Anesthesia video laryngoscope optical system

Abstract

The application discloses an anesthetic video laryngoscope optical system, and belongs to the technical field of medical instruments, in particular to an anesthetic video laryngoscope optical imaging system specially used for tracheal intubation operation for establishing an artificial airway in general anesthesia and emergency resuscitation. The system solves the problem that it is difficult to balance between an ultra-large field angle, a large depth of field, extreme compactness and low cost in the design of a video laryngoscope optical system. The system comprises a first lens, a first double-cemented lens group and a second double-cemented lens group arranged in sequence along an optical axis from an object side. The anesthetic video laryngoscope optical system is suitable for being used as an anesthetic video laryngoscope optical imaging system for tracheal intubation operation for establishing an artificial airway in general anesthesia and emergency resuscitation.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to an optical imaging system for an anesthesia video laryngoscope specifically used for endotracheal intubation procedures to establish an artificial airway during general anesthesia and emergency resuscitation; the system has been specifically optimized for the unique clinical needs of anesthesia intubation procedures. Background Technology

[0002] Video laryngoscopes are key equipment in modern anesthesiology and emergency medicine. They are used to establish artificial airways in scenarios such as general anesthesia and emergency resuscitation. Specifically, by displaying the glottic image captured by a camera installed at the front of the laryngoscope blade on the screen in real time, the operator can perform endotracheal intubation under indirect vision, thereby significantly reducing the difficulty of managing difficult airways.

[0003] In seeking to improve the performance of video laryngoscopes, those skilled in the art may attempt to reference optical design schemes from medical endoscopes (such as laparoscopes and bronchoscopes) with seemingly similar technical features. However, in-depth clinical practice and optical analysis reveal that, due to fundamentally different clinical application goals, anesthesia video laryngoscopes and diagnostic endoscopes have drastically different and contradictory technical performance requirements. This essential difference means that mature optical solutions in the field of endoscopy cannot be directly transferred or applied to the field of video laryngoscopes, specifically in the following core aspects:

[0004] First, there is a fundamental contradiction between the core mission and performance priorities. The core mission of diagnostic endoscopes is to observe and identify tissue lesions within human cavities; therefore, the highest priority in their optical design is high resolution and high color fidelity. This typically requires the use of large numerical aperture optical structures, aspherical lenses, and complex relay transmission systems to obtain images with extremely high clarity. However, the core mission of anesthesia video laryngoscopes is to quickly and safely guide the endotracheal tube through the glottis; its primary requirement is ease of operation and fault tolerance. During dynamic intubation, the distance between the lens and the glottis is constantly changing. Blindly pursuing high resolution and resulting in shallow depth of field becomes a serious drawback—because even small distance fluctuations can cause image blurring, interfering with or even misleading the operation. Therefore, the optical design of video laryngoscopes must prioritize a sufficiently large depth of field, which usually comes at the cost of sacrificing numerical aperture and ultimate resolution. This design philosophy of "depth of field prioritizing ultimate resolution" runs counter to the "resolution-first" design principle of endoscopes.

[0005] Secondly, the design motivations and requirements for the field of view are drastically different. Diagnostic endoscopes are designed with the goal of providing detailed observation within specific cavities, and their field of view is typically moderate. However, after being inserted into the patient's mouth, the end of the lens of anesthesia video laryngoscopes is relatively fixed, requiring rapid glottic localization within a limited space. Therefore, it usually needs an extremely large field of view (generally ≥60°, preferably ≥80°) to obtain the largest possible observation range on the screen at once, enabling rapid localization and avoiding repeated adjustments to the lens position that prolong operation time and increase patient risk. This rigid requirement for an extremely large field of view presents more stringent and unique challenges to the optical system's large field of view and aberration correction.

[0006] Third, there are significant differences in structural size, imaging methods, and cost constraints. To accommodate narrow natural cavities such as the nasal cavity and sinuses, many fine-diameter endoscopes use fiber optic image transmission bundles. However, their resolution is limited by the number of fibers, making it difficult to meet the demands of real-time high-definition video streaming. Rigid endoscopes that achieve high-definition levels generally use relay systems (rod endoscope systems) composed of multiple lenses to transmit images over long distances. These systems are complex, expensive, and difficult to miniaturize while maintaining image quality. In contrast, anesthesia video laryngoscopes use a lens group to directly image object-side light onto a CCD / CMOS image sensor integrated at the front of the lens. This direct imaging method eliminates the complex and expensive relay transmission system, resulting in a simpler optical path that greatly facilitates the compact design and low-cost manufacturing of laryngoscope blades. It also better meets the requirements of high frame rates and low latency for real-time video streaming.

[0007] In summary, due to specific constraints in terms of depth of field, field of view, structural size, and cost, anesthesia video laryngoscopes constitute a unique technical field. Directly applying endoscopic optical solutions centered on "high resolution" and complex imaging systems will result in video laryngoscopes failing to meet clinical needs in key indicators such as depth of field, field of view, cost, and reliability. Therefore, there is an urgent need in this field for an innovative optical solution specifically designed for anesthesia intubation scenarios, achieving an optimal balance between a large field of view, large depth of field, small size, low cost, and sufficiently clear imaging. Summary of the Invention

[0008] This invention proposes an anesthesia video laryngoscope optical system, which solves the problem of balancing ultra-wide field of view, large depth of field, extreme structural compactness and low cost in the design of video laryngoscope optical systems.

