Confocal scanning objective lens and endoscope

Abstract

The confocal scanning objective lens comprises a driving device and at least two lenses, the at least two lenses comprise a first lens, the first lens extends in the length direction of the first lens and comprises a far end and a near end, light from a detected part enters the first lens from the far end, and light from the detected part enters the second lens from the near end. The light is transmitted along the first lens and is emitted from the near end in a convergent form, so that the light further passes through other lenses except the first lens of the at least two lenses, and the driving device can drive the far end to move so as to enable the far end to correspond to different positions of the detected part. According to the utility model, the far end of the first lens can be driven to move so as to enable the first lens to correspond to different positions of the detected part, the far end of the first lens is imaged based on the obtained light when corresponding to any position of the detected part, and the images obtained corresponding to all the positions can be spliced to obtain the image of the detected part. The field of view for imaging a detected part can be increased.

Description

Technical Field

[0001] The utility model relates to the field of optical systems, in particular to a confocal scanning objective lens and an endoscope. Background Art

[0002] A confocal endoscope is a device that combines confocal microscopy and endoscopy. It enters the body cavity through natural or artificial channels to perform microscopic imaging of tissues. As a high-resolution endoscope, the confocal endoscope can distinguish tissue structures of tens or even a few microns, and can play the role of optical biopsy during surgery. However, the field of view of existing confocal endoscopes is very small, and the area that can be observed at one time is very limited. In existing technologies, it is within 0.5mm, which affects the inspection efficiency. Utility Model Content

[0003] The utility model aims to provide a confocal scanning objective lens and an endoscope, which can increase the field of view of imaging of the inspected part.

[0004] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0005] A confocal scanning objective lens, comprising:

[0006] At least two lenses, the at least two lenses include a first lens, the first lens extends along its length direction and includes a distal end and a proximal end, so that light from the inspected part enters the first lens from the distal end, the light propagates along the first lens and is emitted from the proximal end in a converging form, and the light further passes through other lenses of the at least two lenses except the first lens;

[0007] A driving device connected to the distal end of the first lens drives the distal end to move so that the distal end corresponds to different positions of the inspected part.

[0008] Optionally, the first lens is a gradient refractive index lens.

[0009] Optionally, the refractive index of the first lens is expressed as:

[0010] Where r represents the radial distance from the central axis of the first lens, n1 represents the refractive index of the center of the first lens, represents the gradient constant.

[0011] Optionally, the first lens causes the light entering the first lens to propagate in a bent form.

[0012] Optionally, the proximal end of the first lens is fixed.

[0013] Optionally, the movement trajectory of the distal end driven by the driving device is a circular spiral line.

[0014] Optionally, the at least two lenses also include a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged between the proximal end of the first lens and the image plane, the second lens has positive optical power, the third lens has positive optical power, the fourth lens has negative optical power, and the fifth lens has positive optical power.

[0015] Optionally, the object side surface of the second lens is a plane, and the image side surface is a convex surface, the object side surface of the fourth lens is a convex surface, and the image side surface is a concave surface, the object side surface of the fifth lens is a plane, and the image side surface is a convex surface, and the third lens is a cemented lens, which includes a first sub-lens and a second sub-lens, the object side surface of the first sub-lens is a concave surface, and the image side surface is a concave surface, and the object side surface of the second sub-lens is a convex surface, and the image side surface is a convex surface.

[0016] Optionally, the optical axis of the proximal end of the first lens is coaxial with the optical axis of the second lens.

[0017] A confocal endoscope, comprising:

[0018] The confocal scanning objective lens described in any one of the above items;

[0019] An imaging photosensitive element is arranged on the image plane of the confocal scanning objective lens and is used for imaging based on the light acquired by the confocal scanning objective lens.

[0020] It can be known from the above technical scheme that a confocal scanning objective provided by the utility model includes a driving device and at least two lenses, wherein the at least two lenses include a first lens, the first lens extends along its own length direction and includes a distal end and a proximal end, so that the light from the inspected part enters the first lens from the distal end, the light propagates along the first lens and is emitted from the proximal end in a converging form, so that the light further passes through other lenses of at least two lenses except the first lens, and the driving device is connected to the distal end of the first lens, and can drive the distal end to move so that the distal end corresponds to different positions of the inspected part. The confocal scanning objective of the utility model can drive the distal end of the first lens to move so that the first lens corresponds to different positions of the inspected part, and can perform imaging based on the light obtained by the confocal scanning objective when the distal end of the first lens corresponds to any position of the inspected part, and can splice the images corresponding to each position to obtain the image of the inspected part, so that the image of the inspected part obtained can cover each position of the inspected part scanned by the first lens, which can increase the field of view of imaging the inspected part.

