Biologic Identification Lens Assembly with Narrow View Angle
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Solution Overview
Problem
Existing lens assemblies with wide view angles are not suitable for biologic characteristic identification, such as vein or iris identification, due to inadequate optical characteristics and miniaturization requirements.
Innovation Solution
A lens assembly comprising two lenses with specific refractive power distributions and aspheric surfaces, optimized by constraints on focal lengths, central thicknesses, and curvature radii, to achieve a narrow view angle less than 35° and good optical characteristics, applicable for biologic characteristic identification in the 750 nm to 900 nm wavelength range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a lens assembly with negative refractive power lens and positive refractive power lens is used, then the lens can be miniaturized, but the view angle becomes too wide for biologic characteristic identification
Solution Approach 1:
The patent applies parameter changes by precisely controlling the refractive power distribution between lenses, the proportion of central thickness to focal length, and the axial distance ratios. By adjusting these parameters within specific ranges, the lens assembly achieves both miniaturization and narrow view angle (less than 35 degrees), resolving the contradiction between small size and appropriate field of view for biologic identification.
2Device complexity
If the refractive power distribution and thickness proportions are not fully optimized, then the lens assembly structure is simpler, but the view angle remains too wide and optical characteristics are insufficient
Solution Approach 1:
The patent optimizes parameters including the proportion of central thickness of the first lens to the focal length (0.10 ≤ d1/f ≤ 0.20), the axial distance ratio (0.24 ≤ d2/f ≤ 0.50), and refractive power distribution. These parameter optimizations enhance optical characteristics and narrow the view angle to less than 35 degrees, improving identification accuracy without significantly increasing structural complexity.
Solution Approach 2:
The patent employs aspheric surfaces for both lenses instead of traditional spherical surfaces. The aspheric coefficients (k1 and k2) are optimized to control aberrations and refine the view angle. This curvature optimization improves optical performance and identification accuracy while maintaining a compact two-lens structure.
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 lens assembly achieves a narrow view angle and miniaturization, ensuring accurate biologic characteristic identification with improved optical performance, suitable for applications like fingerprint, vein, and iris identification.
Implementation Method 1
a first lens with positive refractive power and a second lens with negative refractive power
Implementation Method 2
the distribution of the refractive power of the first lens and the second lens, the proportion of the central thickness of the first lens to the focal length of the lens assembly
Data Source
AI summary
A lens assembly for biologic characteristic identification is provided in the present disclosure. The lens assembly includes a first lens with positive refractive power and a second lens with negative refractive power, arranged in sequence from the object side to the image side and satisfy conditions: −0.95≦f1/f2≦−0.68; 0.10≦d1/f≦0.20; 0.24≦d2/f≦0.50; −3.50≦(R1+R2)/(R1−R2)≦−1.80; f is the focal length of the lens assembly, f1 and f2 is the focal lengths of the first lens and the second lens, d1 and d2 is the central thickness of the first lens and the axial distance from the image side of the first lens to the object side of the second lens, R1 and R2 is the curvature radius of the object side and the image side of the first lens.