[0009] The present invention discloses an anesthesia video laryngoscope optical system, the system comprising: a first lens, a first cemented doublet lens group, and a second cemented doublet lens group arranged sequentially along the optical axis from the object side;

[0010] The object plane side of the first lens serves as the aperture stop;

[0011] The first cemented doublet lens group is composed of a second lens and a third lens cemented together; wherein, the front lens closer to the object side is the second lens, and the rear lens is the third lens;

[0012] The second cemented doublet lens group is composed of a fourth lens and a fifth lens cemented together; wherein, the front lens closer to the object side is the fourth lens, and the rear lens is the fifth lens;

[0013] The first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all spherical glass lenses, suitable for endotracheal intubation in video laryngoscopes.

[0014] Furthermore, a preferred embodiment is provided in which the optical parameters of the system satisfy the following relationship:

[0015] 0.9 ≤ IH / f ≤ 1.1

[0016] 33.8 ≤ L ≤ 95.8

[0017] 0.26≤IH / TTL≤0.39

[0018] 1.0 ≤ d1 / f ≤ 1.5

[0019] 1.65≤Bf / f≤1.8

[0020] 1.9 ≤ |fL1 / f| ≤ 2.1

[0021] 1.7 ≤ |f²³ / f| ≤ 1.95

[0022] 5.8 ≤ |f45 / f| ≤ 6.2

[0023] 0.7≤FNO / TTL≤0.82

[0024] in:

[0025] f is the focal length of the anesthesia video laryngoscope optical system; IH is half the optical image height of the anesthesia video laryngoscope optical system; L is the working distance of the anesthesia video laryngoscope optical system; TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the anesthesia video laryngoscope optical system; d1 is the center thickness of the first lens; Bf is the distance on the optical axis from the image side of the fifth lens to the imaging surface of the anesthesia video laryngoscope optical system; fL1 is the effective focal length of the first lens; f23 is the overall effective focal length of the second and third lenses; f45 is the overall effective focal length of the fourth and fifth lenses; FNO is the aperture number of the anesthesia video laryngoscope optical system.

[0026] Furthermore, in a preferred embodiment, the distance between the first lens and the first cemented doublet lens group, and between the first cemented doublet lens group and the second cemented doublet lens group, is 0 mm.

[0027] Furthermore, a preferred embodiment is provided in which the first lens has a concave surface on the side closer to the object and a convex surface on the side farther from the object;

[0028] In the first cemented doublet lens group and the second cemented doublet lens group:

[0029] The front lens has a convex surface on the side closer to the object and a concave surface on the side farther from the object; the rear lens has convex surfaces on both sides.

[0030] Furthermore, a preferred embodiment is provided, wherein the radius of curvature of the first lens on the object plane ranges from -1.5 mm to -3 mm, and the radius of curvature on the image plane ranges from -4 mm to -7 mm.

[0031] Furthermore, a preferred embodiment is provided, wherein the object-side radius of curvature of the first doublet lens group ranges from 9 mm to 14 mm, the cemented surface radius of curvature ranges from 2 mm to 4 mm, and the image-side radius of curvature ranges from -4 mm to -6 mm.

[0032] Furthermore, in a preferred embodiment, the object-side radius of curvature of the second doublet lens group ranges from 9 mm to 14 mm, the cemented surface radius of curvature ranges from 2 mm to 4 mm, and the image-side radius of curvature ranges from -10 mm to -16 mm.

[0033] Furthermore, in a preferred embodiment, the center thickness of the first lens is 2 mm to 4 mm;

[0034] In the first cemented doublet lens group, the thickness of the lens closer to the object is 0.5 mm to 1 mm, and the thickness of the lens farther from the object is 1.8 mm to 2.5 mm.

[0035] In the second cemented doublet lens group, the thickness of the lens closer to the object is 0.4 mm to 0.8 mm, and the thickness of the lens farther from the object is 1 mm to 1.8 mm.

[0036] Furthermore, a preferred embodiment is provided, wherein the system has a field of view of not less than 90° and a depth of field of not less than 62 mm, and is suitable for dynamic endotracheal intubation operations.

[0037] Furthermore, a preferred embodiment is provided, wherein the total optical length of the system is no more than 13 mm and the maximum diameter of the optical system is no more than 4.6 mm, which is suitable for the miniaturization and lightweight design requirements of video laryngeal blades.

[0038] The present invention has the following beneficial effects:

[0039] 1. The anesthesia video laryngoscope optical system of the present invention, by employing a specific optical structure composed of five conventional spherical glass lenses and setting the object plane side of the first lens as an aperture stop, achieves an ultra-large field of view of 90°, optimized specifically for the large field of view requirements of video laryngoscopes. This solves the unique clinical challenge of rapidly locating the glottis within the limited space of the oral cavity using a video laryngoscope.

[0040] 2. The anesthesia video laryngoscope optical system of the present invention, through innovative optical path design and lens combination, achieves excellent imaging quality with MTF>0.1 at 138 lp / mm and MTF>0.2 at 110 lp / mm while ensuring an ultra-large field of view. Under the rigid requirement of a video laryngoscope with an ultra-large field of view of ≥90°, it still achieves imaging quality sufficient to clearly present the details of the glottis, providing a reliable visual basis for the accurate and safe guidance of endotracheal tubes.

