.2; and/or the presence of a gas in the gas,

0.8≤CT9/T89≤1.1；

wherein, CT5 is an axial thickness of the fourth lens element, T45 is an axial distance from an image-side surface of the third lens element to an object-side surface of the fourth lens element, CT7 is an axial thickness of the sixth lens element, T78 is an axial distance from the image-side surface of the sixth lens element to an object-side surface of the seventh lens element, CT9 is an axial thickness of the eighth lens element, and T89 is an axial distance from the image-side surface of the seventh lens element to an object-side surface of the eighth lens element.

In one embodiment, the optical adapter satisfies the following conditional expression:

1.5mm≤CT6/n6≤2.0mm；

wherein CT6 is a thickness of the fifth lens element on an optical axis, and n6 is a refractive index of the fifth lens element.

In one embodiment, the optical adapter satisfies the following conditional expression:

0.1≤CT7/f7≤0.2；

wherein CT7 is the thickness of the sixth lens element on the optical axis, and f7 is the effective focal length of the sixth lens element.

A camera head, comprising a polarization-maintaining beam splitting element, a visible light image sensor, a polarized light image sensor and the optical adapter according to any of the above embodiments, wherein the polarization-maintaining beam splitting element is disposed on the image side of the eighth lens and configured to split an incident light beam into two beams and emit the two beams, and the polarization state of the two beams emitted from the polarization-maintaining beam splitting element is the same as the polarization state of the incident light beam from the polarization-maintaining beam splitting element; the visible light image sensor is used for receiving one of the beams of light emitted by the polarization-maintaining light splitting element; the polarized light image sensor is used for receiving the other beam of light emitted by the polarization-maintaining light splitting element.

In one embodiment, the polarization-maintaining beam splitter includes two right-angle prisms and a polarization-maintaining beam splitting film disposed at an interface of the two right-angle prisms, the polarization-maintaining beam splitting film is inclined to a main optical axis of the eighth lens, and a portion of incident light of the polarization-maintaining beam splitter transmits through the polarization-maintaining beam splitting film to form a beam of light, and a portion of incident light is reflected by the polarization-maintaining beam splitting film to form another beam of light.

A polarized light endoscope comprising the camera head of any of the above embodiments.

Above-mentioned optical adapter, the focal power and the face type of each lens can obtain reasonable configuration to can rationally control the trend of light, effectively rectify aberrations such as distortion, coma, the field curvature of optical adapter, and promote optical adapter's light flux volume, thereby be favorable to promoting optical adapter's imaging quality, make optical adapter can acquire the sharp image of shot object, be applied to and be favorable to going on smoothly of diagnosis or treatment in the polarized light endoscope, be favorable to shortening optical adapter's overall length simultaneously.

Drawings

FIG. 1 is a schematic diagram of a camera head in some embodiments;

FIG. 2 is a graph of a transfer function for an optical adapter in some embodiments;

FIG. 3 is a defocus plot of an optical adapter in some embodiments;

FIG. 4 is a stippling diagram of an optical adapter in some embodiments;

FIG. 5 is a graph of field curvature and distortion for an optical adapter in some embodiments.

Detailed Description

In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, as those skilled in the art will be able to make similar modifications without departing from the spirit and scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be interconnected within two elements or in a relationship where two elements interact with each other unless otherwise specifically limited. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present application, unless expressly stated or limited otherwise, a first feature "on" or "under" a second feature may be directly contacting the second feature or the first and second features may be indirectly contacting the second feature through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature "under," "beneath," and "under" a second feature may be directly under or obliquely under the second feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. As used herein, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are for purposes of illustration only and do not denote a single embodiment.

Referring to fig. 1, a camera head 10 is provided that may be used in a medical device, such as any suitable type of hard or soft tube polarized light endoscope. In some embodiments, the camera 10 may include an optical adapter including, in order from an object side to an image side along the optical axis 110, a first lens E2, a second lens E3, a third lens E4, a fourth lens E5, a fifth lens E6, a sixth lens E7, a seventh lens E8, and an eighth lens E9. In some embodiments, the optical adapter may further include a first protective element E1 disposed on the object side of the first lens E2, and a second protective element E10 and a third protective element E11 disposed on the image side of the eighth lens E9 and in order from the object side to the image side along the optical axis 110. The first protection element E1, the second protection element E10, and the third protection element E11 may be plate glass. The first protective element E1 and the second protective element E10 protect the first lens E2 to the eighth lens E9, and the third protective element E11 protects elements provided on the image side of the third protective element E11.

