Zoom Optical Layout for Stable Focus and Angle of View
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Solution Overview
Problem
Conventional zoom optical systems experience significant variation in angle of view during focusing, which is challenging to address while maintaining optical system brightness and correcting various aberrations.
Innovation Solution
The zoom optical system is designed with specific conditional expressions to control the focal lengths, magnifications, and distances between lens groups, ensuring that the focusing group moves appropriately, thereby reducing angle of view variation and maintaining optical system brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the focusing group moves toward the image during focusing, then the angle of view changes significantly, but maintaining optical system brightness and correcting aberrations becomes difficult
Solution Approach 1:
The patent applies parameter changes by precisely controlling the focal length ratio (fF/fBaw between 1.80-3.40) and magnification ratio (Fw/(-βBaw) between 2.00-3.40) of lens groups. By adjusting these optical parameters within specific ranges, the system achieves stable angle of view during focusing while maintaining adequate brightness and aberration correction
Solution Approach 2:
The patent segments the optical system into distinct functional groups: a focusing group (GF) responsible for focusing operations, and an image-side group (GC) that remains relatively fixed. This segmentation allows the focusing group to move independently toward the image plane during focusing without causing significant angle of view variation, while the image-side group maintains the overall optical path and brightness
2Reliability
If the focusing group moves toward the image during focusing, then focusing from infinity to short distance is achieved, but coma and spherical aberrations increase
Solution Approach 1:
The patent controls aberrations by maintaining specific parameter ranges: the focal length ratio fF/fBaw between 1.80-3.40 and magnification ratio Fw/(-βBaw) between 2.00-3.40. These parameter constraints ensure that when the focusing group moves during focusing, the induced coma and spherical aberrations remain within acceptable limits
Solution Approach 2:
The image-side group (GC) acts as an intermediary between the focusing group and the image plane. This group includes lenses that help correct aberrations generated by the focusing group's movement, serving as an optical mediator that compensates for the harmful effects of focusing motion
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 system achieves reduced angle of view variation during focusing, while ensuring adequate brightness and effective correction of aberrations such as coma and spherical aberrations.
Implementation Method 1
a preceding lens group having a negative refractive power; and a succeeding lens group having a positive refractive power
Data Source
AI summary
A variable magnification optical system (ZL) comprises a preceding lens group (GA) having negative refractive power and a succeeding lens group (GB) having positive refractive power, which are arranged in order from the object side along an optical axis. The succeeding lens group (GB) has a focusing group (GF) and an image-side group (GC) disposed closer to the image side than the focusing group (GF), the focusing group (GF) moves to the image side along the optical axis from focusing on an object at infinity to focusing on a close-distance object, and the following conditional expression is satisfied.1.80<fF/fBaw FNow<3.40wherefF is the focal length of the focusing group (GF),fBaw is the focal length in the wide-angle end state of an image-side lens group (GBa) composed of lenses disposed on the image side from the focusing group (GF), andFNow is the F-number of the variable magnification optical system (ZL) in the wide-angle end state.