Telescopic Sight Correction Field Lens Aberration Control
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Solution Overview
Problem
High-zoom telescopic sights face challenges in correcting image errors across the entire magnification range, particularly at low magnifications, leading to visible aberrations like coma and spherical aberration, which affect image quality and user experience.
Innovation Solution
Incorporating a non-movable correction field lens between the objective-side image plane and the field lens in the telescopic sight's reversing system, which corrects image errors before they propagate through the system, reducing mechanical complexity and cost while maintaining ease of use and long service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the lens system is designed to compensate for image aberrations at high magnifications, then image quality at high magnification is improved, but visible residual aberrations appear at low magnifications
Solution Approach 1:
The optical system is divided into multiple lens groups with different functions: the first lens group (objective) handles high-magnification aberration correction, while the second lens group (erector system with field lens) addresses low-magnification aberrations. This segmentation allows each group to be optimized for its specific magnification range, resolving the contradiction between high and low magnification image quality.
Solution Approach 2:
Different regions of the optical system are assigned different optical characteristics. The field lens in the erector system is specifically designed with optical properties tailored to correct aberrations at low magnifications, while the objective lens is optimized for high magnification. This local optimization ensures good image quality across the entire magnification range without compromising either extreme.
2Manufacturing precision
If a third movable optical element is added to the erector system to reduce image aberrations, then image quality is improved, but device complexity and cost increase
Solution Approach 1:
The field lens is extracted from the movable erector system components and positioned as a fixed element between the objective and the erector system. This extraction reduces the number of movable parts while maintaining the aberration correction function, thereby reducing device complexity and cost without sacrificing image quality.
Solution Approach 2:
Instead of adding more movable elements to the erector system to correct aberrations, the solution inverts the approach by placing a fixed field lens in the objective path before the erector system. This reverse thinking achieves aberration correction with fewer moving parts, reducing complexity while maintaining precision.
3Manufacturing precision
If aspherical lenses are used within the erector system to reduce image aberrations, then image quality is improved, but manufacturing cost increases
Solution Approach 1:
The solution uses standard spherical lenses with optimized positions and configurations rather than expensive aspherical lenses. The field lens and erector system lenses are designed as simple spherical elements that achieve aberration correction through their optical arrangement, not through complex aspherical surfaces, thereby reducing manufacturing cost while maintaining image quality.
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 significantly reduces various image errors, including spherical aberration and coma, across all magnifications, ensuring a sharp, brilliant, and well-illuminated image, even at low magnifications, without increasing the complexity or weight of the telescopic sight.
Implementation Method 1
a correction field lens (40) is arranged between the objective-side image plane (BE1) and the field lens (50)... This configuration significantly reduces various image errors, including spherical aberration and coma
Implementation Method 2
The objective lens is a converging optical system for the real optical image of the target object
Implementation Method 3
an intermediate image projected by the lens in an objective-side image plane is magnified and projected in an eyepiece-side image plane
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
The riflescope has an inverting system (30) with an objective-side field lens (50) arranged between an objective lens (10) and an eyepiece (20). Relatively displaceable optical elements (31,32) are arranged between objective and field lenses. The optical elements are designed relative to objective side image plane (BE1) and eyepiece image plane (BE2). An intermediate image with a variable magnification eyepiece erected in eyepiece image plane, is mapped by moving the optical elements. A correction field lens (40) is arranged between objective side image plane and field lens.