The first protective element E1 has an object-side surface S1 and an image-side surface S2, the first lens E2 has an object-side surface S3 and an image-side surface S4, the second lens E3 has an object-side surface S5 and an image-side surface S6, the third lens E4 has an object-side surface S7 and an image-side surface S8, the fourth lens E5 has an object-side surface S9 and an image-side surface S10, the fifth lens E6 has an object-side surface S12 and an image-side surface S13, the sixth lens E7 has an object-side surface S14 and an image-side surface S15, the seventh lens E8 has an object-side surface S16 and an image-side surface S17, the eighth lens E9 has an object-side surface S18 and an image-side surface S19, the second protective element E10 has an object-side surface S20 and an image-side surface S21, and the third protective element E11 has an object-side surface S22 and an image-side surface S23.

In some embodiments, the optical adapter is further provided with a stop S11, and the stop S11 may be provided between the fourth lens E5 and the fifth lens E6.

In some embodiments, the camera 10 further includes a camera body, which may include a polarization maintaining beam splitter element E12 disposed on the image side of the eighth lens E9, for example, the polarization maintaining beam splitter element E12 may be disposed on the image side of the third protection element E11. The light beam emitted from the eighth lens E9 can enter the polarization maintaining beam splitter E12, and the polarization maintaining beam splitter E12 can split the incident light beam into two light beams and emit the two light beams in different directions. For example, the polarization maintaining splitter E12 may include an incident surface S24, an emergent surface S25 and an emergent surface S26, and the light emitted from the eighth lens E9 enters the polarization maintaining splitter E12 through the incident surface S24 and is split into two beams by the polarization maintaining splitter E12, and the two beams exit the polarization maintaining splitter E12 through the emergent surface S25 and the emergent surface S26 respectively.

Specifically, in some embodiments, the first lens E2 has positive optical power, and the object-side surface S3 of the first lens E2 is convex. The second lens element E3 has positive refractive power, and the object-side surface S5 and the image-side surface S6 of the second lens element E3 are convex and concave. The third lens E4 has negative refractive power, and the image-side surface S8 of the third lens E4 is concave. The fourth lens element E5 has negative power, and the object-side surface S7 and the image-side surface S8 of the fourth lens element E5 are convex and concave. The fifth lens element E6 has negative power, and the object-side surface S12 and the image-side surface S13 of the fifth lens element E6 are concave and convex, respectively. The sixth lens element E7 has negative refractive power, and the object-side surface S14 and the image-side surface S15 of the sixth lens element E7 are concave and convex, respectively. The seventh lens element E8 has positive refractive power, and the object-side surface S16 and the image-side surface S17 of the seventh lens element E8 are concave and convex. The eighth lens E9 has positive refractive power, and an object-side surface S18 of the eighth lens E9 is convex.