[0021] The utility model also provides a confocal endoscope, which can achieve the above beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A light propagation path diagram of a confocal scanning objective lens provided in an embodiment of the utility model;

[0024] Figure 2 A schematic diagram of the arrangement of a confocal scanning objective lens and an imaging photosensitive element provided in an embodiment of the utility model;

[0025] Figure 3 An MTF curve diagram of a confocal scanning objective imaging provided by an embodiment of the utility model;

[0026] Figure 4 A light fan diagram of a confocal scanning objective provided by an embodiment of the utility model when the field height is 0 mm;

[0027] Figure 5 A light fan diagram of a confocal scanning objective provided by an embodiment of the utility model when the field height is 0.18 mm;

[0028] Figure 6 A point diagram of a confocal scanning objective lens imaging provided by an embodiment of the utility model;

[0029] Figure 7 A moving trajectory of the distal end of a first lens of a confocal scanning objective lens provided in an embodiment of the utility model;

[0030] Figure 8 A flow chart of an imaging method using a confocal scanning objective lens provided in an embodiment of the utility model.

[0031] The reference numerals in the drawings of the specification include:

[0032] 101 - first lens, 102 - second lens, 103 - third lens, 104 - fourth lens, 105 - fifth lens, 106 - first sub-lens, 107 - second sub-lens, 108 - driving device, 109 - imaging photosensitive element. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0034] This embodiment provides a confocal scanning objective lens, comprising:

[0035] At least two lenses, the at least two lenses include a first lens, the first lens extends along its length direction and includes a distal end and a proximal end, so that light from the inspected part enters the first lens from the distal end, the light propagates along the first lens and is emitted from the proximal end in a converging form, and the light further passes through other lenses of the at least two lenses except the first lens;

[0036] A driving device connected to the distal end of the first lens drives the distal end to move so that the distal end corresponds to different positions of the inspected part.

[0037] The at least two lenses are arranged in sequence from the object side to the image side, and the first lens is closest to the object side. The light from the inspected part enters the first lens from the far end of the first lens, the light propagates along the first lens and is emitted from the near end thereof in a converging form, and the light further passes through other lenses of the at least two lenses except the first lens to realize imaging of the inspected part.

[0038] The driving device drives the distal end of the first lens to move, so that the distal end of the first lens corresponds to different positions of the inspected part. When the distal end of the first lens corresponds to any position of the inspected part, the light from the position of the inspected part enters the first lens and enters the confocal scanning objective.

[0039] The confocal scanning objective lens of this embodiment can drive the distal end of the first lens to move so that the first lens corresponds to different positions of the inspected part. When the distal end of the first lens corresponds to any position of the inspected part, imaging can be performed based on the light acquired by the confocal scanning objective lens. The images corresponding to various positions can be spliced ​​to obtain an image of the inspected part. Then, the obtained image of the inspected part can cover various positions of the inspected part scanned by the first lens, thereby increasing the field of view of imaging the inspected part.

[0040] The light from the inspected part enters the first lens, propagates along the first lens and is emitted in a converging form, so that the light can be focused and imaged after further passing through at least two lenses other than the first lens. The first lens can be a gradient refractive index lens, which is formed using a medium with a gradient refractive index. In some embodiments, the first lens has a radial refractive index gradient, that is, the refractive index of the first lens changes along its radial direction, and the equal refractive index surface can be a cylindrical surface system symmetrical about the central axis, which can make the light entering the first lens propagate along the first lens and be emitted in a converging form. The central axis of the first lens is along its length direction.

[0041] In some embodiments, the refractive index of the first lens may be expressed as: Where r represents the radial distance from the central axis of the lens, n1 represents the refractive index at the center of the lens, represents the gradient constant, It reflects the degree of bending of light in the lens. The larger the value, the greater the degree of light bending. As the radial distance from the center of the lens increases, the refractive index decreases quadratically, and the steepness of the parabolic decline depends on the gradient constant. In practical applications, the gradient constant of the first lens can be set according to the imaging requirements and the requirements for the deflection of light by the first lens. As well as diameter and length. Figure 1 , Figure 1 A light propagation path diagram of a confocal scanning objective lens provided in this embodiment, the objective lens shown includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104 and a fifth lens 105 arranged in sequence from the object side to the image side, and the light entering the first lens 101 propagates along the first lens 101, the light propagates in a bent form in the first lens 101, and is emitted in a converging form and incident on the second lens 102. In some embodiments, the diameter of the first lens 101 is in the range of 1-2 mm, and has a certain toughness.