[0041] 3. The anesthesia video laryngoscope optical system described in this invention achieves a depth of field of 62 mm through specific optical parameter design. This depth of field performance is sufficient to meet the requirements of changing object distances during dynamic intubation operations, ensuring that the image remains clear and stable during catheter advancement, thus ensuring the success rate and safety of the operation. This differs from the endoscope design philosophy of sacrificing depth of field in pursuit of ultimate resolution, and solves the key defect that directly applying endoscope solutions will lead to blurred images in video laryngoscopes during dynamic operations.

[0042] 4. The anesthesia video laryngoscope optical system described in this invention achieves an extremely compact structure with a total lens optical length of only 13 mm and a maximum optical system diameter of only 4.6 mm by adopting an optical path design that directly images onto the front-end sensor and optimizing the lens arrangement. This design is not only cost-effective but also makes the entire optical system extremely compact, meeting the miniaturization and lightweight requirements of the objective lens of the video laryngoscope, ensuring the flexibility and convenience of operating the video laryngoscope in the patient's oral cavity, and providing a high-performance, low-cost optical system optimized for endotracheal intubation.

[0043] 5. The anesthesia video laryngoscope optical system of the present invention, by adopting all conventional spherical glass lenses, significantly reduces the manufacturing cost and processing difficulty of the system, which is conducive to popularization and promotion. On the other hand, the optical glass material has excellent chemical stability and mechanical strength, and the bonding process is stable, which enables it to withstand the strict clinical sterilization process and meet the reliability requirements of the video laryngoscope as a reusable medical device.

[0044] This invention discloses an anesthesia video laryngoscope optical system. Through the synergistic effect of the aforementioned technical means, it successfully solves the dilemma of balancing conflicting needs in anesthesia video laryngoscopes, including a wide field of view, large depth of field, miniaturization, low cost, sufficiently clear imaging, and reusability stability. It is specifically designed for endotracheal intubation procedures to establish artificial airways during general anesthesia and emergency resuscitation. Its design philosophy and performance priorities differ fundamentally from those of diagnostic endoscopes, and those skilled in the art cannot derive technical inspiration from other technical fields such as endoscopy, thus providing a reliable and economical dedicated optical solution for clinical practice. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the structure of an anesthesia video laryngoscope optical system in one embodiment of the present invention;

[0047] Figure 2 In one embodiment of the present invention, a modulation transfer function (MTF) curve of an anesthesia video laryngoscope optical system is shown.

[0048] Figure 3 A dot diagram of an anesthesia video laryngoscope optical system in one embodiment of the present invention;

[0049] Figure 4 In one embodiment of the present invention, a field curvature and distortion diagram of an anesthesia video laryngoscope optical system is provided.

[0050] Figure 5 In one embodiment of the present invention, a relative illumination diagram of an anesthesia video laryngoscope optical system is provided. Detailed Implementation

[0051] To make the technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail and completely below with reference to the accompanying drawings. The various embodiments described below are only some preferred embodiments of the present invention, and not all of them; the various embodiments described below are intended to explain the present invention and should not be construed as limiting the present invention; reasonable combinations of the technical features defined in the various embodiments of the present invention, as well as all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort, are all within the scope of protection of the present invention.

[0052] Implementation Method 1: An anesthesia video laryngoscope optical system, the system comprising: a first lens, a first cemented doublet lens group, and a second cemented doublet lens group arranged sequentially along the optical axis from the object side;

[0053] The object plane side of the first lens serves as the aperture stop;

[0054] The first cemented doublet lens group is composed of a second lens and a third lens cemented together; wherein, the front lens closer to the object side is the second lens, and the rear lens is the third lens;

[0055] The second cemented doublet lens group is composed of a fourth lens and a fifth lens cemented together; wherein, the front lens closer to the object side is the fourth lens, and the rear lens is the fifth lens;

[0056] The first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all spherical glass lenses, suitable for endotracheal intubation in video laryngoscopes.

[0057] In this embodiment, the object side refers to the side in which light enters the optical system (an anesthesia video laryngoscope optical system), that is, the side where the observed object is located.

[0058] Application in video laryngoscopy: on the side where the patient's glottis is located. Light is emitted from the glottis (or reflected after illumination) and enters the optical system of the laryngoscopy.

[0059] The "object side" is from the perspective of the entire optical system, indicating the direction of light transmission and the starting point of the element arrangement. It defines the coordinate system of the entire sequence.

[0060] In this embodiment, "object side" is a more relative term, specifically referring to the surface of an optical element (such as the first lens) that is closer to the "object side." In contrast, "image side" refers to the surface of the element that is closer to the "image side."

[0061] Example: For a single lens (such as the first lens), it has two surfaces. The surface closer to the object being photographed (or the object side) is called the "object side"; the surface closer to the imaging sensor is called the "image side".

[0062] In this embodiment, the image plane side refers to the side in which light rays exit the optical system, that is, the side where the image sensor (such as CCD / CMOS) imaging plane is located.

[0063] Application in video laryngoscopes: This refers to the side where the image sensor is located. Light rays processed by the optical system converge here to form a clear image.