The positive focal power of the first lens element E2 is matched with the convex surface shape of the object-side surface S3 of the first lens element E2, which is favorable for capturing light rays of each field of view and shortening the total length of the optical adapter. The positive focal power and the convex-concave surface type of the second lens E3 are matched with the focal power and the surface type of the first lens E2, so that coma aberration and other aberrations of the optical adapter can be favorably corrected, the imaging quality of the optical adapter is improved, meanwhile, light rays can be favorably converged towards the image side, the total length of the optical adapter can be favorably shortened, and the miniaturization design is realized. The negative focal power and the surface type of third lens E4 and fourth lens E5 cooperate each other, be favorable to the light that first lens E2 collected to gently pass through to image side at third lens E4 and fourth lens E5, be favorable to the focal power of four preceding lenses of rational distribution optical adapter, thereby be favorable to rectifying and balancing each item aberration of optical adapter, and be favorable to the miniaturized design of optical adapter, the position design of cooperation diaphragm S11, still be favorable to making light be full of diaphragm S11, thereby be favorable to promoting the relative illuminance that optical adapter imaged. The position design of the diaphragm S11 is matched with the focal power and the surface type design of each lens of the optical adapter, so that the optical adapter can form a Gaussian structure with the left and right symmetry of the diaphragm S11, the chromatic aberration, the coma aberration, the field curvature and other aberrations of the optical adapter can be eliminated, and the imaging quality of the optical adapter is further improved. The positive focal power of the fifth lens E6 is matched with the concave-convex surface type of the fifth lens E6, so that light rays are smoothly transited in the fifth lens, aberration such as distortion of the optical adapter is favorably corrected, aberration sensitivity of the optical adapter is reduced, risk of ghost image generation is reduced, imaging quality of the optical adapter is favorably improved, tolerance sensitivity of the optical adapter is favorably reduced, and manufacturing and assembling of the optical adapter are favorably realized. The negative focal power of the sixth lens element E7, in cooperation with the concave-convex shape of the sixth lens element E7, is favorable for gently diverging the light toward the image side, and is favorable for correcting aberrations, such as curvature of field, generated by each lens element on the object side of the sixth lens element E7. The positive focal power and the concave-convex surface type of the seventh lens E8 are matched with the focal power and the surface type design of the sixth lens E7, so that the size of an imaging surface of the optical adapter is increased, and the light flux of the optical adapter is increased, so that the relative illumination of the optical adapter and the illumination of the edge field imaging are increased, and the imaging quality of the optical adapter under a weak light environment is improved. The positive focal power of the eighth lens element E9, in cooperation with the convex surface shape of the object-side surface S18 of the eighth lens element E9, is favorable for converging light rays toward aberration, thereby being favorable for improving the matching degree of the incident angle of light rays on the imaging surface with the image sensor, and further being favorable for improving the imaging quality of the optical adapter.

Possess foretell focal power and face type characteristic, the focal power and the face type of each lens can obtain reasonable configuration, thereby can rationally control the trend of light, effectively rectify aberrations such as distortion, coma, field curvature of the optics adapter, and promote the light flux volume of optics adapter, thereby be favorable to promoting the imaging quality of optics adapter, make the optics adapter can acquire the clear image of quilt shot thing, be applied to and be favorable to going on smoothly of diagnosis or treatment in the polarized light endoscope, be favorable to shortening the total length of optics adapter simultaneously, be favorable to the optics adapter to realize miniaturized design, thereby be favorable to the equipment and the use of optics adapter in the polarized light endoscope.

Further, in some embodiments, the camera body of the camera 10 further includes a visible light image sensor (not shown) for receiving one of the beams emitted from the polarization maintaining beam splitter element E12 and a polarized light image sensor (not shown) for receiving the other beam emitted from the polarization maintaining beam splitter element E12. For example, the visible light image sensor may be disposed at one side of the polarization maintaining splitter E12 and opposite to the light exit surface S25 to receive the light emitted from the light exit surface S25, and the polarized light image sensor may be disposed at the other side of the polarization maintaining splitter E12 and opposite to the light exit surface S25 to receive the light emitted from the light exit surface S25. It can be understood that, due to the arrangement of the polarization-maintaining beam splitting element E12, the camera head 10 can be regarded as having two imaging surfaces, and the two imaging surfaces of the camera head 10 coincide with the photosensitive surfaces of the visible light image sensor and the polarized light image sensor, respectively.

In some embodiments, the polarization states of the two beams of light emitted from the polarization maintaining beam splitting element E12 are the same as the polarization state of the incident light (the light emitted from the eighth lens E9) of the polarization maintaining beam splitting element E12, in other words, the polarization maintaining beam splitting element E12 does not change the polarization state of the light while achieving the beam splitting effect, so that the polarized light image sensor can better restore the subject image according to the received light.

It should be noted that in the present application, the optical adapter can receive polarized light, for example, when the camera head 10 is applied to a polarized light endoscope, the light source of the polarized light endoscope can emit polarized light, for example, the light source emits circularly polarized light. In the camera 10, the focal power and the surface shape of each lens can be reasonably configured, so that the optical adapter has good imaging quality, and meanwhile, the visible light image sensor can acquire a visible light (white light) image of one light beam, so as to acquire a clear image of a shot object and the background of a working environment, while the polarized light image sensor can process the polarization information of the other received light beam, so as to acquire a clear image of the shot object in multiple levels. Due to the fact that the polarized light is high in permeability, through multi-level processing of the polarized light image sensor, the fact that substances such as normal saline, blood, bone residues, soft tissue residues and stone particles penetrate through the working environment can be achieved, a real and clear image of a shot object is obtained, and the influence of scattering phenomena of the substances in the working environment on the imaging definition of the shot object is avoided. The mutual verification and supplement of images acquired by the visible light image sensor and the polarized light image sensor can effectively acquire real and clear images of a shot object, and is favorable for smooth diagnosis or treatment.

