Image Pickup Optical System Aberration Control via Lens Unit Segmentation
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Solution Overview
Problem
Image pickup optical systems face challenges in achieving high optical performance with a wide field angle and large aperture ratio, as existing configurations struggle to balance aberration cancellation and resolving power, particularly when dealing with off-axis light fluxes and large apertures.
Innovation Solution
The optical system consists of a first lens unit with negative refractive power, a second lens unit with positive refractive power, and a third lens unit with negative refractive power, arranged symmetrically with respect to an aperture stop, where the third lens unit includes a negative lens and a positive lens, and specific focal length ratios and conditional expressions are used to optimize refractive powers and lens lengths for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the third lens unit includes a positive lens with strong positive refractive power to reduce the incident angle of off-axis light flux, then the resolving power is improved, but the aberration cancellation with the first lens unit becomes difficult to perform in a balanced manner
Solution Approach 1:
The patent applies parameter changes by precisely controlling the refractive power ratios of the lens units. Specifically, it sets 0.30 < f1/f3 < 0.70 and 0.80 < fGr/f3 < 2.15, where f1 is the focal length of the first lens unit, f3 is the focal length of the third lens unit, and fGr is the focal length of the positive lens in the third lens unit. These parameter constraints balance the refractive powers to achieve both aberration cancellation and high resolving power simultaneously.
2Use of energy by moving object
If the aperture of the image pickup optical system is increased to achieve large aperture ratio, then the light gathering capability is improved, but various aberrations such as spherical aberration and coma tend to increase
Solution Approach 1:
The patent segments the optical system into three distinct lens units with specific refractive power characteristics. The first lens unit has negative refractive power, the second lens unit has positive refractive power and contains the aperture stop, and the third lens unit has negative refractive power. This segmentation allows each unit to be optimized for specific functions, enabling the system to achieve large aperture ratio while controlling aberrations through the coordinated action of the segmented units.
Solution Approach 2:
The patent uses parameter changes by establishing specific conditional expressions for the focal lengths of the lens units. By controlling the ratios f1/f3 and fGr/f3 within specified ranges, the system optimizes the refractive power distribution to minimize aberrations while maintaining large aperture capability.
3Length of stationary object
If the refractive powers of the lens units are made strong to achieve compact entire lens length, then the device size is reduced, but various aberrations are increased and high resolving power over the entire image plane becomes difficult to obtain
Solution Approach 1:
The patent applies parameter changes by optimizing the focal length ratios of the lens units. The conditional expressions 0.30 < f1/f3 < 0.70 and 0.80 < fGr/f3 < 2.15 ensure that the refractive powers are balanced appropriately, allowing the system to achieve compact lens length without excessive aberration generation, thereby maintaining high resolving power across the entire image plane.
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 corrects off-axis aberrations and maintains high resolving power across the entire image plane, achieving high optical performance with a wide field angle and large aperture ratio by appropriately setting the refractive powers of the lens units.
Implementation Method 1
a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a third lens unit having a negative refractive power
Data Source
AI summary
An image pickup optical system includes: from an object side to an image side, a first lens unit having a negative refractive power; a second lens unit having a positive refractive power; and a third lens unit having a negative refractive power. The first lens unit includes one negative lens or two negative lenses, the second lens unit includes a positive lens closest to the object side, and includes a plurality of lenses, the third lens unit includes, from the object side to the image side, a negative lens and a positive lens. A focal length f1 of the first lens unit, a focal length f3 of the third lens unit, a focal length fGr of the positive lens included in the third lens unit, an entire lens length L, and a focal length f of the image pickup optical system are set appropriately.