Video type operating microscope optical system based on parallel light fusion and design method

Abstract

The invention provides a parallel light fusion-based video type operating microscope optical system and a design method, and the design method for realizing a video type operating microscope by adopting a parallel light fusion double-zoom system removes the traditional eyepiece, objective lens and afocal system, and is realized by two continuous zoom systems. A video type operating microscope optical system with high magnification and long working distance is designed, the magnification range is 0.5 *-6 *, the magnification is 12 times, and the working distance is 100 mm; the high-magnification optical system of the operating microscope is richer in application scene, and is a continuous zoom system capable of realizing 0.5 * to 6 *; compared with a gear shifting system, the system is more flexible and can be suitable for surgical operations in more scenes; the zoom ratio is further improved, the exterior mirror is an 8-fold system, and the system is a 12-fold system; the visual field of the object space of the external sight glass system is 15 mm to the minimum, and the visual field of the object space of the external sight glass system is 2 mm to the minimum, so that the external sight glass system can also be used in fine operations such as skin cancer edge cutting and blood vessel observation.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronic technology, and particularly relates to a high magnification ratio optical system for a video type operating microscope with parallel light fusion and a design method thereof. Background Art

[0002] Currently, the main operating microscopes developed and designed in China are binocular microscopes. Researchers and medical staff found that in addition to the surgeon obtaining binocular stereoscopic vision through the eyepiece. The optical system of the binocular operating microscope magnifies the observed lesion and forms an image on the human eye. The specific imaging optical path is as Figure 1 shown, where 1 is the large objective lens of the operating microscope, 2 is the Galileo zoom system (abbreviated as the zoom system), 3 is the eyepiece objective lens with an image rotation prism, and 4 is the eyepiece. The light emitted by the object located on the object focal plane of the operating microscope becomes parallel light after passing through the large objective lens. This parallel light enters the left and right zoom systems respectively; the parallel light enters the zoom system and then exits as parallel light. By changing the positions of the moving group 2a and the compensating group 2b in the zoom system, the purpose of changing the aperture of the outgoing light beam is achieved; this parallel light then enters the eyepiece objective lens system with an image rotation prism. The prism in the system realizes the purpose of adjusting the pupil distance and erecting the image. The eyepiece objective lens converges the incident light beam onto the focal plane of the eyepiece, and then parallel light exits through the eyepiece, thus entering the observer's eyes.

[0003] Currently, the research on the design of the optical system of the binocular operating microscope mainly focuses on the structural design of the large objective lens and the zoom system, etc. In 2006, Wu Kaijun designed a neurosurgical operating microscope. The design workload was huge, mainly involving the design of the large objective lens, the continuous zoom system design, the eyepiece design, etc. In 2016, Yang Lihua designed a continuous zoom large objective lens system based on the stereoscopic operating microscope, with a focal length range of 230 mm to 400 mm and a surgical surface observation range of 20 mm to 125 mm. For the production and use of this system, a corresponding eyepiece system, etc. need to be equipped. It belongs to the partial structural design of the optical system of the operating microscope. In 2025, Hu Zhaorui designed a afocal zoom system for the zoom system of the operating microscope, which can achieve ten-fold continuous zoom from 0.4× to 4×, providing certain technical support for the high magnification ratio requirement of the operating microscope.

[0004] However, the current high-speed development of image processing and informatization, as well as the binocular microscope, have increased the operation difficulty of surgical operations and the occupational injury risk of medical staff to a certain extent. Changing the binocular microscope by combining the operating microscope with intelligent technology has become a new direction for surgical microscopic imaging.

[0005] In 2022, Cao Zhongyu designed a dual-light-path 3D external viewing mirror with variable working distance and five-stage zoom. The design method uses the fusion of two zoom systems.

[0006] AsFigure 2 and 3 As shown in 3 , this solution combines the Greenough - type double - optical - path structure and the infinity - corrected optical system structure of the CMO type, and proposes a new optical structure applicable to 3D zoom external visual microscopes. It uses two image sensors to replace the traditional eyepiece. Each single optical path consists of two sets of zoom subsystems in front and behind, forming an optical structure in the infinity - corrected form. The setting of the double optical paths reduces the overall design difficulty and improves the cost - performance ratio. The combination of the two sets of zoom subsystems in front and behind in the form of an infinity - corrected optical system is more concise than the optical structure of the CMO. While keeping the middle optical path parallel for easy attachment of accessories, it also has the characteristics of being able to change the working distance and magnification ratio simultaneously.

