A multi-aperture imaging system, an endoscope, and an endoscope system

Abstract

The present application discloses a multi-aperture imaging system, an endoscope and an endoscope system, wherein the multi-aperture imaging system comprises a double telecentric system arranged along an optical path, a microlens array and an image sensor, wherein the double telecentric system comprises a first lens, a field aperture and a second lens arranged along the optical path, the microlens array comprises a plurality of sub-lenses arranged in a direction perpendicular to the optical path, and the image sensor is located in an imaging plane of the microlens array. It can be seen that the present application can prevent crosstalk between different imaging units without increasing the structural complexity of the multi-aperture imaging system by coordinating the arrangement of the double telecentric system and limiting the size of the field aperture therein.

Description

Technical Field

[0001] The present application relates to the field of optical imaging technology, and more specifically, to a multi-aperture imaging system, an endoscope, and an endoscope system. Background Art

[0002] At present, multi-aperture imaging can be used to achieve multi-spectral simultaneous imaging, that is, a multi-aperture imaging lens is used in conjunction with an image sensor with mosaic coating for imaging, and different color coating areas on the image sensor can form images of different colors. However, multi-aperture imaging lenses are usually composed of multiple microlenses. When a large field of view is incident, light crosstalk is easily generated between the sub-imaging units corresponding to each microlens, thereby affecting the imaging effect.

[0003] In the related art, multiple optical anti-crosstalk isolation layers are usually added between the multi-aperture imaging lens and the image sensor to prevent light crosstalk between the various sub-imaging units, but this method will undoubtedly greatly increase the structural complexity and processing difficulty of the multi-aperture imaging system.

[0004] Therefore, how to prevent crosstalk between different imaging units without increasing the structural complexity of the multi-aperture imaging system is a technical problem that those skilled in the art need to solve. Summary of the invention

[0005] The purpose of the present application is to provide a multi-aperture imaging system, an endoscope and an endoscope system, which prevent crosstalk between different imaging units without increasing the structural complexity of the multi-aperture imaging system.

[0006] To achieve the above-mentioned object, the present application provides a multi-aperture imaging system, comprising a double telecentric system, a microlens array and an image sensor arranged along an optical path direction, wherein the double telecentric system comprises a first lens, a field stop and a second lens arranged along the optical path direction, the microlens array comprises a plurality of sub-lenses arranged in a direction perpendicular to the optical path direction, and the image sensor is located at an imaging plane of the microlens array;

[0007] The focal length of the first lens is F1, the focal length of the second lens is F2, and the aperture size of the sub-lens in the microlens array is d n , focal length is F 3n ;

[0008] Then, the size D of the field stop satisfies:

[0009] D≤F2×d n / F 3n .

[0010] Preferably, the size D of the field stop satisfies: D=F2×dn / F 3n .

[0011] Preferably, the microlens array includes at least two types of sub-lenses, each type of sub-lens has a different aperture size and focal length;

[0012] The image sensor is located at the focal plane of the sub-lens with the largest focal length;

[0013] The multi-aperture imaging system further comprises:

[0014] The image transfer unit is arranged between other sub-lenses with smaller focal lengths and the image sensor, and is used for transferring the image formed by the sub-lenses with smaller focal lengths to the image sensor.

[0015] Preferably, the image relay unit comprises: a field lens and a relay lens group arranged along the optical path direction, and the field lens is arranged at the focal plane of the sub-lens with a smaller focal length.

[0016] Preferably, the microlens array includes a first type of sub-lenses and a second type of sub-lenses;

[0017] The aperture size of the first type of sub-lens is d1, and the focal length is F 31 , the aperture size of the second type of lens is d2, and the focal length is F 32 , where d1>d2 and F 31 >F 32 ;

[0018] Then, the focal length F4 of the field lens and the focal length F5 of the relay lens assembly respectively satisfy:

[0019] F4=L×F 32 / (2F 32 +L);

[0020] F5=L / 4;

[0021] Wherein, L is the distance between the focal plane of the second type of sub-lens and the focal plane of the first type of sub-lens.

