Multimode Fiber Distal End Imaging for Uniform Illumination
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Solution Overview
Problem
Traditional optical microscopy systems using single mode fibers are limited by their small core diameter, restricting the use of radiation sources to those with good beam quality and limited spectral range, leading to inefficiencies in light transmission and uniformity of illumination, especially when trying to achieve both high resolution and uniform sample illumination.
Innovation Solution
The use of multimode fibers with a core diameter of 1 mm or larger, where the distal end is imaged onto the sample plane or a conjugate plane, providing substantially uniform radiant intensity and improved light utilization efficiency by configuring the light-coupling unit to ensure the transverse distribution of light is uniform, allowing a variety of radiation sources and wavelengths to be used.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single mode fiber is used for illumination, then diffraction-limited point source is achieved, but core diameter is small (3.5 μm) restricting radiation source selection and light transmission efficiency
Solution Approach 1:
The patent changes the core diameter parameter from single mode (3.5 μm) to multimode (≥1 mm), fundamentally altering the fiber's light transmission characteristics. This parameter change enables compatibility with various radiation sources including LEDs and arc lamps while maintaining useful illumination properties through subsequent optical conditioning
2Measurement precision
If single mode fiber is used, then diffraction-limited illumination is achieved, but light transmission efficiency and uniformity are reduced
Solution Approach 1:
The patent increases the core diameter parameter from single mode to multimode fiber, which dramatically increases light transmission efficiency and allows use of high-power radiation sources. The trade-off of larger spot size is compensated by using optical conditioning elements to achieve uniform illumination distribution
Solution Approach 2:
The patent introduces optical conditioning elements (microlens arrays, diffusers, or mode scramblers) as intermediaries between the multimode fiber and sample. These elements condition the light to achieve uniform spatial distribution, compensating for the loss of diffraction-limited focus while maintaining high transmission efficiency
3Loss of energy
If multimode fiber with large core diameter is used, then light transmission efficiency and uniformity are improved, but diffraction-limited resolution is lost
Solution Approach 1:
The patent uses optical conditioning elements (microlens arrays, diffusers, or mode scramblers) as intermediaries to process the light from the large-core multimode fiber. These elements redistribute the light modes to achieve uniform spatial illumination, effectively decoupling the large core diameter benefit from the resolution penalty
4Ease of manufacture
If single mode fiber is used, then laser sources with good beam quality can be coupled efficiently, but spectral range is limited
Solution Approach 1:
The patent changes the fiber core diameter parameter to support multimode operation, which enables coupling of radiation sources with broader spectral ranges including LEDs and arc lamps. The larger core accepts various beam qualities and wavelengths, expanding spectral versatility while maintaining practical coupling efficiency
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 approach enables efficient and uniform illumination of the sample, improving light transmission and resolution in optical microscopy systems, particularly in multi-focal confocal microscopy, by utilizing a broader range of radiation sources and wavelengths, while reducing sensitivity to mechanical and temperature influences.
Implementation Method 1
configuring the light-coupling unit to image the distal end of the multimode fiber onto or sufficiently close to a sample plane to provide substantially uniform illumination of the sample
Implementation Method 2
A transverse distribution of light exiting the distal end of the multimode fiber is substantially uniform
Data Source
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AI summary
Where a multimode fiber (208) is used for light delivery in a microscope system (200) and a transverse distribution of light exiting a distal end (230) of the fiber is substantially uniform, the distal end is imaged onto a plane (250) of a sample (248) to be probed by the microscope system, or at a conjugate plane (252). Alternatively, the distal end is imaged onto a plane sufficiently close to the sample plane or the conjugate plane such that a radiant intensity of light at the sample plane or the conjugate plane is substantially uniform. In the case of a multifocal confocal microscope system (300), the distal end of the multimode fiber is imaged onto a plane (352) of a segmented focusing array (310). Alternatively, the distal end is imaged onto a plane sufficiently close to the segmented focusing array plane such that a radiant intensity of the light at the segmented focusing array plane is substantially uniform.