The specific arrangement of the polarization maintaining beam splitting element E12 is not limited as long as the incident light can be split into two beams of light, and the polarization state of the incident light is not changed, so that the polarized light image sensor can obtain a clear image of a shot object by analyzing the polarized light and discharging the influence of the scattered light.

In some embodiments, the polarization-maintaining beam splitter E12 includes two right-angle prisms and a polarization-maintaining beam splitter film disposed at an interface of the two right-angle prisms, and the polarization-maintaining beam splitter film is inclined to a main optical axis of the eighth lens E89. In some embodiments, one of the right-angle prisms of the polarization-maintaining beam splitter E12 is adjacent to the third protective element E11, one of the right-angle surfaces of the right-angle prism is perpendicular to the main optical axis of the eighth lens E9 and is opposite to the image-side surface S19 of the eighth lens E9 to form the light incident surface S24, and the other right-angle surface is parallel to the main optical axis of the eighth lens E9 and forms the light emitting surface S26. The inclined plane of the other right-angle prism of the polarization-maintaining light splitting element E12 is close to and parallel to the inclined plane of the right-angle prism close to the eighth lens E9, an interface is formed at the junction of the inclined planes of the two right-angle prisms, and the polarization-maintaining light splitting film is arranged on the inclined planes of the two right-angle prisms.

In some embodiments, the polarization maintaining beam splitter film satisfies the following conditional expression: (Rp × Rs)/(Tp × Ts) = 1; where Rp and Tp are the amplitude reflectance and amplitude refractive index on the polarization maintaining beam splitting film of the p component in the incident light (the outgoing light from the eighth lens E89) of the polarization maintaining beam splitting element E12, respectively, and Rs and Ts are the amplitude reflectance and amplitude refractive index on the polarization maintaining beam splitting film of the s component in the incident light of the polarization maintaining beam splitting element E12, respectively. When the condition formula is satisfied, the adjustment effect of the polarization-maintaining light splitting element E12 on the light can be reasonably configured, so that the polarization states of two beams of emergent light of the polarization-maintaining light splitting element E12 are consistent with that of incident light, and the visible light image sensor and the polarized light image sensor can effectively acquire real and clear images of a shot object.

In some embodiments, the polarization maintaining optical film is formed of a multi-layer structure, and at least one layer of the polarization maintaining optical film is made of titanium dioxide and at least one layer of the polarization maintaining optical film is made of silicon dioxide. It can be understood that, through the design to the material and the thickness of each layer structure of polarization-maintaining beam splitting film, the adjusting effect of polarization-maintaining beam splitting film to light can be changed, so that the polarization state of light can not be changed when the polarization-maintaining beam splitting element E12 splits light. For example, in some embodiments, the polarization maintaining beam splitter film may include a titanium dioxide film layer having a thickness of 35.48nm, a silicon dioxide film layer having a thickness of 50.75mm, a titanium dioxide film layer having a thickness of 88.22mm, a silicon dioxide film layer having a thickness of 82.17, and a titanium dioxide film layer having a thickness of 115.98mm, in that order. Of course, the structure of the polarization maintaining beam splitting film is not limited to the above description, and the material and thickness of each layer structure may be set as long as the polarization maintaining beam splitting element E12 can split light without changing the polarization state of the light.

In some embodiments, the angle between the polarization maintaining beam splitter film and the main optical axis of the eighth lens E9 may be 45 °. It can be understood that the incident light entering the polarization maintaining beam splitter E12 from the light entering surface S24 is partially reflected at the polarization maintaining beam splitter and then exits from the light exiting surface S26, and is partially transmitted through the polarization maintaining beam splitter and then exits from the light exiting surface S25.