[0022] Preferably, the first type of sub-lens and its corresponding imaging area in the image sensor have no filter film layer;

[0023] The second type of sub-lens or its corresponding imaging area in the image sensor is provided with a filter film layer.

[0024] Preferably, the first type of sub-lens includes one, the second type of sub-lens includes at least three; the filter film layer includes at least a red light filter film layer, a green light filter film layer and a blue light filter film layer.

[0025] To achieve the above objectives, the present application provides an endoscope, comprising the multi-aperture imaging system as described above.

[0026] Preferably, the endoscope is a rigid body.

[0027] To achieve the above objectives, the present application provides an endoscope system, including the endoscope as described above.

[0028] It can be seen from the above scheme that a multi-aperture imaging system provided by the present application includes a double telecentric system, a microlens array and an image sensor arranged along the light path direction, the double telecentric system includes a first lens, a field stop and a second lens arranged along the light path direction, the microlens array includes a plurality of sub-lenses arranged in a direction perpendicular to the light path direction, and the image sensor is located in the imaging plane of the microlens array; wherein the focal length of the first lens is F1, the focal length of the second lens is F2, and the aperture size of the sub-lenses in the microlens array is d n , focal length is F 3n ; Then, the size D of the field stop satisfies: D≤F2×d n / F 3n .

[0029] The multi-aperture imaging system provided by the present application is provided with a double telecentric system, in which the aperture serves as a field aperture, which limits the light entering the microlens array and controls the field angle of each sub-lens in the microlens array, thereby making the image heights corresponding to the maximum positive field of view of any sub-lens and the maximum negative field of view of the adjacent sub-lens be at the same position or do not interfere with each other, thereby effectively preventing crosstalk between images. It can be seen that the present application can prevent crosstalk between different imaging units without increasing the structural complexity of the multi-aperture imaging system by coordinating the provision of a double telecentric system and limiting the size of the field aperture therein. The present application also discloses an endoscope and an endoscope system, which can also achieve the above-mentioned technical effects.

[0030] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. The drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific implementation methods, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0032] Figure 1 A structural diagram of a multi-aperture imaging system provided in an embodiment of the present application;

[0033] Figure 2 A structural diagram of another multi-aperture imaging system provided in an embodiment of the present application;

[0034] Figure 3 An imaging schematic diagram provided in an embodiment of the present application;

[0035] Figure 4 A structural diagram of an endoscope system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] The embodiment of the present application discloses a multi-aperture imaging system, which prevents crosstalk between different imaging units without increasing the structural complexity of the multi-aperture imaging system.

[0038] See also Figure 1 , is a structural diagram of a multi-aperture imaging system provided in an embodiment of the present application, such as Figure 1 As shown, the multi-aperture imaging system 10 may include a dual telecentric system 100 , a microlens array 200 , and an image sensor 300 arranged along the optical path direction.

[0039] The dual telecentric system 100 includes a first lens 110 , a field stop 120 , and a second lens 130 arranged along the optical path.

[0040] The microlens array 200 is composed of a plurality of sub-lenses Ln;

[0041] The image sensor 300 is located on the imaging plane of the microlens array 200 .

[0042] The focal length of the first lens 110 is F1, the focal length of the second lens 120 is F2, and the aperture size of the sub-lens Ln in the microlens array is d n , focal length is F 3n ; Wherein, n refers to the nth sub-lens;

[0043] Then, the size D of the field stop satisfies:

[0044] D≤F2×d n / F 3n .

[0045] In a specific implementation, the field of view aperture 120 in the double telecentric optical system 100 can limit the light entering the microlens array. The size of the field of view aperture 120 controls the field of view angle entering the microlens array 200, and further controls the size of the sub-block image corresponding to each sub-lens Ln in the microlens array, so that adjacent sub-block images do not overlap, thereby preventing crosstalk between images.