[0007] Finally, the lateral magnification ratios corresponding to the five gears of the designed external visual microscope optical system are 1 / 1.25, 1 / 3.4375, 1 / 5.625, 1 / 7.8125, and 1 / 10 times respectively, with an 8 - fold zoom, and the corresponding working distances are 200 mm, 250 mm, 300 mm, 350 mm, and 400 mm respectively.

[0008] There are currently various domestic surgical zoom microscopes in the domestic market. Their technical parameters generally can achieve a magnification range of 0.7× to 4.5×, with a relatively small zoom ratio. And from the perspective of product form, most of these devices adopt the traditional optical observation mode and mainly rely on the eyepiece for microscopic observation. Some products can be connected to a digital camera by means of an external electronic eyepiece adapter to achieve the function of video image acquisition. However, compared with professional video - type microscope systems, this modified solution still has obvious gaps in terms of image quality, operation convenience, etc., indicating that domestic microscopic devices still need to be further improved in digital integration.

[0009] Therefore, combining the surgical microscope with current new technologies such as digital processing and increasing the magnification of domestic surgical zoom microscopes are the main technical problems to be solved in this invention. Summary of the Invention

[0010] In view of this, the purpose of the present invention is to provide a video - type surgical microscope optical system and design method based on parallel - light fusion, abandoning the traditional optical mode of surgical microscopes, and realizing a continuously variable - magnification optical system of a high - magnification - ratio video - type surgical microscope through a parallel - light - fusion double - zoom system. It provides certain technical support for the research of current surgical microscopes, increases the magnification of current surgical microscopes, and has good development prospects in the field of clinical medicine. From the perspective of technological development trends, this microscopic system integrating advanced optical technology and digital imaging functions will surely promote the development of microsurgery towards higher precision and more intelligent directions.

[0011] A video surgical microscope optical system includes a front zoom system, a rear zoom system, and an image sensor; light is emitted from an object point, exits as parallel light after passing through the front zoom system, and enters the rear zoom system in a parallel light fusion manner. After the light passes through the rear zoom system and forms an image, it converges and enters the image sensor; the object-side half-field range of the video surgical microscope optical system is 1 mm to 12 mm, the half-image height is 6 mm, achieving a high magnification ratio of 12 times, the working distance is 100 mm, and the total system length is within 500 mm.

[0012] Preferably, the lenses in the front zoom system and the rear zoom system are divided into four moving groups and three fixed groups; each fixed group remains stationary, and the moving groups move forward and backward as a whole during zooming to achieve zooming; light diverges from the object surface and enters the first fixed group. After converging inside the first fixed group, the light diverges and enters the first moving group; the light passes through the second convergence of the first moving group and enters the second moving group, and after divergence, it enters the second fixed group; the second fixed group converges the light and then enters the third moving group; the light passes through the third moving group, converges first and then diverges, enters the fourth moving group, and after convergence, finally enters the third fixed group, where it diverges first and then converges, and finally focuses on the image plane of the image sensor.

[0013] Preferably, the first fixed group includes a plano-convex lens and a plano-concave lens;

[0014] The first moving group includes two convex lenses;

[0015] The second moving group is a cemented lens composed of two lenses;

[0016] The second fixed group includes two cemented lenses, three convex lenses, and a concave lens;

[0017] The third moving group includes a cemented lens and a concave lens;

[0018] The fourth moving group includes two convex lenses and a cemented lens;

[0019] The third fixed group includes a concave lens and three convex lenses.

[0020] Preferably, the air gaps of the four moving groups and the three fixed groups during zooming are as follows in the table:

[0021]

[0022] A design method for the optical system of a video surgical microscope, comprising: designing the front zoom optical system and the rear zoom optical system respectively; wherein, for the front zoom optical system, its optical path is mirror-inverted along the optical axis to make it incident with parallel light and then converge on the image plane for imaging. After the design is completed, it is mirror-inverted back; then, according to the pupil matching principle, the designed front and rear zoom optics are used to realize the design of the continuous zoom optical system of the video surgical microscope by means of the parallel light fusion method.