The visible light image sensor and the polarized light image sensor can be any suitable CCD image sensor or CMOS image sensor, the visible light image sensor can be an image sensor capable of imaging in a visible light wave band, and the polarized light image sensor can be an image sensor sensitive to the polarization state of light or an image sensor suitable for polarized light imaging. The type of the polarized light image sensor and the method for analyzing the polarized light are not limited, as long as the polarization state of the polarized light can be analyzed to obtain a multi-level image of the object.

For example, in some embodiments, the polarized light image sensor processes polarization information of incident light in a manner of a focal plane, and the polarized light image sensor may employ virtual pixel points composed of four physical pixel points, and the corresponding polarization angles are 0 °, 45 °, 90 °, and 135 °, respectively, so as to obtain a multi-level real and clear image of a subject through polarization information in polarized light.

The combination of the polarization-maintaining light-splitting element E12, the visible light image sensor and the polarized light image sensor is adopted to process the visible light and the polarized light of the shot object to obtain a clear image of the shot object, the polarization-maintaining light-splitting element E11 is simple in structure, low in design and manufacturing cost and small in size, and can be smoothly arranged between the eighth lens E9 and an imaging surface. Compared with the traditional light splitting system which splits light according to the wavelength of light or has a complex design, the camera 10 has the advantages of small size, low cost and the like.

In some embodiments, the image-side surface S4 of the first lens E2 is a plane, the object-side surface S7 of the third lens E4 is a plane, and the image-side surface of the eighth lens E9 is a plane. The focal power and the surface type of each lens are matched, so that the trend of light rays can be reasonably controlled, and the effects of miniaturization, good imaging quality and the like of the camera 10 are further realized. The combination of the plane and the curved surface is also beneficial to reducing the design and manufacturing difficulty of each lens of the camera 10 and reducing the manufacturing cost of the camera 10. Of course, the lens surface configured as a plane may also be a concave surface or a convex surface with a gentle curvature, as long as the trend of light can be reasonably controlled, so that the camera 10 can achieve the effects of miniaturization design, good imaging quality and the like.

In some embodiments, the lenses of the camera 10 are coaxially arranged, and the common axis of the lenses is the optical axis 110 of the camera 10.

In some embodiments, the optical adapter satisfies the conditional expression: CT2/T12 is more than or equal to 0.4 and less than or equal to 0.6; wherein, CT2 is a thickness of the first lens element E2 on the optical axis 110, i.e., a central thickness of the first lens element E2, and T12 is a distance between the image-side surface S2 of the first protective element E1 and the object-side surface S3 of the first lens element E2 on the optical axis 110, i.e., an air interval between the first protective element E1 and the first lens element E2 on the optical axis. When satisfying above-mentioned conditional expression, can rationally dispose the specific value of the central thickness of first lens E2 and the air interval between first lens E2 and the first protective element E1, be favorable to making the thing side of first lens E2 have sufficient fitting space to be favorable to the equipment of optics adapter, also be favorable to shortening the total length of optics adapter simultaneously, realize miniaturized design, still be favorable to first lens E2 effectively to collect the light of each visual field in addition.

In some embodiments, the optical adapter satisfies the conditional expression: CT3/CT2 is more than or equal to 0.8 and less than or equal to 1.1; wherein, CT3 is the thickness of the second lens element E3 on the optical axis 110, i.e. the central thickness of the second lens element E3, and CT2 is the thickness of the first lens element E2 on the optical axis 110, i.e. the central thickness of the first lens element E2. When satisfying above-mentioned conditional expression, the ratio of the central thickness that can rational configuration second lens E3 and first lens E2 for first lens E2 and second lens E3 can effectively cooperate, with the light of collecting each visual field well, and shorten the total length of optics adapter, can also effectively rectify aberrations such as coma simultaneously, promote the imaging quality of optics adapter.

In some embodiments, the optical adapter satisfies the conditional expression: f4/f3 is more than or equal to 8.5 and less than or equal to-6.5; wherein f4 is the effective focal length of the third lens E4, and f3 is the effective focal length of the second lens E3. When the above conditional expressions are satisfied, the ratio of the effective focal lengths of the third lens E4 and the second lens E3 can be reasonably configured, which is beneficial to the smooth transition of light between the second lens E3 and the third lens E4, so that the third lens E4 is beneficial to correcting various aberrations generated by the first lens E2 and the second lens E3, and further beneficial to improving the imaging quality of the camera 10, and reducing the aberration sensitivity of the camera 10.

