Dichroic Prism Beam Splitter for Dual-Sensor Video Endoscopy
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Solution Overview
Problem
Conventional endoscopes that capture both white light and fluorescence images with a single optical path and a single image sensor suffer from low frame rates and reduced sensitivity and brightness due to shuttering between frames and optical elements along the shared path, making them unsuitable for chip-on-the-tip endoscopes.
Innovation Solution
A beam splitting device with a specific design that includes a first prism, a second prism, and a dichroic beam splitting layer, allowing simultaneous capture of white light and fluorescence images by separate image sensors, optimized for a compact form factor suitable for endoscope shafts, using a dichroic beam splitter to reflect and transmit light of different spectral regions through adjacent prism surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single optical path and single image sensor are used to capture both white light and fluorescence images, then the device complexity is reduced, but the frame rate is significantly lowered and sensitivity is reduced
Solution Approach 1:
The single optical path is segmented into two separate optical paths using a beam splitter. The first optical path directs white light images to a first image sensor, while the second optical path directs fluorescence images to a second image sensor. This segmentation allows simultaneous capture of both image types at full frame rates without shuttering, resolving the contradiction between device complexity and productivity.
Solution Approach 2:
A beam splitter is introduced as an intermediary component in the optical path. This beam splitter divides the incoming light into two separate paths based on wavelength, enabling simultaneous detection by two different sensors without requiring complex mechanical shuttering mechanisms, thus maintaining relatively simple device architecture while achieving high frame rates.
2Device complexity
If a single optical path is shared between white light and fluorescence imaging, then the device structure is simplified, but the sensitivity and brightness of fluorescence images are reduced
Solution Approach 1:
The optical path is segmented into dedicated white light and fluorescence paths using a beam splitter. Each path is optimized for its specific function with dedicated image sensors, eliminating the need for shuttering and allowing maximum light collection for fluorescence imaging, thereby improving sensitivity while maintaining a relatively simple overall structure.
Solution Approach 2:
Different regions of the optical system are optimized for different functions: the first optical path and first image sensor are optimized for white light imaging, while the second optical path and second image sensor are optimized for fluorescence imaging. This local optimization allows each path to maximize its performance for the specific spectral region it handles, improving fluorescence sensitivity without requiring complete system redesign.
3Productivity
If two complete objective systems are placed in parallel to capture white light and fluorescence images separately, then the frame rate and sensitivity are improved, but the space requirements and device complexity increase significantly
Solution Approach 1:
Two complete objective systems are merged into a single shared objective system that serves both white light and fluorescence imaging. The beam splitter divides the light path after the single objective, allowing both imaging modes to share the same optical components and space, thereby achieving high frame rates and sensitivity without the space requirements of two separate systems.
Solution Approach 2:
A single objective system is designed to serve multiple functions by capturing both white light and fluorescence light simultaneously. The beam splitter enables this single objective to feed two different imaging paths, making the objective system universal and eliminating the need for separate objectives, thus saving space in the endoscope shaft while maintaining high performance.
4Device complexity
If shuttering is used to alternate between white light and fluorescence frames, then the optical path can be shared, but the overall frame rate is reduced to at most half of a white light only system
Solution Approach 1:
The beam splitter enables continuous simultaneous capture of both white light and fluorescence images without interruption or alternating shuttering. Both image sensors operate continuously at full frame rate, eliminating the time loss associated with sequential capture and ensuring no frames are missed, thereby resolving the time loss contradiction while maintaining a simple shared optical path configuration.
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 enables high frame rates, increased sensitivity, and improved brightness for both white light and fluorescence images, overcoming the limitations of conventional systems by maintaining a compact design suitable for chip-on-the-tip endoscopes.
Implementation Method 1
a dichroic beam splitting layer arranged between the adjacent surfaces so that incoming light is reflected by the first internal incident surface of the first prism, incident on the first exit surface of the first prism, and is split by the dichroic beam splitting layer into first light of a first spectral region and second light of a second spectral region
Data Source
AI summary
A beam splitting device for a distal end of an endoscope, the beam splitting device comprising a first prism with a first entrance surface, a first internal incident surface, and a first exit surface; and a second prism with a second entrance surface and a second exit surface; and a dichroic beam splitting layer. The first exit surface of the first prism and the second entrance surface of the second prism are adjacent and the dichroic beam splitting layer is arranged between the surfaces so incoming beams comprising first and second spectral regions are reflected by the first internal incident surface of the first prism, incident on the first exit surface of the first prism and are split by the dichroic beam splitting layer into beams of the first spectral region and the second spectral region. An objective system and an endoscope with the beam splitting device are also presented.