[0023] The present invention has the following beneficial effects:

[0024] The present invention provides an optical system and a design method for a video surgical microscope based on parallel light fusion. The design method of the video surgical microscope is realized by using a dual-zoom system based on parallel light fusion, removing the traditional eyepiece, objective lens, and afocal system, and replacing them with two continuous zoom systems for design; an optical system for a video surgical microscope with a high magnification ratio and a long working distance is designed, with a magnification range of 0.5× to 6×, a 12-fold magnification, and a working distance of 100 mm.

[0025] The high-magnification optical system of the surgical microscope of the present invention has a richer application scenario: the design of the external viewing mirror system is a gear system, and there are only five gear changes during use. This system is a continuous zoom system, which is a continuous zoom system that realizes 0.5× to 6×. Therefore, compared with the shift system, this patent is more flexible and can be applied to surgical operations in more scenarios; in terms of the magnification ratio, it is further improved. The external viewing mirror is an 8-fold system, and this system is a 12-fold system.

[0026] The system can observe the picture more carefully. The minimum object-side field of view of the external viewing mirror system is 15 mm, and the minimum object-side field of view of the system of the present invention is 2 mm. Therefore, it can also be used in fine surgeries such as the marginal cutting of skin cancer and blood vessel observation. Description of the Drawings

[0027] Figure 1 It is a component of the optical system of a binocular surgical microscope;

[0028] Figure 2 It is a schematic diagram of the optical structure of a 3D external viewing mirror;

[0029] Figure 3 It is the optical structure of a 3D external viewing mirror;

[0030] Figure 4 It is the design flow chart of the optical system of the present invention;

[0031] Figure 5 It is the evolution of the structure of the microscopic optical system;

[0032] Figure 6It is the design schematic diagram of the optical system of the video surgical microscope, where 6(a) is the front zoom system, 6(b) is the rear zoom system, and 6(c) is the video surgical microscope system;

[0033] Figure 7(a) is the design schematic diagram of the reverse optical path; Figure 7(b) is the design process of the flip of the front zoom system;

[0034] Figure 8 It is the optimized front zoom system;

[0035] Figure 9 It is the optical path diagram of the rear zoom system, and the focal lengths from top to bottom are 300mm, 240mm, 136mm, and 90mm respectively;

[0036] Figure 10 It is the optical path diagram of the continuous zoom system of the video surgical microscope, and the magnification factors are 6, 3, 0.85, and 0.5 times respectively;

[0037] Figure 11 It is the optical path diagram of the optical system of the video surgical microscope in the embodiment of the present invention. Specific implementation mode

[0038] The following combines the accompanying drawings and gives examples to describe the present invention in detail.

[0039] The present invention separately optimizes and designs the surgical microscope optical path into a front zoom system and a rear zoom system, and then fuses the two systems to comprehensively optimize and evaluate the image quality of the continuous zoom system of the video surgical microscope to ensure the excellent imaging of the system. The specific process is as Figure 4 shown.

[0040] Method concept: The optical system of the video surgical microscope (optical path feature: point incident and point exiting) splits the optical path into two zoom systems (front system: point incident and parallel light exiting; rear system: parallel light incident and point exiting), and then realizes the target video surgical microscope optical system through the fusion of parallel light. Both zoom systems use mechanical zoom compensation to achieve the zoom function of the system. Among them, the front zoom system adopts the reverse optical path design, and the reverse optical path design method can more simply realize the design of the front zoom system.

[0041] The front zoom optical system replaces the traditional fixed focal length objective lens. This system can adjust the object surface size and mainly realizes the control of the system working distance and the design of the object surface range. The design method adopts the reverse optical path design, that is, parallel light is incident and converges on the image plane through the system to form an image. Therefore, before fusion, the front zoom system needs to be mirror-flipped along the optical axis and then can be fused with the rear zoom system.

[0042] The rear zoom optical system replaces the conventional afocal zoom module and the eyepiece objective lens, achieving the stability of the system image height and the constancy of the image plane position. It receives the parallel optical path of the front zoom system and is designed for the forward optical path.

[0043] After separately designing the front and rear zoom optical systems, according to the pupil matching principle, the continuous zoom optical system of the video surgical microscope can be realized by using the parallel light fusion method. The microscopic system is realized by the way of parallel light fusion. The fused microscopic system has four moving components, and the zoom effect is realized by the linkage method.

