Weapon Sight Lens Assembly Focus Adjustment Minimize Image Shift
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Solution Overview
Problem
Conventional lens assemblies in weapon sights experience image shift and boresight misalignment due to unwanted movements along the X-axis and Y-axis during focus adjustment, leading to reduced accuracy and increased probability of missing a target.
Innovation Solution
A lens assembly with a focal plane array coaxial to the optical axis, where parameters such as lateral position, axial displacement, thickness, material, effective focal length, radius of curvature, conic constants, and higher-order aspheric coefficients are optimized to minimize image shift error, and a sensor-processor system is used to detect and correct any misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the distance between the FPA and the objective lens is adjusted to achieve focus at various ranges, then the focus adjustment is improved, but image shift and boresight misalignment occur due to unwanted movements along the X-axis and Y-axis
Solution Approach 1:
The lens assembly is divided into multiple independent lens elements (first lens, second lens, third lens) that can be individually positioned and adjusted. This segmentation allows independent optimization of each element's contribution to focus adjustment while minimizing their individual contributions to image shift, resolving the contradiction between focus adaptability and alignment precision.
Solution Approach 2:
Each lens element is assigned specific local optical properties and positioning parameters (lateral position, axial displacement, thickness, radius of curvature, conic constants, aspheric coefficients) that are optimized to minimize image shift. This local quality approach ensures that while the overall system provides focus adjustment capability, each component contributes minimally to unwanted lateral movements, thereby maintaining alignment precision.
2Device complexity
If mechanical assembly is used to adjust focus by moving components along the Z-axis, then the focus adjustment mechanism is simplified, but cross coupling of movement along the X-axis and Y-axis occurs leading to image shift
Solution Approach 1:
The patent optimizes specific parameters of each lens element including lateral position, axial displacement, thickness, material properties, effective focal length, radius of curvature, conic constants, and higher order aspheric coefficients. By carefully selecting and adjusting these parameters, the system achieves focus adjustment while minimizing the cross-coupling effects that cause image shift, thus maintaining alignment precision without requiring complex mechanical assemblies.
3Manufacturing precision
If multiple lens elements are added to minimize image shift error, then the image shift error is reduced, but the device complexity increases
Solution Approach 1:
The lens assembly is segmented into multiple elements (first lens, second lens, third lens) where each element is optimized for specific parameters. This segmentation allows the system to minimize image shift error through coordinated optimization of individual elements rather than requiring a single complex element, achieving high alignment precision with manageable device complexity.
Solution Approach 2:
Each lens element serves multiple functions: contributing to the overall focus adjustment capability while simultaneously being optimized to minimize image shift. This multi-functionality allows the system to achieve both focus adaptability and alignment precision without proportionally increasing device complexity, as each element performs dual roles.
Data Source
AI summary
A lens assembly for a weapon sight includes a first lens having an optical axis and a focal plane array (FPA) coaxial with the optical axis of the first lens. A first parameter of the first lens is selected that minimizes an error in image shift when the weapon sight lens assembly is adjusted for focus. The first parameter of the first lens can be at least one of a lateral position, axial displacement, thickness, effective focal length, material, effective focal length, radius of curvature, conic constants, and higher order aspheric coefficients of the first lens. A sensor can detect a position of the lens and a processor can compare the measured position to an ideal position and use a lookup table to display a corrected reticle position or corrected scene. An actuator may move the lens to the ideal position from the measured position.