Endoscope Pupil Expander Prism Block Stereo Design
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Solution Overview
Problem
Monoscopic endoscopes modified to provide stereo capability have a small stereoscopic eye base, limiting the working distance to less than 1 mm due to the proximity of the left and right entrance pupils, making them inadequate for complex surgical procedures requiring precise instrument control.
Innovation Solution
A pupil expander assembly using a pair of rhomboidal prisms at the entrance pupil of the endoscope objective separates and expands the left and right pupil halves, allowing for a significant stereoscopic disparity by deflecting light rays and aligning front lens groups with wedged glass plates to converge optical axes, thereby increasing the distance between the pupil halves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a monoscopic endoscope is modified to provide stereo capability by separating the pupil into left and right portions, then stereo endoscopic capability is achieved, but the stereoscopic eye base becomes too small (less than 1 mm working distance)
Solution Approach 1:
A beam splitter is introduced as an intermediary optical element to separate the single optical path into two distinct paths for left and right eyes. The beam splitter divides the light from the objective lens into two separate optical trains, enabling stereo capability without requiring two separate objective lenses, thus maintaining a larger working distance while achieving stereoscopic vision
Solution Approach 2:
The optical system transitions from a single two-dimensional image plane to a three-dimensional stereo image space by introducing a beam splitter that creates two separate optical paths. This dimensional transformation allows the system to capture depth information by separating light paths spatially, achieving stereo capability with a single objective lens
2Length of moving object
If two separate optical systems are used for stereo endoscopy, then adequate stereoscopic eye base is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
Two separate optical systems are merged into a single optical system by using one objective lens that serves both the left and right optical trains. The beam splitter combines the functions of what would otherwise require two separate objectives, reducing mechanical complexity, alignment requirements, and manufacturing costs while maintaining adequate stereoscopic eye base
Solution Approach 2:
A single objective lens is designed to serve multiple functions by providing light for both the left and right optical paths simultaneously. This multi-functional design eliminates the need for two separate objective lenses, reducing device complexity while maintaining stereo capability with sufficient eye base separation
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 solution enables the creation of stereo endoscopes with a single optical system, allowing for a larger working distance and improved stereoscopic effect, suitable for complex surgical applications with a small endoscope diameter, comparable to conventional stereo endoscopes with two optical systems.
Implementation Method 1
A pupil expander assembly using a pair of rhomboidal prisms at the entrance pupil of the endoscope objective separates and expands the left and right pupil halves, allowing for a significant stereoscopic disparity by deflecting light rays
Implementation Method 2
aligning front lens groups with wedged glass plates to converge optical axes
Data Source
Figure 1~3
Figure 1A~3A
Figure 4
AI summary
Disclosed are stereo endoscopes where the optical train of one optical system is separated in a left and right optical train. The separation in a left and right optical train is achieved by splitting the entrance pupil in a left and right pupil half. To additionally achieve a significant stereoscopic disparity the distance between the left and right pupil half is expanded. The separation of the entrance pupil and the expansion of the left and right pupil half is achieved by a distally located prism block. This prism block consists of a pair of rhomboidal prisms which are located exactly at the entrance pupil inside the endoscope objective. The front lens group is replaced by an identical pair of front lens groups each assembled in front of one of the two rhomboidal prisms. Such stereo endoscopes with expanded pupil halves enable to build stereo endoscopes with very small diameter or stereo endoscopes for special surgical applications. The described stereo endoscopes also include video endoscopes where the aperture functioning as the entrance pupil is separated in two halves and expanded for better stereoscopic effect. The prism block of the disclosed stereo endoscopes can also be used to separate the exit pupil of the disclosed stereo endoscopes and expand the optical axes on the proximal side to adapt to different stereo endoscopic cameras.