[0046] The microlens array 200 includes a plurality of sub-lenses Ln arranged in a direction perpendicular to the optical path, and each sub-lens Ln can image the parallel light emitted by the double telecentric optical system 100 separately, forming a plurality of sub-block images for the same object side, wherein, since there is a certain offset between each sub-lens Ln, there is a specific position offset between the sub-block images accordingly. Specifically, the light of the object side can form parallel light through the double telecentric optical system 100, and enter the microlens array 200, and each sub-lens Ln in the microlens array 200 images it separately, and finally forms a plurality of sub-block images with specific sizes and offsets and no crosstalk.

[0047] If the microlens array includes n sub-lenses, the aperture size of each sub-lens is d, and the focal length is F3; then, the critical condition for no crosstalk between sub-block images is that the image heights corresponding to the maximum positive field of view of a sub-lens and the maximum negative field of view of the adjacent sub-lens are at the same position, then the maximum size of the sub-block image formed by each sub-lens is d, that is, the maximum image height of the sub-lens is d / 2, so the field angle of the sub-lens is obtained as To limit the field of view angle, it is necessary to control the field aperture, so the field aperture size D should be F2×d / F3, the total field of view angle φ=D / 2F1=F2×d / 2F1F3, and the total image plane size S=nd.

[0048] Therefore, it can be understood that when the field stop D in the double telecentric optical system satisfies D≤F2×d n / F 3n When the field of view of each sub-lens Ln is limited Make the maximum image height of each sub-block image no more than d n / 2, ensuring that any adjacent sub-block images will not overlap and preventing crosstalk between images. Optionally, in practical applications, in order to improve the spatial resolution of each sub-block image, D can be set to F2×d n / F 3n .

[0049] Based on the above technical solution, it can be known that the multi-aperture imaging system provided by the present application is provided with a double telecentric system, in which the aperture is used as a field aperture to limit the light entering the microlens array, and control the field angle of each sub-lens in the microlens array, so that the image heights corresponding to the maximum positive field of view of any sub-lens and the maximum negative field of view of the adjacent sub-lens are at the same position or do not interfere with each other, thereby effectively preventing crosstalk between images. It can be seen that the embodiment of the present application can prevent crosstalk between different imaging units without increasing the structural complexity of the multi-aperture imaging system by coordinating the setting of a double telecentric system and limiting the size of the field aperture therein.

[0050] Further, based on the above embodiments, it can be known that in order to avoid optical crosstalk between sub-block images, the size of the sub-block image formed by each sub-lens Ln should not exceed the aperture size d of the sub-lens Ln. n ; Again, in practical applications, the size D of the field stop and the focal length F2 of the second lens are usually fixed values; thus, combined with the above formula D = F2 × d n / F 3n It can be seen that the size of the sub-block image is proportional to the focal length F of the corresponding sub-lens 3n Roughly positively correlated: the aperture size d of the sub-lens n The larger the size of the sub-block image, the larger the focal length F of the sub-lens. 3n The bigger.

[0051] It can be seen that when using different aperture sizes d n and focal length F 3n The microlens array is composed of multiple sub-lenses, and the aperture size and focal length of these sub-lenses satisfy D≤F2×d n / F 3n When the sub-block images are obtained in different sizes, it is possible to obtain sub-block images, and at the same time, it is possible to ensure that no optical crosstalk occurs between the sub-block images.

[0052] In view of this, if Figure 2 As shown, the embodiment of the present application further provides another multi-aperture imaging system 20, which can form a plurality of sub-block images of different sizes according to actual needs.

[0053] The multi-aperture imaging system 20 is as follows: Figure 1 The multi-aperture imaging system 10 shown is distinguished by:

[0054] In the multi-aperture imaging system 20, the microlens array 200 includes at least two types of sub-lenses, each type of sub-lens has a different aperture size to form sub-block images of at least two sizes; and each type of sub-lens has a different focal length to satisfy D≤F2×d n / F3n , ensuring that there is no optical crosstalk between the sub-block images.

