Optical System With Axial Focusing Group for Angle-of-View Stability
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Solution Overview
Problem
Existing optical systems experience significant fluctuations in angle of view during focusing, particularly when transitioning between focusing on infinity and short-distance objects, which affects the optical performance and stability.
Innovation Solution
The optical system is designed with a preceding lens group having negative refractive power and a succeeding lens group having positive refractive power, where the focusing group within the succeeding lens group moves along the optical axis during focusing. This configuration satisfies specific conditional expressions to minimize angle of view fluctuations, including focal length and magnification ratios, ensuring optimal optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the focusing group moves to an image side during focusing from infinity to short-distance object, then the focusing capability is improved, but the angle of view fluctuates significantly
Solution Approach 1:
The patent applies parameter changes by carefully controlling the movement distance of the focusing group relative to the focal lengths of the succeeding lens group and image-side group. The conditional expression 0.79 ≤ fB/(fC + fB) < 0.98 defines an optimal range for the movement parameter, where fB is the focal length of the succeeding lens group and fC is the focal length of the image-side group. By adjusting this parameter within the specified range, the system achieves both effective focusing capability and minimal angle of view fluctuation.
2Speed
If the focusing group moves along the optical axis during focusing, then the focusing speed is improved, but the optical performance stability deteriorates
Solution Approach 1:
The patent controls the focusing group's movement parameters to maintain optical performance stability while achieving high-speed focusing. The conditional expression on fB and fC defines the optimal movement range that prevents excessive angle of view fluctuation during rapid focusing transitions, thereby maintaining reliability.
Solution Approach 2:
The patent implements a dynamic focusing system where the focusing group moves along the optical axis at controlled speeds and distances. The movement is dynamically adjusted based on the object distance, allowing high-speed focusing for distant objects while reducing movement for close-up focusing to maintain optical stability.
3Adaptability or versatility
If the focusing group moves a larger distance for short-distance focusing, then the focusing range is improved, but the angle of view fluctuation increases
Solution Approach 1:
The patent optimizes the focusing range while minimizing angle of view fluctuation by constraining the movement parameters within specific ranges. The conditional expression involving fB and fC ensures that even when the focusing group moves significant distances for close-up focusing, the angle of view remains relatively consistent, thereby expanding the effective focusing range without sacrificing stability.
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 effectively suppresses angle of view fluctuations and enhances high-speed focusing capabilities while maintaining excellent optical performance and correcting various aberrations, such as coma and curvature of field, across different focusing distances.
Implementation Method 1
a preceding lens group GA having a negative refractive power and a succeeding lens group GB having a positive refractive power, which are arranged in order from an object side along an optical axis
Data Source
AI summary
An optical system (OL) formed from a preceding lens group (GA) having a negative refractive power, and a succeeding lens group (GB) having a positive refractive power, the lens groups being arranged in order from the object side along the optical axis. The succeeding lens group (GB) has: a focusing group (GF) having a positive refractive power, the focusing group (GF) being positioned furthest toward the object side of the succeeding lens group (GB); and an image-side group (GC) positioned further toward the image side than the focusing group (GF). During focusing from an infinitely distant object to a short-distance object, the focusing group (GF) moves toward the image side along the optical axis and satisfies the following conditional expression.0.78<fB/fC<1.In this conditional expression,fB is the focal distance of the succeeding lens group GB, andfC is the focal distance of the image-side group GC.