[0044] Finally, an optical system of a video surgical microscope with a high magnification ratio (12 times, magnification range 0.5× - 6×) is realized by adopting a new design scheme.

[0045] 1. Theoretical analysis

[0046] According to the principle of the video surgical microscope system, this system adopts a single optical path design, does not require the assembly of an eyepiece, can directly transmit the image to the image sensor, and realizes the connection with the video system. Figure 4 The design idea of the overall structure of the video surgical microscope system is shown.

[0047] Figure 5 (a) In it, the traditional visual single-path optical system consists of an objective lens, an afocal zoom system, an eyepiece objective lens system, and an eyepiece. Different from this, the surgical microscope optical system directly receives the image through the image sensor, so that the traditional visual device can no longer use the eyepiece. Therefore, the structure of the present invention will be constructed based on this.

[0048] Figure 5 (b) In it, the system with the eyepiece removed and the image sensor added can be seen. Currently, the mainstream surgical microscopes generally adopt a fixed focal length objective lens design, and its imaging range is strictly limited, and it can only form a clear image for observation targets of specific sizes. However, various microsurgical operations have different requirements for the object surface size and zoom. In order to enable the video surgical microscope system to flexibly meet the surgical requirements of zoom and different object surface sizes and improve the versatility of the system, this study adopts a zoom system with a reverse optical path design to replace the traditional fixed focal length objective lens. This module can keep the parallelism of the outgoing light beam while changing the object surface size and is the front zoom system.

[0049] Such as Figure 5As shown in (c), by optimizing the system architecture, the afocal zoom module and the eyepiece imaging component that are necessary in the traditional design are cancelled, and a rear zoom component is introduced as the core compensation unit. These two zoom systems designed based on the infinite conjugate optical principle work together, and a complete video-type microscopic continuous zoom system is formed through an innovative method of parallel light fusion. In this system, the front zoom component can not only regulate the object field of view range, but also be responsible for guiding the processed parallel light beam into the subsequent system; the cooperating rear zoom component undertakes the key tasks of stabilizing the image plane position and image height. By precisely converging the incident parallel light beam, it jointly realizes the continuous adjustment of the overall magnification of the system with the front zoom component. This innovative architecture of the dual-zoom system collaborative design through parallel light fusion not only simplifies the optical path complexity of the traditional microscope, but also significantly improves the optical performance stability of the system during the zoom process.

[0050] Figure 5 (c) and (d) mainly illustrate the reasons for the selection of the parallel light fusion method in the present invention. Figure 5 (c) is the fusion method of point convergence and point emergence. The light rays emitted by the front zoom system converge into a point and then enter the rear zoom system from the point. The fusion process requires a certain optical path distance, which increases the total length of the system and is not conducive to miniaturization design. Figure 5 (d) is the fusion method of parallel light. The light rays of the front zoom system are emitted as parallel light and then enter the rear zoom system in the form of parallel light. This method well reduces the effective length of the system and meets the requirements of system compactness. Therefore, the parallel light fusion method is preferred in this design. Therefore, Figure 5 (d) is the overall structural schematic diagram of this design. For the parallel light fusion method, it is difficult to evaluate the image quality of the system in the design of the optical path where the front zoom system has point incidence and parallel light emergence. Therefore, both the front and rear systems are designed with the optical path of parallel light incidence and point emergence.

[0051] Based on the determination of the overall structure, Figure 6 The fusion design schematic diagram of the video-type surgical microscope system is specifically shown. Figure 6 (a) is the front zoom system. It can be seen from the figure that the light rays are emitted from the object point and finally emitted in the form of parallel light. Therefore, in the design of the front zoom system, the reverse optical path design is adopted. From Figure 6 (b), it can be seen that after the front zoom system emits parallel light, it then enters the rear zoom system in the form of parallel light fusion. After the light rays are imaged by the rear zoom system, they converge and enter the image sensor. Therefore, the design of the rear zoom system adopts the forward optical path design.

[0052] The fusion of the two systems is as shown in Figure 6 (c). The principle of pupil matching is mainly adopted to ensure the matching of the exit pupil size of the front zoom system and the entrance pupil size of the rear zoom system, and the exit pupil position of the front zoom system is consistent with the entrance pupil position of the rear zoom system.

