Variable-Magnification Optical System with Constant Image Plane
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Solution Overview
Problem
Existing optical systems for image pickup apparatuses face challenges in achieving both a reduction in weight and maintaining favorable optical characteristics when incorporating a variable-magnification optical system, particularly due to issues with downsizing and aberration variations.
Innovation Solution
The optical system design includes a main optical system with specific lens configurations and a variable-magnification optical system inserted between the aperture stop and image plane, maintaining a constant distance to the image plane, and adhering to specific inequalities to optimize weight reduction and aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable-magnification optical system is inserted into the main optical system, then the focal length can be changed, but the weight of the entire system increases
Solution Approach 1:
The variable-magnification optical system is nested within the main optical system by inserting it into the optical path between the aperture stop and the image plane. This allows the extender to be integrated into the existing structure, sharing the optical path and mechanical housing, thereby minimizing additional weight while maintaining focal length change capability.
Solution Approach 2:
The patent employs a movable lens unit within the variable-magnification optical system that can be shifted along the optical axis to change magnification. This dynamic adjustment mechanism allows focal length variation without requiring multiple complete optical systems, reducing overall weight while maintaining adaptability.
2Adaptability or versatility
If the variable-magnification optical system is inserted between the aperture stop and image plane, then the optical path is extended, but the distance from the first lens surface to the image plane must be adjusted
Solution Approach 1:
The patent maintains the distance from the first lens surface to the image plane constant by adjusting the position of the variable-magnification optical system within the optical path. This parameter control ensures that the overall optical system length remains unchanged while still achieving variable magnification through the inserted system.
3Length of stationary object
If the negative lens G1N is positioned closer to the object side, then the optical path is extended, but the distance D1N increases affecting the inequality condition
Solution Approach 1:
The patent controls the position of the negative lens G1N to satisfy the inequality condition 0.20 < D1N/LD < 0.50, where LD is the distance from the first lens surface to the image plane. This parameter control ensures optimal optical performance while maintaining manufacturing feasibility and positioning precision.
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 achieves favorable optical characteristics while reducing the overall system weight and minimizing aberration variations, enabling efficient downsizing of the optical system.
Implementation Method 1
an optical system includes a main optical system including an aperture stop, and a variable-magnification optical system configured to be removably inserted between the aperture stop and an image plane
Data Source
AI summary
An optical system includes a main optical system including an aperture stop, and a variable-magnification optical system configured to be removably inserted between the aperture stop and an image plane. A distance from a lens surface that is the closest to an object side in the main optical system to the image plane is constant before and after insertion and removal of the variable-magnification optical system. The main optical system includes a plurality of positive lenses and a plurality of negative lenses. A distance from the lens surface that is the closest to the object side in the main optical system to a lens surface of a negative lens that is the closest to the object side among the plurality of negative lenses and a total length of the main optical system satisfy a predetermined relationship.