In some embodiments, the optical adapter satisfies the conditional expression: CT5/T45 is more than or equal to 1.1 and less than or equal to 1.3; wherein, CT5 is a thickness of the fourth lens element E5 on the optical axis 110, i.e., a center thickness of the fourth lens element E5, and T45 is a distance from the image-side surface S8 of the third lens element E4 to the object-side surface S9 of the fourth lens element E5 on the optical axis 110, i.e., an air space between the third lens element E4 and the fourth lens element E5 on the optical axis 110. When satisfying above-mentioned conditional expression, can rationally dispose the central thickness of fourth lens E5 and the air interval's between third lens E4 and the fourth lens E5 ratio, make third lens E4 and fourth lens E5 can effectively cooperate and gently diverge light to image side, be favorable to promoting the light flux amount of optical adapter, be favorable to rectifying the aberration that first lens E2 and second lens E3 produced simultaneously, promote the imaging quality of optical adapter, also be favorable to shortening the total length of optical adapter simultaneously, realize miniaturized design.

In some embodiments, the optical adapter satisfies the conditional expression: CT7/T78 is more than or equal to 1.8 and less than or equal to 2.2; wherein, CT7 is the thickness of the sixth lens element E7 on the optical axis 110, i.e. the central thickness of the sixth lens element E7, and T78 is the distance from the image-side surface S15 of the sixth lens element E7 to the object-side surface S16 of the seventh lens element E8 on the optical axis 110, i.e. the air space between the sixth lens element E7 and the seventh lens element E8 on the optical axis 110. When the conditional expressions are met, the ratio of the central thickness of the sixth lens E7 to the air interval between the sixth lens E7 and the seventh lens E8 can be reasonably configured, so that the sixth lens E7 and the seventh lens E8 can be effectively matched, aberrations such as field curvature and the like generated by the aberration lenses of the sixth lens E7 can be effectively corrected, the light transmission amount of the optical adapter is improved, and the imaging quality of the optical adapter is further improved.

In some embodiments, the optical adapter satisfies the conditional expression: CT9/T89 is more than or equal to 0.8 and less than or equal to 1.1; wherein, CT9 is the thickness of the eighth lens element E9 on the optical axis 110, i.e. the center thickness of the eighth lens element E9, and T89 is the distance from the image-side surface S17 of the seventh lens element E8 to the object-side surface S18 of the eighth lens element E9 on the optical axis 110, i.e. the air space between the seventh lens element E8 and the eighth lens element E9 on the optical axis 110. When satisfying above-mentioned conditional expression, can the rational configuration eighth lens E9 the central thickness and the air interval's between seventh lens E8 and the eighth lens E9 ratio, be favorable to seventh lens E8 and eighth lens E9 to cooperate well in order to transition to the imaging surface gently with light, be favorable to restraining the production of aberration, and promote the incident angle of light on the imaging surface and image sensor's matching degree, also be favorable to promoting camera 10's light flux simultaneously, and then be favorable to promoting camera 10's imaging quality.

In some embodiments, the optical adapter satisfies the conditional expression: CT6/n6 is more than or equal to 1.5mm and less than or equal to 2.0mm; where CT6 is the thickness of the fifth lens element E6 on the optical axis 110, i.e. the central thickness of the fifth lens element E6, and n6 is the refractive index of the fifth lens element E6. When satisfying above-mentioned conditional expression, the ratio of the central thickness and the refracting index of fifth lens E6 of can rational configuration, thereby the adjustment effect of rational configuration fifth lens E6 to the light, make the light can be in the gentle transition of fifth lens E6, be favorable to fifth lens E6 to rectify each item aberration of camera 10, and reduce the production of ghost, also be favorable to making the face type of fifth lens E6 can not excessively bend simultaneously, be favorable to reducing the tolerance sensitivity of camera 10, thereby be favorable to manufacturing and the equipment of camera 10.

In some embodiments, the optical adapter satisfies the conditional expression: CT7/f7 is more than or equal to 0.1 and less than or equal to 0.2; where CT7 is the thickness of the sixth lens element E7 on the optical axis 110, and f7 is the effective focal length of the sixth lens element E7. When the above conditional expressions are satisfied, the ratio of the central thickness of the sixth lens E7 to the effective focal length can be reasonably configured, so that light can be smoothly transited through the sixth lens E7, which is beneficial to correcting aberrations such as field curvature generated by each lens at the object side of the sixth lens E7, and is beneficial to improving the imaging quality of the camera 10, and in addition, the total length of the optical adapter can be favorably shortened, and the miniaturization design is realized.