[0064] Implementation Method 2: The optical parameters of the system satisfy the following relationship:

[0065] 0.9 ≤ IH / f ≤ 1.1

[0066] 33.8 ≤ L ≤ 95.8

[0067] 0.26≤IH / TTL≤0.39

[0068] 1.0 ≤ d1 / f ≤ 1.5

[0069] 1.65≤Bf / f≤1.8

[0070] 1.9 ≤ |fL1 / f| ≤ 2.1

[0071] 1.7 ≤ |f²³ / f| ≤ 1.95

[0072] 5.8 ≤ |f45 / f| ≤ 6.2

[0073] 0.7≤FNO / TTL≤0.82

[0074] in:

[0075] f is the focal length of the anesthesia video laryngoscope optical system; IH is half the optical image height of the anesthesia video laryngoscope optical system; L is the working distance of the anesthesia video laryngoscope optical system; TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the anesthesia video laryngoscope optical system; d1 is the center thickness of the first lens; Bf is the distance on the optical axis from the image side of the fifth lens to the imaging surface of the anesthesia video laryngoscope optical system; fL1 is the effective focal length of the first lens; f23 is the overall effective focal length of the second and third lenses; f45 is the overall effective focal length of the fourth and fifth lenses; FNO is the aperture number of the anesthesia video laryngoscope optical system.

[0076] Implementation method 3: The distance between the first lens and the first cemented doublet lens group, and the distance between the first cemented doublet lens group and the second cemented doublet lens group, are both 0 mm.

[0077] In this embodiment, the distance between the first lens and the first cemented doublet lens group, and between the first cemented doublet lens group and the second cemented doublet lens group, is 0 mm, that is, the contact surfaces are in close contact with each other and there is no air gap (or the air gap is 0 mm).

[0078] Implementation method 4: The side of the first lens closer to the object is concave, and the side farther from the object is convex;

[0079] In the first cemented doublet lens group and the second cemented doublet lens group:

[0080] The front lens has a convex surface on the side closer to the object and a concave surface on the side farther from the object; the rear lens has convex surfaces on both sides.

[0081] In this embodiment, the first lens has a concave surface on the side closer to the object and a convex surface on the side farther from the object; that is, the object side of the first lens is concave and the image side is convex.

[0082] In this embodiment, in the first cemented doublet lens group and the second cemented doublet lens group, the front lens has a convex surface on the side closer to the object and a concave surface on the side farther from the object; the rear lens has convex surfaces on both sides.

[0083] In the first cemented doublet lens group, the front lens has a convex surface on the side closer to the object (i.e., the object surface side of the second lens) and a concave surface on the side farther from the object (i.e., the image surface side of the second lens); the rear lens (i.e., the third lens) has convex surfaces on both sides.

[0084] In the second cemented doublet lens group, the front lens has a convex surface on the side closer to the object (i.e., the object surface side of the fourth lens) and a concave surface on the side farther from the object (i.e., the image surface side of the fourth lens); the rear lens (i.e., the fifth lens) has convex surfaces on both sides.

[0085] Implementation Method 5: The radius of curvature of the first lens on the object plane ranges from -1.5mm to -3mm, and the radius of curvature on the image plane ranges from -4mm to -7mm.

[0086] Implementation Method 6: In the first doublet lens group, the radius of curvature on the object side ranges from 9mm to 14mm, the radius of curvature on the cemented surface ranges from 2mm to 4mm, and the radius of curvature on the image side ranges from -4mm to -6mm.

[0087] In this embodiment, the object plane side of the first cemented doublet lens group refers to the object plane side when the first cemented doublet lens group is taken as a whole, that is, the side of the first cemented doublet lens group that is closer to the object.

[0088] In this embodiment, the image plane side of the first cemented doublet lens group refers to the image plane side when the first cemented doublet lens group is considered as a whole, that is, the side of the first cemented doublet lens group that is far away from the object.

[0089] In this embodiment, the cemented surface in the first cemented lens group refers to the side where the second lens and the third lens are cemented together.

[0090] Implementation Method 7: In the second doublet lens group, the radius of curvature on the object side ranges from 9 mm to 14 mm, the radius of curvature on the cemented surface ranges from 2 mm to 4 mm, and the radius of curvature on the image side ranges from -10 mm to -16 mm.

[0091] In this embodiment, the object plane side of the second cemented doublet lens group refers to the object plane side when the second cemented doublet lens group is considered as a whole, that is, the side of the second cemented doublet lens group that is closer to the object.

[0092] In this embodiment, the image plane side of the second cemented doublet lens group refers to the image plane side when the second cemented doublet lens group is considered as a whole, that is, the side of the second cemented doublet lens group that is furthest from the object.

[0093] In this embodiment, the cemented surface in the second cemented lens group refers to the side where the fourth lens and the fifth lens are cemented together.

[0094] Embodiment 8: The center thickness of the first lens is 2 mm to 4 mm;

[0095] In the first cemented doublet lens group, the thickness of the lens closer to the object is 0.5 mm to 1 mm, and the thickness of the lens farther from the object is 1.8 mm to 2.5 mm.

[0096] In the second cemented doublet lens group, the thickness of the lens closer to the object is 0.4 mm to 0.8 mm, and the thickness of the lens farther from the object is 1 mm to 1.8 mm.

[0097] In this embodiment, the lens closest to the object in the first cemented doublet lens group is the second lens.

[0098] In this embodiment, the lens on the side furthest from the object in the first cemented doublet lens group is the third lens.

[0099] In this embodiment, the lens closest to the object in the second cemented doublet lens group is the fourth lens.

[0100] In this embodiment, the lens on the side furthest from the object in the second cemented doublet lens group is the fifth lens.

[0101] Implementation Method 9: The system has a field of view of not less than 90° and a depth of field of not less than 62 mm, and is suitable for dynamic endotracheal intubation operations.