[0055] Further, it can be understood that, since the object side has the same field of view, after passing through the sub-lenses of different focal lengths, the imaging positions are not located on the same plane, and the imaging position of the sub-lens with a larger focal length is farther away from the sub-lens. Therefore, in this embodiment, the image sensor 300 is located on the focal plane of the sub-lens with the largest focal length; and in order to make all the sub-block images located on the same plane (i.e., the image sensor 300), the multi-aperture imaging system 20 further includes: an image transfer unit 400 disposed between other sub-lenses with smaller focal lengths and the image sensor 300, for transferring the images formed by other sub-lenses with smaller focal lengths to the focal plane of the sub-lens with the largest focal length.

[0056] Specifically, the image relay unit 400 includes: a field lens 410 and a relay lens group 420 arranged along the light path direction. The field lens 410 is arranged at the focal plane of the sub-lens with a smaller focal length, and is used to collect the image formed by the sub-lens with a smaller focal length and limit the light entering the relay lens group 420. The relay lens group 420 is used to re-image the light output by the field lens onto the image sensor 300.

[0057] As a feasible implementation, the microlens array 200 may include a first type of sub-lens 210 and a second type of sub-lens 220; the aperture size of the first type of sub-lens 210 is d1, and the focal length is F 31 The aperture size of the second type lens 220 is d2, and the focal length is F 32 , where d1>d2, F 31 >F 32 , and the size of the field stop 120 D = F2d1 / F 31 =F2d2 / F 32 .

[0058] Since the focal length F of the first type of sub-lens 210 31 Greater than the focal length F of the second type of sub-lens 220 32 Therefore, the image sensor 300 is located on the focal plane of the first type of sub-lens 210, and the image transfer unit 400 needs to transfer the image formed by the second type of sub-lens 220 to the image sensor 300. Specifically, according to the focal length F of the first type of sub-lens 210 31 and the focal length F of the second type of sub-lens 220 32, the distance L between the focal plane of the first type of sub-lens 210 and the focal plane of the second type of sub-lens 220 can be obtained; in order not to change the size of the image formed by the second type of sub-lens 220, following the principle of 2 times the focal length, the focal length F5 of the relay lens group 420 can be obtained = L / 4. In order to ensure that the optical elements between the focal plane of the first type of sub-lens 210 and the focal plane of the second type of sub-lens 220 do not interfere with the imaging of adjacent apertures, it is necessary to set the field lens 410 at the focal plane of the second type of sub-lens 220, and adjust the focal length of the field lens 410 so that the size of the relay lens group 420 is minimized, then the focal length F4 of the field lens 410 = L×F 32 / (2F 32 + L).

[0059] Among them, it is understandable that although Figure 2 Only one first-type sub-lens 210 and one second-type sub-lens 220 are shown in the figure, but in actual applications, the number of the first-type sub-lens 210 and the second-type sub-lens 220 can be 1, 2, 3 or more, respectively, which can be determined according to actual needs. Correspondingly, the number, setting position and optical characteristics of the field lens 410 and the relay lens group 420 in the image relay unit 400 can also be changed accordingly according to actual needs.

[0060] Furthermore, in order to simultaneously capture multi-spectral images, filter layers of different colors may be provided on each sub-lens or its corresponding imaging region in the image sensor.

[0061] Preferably, the first type of sub-lens 210 and its corresponding imaging area in the image sensor have no filter film layer; the second type of sub-lens 220 or its corresponding imaging area in the image sensor is provided with a filter film layer.

[0062] Among them, since the monochrome sensor used to collect grayscale images has stronger photosensitivity and can reduce light loss caused by filtering, and the human eye is more sensitive to structural details but less sensitive to colors, a larger imaging area can be allocated to the grayscale image, and a smaller imaging area to the color image, so that the output grayscale image has a higher spatial resolution while retaining the color image with a lower spatial resolution.

