Objective Optical Filter With Dual Transmission Zones for Fluorescence Imaging
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Solution Overview
Problem
Conventional endoscopes using a single F-number for both fluorescence and visible light imaging result in reduced fluorescence illumination intensity and resolution, with a shorter depth of field for fluorescence images compared to white light images due to identical aperture sizes across the wavelength spectrum.
Innovation Solution
An optical filter designed as an aperture with separate transmission zones for white light and fluorescence light, allowing different F-numbers and aperture diameters for each wavelength band, enhancing fluorescence illumination and maintaining the depth of field for white light imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single F-number is used for both fluorescence and white light imaging, then the optical system structure is simple, but the fluorescence illumination intensity and resolution are reduced
Solution Approach 1:
The patent applies local quality by creating different aperture characteristics for different wavelength ranges within the same optical system. The aperture is designed with a first aperture for visible light and a second aperture for fluorescence light, allowing each wavelength range to have optimized local optical properties (different F-numbers) while maintaining overall system simplicity
Solution Approach 2:
The aperture is segmented into multiple independent aperture openings, each optimized for specific wavelength ranges. This segmentation allows the system to have different F-numbers for different spectral bands, improving fluorescence image quality without requiring completely separate optical paths
2Device complexity
If a single aperture size is used across the wavelength spectrum, then the optical system is simple, but the depth of field for fluorescence images is reduced
Solution Approach 1:
The patent implements local quality by providing different aperture sizes for different wavelength ranges. The first aperture optimizes depth of field for visible light imaging while the second aperture optimizes for fluorescence light, allowing each wavelength range to have its depth of field independently optimized without increasing overall system complexity
3Illumination intensity
If a larger aperture is used to improve fluorescence light collection, then the fluorescence illumination intensity increases, but the depth of field for white light imaging decreases
Solution Approach 1:
The aperture is divided into separate segments for different wavelength ranges. The second aperture (for fluorescence) can be larger to collect more fluorescence photons, while the first aperture (for visible light) maintains the appropriate size for optimal depth of field, eliminating the trade-off that would exist with a single unified aperture
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 optical filter achieves brighter and higher resolution fluorescence images while maintaining the same or similar optical resolution for white light and fluorescence light, optimizing image quality for both by tuning F-numbers and aperture sizes for each wavelength band.
Implementation Method 1
the optical filter comprises at least a first transmission zone for transmittance of a first wavelength band and a second transmission zone for transmittance of a second wavelength band, wherein at least one of the two transmission zones comprises a filter coating
Data Source
AI summary
An objective system of a medical scope including an optical filter is disclosed. The optical filter includes a light incident side and a light exit side, a central region around an optical axis, and a peripheral region and is designed as an aperture with a single optical axis for white light and fluorescence light. The optical filter includes a first transmission zone for a transmittance of a first wavelength band and a second transmission zone for a transmittance of a second wavelength band at least partially different from the first wavelength band. At least one of the two transmission zones includes a filter coating. As a result, when both white light and fluorescence light pass the optical filter, a light beam cone of the fluorescence light has a larger diameter than a light beam cone of white light or vice versa.