Endoscope Objective Optical System Wide Angle Small Lens Diameter
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Solution Overview
Problem
Existing endoscope objective optical systems face challenges in achieving a wide angle of view with a small effective luminous flux diameter on the lens surface closest to the object, while maintaining good optical performance, due to limitations in lens size and illumination light distribution, and the need for a compact design to accommodate a cover glass for sterilization and infection prevention.
Innovation Solution
The objective optical system forms an intermediate image at a position conjugate to the object surface and on an imaging plane, satisfying specific conditional expressions to achieve a wide angle of view with a small effective luminous flux diameter and good optical performance, including the use of a plane-parallel plate closer to the object than the lens surface, which allows for reduced lens diameter and improved illumination distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the effective luminous flux diameter on the lens surface closest to the object is increased to achieve a wide angle of view, then the angle of view is improved, but the diameter of the lens close to the object is increased
Solution Approach 1:
The optical system is divided into multiple lens groups with different functions. The first lens group (closest to object) has a smaller diameter and is optimized for light gathering, while subsequent lens groups handle different aspects of image formation and aberration correction. This segmentation allows the first lens to maintain a small diameter while the overall system achieves a wide angle of view through the coordinated action of multiple groups.
Solution Approach 2:
Instead of increasing the diameter of the first lens to achieve a wide angle, the patent uses multiple lens groups arranged in sequence along the optical axis. The wide angle capability is achieved through the combined optical power and arrangement of these groups rather than through the aperture size of a single lens, effectively moving the solution from a two-dimensional (lens diameter) to a three-dimensional (multi-group axial arrangement) approach.
2Area of moving object
If the lens close to the object is increased in size, then the angle of view is improved, but the disposition of the illumination light distribution-optical system is limited
Solution Approach 1:
The illumination system is separated from the imaging optical path and disposed independently in the proximal area. This segmentation allows the illumination light distribution-optical system to be positioned without being constrained by the size of the first imaging lens, enabling flexible arrangement of illumination components while maintaining the wide angle capability of the imaging system.
3Area of stationary object
If the diameter of the cover glass is increased to accommodate the lens size, then the lens can be properly positioned, but the size of the endoscope is increased
Solution Approach 1:
The optical system uses multiple small-diameter lens groups instead of a single large lens, which allows the cover glass diameter to be determined by the largest lens group rather than a single large aperture. This segmentation enables the cover glass to maintain a small diameter while still accommodating all necessary optical components within the compact endoscope structure.
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 ensures a sufficient angle of view, prevents excessive lens diameter, and allows for effective illumination, while simplifying sterilization and infection prevention measures, resulting in an endoscope with improved image quality and reduced size.
Implementation Method 1
An objective optical system for an endoscope forms an intermediate image at a position conjugate to an object surface and forms the intermediate image on an imaging plane again
Implementation Method 2
the objective optical system for an endoscope further comprises a plane-parallel plate provided to be closer to the object than the lens surface closest to the object
Data Source
AI summary
An objective optical system for an endoscope forms an intermediate image at a position conjugate to an object surface and forms the intermediate image on an imaging plane again, and is adapted to satisfy Conditional expressions (1) to (3) in a case in which a maximum effective image height on the imaging plane is denoted by HI, a focal length of the entire system is denoted by f, an effective luminous flux diameter on a lens surface closest to an object is denoted by FD, a maximum effective luminous flux diameter among effective luminous flux diameters on lens surfaces of the entire system is denoted by BD, and a paraxial relay magnification of the intermediate image on the imaging plane is denoted by βR.0.7<HI|f| (1)FD/BD<0.5 (2)−2<βR<−0.8 (3)