[0063] Therefore, in some embodiments, the first type of sub-lens 210 can be used to collect grayscale images, and the second type of sub-lens 220 can be used to collect color images. Specifically, a filter film layer is set on the second type of sub-lens 220 or its corresponding imaging area in the image sensor 300 to collect sub-block images of corresponding colors, while no filter film layer is set on the first type of sub-lens 210 and its corresponding imaging area in the image sensor 300 to collect grayscale sub-block images. By fusing the grayscale image with higher spatial resolution with the color image with lower spatial resolution, a multispectral image with higher definition can be obtained when a single image sensor is used.

[0064] Among them, since a multispectral image is usually composed of a red image signal, a green image signal and a blue image signal, in practical applications, the first type of sub-lens 210 may include one, the second type of sub-lens 220 may include at least three, and the filter film layer may include a red light filter film layer, a green light filter film layer and a blue light filter film layer.

[0065] Of course, in order to collect more color image signals to achieve multi-mode imaging, the second type of sub-lens 220 may also include more, for example, Figure 3 As shown, the color image formed therein may also include a fluorescent image and a UV image (ie, a blue-violet light image).

[0066] It can be seen that the microlens array in this embodiment includes different types of sub-lenses, which can form sub-block images with different imaging area sizes. By setting the image transfer unit, all sub-block images are located on the same plane, thereby obtaining sub-block images with different frames.

[0067] Furthermore, grayscale images can be captured with a larger pixel area, and color images can be captured with a smaller pixel area. The grayscale image with higher spatial resolution and the color image with lower spatial resolution can be fused, so that a higher image spatial resolution can be obtained while using a single image sensor.

[0068] An embodiment of the present application discloses an endoscope, which may include a multi-aperture imaging system as provided in any of the above embodiments.

[0069] For a specific implementation, see Figure 4 , is a structural diagram of an endoscope provided in an embodiment of the present application. Figure 4As shown, the endoscope includes a mirror tube 2, a light guide interface 3 and an optical imaging system 1 arranged inside the mirror tube 2, and a light guide fiber is arranged between the mirror tube 2 and the optical imaging system 1; the optical imaging system 1 includes an objective lens group 11, a rod lens group 12, an eyepiece group 13 and a multi-aperture imaging system 10 provided in any of the above embodiments along the light path direction.

[0070] The light guide interface 3 is connected to a light guide that provides an external light source. The external light source may include an illumination light source and / or an excitation light source. The illumination light generated by the light guide interface enters the light guide fiber in the mirror tube. The light output end face of each light guide fiber has a certain divergence angle, and is transmitted to the distal end face of the mirror tube 2 through the light guide fiber to illuminate the biological tissue to be inspected. The light reflected from the surface of the biological tissue is collected by the objective lens group 11, transmitted by the rod lens group 12, received by the eyepiece group 13, and then formed by the multi-aperture imaging system 10 to form a sub-block image with a specific color and a specific spatial distribution.

[0071] Among them, the field of view aperture in the double telecentric optical system can limit the light entering the microlens array. The size of the field of view aperture controls the field of view angle entering the microlens array, and then controls the size of the sub-block image corresponding to each sub-lens in the microlens array, so that adjacent sub-block images will not overlap, preventing crosstalk between images. The microlens array includes a plurality of sub-lenses arranged in a vertical direction along the direction of the optical path. Each sub-lens can separately image the parallel light formed by the double telecentric optical system to form a plurality of sub-block images. These sub-block images are images of the same object, and there is a specific position offset between the sub-block images. In this way, the parallel light output by the eyepiece passes through the double telecentric optical system, the microlens array, and the rear image transfer system when necessary, and finally forms a number of sub-block images with specific sizes and offsets and no crosstalk.

[0072] In addition, it should be noted that in the present embodiment, the endoscope is taken as a rigid endoscope as an example for explanation, mainly because the space for placing the multi-aperture imaging system in a rigid endoscope is usually more ample, and it is particularly appropriate to apply the multi-aperture imaging system provided in the present application to a rigid endoscope; but it can be understood that when process conditions permit, the multi-aperture imaging system provided in the embodiment of the present application can also be applied to an endoscope with a flexible insertion portion, that is, the endoscope provided in the embodiment of the present application can also be a soft endoscope.

