Photographic Lens Sagittal Lateral Aberration Correction
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Solution Overview
Problem
Existing photographic lens systems with an f-number of approximately 1.4 and a half angle-of-view of 14° suffer from undercorrected sagittal lateral aberration due to strong negative refractive power on concave surfaces, making correction difficult.
Innovation Solution
Incorporating an intermediate negative lens element with the weakest negative refractive power between the negative lens elements on either side of the diaphragm, along with a focusing mechanism where the most image-side lens element is stationary and others move towards the object for close-distance focusing, to correct sagittal lateral aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strong negative refractive power is used on concave surfaces of negative lens elements, then the lens system can achieve the required focal length and f-number, but sagittal lateral aberration becomes undercorrected and difficult to correct
Solution Approach 1:
The patent divides the negative refractive power function into multiple segments by using three separate negative lens elements (13, 14, 15) instead of one or two elements with strong negative power. Each element has a specific concave surface configuration, with the intermediate negative lens element (14) having the weakest negative refractive power positioned between the other two negative elements. This segmentation allows progressive correction of sagittal lateral aberration while maintaining the required optical performance.
2Measurement precision
If an intermediate negative lens element with weak negative refractive power is added between negative lens elements, then sagittal lateral aberration can be corrected, but the number of lens elements increases
Solution Approach 1:
The intermediate negative lens element (14) acts as an intermediary component between the first negative lens element (13) and the second negative lens element (15). This intermediate element with weak negative refractive power mediates the optical path, progressively adjusting the light rays to correct sagittal lateral aberration. The intermediate element's specific position and weak power configuration allow it to bridge the optical functions of the stronger negative elements while adding minimal complexity.
3Ease of operation
If the entire lens system is advanced for focusing, then focusing mechanism is simple, but spherical aberration correction is insufficient for close-distance objects
Solution Approach 1:
The patent implements a dynamic focusing mechanism where the most image-side lens element (19) remains stationary while all other lens elements (11-18) move toward the object for close-distance focusing. This dynamic configuration allows the moving lens elements to maintain optimal spacing and positioning for spherical aberration correction at different object distances, while the stationary image-side element provides a stable reference point for the optical system.
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 sagittal lateral aberration while minimizing other aberrations, such as meridional lateral and chromatic aberrations, and reduces chromatic aberration by ensuring the maximum Abbe number of positive lens elements meets specific conditions.
Implementation Method 1
An intermediate negative lens element, having the weakest negative refractive power out of all of the negative lens elements provided in the photographic lens system, is provided between the negative lens element having the concave surface facing toward the image and the negative lens element having the concave surface facing toward the object
Implementation Method 2
a positive lens element which is cemented to the negative lens element
Data Source
AI summary
A photographic lens system includes a positive lens element, a positive lens element, a negative lens element having a concave surface facing toward the image, a diaphragm, a negative lens element having a concave surface facing toward the object, a positive lens element which is cemented to the negative lens element, and two or three positive lens elements, in this order from the object. An intermediate negative lens element, having the weakest negative refractive power out of all of the negative lens elements, is provided between the negative lens element having the concave surface facing toward the image and the negative lens element having the concave surface facing toward the object.