In some embodiments, the optical adapter satisfies the conditional expression: the Semi-FOV is more than or equal to 8 degrees and less than or equal to 12 degrees; f is more than or equal to 28mm and less than or equal to 33mm; where Semi-FOV is half of the maximum field angle of the camera 10 and f is the effective focal length of the camera 10. When the condition formula is met, the field angle and the effective focal length range of the system can be reasonably configured, the total length of the system can be favorably compressed by matching the refractive power and the surface type design of each lens of the system, meanwhile, the aberration sensitivity of the system can also be reduced, the imaging quality of the system is improved, the field angle of the system cannot be too small, and therefore the image taking requirement of polarized light endoscope diagnosis can be met.

In some embodiments, the object-side surface and the image-side surface of each lens of the camera 10 are spherical surfaces, and while the above effects are achieved, the arrangement of the spherical surfaces is also beneficial to reducing the difficulty in designing and manufacturing the camera 10, and is also beneficial to reducing the size of the camera 10, thereby being beneficial to the application of the camera 10 in a polarized light endoscope. In some embodiments, the lens of the camera 10 may be made of glass or plastic, or may be any combination of glass and plastic, and the glass lens is favorable for the camera 10 to have good optical performance and temperature resistance, and the plastic lens is favorable for reducing the weight and manufacturing cost of the camera 10.

Referring to fig. 2, fig. 3, fig. 4 and fig. 5, fig. 2 is a graph of a transfer function (MTF) of an optical adapter in some embodiments, fig. 3 is a graph of a defocus of an optical adapter in some embodiments, fig. 4 is a graph of a dot-column of an optical adapter in some embodiments, and fig. 5 is a graph of curvature of field and a graph of distortion of an optical adapter in some embodiments, in sequence from left to right. As can be seen from fig. 2 to 5, when the resolution of the optical adapter satisfies 250lp/mm, the MTF value in the full field is greater than 0.2 and is close to the diffraction limit, the diffuse spots in the dot-column diagram of the optical adapter are all smaller than the airy spots, the diameters of the light spots are all contained in the airy spots and are at the diffraction limit, and the distortion of the optical adapter is controlled within 2%. Therefore, the optical adapter has the effects of low distortion and high imaging quality.

Further, in some embodiments, the optical adapter satisfies the data of table 1 below, and the effects obtainable by satisfying the following data can be obtained from the above description.

TABLE 1

In some embodiments, the present application further provides a polarized light endoscope (not shown) including a light source and the camera 10 as described in any of the above embodiments, wherein the light source can emit polarized light toward a subject, and the camera 10 can receive the polarized light reflected by the subject. Of course, the light emitted from the light source may also include a light component having no polarization state, as long as the light emitted from the light source has at least a part of a polarization state to enable the polarized light image sensor to acquire the polarization information of the subject. The polarized light endoscope can be any suitable hard tube polarized light endoscope or soft tube polarized light endoscope. The type of the polarized light emitted by the light source is not limited, for example, the polarized light can be circularly polarized light, and the object is illuminated by the circularly polarized light, so that the effect of transmitting substances such as blood, bone residues, soft tissue residues, stone particles and the like in a working environment can be realized, and a real and clear image of the object can be obtained. The camera 10 is adopted in the polarized light endoscope, the camera 10 has the effects of small size, low distortion, high imaging quality and the like, and meanwhile, the influence of scattering phenomenon of a working environment on the imaging quality can be reduced by matching with the arrangement of the polarization-preserving light splitting element E12, the visible light image sensor and the polarized light image sensor, so that a clear image of a shot object can be obtained, and the smooth diagnosis or treatment is facilitated.

