Orthogonal Image Sensor Placement in Thin Endoscope Optical Systems
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Solution Overview
Problem
Endoscopes with very thin shafts and small distal head diameters face challenges in image focusing due to the size of the image sensor, which can limit image resolution and quality, and reducing sensor size increases production costs.
Innovation Solution
An optical system with a proximal lens having a smaller proximal portion and a larger distal portion, where the image sensor is placed orthogonal to the optical axis, utilizing a reflective prism to divert light rays, allowing the image sensor to be positioned at an optimal focal distance without reducing its size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the image sensor size is reduced to accommodate thin shaft endoscopes, then the distal head diameter can be reduced, but the image resolution and quality deteriorate
Solution Approach 1:
The patent applies dimensionality change by positioning the image sensor orthogonal to the optical axis rather than along it. This reorients the sensor plane perpendicular to the light path, allowing the sensor to be placed at the focal plane without increasing the axial length. The sensor's active surface is arranged in a plane perpendicular to the optical axis, enabling standard sensor sizes to be used in thin-endoscope configurations without sacrificing resolution.
Solution Approach 2:
The patent introduces a reflective prism as an intermediary optical element that redirects light rays from the objective lens onto the image sensor. This prism acts as a mediator between the optical system and the sensor, enabling the sensor to be positioned at the optimal focal distance while maintaining a compact distal head diameter. The prism facilitates the orthogonal arrangement by reflecting light at the appropriate angle to reach the sensor plane.
2Length of moving object
If the image sensor size is reduced for thin shaft endoscopes, then the distal head can be made smaller, but production costs increase due to customized sensors
Solution Approach 1:
By reorienting the image sensor to an orthogonal position relative to the optical axis, the patent enables the use of standard-sized, off-the-shelf image sensors rather than requiring customized miniaturized sensors. This dimensional reorientation allows standard sensors to fit within the compact distal head geometry, thereby reducing manufacturing costs while maintaining acceptable image quality.
Solution Approach 2:
The reflective prism serves as an intermediary that enables standard image sensors to be used in thin-endoscope applications. Without the prism, standard sensors would be too large for the distal head; with the prism, the light path is redirected to accommodate standard sensor dimensions, eliminating the need for expensive customized sensors.
3Area of stationary object
If the proximal portion of the lens is made smaller, then space for the image sensor is increased, but the optical focusing capability may be compromised
Solution Approach 1:
The patent segments the lens into two distinct portions with different functions: the distal portion (larger) that collects and focuses light, and the proximal portion (smaller) that allows optical access to the image sensor. This segmentation enables each portion to be optimized for its specific function, maintaining focusing capability while creating space for the sensor.
Solution Approach 2:
The lens is designed with asymmetric dimensions where the distal portion has a larger cross-sectional area than the proximal portion. This asymmetric geometry allows the lens to effectively collect light over a larger area while maintaining a smaller proximal opening that accommodates the orthogonal image sensor placement, thus balancing optical performance with spatial constraints.
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 optimizes space for the image sensor in thin endoscopes, enabling reduced video objective sizes without compromising image quality, and allows for a standard image sensor to be used in thin shaft endoscopes, such as cystoscopes, while providing freed space for other functionalities.
Implementation Method 1
utilizing a reflective prism to divert light rays
Data Source
AI summary
Optical system for implementation in an endoscope comprising: a most proximal lens with an optical axis, a proximal portion and a distal portion aligned parallel to the optical axis, an image sensor with an active surface containing an array of light sensitive pixels, and a reflective prism. The system is characterized in that the sensor image is placed orthogonal to the optical axis, with the active surface facing the reflective prism, wherein the proximal portion is smaller than the distal portion, wherein the proximal portion overlaps along a length of the image sensor parallel to the optical axis, wherein the distal portion overlaps with a height of the image sensor perpendicularly to the optical axis, and wherein the image sensor can be positioned at a focal position of the optical system.