Passive Bent-Fiber Illumination for Rapid Speckle Reduction
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Solution Overview
Problem
Existing speckle reduction techniques for conventional imaging are not suitable for flow cytometry due to their reliance on active methods that require significant hardware and operate on timescales of milliseconds, which are incompatible with the short exposure times needed for high-speed imaging.
Innovation Solution
A passive speckle reduction system using a multimode optical fiber wound around a spindle to create continuous bends, combined with synchronized laser diodes emitting at different wavelengths, to achieve rapid modal mixing and reduce speckle in images within a time frame suitable for flow cytometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active speckle reduction methods (vibrating fiber, spinning disk, spinning optical fibers) are used, then speckle patterns are averaged over time to reduce speckle, but the hardware complexity and footprint increase significantly
Solution Approach 1:
The patent extracts the speckle-reducing property from complex active mechanisms and embeds it in the passive optical fiber structure itself through controlled bending. The fiber's physical configuration (bends, coils, or windings) inherently creates multiple propagation modes that average speckle patterns without requiring external vibration or rotation mechanisms.
Solution Approach 2:
The optical fiber serves dual functions: transmitting light and simultaneously reducing speckle through its own structural characteristics. The bent or coiled fiber configuration enables modal mixing and speckle reduction intrinsically, without requiring separate active components to perform the speckle reduction function.
2Object-affected harmful factors
If spinning disk or vibrating fiber methods are used, then speckle patterns are generated and averaged over time, but the exposure time increases to milliseconds which is incompatible with high-speed flow cytometry
Solution Approach 1:
The patent performs the speckle-averaging action in advance by pre-configuring the optical fiber with bends or coils that create multiple propagation modes. This structural preparation ensures that when light passes through the fiber during the short exposure, the speckle patterns are already mixed and averaged, eliminating the need for time-based averaging during the exposure itself.
Solution Approach 2:
The patent replaces time-based mechanical averaging (spinning, vibrating) with a spatial structural approach. Instead of moving the fiber or disk during exposure to average speckle over time, the fiber is permanently bent or coiled to create multiple spatial paths that inherently mix speckle patterns instantaneously during the short exposure window.
3Object-affected harmful factors
If vibration-based approaches are used to achieve multimode illumination, then speckle is reduced, but the frequency requirements (tens of Hz to tens of kHz or more than 10 MHz) introduce undesired hardware complexity
Solution Approach 1:
Instead of using vibration to dynamically switch between modes during exposure, the patent inverts the approach by using a static bent fiber structure that passively supports multiple modes simultaneously. The fiber's geometry (bends, coils, windings) naturally guides light through multiple paths without requiring any vibration or movement to activate the different modes.
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 system effectively reduces speckle in images captured by high-speed cameras, enabling high-quality imaging in flow cytometry applications with minimal hardware complexity.
Implementation Method 1
an optic fiber disposed so as to communicate light pulses having a plurality of modes between the laser source and a target position so as to reduce speckles in a captured image
Implementation Method 2
at least some of the optic fiber being present in one or more layers wrapped about a spindle
Data Source
AI summary
Provided are laser sources, the laser sources comprising at least one diode; and an optic fiber of a predefined length disposed between the laser source and a position for a target such that the optic fiber communicates light pulses from the laser source as a source light to the position for the target, wherein the position is illuminated by the source light so as to reduce speckles in a captured image of the target. Also provided are methods for providing source light for generating an image, comprising: generating illumination with one or more laser diodes; and passing the illumination through an optic fiber having a plurality of bends therein such that source light is emitted from the optic fiber so as to illuminate a target with the source light, the source light reducing speckles in an image of the target.