[0102] Implementation method 10: The total optical length of the system is no more than 13 mm and the maximum diameter of the optical system is no more than 4.6 mm, which is suitable for the miniaturization and lightweight design requirements of video laryngeal blades.

[0103] It should be noted that the anesthesia video laryngoscope optical system proposed in this embodiment solves the problem of achieving the best balance between ultra-wide field of view, large depth of field, extreme structural compactness, and low cost in the design of video laryngoscope optical systems. Specifically, the existing technology mainly has the following technical problems:

[0104] Insufficient depth of field: Current technologies prioritize high resolution, resulting in optical systems with excessively shallow depth of field. During dynamic intubation with a video laryngoscope, the object distance constantly changes, and shallow depth of field causes frequent image blurring, severely interfering with operational safety and success rate.

[0105] The dilemma of balancing field of view and image quality: To meet the rigid clinical need for rapid glottic localization using video laryngoscopy, an extremely large field of view (≥80°) is required. However, simply expanding the field of view introduces severe astigmatism, field curvature, and distortion, leading to a sharp decline in image edge quality and affecting the assessment of key structures around the glottis.

[0106] Structural size and cost issues: Only 5 spherical glass elements are required, reducing costs; at the same time, a compact structure with a total lens optical length of only 13 mm and a maximum optical system diameter of only 4.6 mm is achieved, meeting the requirements for miniaturization and lightweighting of laryngeal lenses.

[0107] This embodiment presents an anesthesia video laryngoscope optical system that, through its innovative optical design, overcomes several of the aforementioned technical challenges and provides a comprehensive solution specifically tailored for the field of video laryngoscopes.

[0108] In this embodiment, the anesthesia video laryngoscope optical system achieves the following effects by employing a specific aperture position design (i.e., the object plane side of the first lens is used as the aperture):

[0109] (1) Achieving an ultra-wide field of view: Video laryngoscopes need to quickly locate the glottis within the narrow space of the oral cavity, and an ultra-wide field of view is a rigid requirement. Placing the aperture at the very front of the entire optical system becomes the first "gate" that limits the imaging beam, and its position determines the range of light that the system can receive. For video laryngoscopes that require a 90° ultra-wide field of view, the aperture is placed in front to allow edge light rays at extremely large angles to enter the system.

[0110] (2) Determine the system's aperture stop to control the amount of light entering and the depth of field: The aperture stop, as the aperture stop, determines the system's aperture and depth of field. The aperture stop is the stop that limits the thickness (aperture angle) of the imaging beam. Setting it on the object side of the first lens fixes its position as the aperture stop. The size of the aperture stop determines the amount of light entering the system, affecting the brightness and signal-to-noise ratio of the image. The depth of field is directly related to the aperture size (F-number). The larger the F-number (the smaller the aperture), the greater the depth of field. Video laryngoscopes require a sufficiently large depth of field (e.g., 62mm) to cope with changes in object distance during dynamic cannulation.

[0111] (3) Working in conjunction with the concave surface of the first lens to optimize the optical path: The first lens adopts a negative focal length design with a concave object side, which has the function of diverging light, and this object side is set as the aperture stop of the system. This integrated design allows the edge light rays with the largest field of view to be effectively controlled as soon as they enter the system, so that they can enter at a gentler angle and diverge through the concave surface, creating favorable conditions for subsequent lens group to correct aberrations.

[0112] Reduce the pressure of light deflection: Reduce the pressure on subsequent lens groups (especially cemented doublets) to correct aberrations (such as coma and astigmatism), so that good image quality can still be achieved with five spherical lenses even at such a large field of view.

[0113] It facilitates structural compactness: This front-mounted "negative-positive" lens combination helps to achieve a wide field of view while maintaining a short back focal length, allowing the overall lens length to be shorter (e.g., 13mm), thus creating conditions for the miniaturization of the entire laryngeal lens.

[0114] In this embodiment, the anesthesia video laryngoscope optical system, by strictly controlling the thickness and air gap of each lens (with a gap of 0) and optimizing the radius of curvature of the cemented surface in the doublet lens group, can effectively correct astigmatism and field curvature while achieving a large depth of field (62mm). The effect is that excellent aberration correction ensures that the image quality is sufficient to meet the functional requirements of assisted positioning throughout the entire depth of field and field of view. The operator can clearly identify the relative positions of the glottis and its surrounding key structures (such as the arytenoid cartilage and vocal cords), thereby safely completing catheter guidance. This ability to achieve functionally clear imaging under large depth of field and large field of view is the result of optimization specifically for video laryngoscope operation.

[0115] In this embodiment, the anesthesia video laryngoscope optical system adopts a fully fixed structure design with all spherical lenses and no moving parts, enabling the product to withstand repeated chemical disinfection processes required in clinical practice (such as soaking and wiping with disinfectant). Its optical glass material has high chemical stability and mechanical strength, and the bonding process is stable, ensuring the long-term reliability of the product as a reusable medical device.

[0116] In this embodiment, the aforementioned anesthesia video laryngoscope optical system, by extremely limiting the total optical length (TTL) to within 13 mm, leaves ample space for the mechanical structure design of the entire video laryngoscope blade. This allows laryngoscope manufacturers to add anti-fog heating elements at the blade tip, integrate suction tubing, or use more robust materials to increase blade strength for difficult airways without sacrificing optical performance, thereby creating a more functional and reliable overall product. This shorter TTL provides a crucial optical foundation for the overall miniaturization and functional integration of the laryngoscope blade (such as reserving space for adding anti-fog or suction tubing).