All possible combinations of the technical features of the above embodiments may not be described for the sake of brevity, but should be considered as within the scope of the present disclosure as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the concept of the present invention, several variations and modifications can be made, which all fall within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims (10)

1. An optical adapter, wherein the number of lenses having optical power in the optical adapter is eight, and the optical adapter comprises, in order from an object side to an image side along an optical axis:

a first lens having a positive optical power, an object side surface of the first lens being convex;

the second lens with positive focal power is provided, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

a third lens with negative focal power, wherein the image side surface of the third lens is a concave surface;

the fourth lens is provided with negative focal power, the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface;

the lens comprises a fifth lens with negative focal power, wherein the object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a convex surface;

the sixth lens with negative focal power is characterized in that the object side surface of the sixth lens is a concave surface, and the image side surface of the sixth lens is a convex surface;

the seventh lens with positive focal power is characterized in that the object side surface of the seventh lens is a concave surface, and the image side surface of the seventh lens is a convex surface;

an eighth lens having a positive optical power, an object side surface of the eighth lens being convex.

2. The optical adapter according to claim 1, further comprising a first protective element provided on an object side of the first lens, wherein the optical adapter satisfies the following conditional expression:

0.4≤CT2/T12≤0.6；

wherein CT2 is a thickness of the first lens element on the optical axis, and T12 is a distance from the image-side surface of the first protection element to the object-side surface of the first lens element on the optical axis.

3. The optical adapter according to claim 1, wherein the optical adapter satisfies the following conditional expression:

0.8≤CT3/CT2≤1.1；

wherein CT3 is the thickness of the second lens element on the optical axis, and CT2 is the thickness of the first lens element on the optical axis.

4. The optical adapter according to claim 1, wherein the optical adapter satisfies the following conditional expression:

-8.5≤f4/f3≤-6.5；

wherein f4 is an effective focal length of the third lens, and f3 is an effective focal length of the second lens.

5. The optical adapter according to claim 1, wherein the optical adapter satisfies the following conditional expression:

CT5/T45 is more than or equal to 1.1 and less than or equal to 1.3; and/or the presence of a gas in the gas,

CT7/T78 is more than or equal to 1.8 and less than or equal to 2.2; and/or the presence of a gas in the atmosphere,

0.8≤CT9/T89≤1.1；

wherein, CT5 is the thickness of the fourth lens element on the optical axis, T45 is the distance from the image-side surface of the third lens element to the object-side surface of the fourth lens element on the optical axis, CT7 is the thickness of the sixth lens element on the optical axis, T78 is the distance from the image-side surface of the sixth lens element to the object-side surface of the seventh lens element on the optical axis, CT9 is the thickness of the eighth lens element on the optical axis, and T89 is the distance from the image-side surface of the seventh lens element to the object-side surface of the eighth lens element on the optical axis.

6. The optical adapter according to claim 1, wherein the optical adapter satisfies the following conditional expression:

1.5mm≤CT6/n6≤2.0mm；

wherein CT6 is a thickness of the fifth lens element on the optical axis, and n6 is a refractive index of the fifth lens element.

7. The optical adapter according to claim 1, wherein the optical adapter satisfies the following conditional expression:

0.1≤CT7/f7≤0.2；

wherein CT7 is the thickness of the sixth lens element on the optical axis, and f7 is the effective focal length of the sixth lens element.

8. A camera head, comprising a polarization maintaining beam splitting element, a visible light image sensor, a polarized light image sensor and the optical adapter of any one of claims 1 to 7, wherein the polarization maintaining beam splitting element is disposed on the image side of the eighth lens and configured to be capable of splitting an incident light ray into two light beams and emitting the two light beams, and the polarization state of the two light beams emitted by the polarization maintaining beam splitting element is the same as the polarization state of the incident light ray of the polarization maintaining beam splitting element; the visible light image sensor is used for receiving one of the beams of light emitted by the polarization-maintaining light splitting element; the polarized light image sensor is used for receiving the other beam of light emitted by the polarization-maintaining light splitting element.

9. The camera head according to claim 8, wherein the polarization-maintaining beam splitter comprises two right-angle prisms and a polarization-maintaining beam splitting film disposed at an interface of the two right-angle prisms, the polarization-maintaining beam splitting film is inclined to a main optical axis of the eighth lens, and a portion of incident light of the polarization-maintaining beam splitter transmits through the polarization-maintaining beam splitting film to form a beam of light, and a portion of incident light of the polarization-maintaining beam splitter is reflected by the polarization-maintaining beam splitting film to form another beam of light.

10. A polarized light endoscope, comprising a camera head according to claim 8 or 9.

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