[0073] The endoscope provided by the embodiment of the present application, wherein the aperture in the double telecentric system serves as a field aperture, limits the light entering the microlens array, controls the field angle of each sub-lens in the microlens array, and thereby makes the image heights corresponding to the maximum positive field of view of any sub-lens and the maximum negative field of view of the adjacent sub-lens be at the same position or do not interfere with each other, thereby effectively preventing crosstalk between images. It can be seen that the embodiment of the present application can prevent crosstalk between different imaging units without increasing the structural complexity of the multi-aperture imaging system by coordinating the setting of a double telecentric system and limiting the size of the field aperture therein.

[0074] The present application also provides an endoscope system, including the endoscope provided by any of the above embodiments, and may also include an endoscope light source for providing illumination light for the endoscope and an image processor for processing the image signal output by the image sensor. The endoscope system provided by the present application can also achieve the technical effects achieved by the above endoscopes.

[0075] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of this application, several improvements and modifications can be made to this application, and these improvements and modifications also fall within the scope of protection of the claims of this application.

[0076] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A multi-aperture imaging system, characterized in that: It comprises a double telecentric system, a microlens array and an image sensor arranged along an optical path, wherein the double telecentric system comprises a first lens, a field stop and a second lens arranged along the optical path, the microlens array comprises a plurality of sub-lenses arranged in a direction perpendicular to the optical path, and the image sensor is located at an imaging plane of the microlens array; The focal length of the first lens is F1, the focal length of the second lens is F2, the aperture size of the sub-lens in the microlens array is dn, and the focal length is F3n; Then, the size D of the field stop satisfies: D≤F2×dn / F3n.

2. The multi-aperture imaging system according to claim 1, characterized in that: The microlens array includes at least two types of sub-lenses, each type of sub-lens has a different aperture size and focal length; The image sensor is located at the focal plane of the sub-lens with the largest focal length; The multi-aperture imaging system further comprises: The image transfer unit is arranged between the sub-lens other than the sub-lens with the largest focal length and the image sensor, and is used for transferring the image formed by the sub-lens other than the sub-lens with the largest focal length to the image sensor.

3. The multi-aperture imaging system according to claim 2, characterized in that: The image relay unit comprises: a field lens and a relay lens group arranged along the optical path direction, and the field lens is arranged at the focal plane of the sub-lens except the sub-lens with the largest focal length.

4. The multi-aperture imaging system according to claim 3, characterized in that: The microlens array includes a first type of sub-lenses and a second type of sub-lenses; The aperture size of the first type of sub-lens is d1, and the focal length is F31, and the aperture size of the second type of sub-lens is d2, and the focal length is F32, wherein d1>d2 and F31>F32; Then, the focal length F4 of the field lens and the focal length F5 of the relay lens assembly respectively satisfy: F4 = L × F32 / (2F32 + L); F5=L / 4; Wherein, L is the distance between the focal plane of the second type of sub-lens and the focal plane of the first type of sub-lens.

5. The multi-aperture imaging system according to claim 4, characterized in that: The first type of sub-lens and its corresponding imaging area in the image sensor have no filter film layer; The second type of sub-lens or its corresponding imaging area in the image sensor is provided with a filter film layer.

6. The multi-aperture imaging system according to claim 5, characterized in that: The first type of sub-lens includes one, and the second type of sub-lens includes at least three; the filter film layer includes at least a red light filter film layer, a green light filter film layer and a blue light filter film layer.

7. An endoscope, characterized in that: Comprising the multi-aperture imaging system as described in any one of claims 1 to 6.

8. The endoscope according to claim 7, characterized in that The endoscope is a rigid body.

9. An endoscope system, characterized in that: Comprising an endoscope as described in claim 7 or 8.

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