[0117] In this embodiment, the anesthesia video laryngoscope optical system, by employing conventional spherical glass lenses and a simple optical path design, eliminates the need for complex aspherical processing techniques or precise fiber optic image bundle drawing processes in its manufacturing. This significantly lowers the production process threshold and manufacturing costs, enabling the widespread adoption of this high-performance professional medical device and better aligning with the market demand for the widespread deployment of video laryngoscopes as basic anesthesia and emergency equipment. This contrasts sharply with the high-cost, high-value-added approach followed by many high-end diagnostic endoscopes that utilize expensive aspherical lenses, complex relay systems, or fiber optic bundles.

[0118] In summary, this invention not only meets the unique requirements of video laryngoscopes in terms of optical parameters (such as a 90° field of view and a 62mm depth of field), but also features specialized and synergistic design across multiple dimensions, including mechanical integration (ultra-short TTL), manufacturing and cost (global reach, low cost), and environmental adaptability (high reliability). The adoption of these technical means and their resulting technical effects closely revolve around and thoroughly serve the specific field of "video laryngoscopes," exhibiting fundamental differences in design goals, technical routes, and evaluation systems compared to fields such as "endoscopes." Therefore, this invention possesses originality and non-obviousness.

[0119] Implementation Method 11: This implementation method provides a simulation experiment of the aforementioned anesthesia video laryngoscope optical system. The simulation results are as follows: Figures 2 to 5 As shown.

[0120] (1) such as Figure 2 (The modulation transfer function (MTF) curve is shown in the figure.)

[0121] This figure shows the modulation transfer function (MTF) curves of the optical system in the central field of view (0.00 degrees), the 0.5 field of view (22.50 degrees), and the peripheral field of view (45.00 degrees). The figure includes curves in both the meridional (T) and sagittal (S) directions.

[0122] The two black "diffraction limit" curves represent the theoretical upper limit of the performance of an ideal optical system.

[0123] The X-axis represents the spatial frequency (unit: period / mm), and the Y-axis represents the magnitude of the optical transfer function (OTF), i.e., the MTF value, ranging from 0 (completely blurred) to 1 (ideally sharp).

[0124] Simulation results explanation:

[0125] ① Excellent imaging quality: The MTF curve demonstrates that this optical system maintains good modulation contrast at the critical frequency of 100 lp / mm, and its resolution meets the standard requirements for 1080P high-definition imaging. This means that the system can provide a sufficient image basis for video laryngoscopes to clearly display the anatomical details of the glottis.

[0126] ② Uniform image quality across the entire field of view: From 0 degrees (center field of view) to 22.5 degrees (0.5 field of view), and then to 45 degrees (edge ​​field of view), although the MTF curves of each field of view show reasonable attenuation, usable contrast is maintained within the operating frequency range (e.g., 0-100 lp / mm). This indicates that the imaging quality of this system from the center to the edge can meet the functional requirements of rapid positioning and assisted guidance of the video laryngoscope at a 90° ultra-wide field of view. The operator can obtain sufficiently clear images in all areas of the screen to avoid positioning difficulties caused by edge blurring.

[0127] (2) such as Figure 3 As shown in the (point-and-line diagram):

[0128] The dot plot shows the convergence of different wavelengths of light (F-ray (0.486133μm), d-ray (0.587562μm), and C-ray (0.656273μm)) from different field angles (0.00 degrees, 22.50 degrees, and 45.00 degrees) on the image plane after passing through the optical system.

[0129] In the image, the dots of different colors represent the actual landing points of light rays of different wavelengths on the image plane.

[0130] The black circles in each subfigure represent the Airy disk size of the system at the diffraction limit, used to evaluate image quality.

[0131] The supplementary data for the dot plot is as follows, generally comparing the RMS radius with the Airy disk radius:

[0132]

[0133] Simulation results explanation:

[0134] ① Excellent aberration correction: Aberration correction is excellent, and the central field of view is close to the diffraction limit. In the dot plot at the 0-degree field of view (center), it can be seen that the light spots representing different wavelengths almost completely overlap, and their distribution range is much smaller than the Airy disk. This indicates that in the central field of view, the system achieves excellent correction for both monochromatic and chromatic aberrations, and the image quality is very close to the theoretical diffraction limit. This ensures that when the glottis is located at the center of the image, a clear image with extremely high sharpness and color fidelity can be presented. Furthermore, even at the maximum 45-degree field of view, the convergence points of light rays of different wavelengths are still concentrated in a very small area, which fully demonstrates the excellent aberration correction of the optical system of this invention.

[0135] ② Excellent image quality uniformity across the entire field of view: As the field of view increases to 22.50 degrees and 45.00 degrees (edge), although some dispersion occurs in the light spots of different wavelengths, their overall distribution is still effectively controlled within the Airy disk range or comparable to its size. This quantitatively demonstrates that even in the 90° edge region of the entire field of view, aberrations such as astigmatism, field curvature, and magnification chromatic aberration are well controlled. Combined with the quantitative results in the supplementary data that the RMS radius is smaller than the Airy disk radius, this strongly confirms that the optical system of this invention can provide uniform and clear imaging quality that meets the requirements of high-definition video laryngoscopes across the entire ultra-large field of view, avoiding the risk of affecting rapid positioning due to edge image quality degradation.

