Three-Unit Telephoto Optical System for Compact Aberration Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Telephoto optical systems face challenges in achieving a long focal length, small F-number, and reducing size and weight while effectively correcting aberrations, particularly chromatic aberration, due to increased lens effective diameter and weight with a large aperture.
Innovation Solution
The optical system is configured with a first lens unit having positive refractive power, a second lens unit with negative refractive power that moves for focusing, and a third lens unit with negative refractive power, where the third lens unit is designed to satisfy specific conditional inequalities to correct aberrations while reducing size and weight, by appropriately distributing lens thickness and focal lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the telephoto optical system is configured to have a large aperture, then the F-number is reduced, but the effective diameter of the lens is increased which increases size and weight
Solution Approach 1:
The optical system is divided into three distinct lens units with different refractive power characteristics. The first lens unit has positive refractive power, the second has negative refractive power and is movable for focusing, and the third has negative refractive power. This segmentation allows each unit to be optimized independently for weight reduction while maintaining the required aperture performance.
Solution Approach 2:
The patent applies specific conditional inequalities to control the parameters of the third lens unit: its total optical length must satisfy 0.05 < TL3/TL < 0.50, the sum of lens thicknesses must satisfy 0.03 < SD3/TL < 0.30, and the maximum lens thickness must satisfy 0.005 < DM3/TL < 0.05. These parameter constraints optimize the balance between aperture size and weight reduction.
2Illumination intensity
If the telephoto optical system is configured to have a large aperture, then the F-number is reduced, but the effective diameter of the lens is increased which increases system size
Solution Approach 1:
By segmenting the optical system into three lens units with specific refractive power distributions, the patent reduces the overall system length while maintaining large aperture capability. The third lens unit's specific dimensional constraints ensure compact packaging without compromising optical performance.
Solution Approach 2:
The conditional inequalities for the third lens unit parameters (TL3/TL between 0.05 and 0.50, SD3/TL between 0.03 and 0.30, DM3/TL between 0.005 and 0.05) are specifically designed to minimize system length while maintaining the required aperture diameter for low F-number operation.
3Illumination intensity
If the effective diameter of the lens is increased to achieve large aperture, then the F-number is reduced, but the weight of the lens is increased
Solution Approach 1:
The lens system is segmented into three units where the third lens unit contains multiple individual lenses with specific thickness constraints. This segmentation allows weight optimization by carefully controlling the size and material distribution of each lens element while maintaining the overall aperture diameter.
Solution Approach 2:
The patent controls lens weight by constraining the sum of lens thicknesses in the third unit (SD3/TL between 0.03 and 0.30) and the maximum individual lens thickness (DM3/TL between 0.005 and 0.05). These parameter controls reduce material usage while maintaining optical performance for large aperture operation.
4Length of moving object
If the aperture is increased to achieve long focal length, then the telephoto ratio is improved, but chromatic aberration becomes more difficult to correct
Solution Approach 1:
The optical system uses three lens units with alternating positive and negative refractive powers. This segmentation creates multiple opportunities for aberration correction at different stages of light transmission, enabling effective chromatic aberration correction even at large apertures and long focal lengths.
Solution Approach 2:
The specific parameter constraints on the third lens unit (particularly the ratio of its total optical length to the overall system length, and the distribution of lens thicknesses) are optimized to control chromatic aberration. These parameter controls ensure that the telephoto ratio can be achieved without excessive aberration.
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 solution achieves both size and weight reduction and satisfactory correction of various aberrations, including chromatic and spherical aberrations, by optimizing the third lens unit's configuration.
Implementation Method 1
a first lens unit having positive refractive power
Implementation Method 2
a second lens unit with negative refractive power and configured to move in focusing
Implementation Method 3
a third lens unit with negative refractive power... satisfactory correction of various aberrations, including chromatic and spherical aberrations
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An optical system includes a first unit having positive refractive power, a second unit having 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. Among distances on the optical axis between two adjacent lenses in the optical system, a distance between a lens closest to the object side and a lens adjacent thereto is largest. 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.