Four-Lens Optical System with Diffractive Pattern for Compact Imaging
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Solution Overview
Problem
Existing optical systems for compact digital cameras in mobile devices face challenges in achieving both high performance and small size, particularly in the arrangement and refractive properties of lenses.
Innovation Solution
The optical system is designed with specific refractive index and Abbe number ranges for lenses, including aspheric surfaces and a diffractive pattern, along with a negative refractive power for the fourth lens, to satisfy equations that optimize focal length and refractive power distribution, and incorporates a filter and aperture to enhance performance and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the optical system uses conventional lens arrangements with positive and negative refractive power lenses, then the system can achieve basic imaging function, but the total optical length becomes large and performance is limited
Solution Approach 1:
The patent applies parameter changes by precisely controlling the refractive index (n2=1.505-1.545) and Abbe number (v1=20.0-30.0, v3=20.0-30.0) of lens materials, and by optimizing the refractive power distribution (φ2/φ1=0.30-0.60, φ4/φ1=-0.10 to -0.30) to achieve both compact size and high imaging performance
Solution Approach 2:
The patent uses composite material principles by combining lenses with different refractive indices and Abbe numbers (first lens with high Abbe number, second lens with specific refractive index range, third lens with specific Abbe number range) to correct chromatic aberration and optimize optical performance in a compact configuration
2Length of moving object
If the second lens has high refractive power to reduce optical length, then the system becomes more compact, but aberration control becomes difficult and performance deteriorates
Solution Approach 1:
The patent optimizes the refractive power distribution by constraining φ2/φ1=0.30-0.60, preventing the second lens from having excessive refractive power while still achieving compact size through coordinated design of all four lenses and precise material parameter selection
Solution Approach 2:
The patent assigns specific material properties to specific lens positions: the first lens uses high Abbe number material for chromatic aberration correction, the second lens uses material with n2=1.505-1.545 for controlled refraction, and the third lens uses material with v3=20.0-30.0, creating local optimization throughout the system
3Reliability
If aspheric surfaces and diffractive patterns are added to lens surfaces, then imaging performance and compactness are improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs aspheric surfaces on all four lenses to correct spherical aberration and other monochromatic aberrations, enabling high imaging performance in a compact configuration. The aspheric profiles are optimized to work synergistically with the diffractive patterns
Solution Approach 2:
The patent introduces diffractive patterns as intermediary structures on lens surfaces to correct chromatic aberration and enhance focusing capability. These micro-structures act as optical mediators that work in conjunction with the aspheric surfaces and refractive properties to achieve superior performance
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
This design results in an optical system with improved performance and a significantly smaller size, as evidenced by the satisfaction of specific equations related to focal length and refractive power ratios, achieving a very short total optical length while maintaining high image quality.
Implementation Method 1
at least one surface of the surface of the first lens facing the object side and the image surface may include a diffractive pattern
Implementation Method 2
surfaces of the first to fourth lenses facing the object side and surfaces of the first to fourth lenses facing the image side may be aspheric surfaces
Data Source
AI summary
Disclosed is an optical system. The optical system includes first to fourth lenses sequentially arranged from an object side to an image surface, and satisfies Equation 1,1.5<n2<1.55,20<v1<30, and20<v3<30, Equation 1in which n2 represents a refractive index of the second lens, v1 represents an abbe number of the first lens, and v3 represents an abbe number of the third lens.