[0136] ③Supporting large depth of field: Good aberration correction is the foundation for achieving a large depth of field. Only when the inherent aberrations of the system itself are very small will the new aberrations caused by changes in object distance (i.e., within the depth of field range) not cause a sharp deterioration in image quality. Therefore, this figure indirectly supports the fact that this system can achieve a large depth of field of 62mm.

[0137] ④ Supplementary data for the dot plot: Provides quantified data of aberrations under different fields of view.

[0138] Airy disk radius (7.147 μm): It is the theoretical minimum circle of confusion diameter of an optical system under the diffraction limit, and is the theoretical benchmark for evaluating image quality.

[0139] RMS radius: This is the root mean square radius of the image point dispersion in a real optical system. It comprehensively reflects various geometric aberrations present in the system (such as spherical aberration, coma, astigmatism, etc.). The closer the RMS radius is to, or even smaller than, the Airy disk radius, the better the aberration correction of the system, and the closer the imaging quality is to the physical theoretical limit.

[0140] The imaging quality of the central field of view is excellent, approaching the diffraction limit: the RMS radius of field 1 (corresponding to the central field of view) is only 0.489 μm. Technical effect: The system's central field of view has extremely high imaging sharpness and resolution, ensuring that when the glottis, the core observation target, is in the center of the image, it presents extremely clear and unblurred details, providing the most accurate visual guidance for duct alignment.

[0141] Excellent control of edge field-of-view aberrations and uniform image quality across the entire field of view: the RMS radii of field of view 2 and field of view 3 (corresponding to the edge field of view) are 4.180 μm and 3.633 μm, respectively. Technical effect: This optical system achieves excellent aberration correction throughout the entire ultra-large field of view. It ensures that key structures such as the arytenoid cartilage and epiglottis, imaged at the edge of the screen, maintain sufficient sharpness, avoiding misjudgments caused by severe degradation in edge image quality, and fully meeting the functional requirements for rapid positioning of the video laryngoscope.

[0142] (3) such as Figure 4 (Field curvature and distortion diagram) is shown:

[0143] The chart on the left (field curvature plot): its Y-axis coordinate is in millimeters (mm), representing the distance of the image point from the ideal image plane. The straighter the field curvature curve and the closer it is to the 0 mm line on the X-axis, the flatter the image plane.

[0144] The chart on the right (distortion chart): its Y-axis coordinate is usually a percentage (%), representing the degree of image distortion (distortion value). The smaller the distortion value, the less the image is distorted.

[0145] Simulation results explanation:

[0146] ① Field curvature is well controlled, and the image plane is flat: As shown in the figure, the meridional field curvature and sagittal field curvature curves, representing different wavelengths of light, are very close and straight, both closely distributed near the X-axis (0 mm baseline). This indicates that the image plane curvature of this system has been effectively corrected, resulting in a relatively flat imaging surface. Its technical advantage lies in ensuring clear imaging from the center to the edge across the entire 90° ultra-wide field of view, avoiding edge blurring caused by field curvature, and meeting the need for rapid positioning under a large field of view in video laryngoscopes.

[0147] ② The distortion is within a functionally acceptable range and is a reasonable result of the performance trade-off: As shown in the figure, the maximum distortion of this system at the edge field of view ±45° is 30.8%. This is a barrel distortion, a common phenomenon in ultra-wide-angle optical systems. For a video laryngoscope, a functional guiding device, its core task is to quickly and safely guide the endotracheal tube through the glottis, rather than to perform precise measurements of anatomical structures. Therefore, the priority of its optical design is an ultra-large field of view and a large depth of field. Although a certain degree of distortion will cause image deformation, this deformation is stable and predictable (as shown by the smooth curve change in the figure). The operator can accurately judge the relative spatial relationships between objects after a short adaptation, without affecting its core guiding function. Although this design has a distortion level of 30.8%, it successfully achieved a 90° field of view and a 62mm depth of field.

[0148] (4) such as Figure 5 (Relative illumination map) is shown:

[0149] This figure illustrates how the relative illumination of the optical system varies with the Y-field angle. Relative illumination is the ratio of the illumination intensity at the edge of the field of view to that at the center of the field of view, with an ideal value of 1 (i.e., 100%).

[0150] The blue curve in the figure represents the relative illuminance variation curve. The X-axis represents the field of view angle, from 0° (center) to 45° (edge, corresponding to the full field of view of 90°); the Y-axis represents the relative illuminance value, ranging from 0 to 1.0.

[0151] Simulation results explanation:

[0152] ① Uniform illumination across the entire field of view, with no vignetting:

[0153] The curve shown in the figure indicates that from the central field of view (0°) to the maximum edge field of view (45°), the relative illuminance value remains stable at approximately 0.95, and the curve is almost a straight line. This indicates that...

[0154] Even with the significant distortion caused by the large field of view (an ultra-wide 90° field of view), resulting in a central field of view illuminance of less than 1, the overall field of view exhibits uniform illumination without vignetting, making it usable directly. Its technical advantage lies in ensuring extremely uniform brightness across the entire image captured by the video laryngoscope, avoiding vignetting at the edges. This is crucial for clinical operation, as operators do not need to worry about missing key structures around the glottis due to excessive darkness at the screen edges, ensuring rapid and comprehensive observation.