[0053] 2. System Parameters

[0054] Select a 2 / 3-inch CMOS image sensor with a diagonal of 11 mm and a pixel size of 7 μm × 7 μm. Considering a margin, the full image height is set to 12 mm and the half image height is 6 mm.

[0055] The object space field of view range of the system is 2 mm to 24 mm (when designing, a half field of view of 1 mm to 12 mm is used for design). According to the formula for lateral magnification:

[0056]

[0057] y' is the half image height and y is the half object height. After calculation, the magnification range of the zoom system of the video type surgical microscope can be obtained as 0.5× to 6×.

[0058] The resolution of the optical system is determined by the pixel size Δ of the image formed on the image sensor. The image space resolution of this optical system can be calculated from formula (2) as:

[0059] 7 μm = Δ ≤ δ' = δβ ≤ 2Δ = 14 μm (2)

[0060] The image space resolution δ' is taken as 9 μm, and the object space resolution δ ranges from 1.5 μm to 18 μm, which can meet the requirements of microsurgical operations.

[0061] According to the microscope resolution formula:

[0062]

[0063] In the formula, the wavelength λ is set to 0.588 μm, and the object space numerical aperture is 0.01 to 0.23. Similarly, the image space numerical aperture is 0.039.

[0064] The ratio of the focal length of the rear zoom system to that of the front zoom system is the system magnification of the system. Therefore, according to the value of β, by determining the focal length of one system, the focal length range of the other system can be calculated based on the calculation relationship.

[0065] f2' = f1'β (4)

[0066] Set the focal length range of the front zoom system to 50 mm to 180 mm, and set the focal lengths of the four configurations of the front zoom system to 50 mm, 80 mm, 160 mm, and 180 mm respectively. According to formula (4), the focal length range of the rear zoom system can be calculated as 90 mm to 300 mm, and the corresponding four configuration focal lengths are 300 mm, 240 mm, 136 mm, and 90 mm respectively.

[0067] The design specifications of the optical system of the video type surgical microscope are shown in Table 1.

[0068] Table 1 Design Index Requirements

[0069]

[0070] 3. Optical System Design

[0071] The system design is mainly divided into three steps: the design of the front zoom optical system, the design of the rear zoom optical system, and the design of the continuously variable magnification optical system of the video type operating microscope after system integration.

[0072] (1) Design of the front zoom optical system

[0073] The front zoom system realizes the magnification change of the video type operating microscope optical system by changing the size of the object plane. The optical path feature is that the object point is incident and parallel light is emitted. Since the optical design software is good at optimizing and evaluating the imaging of the image point, the reverse optical path design is adopted in the front zoom system. The reverse optical path design is a new type of optical design method. Different from the traditional forward optical path design, it starts from the target image and reversely deduces the design scheme of the optical system. The advantage of this design method is that it can better meet the requirements of the target image and improve the imaging quality of the optical system. In the operation, the actually designed system is shown in Fig. 7(a). Flipping it along the optical axis can obtain the target design system, that is, the exchange of parameters such as the object image plane and the object height image height. Another important function of the front zoom system is to maintain a certain working distance. The working distance is the distance from the lens surface to the actual surgical operation. This system is a long working distance system, so the working distance needs to be maintained above 100 mm.

[0074] From the theoretical level of optical design, the function realization of the front zoom subsystem is relatively simplified, and the specifications of its numerical aperture and object space field of view are relatively loose. Based on this characteristic, theoretically, an optical compensation type zoom scheme with a relatively simple structure can be adopted. However, this scheme has obvious defects in practical applications: the image plane position will shift during the zooming process. Considering that the system needs to maintain the stability of the image plane position, it is necessary to add a compensation lens group to correct this displacement. Finally, a mechanical compensation type zoom structure is adopted as the design scheme. The optimized system architecture is as Figure 8 shown. The aperture stop is located on the first surface, the focal length change range is 50 mm to 180 mm, the image space semi-field of view changes from 1 mm to 12 mm, the total length is 300 mm, and it is a positive group mechanical compensation system composed of two moving groups. The detailed lens parameters are shown in the corresponding Table 3.

