Three-Unit Telephoto Optical System for Compact Aberration Correction
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Solution Overview
Problem
Existing telephoto optical systems face challenges in achieving a long focal length, small F-number, and reduced size and weight while effectively correcting aberrations, particularly chromatic aberration, due to increased lens effective diameter and weight with a large aperture.
Innovation Solution
An optical system configuration with specific conditional inequalities for lens unit distances and refractive powers, including a first lens unit with positive power, a second lens unit moving in focusing, and a third lens unit with negative power, to balance aberration correction and size/weight reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the telephoto optical system is configured to have a large aperture (small F-number), then the light gathering ability and imaging performance are improved, but the effective diameter of the lens on the object side is increased, making it difficult to achieve reduction in size and weight
Solution Approach 1:
The optical system is divided into three lens units with different refractive powers (positive, positive/negative, negative) that can move independently. This segmentation allows each unit to be optimized for specific functions, enabling the system to achieve large aperture with reduced overall size and weight by distributing the optical burden across multiple specialized units rather than requiring a single large lens element.
Solution Approach 2:
The patent applies specific conditional inequalities for the focal lengths and distances between lens units (0.3 < f2/f < 1.0 and 0.05 < d3/f < 0.35) to optimize the optical parameters. By carefully controlling the ratio of focal lengths and inter-unit distances, the system achieves the desired aperture and imaging performance while minimizing the effective diameter and weight of the object-side lens.
2Length of moving object
If the telephoto optical system is configured to have a long focal length, then the telephoto imaging capability is improved, but the effective diameter of the lens on the object side is increased, making it difficult to achieve reduction in size
Solution Approach 1:
The telephoto optical system is segmented into three lens units with different refractive powers arranged in sequence. This segmentation allows the system to achieve long focal length through the combined optical effect of multiple units rather than requiring a single large lens element, thereby reducing the lens area on the object side while maintaining telephoto capability.
Solution Approach 2:
The patent utilizes the dimensional arrangement of multiple lens units along the optical axis with specific distance relationships (0.05 < d3/f < 0.35). By optimizing the axial distribution and spacing of lens units rather than relying on lateral lens size, the system achieves long focal length without increasing the object-side lens area.
3Reliability
If the telephoto optical system is configured to have a large aperture, then the imaging performance is improved, but various aberrations such as chromatic aberration and spherical aberration become more difficult to correct
Solution Approach 1:
The optical system is segmented into three lens units with different refractive powers (positive, positive/negative, negative) that can be independently optimized. This segmentation allows each unit to address specific aberration types, enabling effective correction of chromatic and spherical aberrations even with a large aperture by distributing the correction function across multiple specialized units.
Solution Approach 2:
The patent applies specific conditional inequalities for the focal length ratios (0.3 < f2/f < 1.0) and inter-unit distances (0.05 < d3/f < 0.35) to optimize aberration correction. By carefully controlling these optical parameters, the system achieves the desired aperture and imaging performance while effectively correcting chromatic and spherical aberrations through parameter optimization.
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 system achieves satisfactory aberration correction and reduces size and weight by optimizing lens unit arrangements and refractive powers, adhering to specific distance and thickness ratios.
Implementation Method 1
a first lens unit having positive refractive power
Implementation Method 2
a second lens unit having positive or negative refractive power and configured to move in focusing
Implementation Method 3
a third lens unit having negative refractive power
Data Source
AI summary
An optical system includes a first unit having positive refractive power, a second unit having positive or negative refractive power and configured to move in focusing, and a third unit having negative refractive power in order from an object side to an image side. A distance between adjacent two of the units changes in focusing. When a distance on an optical axis from a lens surface closest to the object side to a lens surface closest to the image side is TL, a distance on the optical axis from a lens surface closest to the object side to a lens surface closest to the image side in the third unit is TL3, a sum of thicknesses, on the optical axis, of lenses in the third unit is SD3, and the largest of the thicknesses of the lenses in the third unit is DM3, the optical system satisfies predetermined conditional inequalities.