[0155] ②The system has sufficient illuminance margin to support post-processing:

[0156] Typically, digital image processing algorithms are used for "distortion correction" to correct optical distortion. This algorithm essentially stretches the image, a process that leads to a decrease in overall image brightness (illuminance). This system boasts a relative illuminance of 0.95 even before correction, indicating ample illuminance margin. The technical advantage lies in the fact that even if subsequent digital distortion correction results in brightness loss, the corrected image maintains a sufficient signal-to-noise ratio and brightness level, preventing it from becoming dark and unusable due to post-processing. This provides significant processing space and flexibility for improving the geometric accuracy of the final image.

[0157] In summary, Figures 2 to 5 Quantitative simulation data, based on imaging resolution (MTF), pixel quality (dot plot), image flatness / distortion (field curvature / distortion), and relative illumination, strongly demonstrate that the optical system of this invention achieves technical effects such as "ensuring excellent imaging quality at a 90° ultra-wide field of view" and "62mm depth of field." These data fully illustrate that the optical performance of this design is specifically optimized to meet the clinical needs of video laryngoscopes, balancing various parameters and exhibiting significant differences in design goals and performance compared to optical systems in other fields such as endoscopy.

[0158] The above description of several specific embodiments further details the technical solution provided by the present invention in order to highlight the advantages and benefits of the technical solution provided by the present invention. However, the above-described specific embodiments are not intended to limit the present invention. Any reasonable modifications and improvements to the present invention, reasonable combinations of embodiments, and equivalent substitutions based on the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An optical system for a video laryngoscope for anaesthesia, characterised in that, The system is composed of a first lens, a first double cemented lens group and a second double cemented lens group arranged in sequence along the optical axis from the object side; The object side of the first lens is used as a diaphragm; The first double cemented lens group is composed of a second lens and a third lens; wherein the former lens near the object side is the second lens, and the latter lens is the third lens; The second double cemented lens group is composed of a fourth lens and a fifth lens; wherein the former lens near the object side is the fourth lens, and the latter lens is the fifth lens; The first lens, the second lens, the third lens, the fourth lens and the fifth lens are all spherical glass lenses, which are suitable for tracheal intubation operation in video laryngoscope; The optical parameters of the system satisfy the following relationships: 0.9≤IH / f≤1.1 33.8 ≤L≤95.8 0.26≤IH / TTL≤0.39 1.0≤d1 / f≤1.5 1.65≤Bf / f≤1.8 1.9≤|fL1 / f|≤2.1 1.7≤|f23 / f|≤1.95 5.8≤|f45 / f|≤6.2 0.7≤FNO / TTL≤0.82 Wherein: f is the focal length of the optical system of the video laryngoscope; IH is half of the optical image height of the optical system of the video laryngoscope; L is the working distance of the optical system of the video laryngoscope; TTL is the distance from the object side of the first lens to the imaging surface of the optical system of the video laryngoscope on the optical axis; d1 is the center thickness of the first lens; Bf is the distance from the image side of the fifth lens to the imaging surface of the optical system of the video laryngoscope on the optical axis; fL1 is the effective focal length of the first lens; f23 is the total effective focal length of the second lens and the third lens; f45 is the total effective focal length of the fourth lens and the fifth lens; FNO is the aperture number of the optical system of the video laryngoscope; The distance between the first lens and the first double cemented lens group, and the distance between the first double cemented lens group and the second double cemented lens group are both 0 mm; The first lens is concave near the object side and convex away from the object side; In the first double cemented lens group and the second double cemented lens group: The former lens is convex near the object side and concave away from the object side; and the latter lens is convex on both sides.

2. The optical system of claim 1, wherein the optical system is configured to provide a field of view of at least 60 degrees. The curvature radius of the object side of the first lens ranges from -1.5 mm to -3 mm, and the curvature radius of the image side ranges from -4 mm to -7 mm.

3. The optical system of claim 1, wherein the optical system is a laryngoscope optical system. In the first double cemented lens group, the curvature radius of the object side ranges from 9 mm to 14 mm, the curvature radius of the cemented surface ranges from 2 mm to 4 mm, and the curvature radius of the image side ranges from -4 mm to -6 mm.

4. The optical system of claim 1, wherein the optical system is a laryngoscope optical system. In the second double cemented lens group, the curvature radius of the object side ranges from 9 mm to 14 mm, the curvature radius of the cemented surface ranges from 2 mm to 4 mm, and the curvature radius of the image side ranges from -10 mm to -16 mm.

5. The optical system of claim 1, wherein the optical system is a laryngoscope optical system. The center thickness of the first lens is 2 mm to 4 mm; In the first double cemented lens group, the thickness of the lens near the object side is 0.5 mm to 1 mm, and the thickness of the lens away from the object side is 1.8 mm to 2.5 mm; The thickness of the lens close to the object side in the second doublet lens group is 0.4-0.8 mm, and the thickness of the lens far from the object side is 1-1.8 mm.

6. The optical system of claim 1, wherein the optical system is a laryngoscope optical system. The system has a field of view angle not less than 90° and a depth of field not less than 62 mm, and is suitable for dynamic tracheal intubation operation.

7. The optical system of claim 1, wherein the optical system is a laryngoscope optical system. The optical total length of the system is not more than 13 mm, and the maximum diameter of the optical system is not more than 4.6 mm, and the system is suitable for miniaturization and light-weight design requirements of video laryngoscope.

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