[0042] In this embodiment, the optical data such as the number, optical power, and surface shape of other lenses included in the objective lens except the first lens 101 are not limited, and can be set according to imaging requirements in practical applications. In some embodiments, the at least two lenses also include a second lens 102, a third lens 103, a fourth lens 104, and a fifth lens 105, which are sequentially arranged between the proximal end and the image plane of the first lens 101, and the second lens 102 has a positive optical power, the third lens 103 has a positive optical power, the fourth lens 104 has a negative optical power, and the fifth lens 105 has a positive optical power. For example, reference can be made to Figure 1The light entering the first lens 101 propagates along the first lens 101 and is emitted in a converging form and incident on the second lens 102. The light further passes through the second lens 102, the third lens 103, the fourth lens 104 and the fifth lens 105 in sequence and is focused onto the image plane. The optical axis of the proximal end of the first lens 101 is coaxial with the optical axis of the second lens 102.

[0043] In some embodiments, the object side surface of the second lens 102 is a plane surface, and the image side surface is a convex surface, the object side surface of the fourth lens 104 is a convex surface, and the image side surface is a concave surface, the object side surface of the fifth lens 105 is a plane surface, and the image side surface is a convex surface, and the third lens 103 is a cemented lens, which includes a first sub-lens 106 and a second sub-lens 107, the object side surface of the first sub-lens 106 is a concave surface, and the image side surface is a concave surface, the object side surface of the second sub-lens 107 is a convex surface, and the image side surface is a convex surface, and the image side surface of the first sub-lens 106 is bonded to the object side surface of the second sub-lens 107. The third lens 103 is a double cemented lens, and based on the surface shapes of the two sub-lenses and the reasonable configuration of their refractive indices, chromatic aberration can be eliminated, and there is no interval between the two sub-lenses, which helps to reduce the overall length of the objective lens. Exemplarily, detailed optical data of each lens are shown in Table 1 below, where the cross section of the first lens 101 is circular, the diameter of the first lens 101 (ie, the diameter of its cross section) is 1.8 mm, the gradient constant is 0.364, and the length is 34.2 mm.

[0044] Table 1

[0045]

[0046]

[0047] In addition, by simulating the imaging effect of the object distance of 0.1 mm based on the objective lens, the following can be obtained: Figure 3 The MTF curve shown in Figure 4 and Figure 5 The light fan diagram shown in Figure 6 Spot diagram shown. Figure 3 When the intermediate frequency is 445.3, the OTF modulus value = 0.4998, that is, when the OTF modulus value is about 50%, the resolution is 445.3lp / mm, which has higher imaging clarity. Figure 4 The corresponding field of view height (i.e. object height) is 0mm. Figure 5 The corresponding field height (i.e. object height) is 0.18 mm. Figure 6 The upper data of any figure is the field of view height (i.e. object height), and the lower data is the image height. Figures 4 to 6 It can be seen that the objective aberration is well optimized.

[0048] In some embodiments, the proximal end of the first lens 101 is fixed, so that the relative position of the proximal end of the first lens 101 and other lenses located on the image side of the first lens 101 is fixed, ensuring that the outgoing light of the first lens 101 is incident on the other lenses located on the image side of the first lens 101. Figure 2 , Figure 2 A schematic diagram of the arrangement of a confocal scanning objective lens and an imaging photosensitive element provided in this embodiment, as shown in the figure, the driving device 108 is connected to the distal end of the first lens 101, and can drive the distal end of the first lens 101 to move to different positions. The proximal end of the first lens 101 is fixed.

