Aspheric Endoscope Lens Design for Wide Field of View
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Solution Overview
Problem
Current endoscopes have large diameters, leading to discomfort during insertion, narrow field of view, and shallow depth of field, making it difficult to inspect narrow lesions and increasing production costs.
Innovation Solution
An endoscope lens design featuring a first concave object side surface and convex image side surface, a second lens with positive or negative refractive power, and a filter between the lenses, with both lenses being aspheric glass or plastic, optimized to reduce diameter and increase field of view and depth of field through specific optical parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the diameter of the endoscope is reduced to reduce patient discomfort and production cost, then the diameter decreases, but the field of view becomes narrower and the depth of field becomes shallower
Solution Approach 1:
The patent employs aspheric lens surfaces with precisely controlled curvature profiles. The first lens has an aspheric object-side surface and the second lens has an aspheric image-side surface, allowing light rays to be focused more efficiently. This curvature optimization enables a smaller diameter lens to achieve the same or better field of view and depth of field performance compared to traditional spherical lenses, directly resolving the contradiction between reduced diameter and maintained imaging capability
Solution Approach 2:
The patent systematically optimizes multiple optical parameters including the refractive indices (n1=1.8514, n2=1.5455), Abbe numbers (ν1=40.10, ν2=56.00), thickness ratios (0.3 < t1/f < 0.6, 0.2 < t2/f < 0.5), and curvature radii ratios (0.5 < r1/r2 < 2.0). By precisely controlling these parameters, the lens achieves superior optical performance with a reduced diameter, simultaneously improving field of view to ≥120° and depth of field to 5-35mm while maintaining compact size
2Quantity of substance
If the diameter of the endoscope is reduced to reduce production cost, then the diameter decreases, but the manufacturing precision requirements increase due to aspheric surfaces
Solution Approach 1:
The patent defines specific parameter ranges for the aspheric surfaces that balance manufacturing feasibility with optical performance. The curvature radius ratios are constrained to 0.5 < r1/r2 < 2.0 and thickness ratios to 0.3 < t1/f < 0.6, which prevents extreme aspheric profiles that would be difficult to manufacture. These controlled parameter changes allow standard precision manufacturing techniques to produce the aspheric lenses while achieving the desired reduced diameter
Solution Approach 2:
The patent specifies using different glass or plastic materials for the first and second lenses with particular refractive indices and Abbe numbers. This material selection allows the aspheric surfaces to be manufactured with conventional techniques while achieving the required optical performance. The composite lens structure with optimized material properties reduces the stringency of manufacturing precision requirements compared to single-material designs
3Length of moving object
If the optical total length is reduced to enable insertion through narrow channels, then the length decreases, but the depth of field becomes shallower
Solution Approach 1:
The aspheric surfaces of both lenses are designed with optimized curvature profiles that increase the effective focal length without proportionally increasing the physical length. The first lens has an aspheric object-side surface and the second lens has an aspheric image-side surface, creating a compact optical path that achieves extended depth of field (5-35mm) within a short optical total length (≤2.0mm), resolving the contradiction between compact size and deep focus range
Solution Approach 2:
The patent employs a nested two-lens configuration where the first lens with positive refractive power and the second lens with negative refractive power are closely spaced. This nested arrangement allows the optical components to be tightly integrated, achieving extended depth of field through the combined optical effect of the two lenses while maintaining a compact overall length suitable for narrow channel insertion
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves a diameter of ≤1.0 mm, an optical total length of ≤2.0 mm, a field of view ≥120°, and a depth of field from 5 mm to 35 mm, reducing patient discomfort and enabling effective inspection of narrow lesions with improved imaging clarity.
Implementation Method 1
a first lens having a concave object side surface and a convex image side surface; a second lens with a positive or negative refractive power
Data Source
AI summary
Provided is an endoscope lens, a camera module and an endoscope. From an object side to an image side, the endoscope lens sequentially includes: a first lens having a concave object side surface and a convex image side surface; a second lens with a positive or negative refractive power; and a filter arranged between the second lens and the image side. Each of the first lens and the second lens is a glass or plastic aspheric lens. The endoscope lens further includes a stop positioned between the first lens and the object side or between the first lens and the second lens.