[0075] Table 2 Lens Data Sheet of the Front Zoom System

[0076]

[0077] During the design process of the front zoom system optical system, a 180° spatial transformation needs to be implemented on its optical path structure. Although this operation can achieve the mirror image processing of the basic lens arrangement through the automatic flipping function in optical design software (such as ZEMAX or CODEV), it should be noted that this automated process only completes the geometric symmetry transformation of the lens material, and the important optical parameters of the system still need to be manually adjusted and optimized. After completing the basic flipping, the key parameters of the system must be correspondingly modified: the original image plane is redefined as the object plane, the exit pupil position is adjusted to the entrance pupil position, and it is ensured that all relevant parameters are converted one by one. After such meticulous parameter correction, the optical performance of the front zoom system can be completely retained to achieve the flipping effect required by the design. As shown in Figure 7(b), the flipped structure after the above systematic processing not only maintains the original optical characteristics but also meets the spatial layout requirements for subsequent system integration.

[0078] (2) Rear zoom optical system design

[0079] When designing the rear zoom system, ensuring the image height stability and the constant image plane position are the core design requirements. This system adopts an optical architecture with parallel light incident and convergent light exiting, so the forward design method can be used. Through the analysis of system characteristics, it is found that compared with the front zoom subsystem, the rear zoom subsystem needs to achieve a larger zoom ratio and a higher F-number, and excellent imaging quality and image plane stability must be maintained throughout the zoom process. Based on these strict requirements, a four-element mechanical compensation structure is finally determined. Although this solution will increase the system complexity and the number of lenses, it can better meet the performance requirements.

[0080] When choosing the compensation form of the zoom system, the requirements for image plane stability need to be considered. The optical compensation method is usually applicable to systems with a relatively small relative aperture, a relatively narrow field of view, and a small zoom ratio, or large magnification systems with less strict requirements for the image plane position. However, this system needs to achieve continuous zoom throughout the process and maintain the image plane stable, and the optical compensation method cannot meet the requirements due to its inherent focal distance dispersion characteristics. Although the full-motion type and the two-group linkage zoom methods can provide excellent imaging quality, their mechanical structures are too complex. Considering factors such as design difficulty and processing accuracy, the mechanical compensation method is finally selected as the optimal solution. For the selection of the compensation component, considering that the system needs to achieve a large magnification ratio (exceeding 10 times) and a long focal length, a four-element positive group mechanical compensation form is used for design. The rear zoom system is as Figure 9 shown, the aperture stop is placed on the first surface, the image height is kept at 6 mm, and Table 3 is the lens data sheet of the rear zoom system.

[0081] Table 3 Rear zoom system lens data

[0082]

[0083] (3) Design of the Optical System of the Video Surgical Microscope

[0084] During the integration of the optical system, when the front zoom system is flipped in the optical path and integrated with the rear zoom system, the basic optical principle of pupil matching must be strictly followed. Specifically, the exit pupil diameter of the previous optical system must be smaller than the entrance pupil size of the subsequent system, and at the same time, the pupil positions of both need to be accurately aligned. This is a key design constraint to ensure efficient light energy transmission and avoid vignetting effects. It should be particularly emphasized that only one aperture stop is allowed in the integrated optical system. Therefore, when integrating the system, the subsystem with a smaller clear aperture should be selected as the aperture stop position of the entire system. This selection is crucial for controlling stray light and optimizing imaging quality.

[0085] After the optical path flip, the front zoom system meets the design requirement of parallel light output. At this time, the exit pupil diameter range of the front zoom system is 7mm to 25mm, and the exit pupil positions of all four configurations are 0. The entrance pupil diameter of the rear zoom system remains greater than 25, and the entrance pupil positions of all four configurations are 0. The rear zoom system is inserted into the flipped front zoom system to achieve the parallel light integration mode of the front and rear systems. This innovative optical path connection method not only perfectly realizes the seamless integration of the front and rear systems but also fully meets the special requirements of the video surgical microscope for the optical system, including key technical indicators such as long working distance, large field of view range, and stable imaging performance. The entire integration process fully considers multiple factors such as pupil matching, aberration balance, and system stability.