[0049] In this embodiment, the movement trajectory of the distal end of the first lens 101 driven by the driving device 108 is not limited, and can be set according to imaging requirements in actual applications. The driving device 108 can drive the distal end of the first lens 101 to move along a preset route to achieve a scanning imaging function. In some embodiments, the movement trajectory of the distal end of the first lens 101 driven by the driving device 108 is a circular spiral line, which can be referred to Figure 7 , Figure 7 The moving track of the distal end of the first lens of a confocal scanning objective provided in this embodiment. In practical applications, the number of turns of the spiral line can be determined according to the field of view of the objective lens and the field of view to be imaged. For example, the field of view of the objective lens is 0.6 mm, and the diameter of the imaging area to be scanned once is required to be 2 mm. The number of turns is determined based on the two and the overlapping area. In this embodiment, the structure of the driving device 108 is not limited, and the driving device 108 can adopt but is not limited to a stepping motor.

[0050] Compared with the prior art, the confocal scanning objective lens of this embodiment solves the defect of small field of view of the confocal objective lens, and uses a gradient refractive index lens (GRIN lens), which will not affect the imaging when the lens is moved. The confocal scanning objective lens can expand the observation field by more than 3 times while maintaining high resolution through lens scanning.

[0051] This embodiment also provides a confocal endoscope, comprising:

[0052] The confocal scanning objective lens as described in any one of the above embodiments;

[0053] An imaging photosensitive element is arranged on the image plane of the confocal scanning objective lens and is used for imaging based on the light acquired by the confocal scanning objective lens.

[0054] The confocal endoscope of this embodiment includes a confocal scanning objective lens which can drive the distal end of the first lens to move so that the first lens corresponds to different positions of the inspected part. When the distal end of the first lens corresponds to any position of the inspected part, imaging can be performed based on the light acquired by the confocal scanning objective lens. The images corresponding to various positions can be spliced ​​to obtain an imaging result of the inspected part. Then, the image of the inspected part obtained can cover various positions of the inspected part scanned by the first lens, thereby increasing the field of view of imaging the inspected part.

[0055] In this embodiment, the structure of the imaging photosensitive element is not limited, and a complementary metal oxide semiconductor (CMOS) imaging photosensitive element may be used but is not limited thereto.

[0056] For further reference Figure 8 , Figure 8 A flow chart of an imaging method using a confocal scanning objective lens provided in this embodiment is provided. As shown in the figure, the imaging method includes the following steps:

[0057] S11: driving the distal end of the first lens 101 to move so that the distal end corresponds to different positions of the inspected part, performing imaging based on the light obtained by the confocal scanning objective lens when the distal end corresponds to any position of the inspected part, and obtaining the moving position of the distal end of the first lens 101 and the corresponding image;

[0058] S12: according to the moving position of the distal end of the first lens 101, stitching the images corresponding to the moving positions to obtain an image of the inspected part.

[0059] When the distal end of the first lens 101 corresponds to any position of the inspected part, light from the inspected part at this position enters the first lens 101 from the distal end of the first lens 101, propagates along the first lens 101 and is emitted from the proximal end in a converging form, and the light can further pass through other lenses of the at least two lenses except the first lens 101, so that imaging can be performed based on the acquired light at this position to obtain an image corresponding to this position.

[0060] Each moving position of the distal end of the first lens 101 and the images corresponding to each moving position can be obtained. Further, according to the moving position of the distal end of the first lens 101, the images corresponding to each moving position are spliced ​​to obtain an image of the inspected part.

[0061] The confocal imaging method of this embodiment drives the distal end of the first lens to move so that the first lens corresponds to different positions of the inspected part. When the distal end of the first lens corresponds to any position of the inspected part, imaging is performed based on the light acquired by the confocal scanning objective lens. The image of the inspected part is obtained by splicing the images corresponding to each position. The obtained image of the inspected part can cover each position of the inspected part scanned by the first lens, thereby increasing the field of view of imaging the inspected part.

[0062] In some embodiments, driving the distal end of the first lens 101 to move so that the distal end corresponds to different positions of the inspected part may include: driving the distal end of the first lens 101 to move so that the distal end of the first lens 101 moves along a preset moving trajectory. In this embodiment, the preset moving trajectory is not limited and can be set according to imaging requirements in actual applications. The preset moving trajectory can be, but is not limited to, a circular spiral line. For example, reference can be made to Figure 7 As shown, Figure 7 The moving trajectory shown is a circular spiral line, which makes the objective lens scan in a spiral manner.

