Magnifying Endoscope Optical System with Movable Lens Unit
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Solution Overview
Problem
Conventional magnifying endoscope optical systems face challenges in maintaining high image quality and sufficient observation depth across varying focal positions due to limitations in F-number adjustment and aberration control, particularly when using image pickup devices with high-density picture elements.
Innovation Solution
A magnifying optical system for endoscopes comprising a first positive lens unit, a second negative lens unit, and a third positive lens unit, where the second negative lens unit moves with the aperture stop along the optical axis, maintaining a consistent F-number ratio and focal length ratios to ensure stable image quality and depth across different observing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the F number is enlarged or aperture stop is reduced to achieve pan-focus performance, then observation depth is improved, but diffraction phenomenon occurs and image quality is lowered
Solution Approach 1:
The patent implements a movable second lens unit that can be positioned at different locations along the optical axis. By moving this lens unit, the system dynamically adjusts the F number and focal length to maintain appropriate aperture settings across varying observation depths, preventing diffraction while achieving pan-focus performance
Solution Approach 2:
The system changes the F number and focal length parameters by repositioning the second lens unit. This allows the optical system to maintain an F number that prevents diffraction (Fno < 1.64P/λ) while still achieving sufficient observation depth through focal length adjustment
2Duration of action of moving object
If the aperture stop is reduced to increase observation depth, then depth of field is improved, but light intensity decreases and image brightness is reduced
Solution Approach 1:
The movable second lens unit enables dynamic adjustment of the optical system's F number. By repositioning this lens unit, the system can maintain a larger aperture (smaller F number) than conventional systems, thereby preserving light intensity and image brightness while still achieving sufficient observation depth through focal length variation
3Manufacturing precision
If conventional optical systems are used with high-density picture element devices, then manufacturing precision is improved, but observation depth becomes insufficient due to small F numbers
Solution Approach 1:
The patent employs a movable second lens unit that can be positioned at different locations along the optical axis. This dynamic adjustment capability allows the system to maintain an appropriately large F number even when used with high-density picture element devices, thereby preserving sufficient observation depth that would otherwise be lost due to the small F numbers inherent in such high-resolution systems
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 allows for minimal change in F-numbers between standard and magnified image observing conditions, preserving sufficient observation depth and image quality, even with high-density image pickup devices, thereby enabling precise and detailed observations without significant degradation.
Implementation Method 1
an objective lens system which consists, in order from the object side, of a first positive lens unit, a second negative lens unit and a third positive lens unit
Data Source
AI summary
A magnifying optical system for endoscope which can be set at least in a usual observing condition (at a wide position) and a condition for observing a magnified image of an object at a short distance (at a tele position) by moving any of one of lens units, and is configured so as to satisfy a condition mentioned below, thereby providing a sufficient observation depth in each observing condition:f(W)/F(T)>0.93. (1)