Aspherical Lens Front Rear Unit Aberration Correction
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Solution Overview
Problem
Existing optical systems, such as the double Gaussian type, face difficulties in correcting aberrations like spherical aberration and curvature of field, especially when miniaturized and with a large aperture ratio, struggling to suppress sagittal flare and coma flare at intermediate angles of view.
Innovation Solution
The optical system is designed with a front unit having a positive refractive power and a rear unit with weakened refractive powers, incorporating aspherical surfaces and a cemented lens configuration to balance aberrations, with specific focal length and refractive power ratios to enhance miniaturization and aperture ratio while reducing overall length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the optical system uses a double Gaussian type configuration with a small number of lenses, then the device complexity is reduced, but the aberration correction performance deteriorates when miniaturized and with large aperture ratio
Solution Approach 1:
The optical system is divided into a front unit (L11, L12, L13) and a rear unit (L21, L22, L23), with each unit containing specific lens configurations. The front unit includes a cemented lens of negative refractive power, while the rear unit includes a cemented lens of positive refractive power. This segmentation allows independent optimization of aberration correction in each unit while maintaining overall system compactness.
Solution Approach 2:
The patent combines negative and positive lenses into cemented lens configurations within the front and rear units. The cemented lens in the front unit has a negative refractive power, while the cemented lens in the rear unit has a positive refractive power. This merging of lens elements with different refractive powers helps correct various aberrations including spherical aberration, coma flare, and curvature of field.
2Illumination intensity
If the optical system has a large aperture ratio, then the light gathering capability is improved, but the sagittal flare and coma flare at intermediate angle of view increase
Solution Approach 1:
The patent applies different refractive power characteristics to different regions of the optical system. The front unit includes a cemented lens with negative refractive power to correct aberrations for on-axis and near-on-axis light, while the rear unit includes a cemented lens with positive refractive power to correct aberrations for off-axis light at intermediate angles. This local differentiation of optical properties enables suppression of sagittal and coma flare while maintaining large aperture ratio.
3Length of moving object
If the optical system is miniaturized, then the overall length is reduced, but the aberration correction becomes more difficult
Solution Approach 1:
The optical system employs a nested configuration where the front unit and rear unit are arranged in sequence with overlapping functional capabilities. The front unit (L11, L12, L13) and rear unit (L21, L22, L23) are designed to work together in a compact arrangement, with the cemented lenses serving dual purposes of aberration correction and space optimization. This nested design enables miniaturization while maintaining effective aberration correction.
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 configuration effectively suppresses aberrations, including coma flare, and allows for a compact, high-performance optical system with a large aperture ratio, maintaining optical performance across various angles of view.
Implementation Method 1
an optical system comprising a front unit having a positive refractive power and a rear unit having weakened refractive powers
Data Source
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AI summary
An optical system (1a, 1b, 1c) includes, in order from an object side to an image side, a front unit (LF) of a positive refractive power, a diaphragm (STO), and a rear unit (LR) of a positive refractive power. The front unit includes, in order from the object side to the image side, a positive lens L11, a positive lens L12, and a negative lens L13. The rear unit includes, in order from the object side to the image side, a negative lens L21, a positive lens L22, and a positive lens L23. A predetermined condition is satisfied.