[0086] The integrated system is a linked zoom system including four moving groups and three fixed groups. The optical path diagram of the final system is as Figure 10 shown. The object space semi-field of view range is 1mm to 12mm, the semi-image height is 6mm, thus achieving a high magnification ratio of 12 times. The working distance is 100mm, and the total system length is within 500mm, realizing a high magnification ratio video surgical microscope optical system. The system includes a first fixed group, which includes lens 1 and lens 2; a first moving group, including lens 3 and lens 4; a second moving group, including lens 5 and lens 6; a second fixed group, including lens 7 to lens 12; a third moving group, including lens 13, lens 14, and lens 15; a fourth moving group, including lens 16, lens 17, lens 18, and lens 19; a third fixed group 3, including lens 20 to lens 23. Among them, each fixed group remains stationary, and during zooming, the moving groups move forward and backward as a whole to achieve zooming.

[0087] The working principle of this system is as follows:

[0088] Light rays diverge from the object surface and enter the fixed group 1 (lens 1, lens 2). The fixed group 1 consists of a plano-convex lens and a plano-concave lens. After converging inside the fixed group 1, the light rays diverge and enter the moving group 1 (lens 3, lens 4). The moving group 1 consists of two convex lenses. The light rays are converged twice by the two convex lenses and then enter the moving group 2 (lens 5, lens 6). The moving group 2 is a cemented lens, which diverges the light rays and then the light rays enter the fixed group 2 (lens 7 - lens 12). The fixed group 2 is composed of two cemented lenses, three convex lenses and one concave lens, which converges the light rays and then the light rays enter the moving group 3 (lens 13, lens 14, lens 15). The moving group 3 consists of a cemented lens that converges light rays and a concave lens. The light rays converge first and then diverge after passing through the moving group 3 and enter the moving group 4 (lens 16 - lens 19). The moving group 4 consists of two convex lenses and one cemented lens, which converges the light rays in this part. Finally, the light rays enter the fixed group 3 (lens 20 - lens 23), which consists of one concave lens and three convex lenses. The light rays diverge after entering the concave lens and are finally converged on the image plane by the three convex lenses.

[0089] Table 4 Parameters of the continuous zoom system of the video type operating microscope

[0090]

[0091]

[0092] Table 5 Data table of zoom positions of the video type operating microscope system

[0093]

[0094]

[0095] In summary, the above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An optical system for a video surgical microscope, characterized in that, It includes a front zoom system, a rear zoom system and an image sensor; light is emitted from an object point, exits as parallel light after passing through the front zoom system, and enters the rear zoom system in a way of parallel light fusion. After the light forms an image through the rear zoom system, it converges and enters the image sensor; the object-side half field of view range of the optical system of the video surgical microscope is 1 mm to 12 mm, the half image height is 6 mm, a high magnification ratio of 12 times is achieved, the working distance is 100 mm, and the total system length is within 500 mm.

2. The optical system of a video-based operating microscope according to claim 1, characterized in that, The lenses in the front zoom system and the rear zoom system are divided into four moving groups and three fixed groups; each fixed group remains stationary, and the moving groups move forward and backward as a whole during zooming to achieve zooming; light diverges from the object surface and enters the first fixed group. After converging inside the first fixed group, the light diverges and enters the first moving group; the light enters the second moving group after double convergence of the first moving group, diverges after passing through it and enters the second fixed group; the second fixed group converges the light and then enters the third moving group; the light converges first and then diverges after passing through the third moving group and enters the fourth moving group, converges after passing through it and finally enters the third fixed group, diverges first and then converges after passing through it, and finally focuses on the image plane of the image sensor.

3. The optical system of a video surgical microscope according to claim 2, wherein: The first fixed group includes a plano-convex lens and a plano-concave lens; The first moving group includes two convex lenses; The second moving group is a cemented lens composed of two lenses; The second fixed group includes two cemented lenses, three convex lenses and a concave lens; The third moving group includes a cemented lens and a concave lens; The fourth moving group includes two convex lenses and a cemented lens; The third fixed group includes a concave lens and three convex lenses.

4. The optical system of a video-based operating microscope according to claim 3, characterized in that, The air spaces of the four moving groups and the three fixed groups during zooming are as follows:

5. A design method for the optical system of a video surgical microscope according to claim 1, 2, 3 or 4, characterized in that, Including: Design the front zoom optical system and the rear zoom optical system respectively; among them, for the front zoom optical system, flip its optical path along the optical axis to make it an optical path structure with parallel light incident and then converging to form an image on the image plane. After the design is completed, flip it back. Then, according to the pupil matching principle, adopt the parallel light fusion method to realize the design of the continuous zoom optical system of the video surgical microscope for the designed front and rear zoom optics.

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