Endoscope Lighting Structure for Miniaturization and Halation Control
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Solution Overview
Problem
Conventional side-viewing endoscopes face challenges in reducing diameter, preventing halation, and achieving uniform illumination, particularly when observing small-diameter objects like inner blood vessels, due to issues with fiber bending, mechanical reliability, and scatter reflections.
Innovation Solution
A lighting structure that uses an optical transmission medium for both pumping and image light, with a wavelength conversion unit and a wavelength-selective reflective unit to separate and direct light effectively, reducing diameter and preventing halation, and includes a cylindrical objective optical system and noise removal filters to enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a fiber bundle is used for illuminating light transmission with bending at the distal end, then illumination direction can be changed, but the endoscope diameter cannot be reduced to 1 mm or less due to space requirements for bending and optical components
Solution Approach 1:
The patent combines the illuminating light transmission function and image transmission function into a single optical fiber bundle. The same fiber bundle that transmits the image also transmits the illuminating light, eliminating the need for separate illumination fibers and reducing the overall endoscope diameter to 1 mm or less.
Solution Approach 2:
The optical fiber bundle serves multiple functions simultaneously: it acts as both the image transmission medium and the illuminating light transmission medium. This multi-functional design reduces the number of components needed and enables miniaturization of the endoscope.
2Illumination intensity
If the distal-end portion of the fiber bundle is bent to change illumination direction, then illumination can be directed to the viewing field, but mechanical reliability decreases due to flexion-induced loss and wire breakage
Solution Approach 1:
By merging the illumination and image transmission functions into one fiber bundle, the patent eliminates the need for separate illumination fibers that would require bending. The single bundle design reduces the number of flexion points and improves mechanical reliability.
3Volume of moving object
If transmission of illuminating light and transmission of image are carried out on the same axis, then the endoscope diameter is reduced, but scatter reflections occur at the object side causing degradation in contrast
Solution Approach 1:
The patent introduces a wavelength conversion unit with fluorescent material as an intermediary. The illuminating light is converted to a different wavelength (visible light) before reaching the object, while the image light (original wavelength) is transmitted directly. This wavelength separation allows both illumination and image transmission on the same axis without scatter reflection interference, maintaining image contrast.
4Volume of moving object
If the object distance is made short in the side-viewing endoscope, then the endoscope can observe small-diameter objects, but uniform illumination is difficult to achieve and halation occurs
Solution Approach 1:
The patent changes the wavelength parameter of the illuminating light by using a wavelength conversion unit. The ultraviolet or blue-violet pumping light is converted to visible light with a longer wavelength, which provides better illumination uniformity and reduces halation effects when observing small-diameter objects at short distances.
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 allows for a compact endoscope design with reduced halation and improved uniform illumination, enabling effective observation of small-diameter objects like inner blood vessels while maintaining image quality.
Implementation Method 1
a wavelength conversion unit (14) including a fluorescent body (15) that receives the pumping light transmitted through the optical transmission medium (11) and irradiates an object (5) with illuminating light (4)
Implementation Method 2
a wavelength-selective reflective unit (13) that selectively reflects one of a wavelength of the pumping light and a wavelength of the image light
Data Source
AI summary
A lighting structure includes: an optical transmission medium that transmits pumping light and image light; an objective optical system that is disposed at a distal-end portion of the optical transmission medium; a wavelength conversion unit comprising a fluorescent body that receives the pumping light transmitted through the optical transmission medium and irradiates an object with illuminating light; and a wavelength-selective reflective unit that selectively reflects one of a wavelength of the pumping light and a wavelength of the image light, thereby emits pumping light that is incident thereto through the optical transmission medium into the fluorescent body and emits image light that is incident from the object into the optical transmission medium through the objective optical system.