[0063] In some embodiments, driving the distal end of the first lens 101 to move so that the distal end corresponds to different positions of the inspected part may include: driving the distal end of the first lens 101 to move so that the distal end of the first lens 101 moves according to a preset moving trajectory within a cycle. Correspondingly, according to the moving position of the distal end of the first lens 101, stitching the images corresponding to the respective moving positions, and obtaining the image of the inspected part may include: according to the respective moving positions of the distal end of the first lens 101 within a cycle, stitching the images corresponding to the respective moving positions, and obtaining the image of the inspected part. Driving the distal end of the first lens 101 to move to perform a scanning process, during the scanning process, each small field of view of the first lens 101 will be imaged onto the imaging photosensitive element 109, and when the first lens 101 moves for a cycle, a complete field of view image acquisition is completed. After corresponding image processing, it is stitched into a complete large field of view image. Compared with the traditional confocal endoscope, it can greatly improve the inspection efficiency.

[0064] In some embodiments, according to the moving position of the distal end of the first lens 101, stitching the images corresponding to each moving position includes: according to the moving position of the distal end of the first lens 101, finding the images of adjacent moving positions and determining the overlapping areas between the images of adjacent moving positions, calculating the similarity of the overlapping areas of the images of adjacent moving positions, determining the stitching positions of the images of adjacent moving positions according to the similarity of the overlapping areas, and stitching the images of adjacent moving positions. According to the driving condition of the distal end of the first lens 101 by the driving device 109, the moving position coordinates of the distal end of the first lens 101 can be obtained, and the position of the corresponding image is determined according to the moving position of the distal end of the first lens 101. For adjacent images, the overlapping areas between adjacent images are determined, the similarity of the overlapping areas of adjacent images is calculated, and according to the similarity of the overlapping areas, it is determined which positions in the image of the adjacent images are the stitching positions, and each image is stitched.

[0065] The above is a detailed introduction to the confocal scanning objective lens and endoscope provided by the utility model. This article uses specific examples to illustrate the principle and implementation method of the utility model. The description of the above embodiment is only used to help understand the method and core idea of ​​the utility model. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the utility model, the utility model can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the utility model.

Claims

1. A confocal scanning objective lens, characterized in that: include: At least two lenses, the at least two lenses include a first lens, the first lens extends along its length direction and includes a distal end and a proximal end, so that light from the inspected part enters the first lens from the distal end, the light propagates along the first lens and is emitted from the proximal end in a converging form, and the light further passes through other lenses of the at least two lenses except the first lens; A driving device connected to the distal end of the first lens drives the distal end to move so that the distal end corresponds to different positions of the inspected part.

2. The confocal scanning objective lens according to claim 1, characterized in that: The first lens is a gradient refractive index lens.

3. The confocal scanning objective lens according to claim 2, characterized in that: The refractive index of the first lens is expressed as: Where r represents the radial distance from the central axis of the first lens, n1 represents the refractive index of the center of the first lens, represents the gradient constant.

4. The confocal scanning objective lens according to claim 1, characterized in that: The first lens causes the light entering the first lens to propagate in a bent form.

5. The confocal scanning objective lens according to claim 1, characterized in that: The proximal end of the first lens is fixed.

6. The confocal scanning objective lens according to claim 1, characterized in that: The movement trajectory of the distal end driven by the driving device is a circular spiral line.

7. The confocal scanning objective lens according to claim 1, characterized in that: The at least two lenses also include a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged between the proximal end of the first lens and the image plane, the second lens has positive optical power, the third lens has positive optical power, the fourth lens has negative optical power, and the fifth lens has positive optical power.

8. The confocal scanning objective lens according to claim 7, characterized in that: The object side surface of the second lens is a plane, and the image side surface is a convex surface, the object side surface of the fourth lens is a convex surface, and the image side surface is a concave surface, the object side surface of the fifth lens is a plane, and the image side surface is a convex surface, and the third lens is a cemented lens, which includes a first sub-lens and a second sub-lens, the object side surface of the first sub-lens is a concave surface, and the image side surface is a concave surface, and the object side surface of the second sub-lens is a convex surface, and the image side surface is a convex surface.

9. The confocal scanning objective lens according to claim 7, characterized in that: The optical axis of the proximal end of the first lens is coaxial with the optical axis of the second lens.

10. A confocal endoscope, characterized in that: include: The confocal scanning objective lens according to any one of claims 1 to 9; An imaging photosensitive element is arranged on the image plane of the confocal scanning objective lens and is used for imaging based on the light acquired by the confocal scanning objective lens.

Images