Optical System with Negative-Positive Lens Units for Wide-Angle Imaging
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Solution Overview
Problem
Image pickup optical systems with wide angles of view face challenges in achieving high optical performance while being compact, due to difficulties in correcting chromatic aberrations and maintaining a compact size, especially with asymmetric lens configurations.
Innovation Solution
An optical system configuration comprising a first lens unit with negative refractive power, an aperture stop, and a second lens unit with positive refractive power, where specific focal length ratios and refractive power distributions are optimized to satisfy conditional expressions, allowing for effective correction of chromatic aberrations and achieving a compact, high-performance design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a wide angle of view is achieved using a fisheye lens with negative distortion, then the image pickup field of view exceeds 80°, but chromatic aberration of magnification becomes difficult to correct
Solution Approach 1:
The optical system is divided into multiple lens units with specific refractive powers (−−++−+− or −−++−+−+) arranged in sequence. Each lens unit contributes to correcting specific types of aberrations while maintaining the wide angle of view, allowing chromatic aberration of magnification to be corrected through the combined effect of segmented lens elements rather than a single monolithic design.
Solution Approach 2:
Different lens elements within the system have specifically tailored refractive powers and dispersion characteristics. The negative lenses and positive lenses are strategically positioned with specific focal length ratios (0.11 < |fG1N/f1| < 0.50 and 0.50 < |fGLN/f| < 2.50) to locally address chromatic aberration correction in different regions of the optical path, enabling effective correction across the entire wide field of view.
2Weight of stationary object
If the optical system is downsized and reduced in weight, then the system becomes compact, but it becomes difficult to satisfactorily correct various aberrations
Solution Approach 1:
The patent optimizes specific parameter ranges including the focal length ratios of negative lenses (0.11 < |fG1N/f1| < 0.50 and 0.50 < |fGLN/f| < 2.50), the distribution of refractive powers across lens units, and the dispersion characteristics of lens materials. These parameter optimizations enable aberration correction in a compact configuration by precisely tuning the optical properties rather than relying on larger physical dimensions.
Solution Approach 2:
The optical system employs multiple lens elements with different refractive powers and dispersion characteristics arranged in a composite structure. The combination of negative and positive lenses with specific material properties creates a composite optical system that corrects various aberrations while maintaining a compact and lightweight form factor.
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 optimized configuration results in an optical system that is compact, achieves a wide angle of view, and effectively corrects various aberrations, including chromatic aberrations, while maintaining high imaging performance.
Implementation Method 1
a first lens unit having a negative refractive power; an aperture stop; and a second lens unit having a positive refractive power
Data Source
AI summary
Provided is an optical system consisting of, in order from an object side to an image side: a first lens unit having a negative refractive power; an aperture stop; and a second lens unit having a positive refractive power, in which each of the first lens unit and the second lens unit includes a negative lens. A focal length (fG1N) of a negative lens (G1N) arranged closest to the object side in the first lens unit, a focal length (fGLN) of a negative lens (GLN) having a largest negative refractive power in the second lens unit, a focal length (f) of the optical system, a focal length (f1) of the first lens unit, and other factors are appropriately set.