Speckle Pattern Analysis Device Using Optical Fourier Filtering
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Solution Overview
Problem
Existing methods for analyzing speckle patterns from biological tissue are cumbersome, expensive, and sensitive to noise, requiring high sampling frequencies and computationally intensive data processing.
Innovation Solution
A device comprising a light source, a Fourier transform element, a spatial bandpass filter, and a photosensitive detector, which collects and processes light scattered from biological tissue to selectively transmit and detect light corresponding to specific speckle sizes, thereby determining speckle contrast without the need for image detectors or high sampling rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional image detectors and high sampling frequencies are used to analyze speckle patterns, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts only the essential information (speckle contrast) from the complex speckle pattern using optical filtering, eliminating the need for complete image acquisition and processing. The spatial frequency filter isolates the specific frequency components corresponding to speckle patterns, allowing direct measurement of contrast without capturing the entire image sequence.
Solution Approach 2:
The patent introduces optical intermediaries (Fourier transform element and spatial frequency filter) between the light source and detector. These intermediaries transform the speckle pattern into the frequency domain and selectively transmit only the relevant frequency components, simplifying the measurement process while maintaining precision.
2Measurement precision
If conventional image detectors and high sampling frequencies are used to analyze speckle patterns, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive, complex image detectors and high-speed sampling systems with simpler, cheaper optical components. The spatial frequency filter and photosensitive detector constitute a much more economical system that achieves the same measurement precision through optical processing rather than computational processing.
Solution Approach 2:
The patent substitutes mechanical/electronic processing systems (image detectors, high-speed cameras, complex signal processing) with an optical system. The optical Fourier transform and spatial filtering perform the measurement functions physically, eliminating the need for expensive electronic imaging and digital processing hardware.
3Measurement precision
If conventional methods are used to analyze speckle patterns, then measurement precision is improved, but sensitivity to noise increases
Solution Approach 1:
The spatial frequency filter extracts only the frequency components corresponding to speckle patterns while rejecting other frequencies that may contain noise. By isolating the specific frequency band of interest, the system becomes less sensitive to noise in other frequency ranges, improving the signal-to-noise ratio for speckle contrast measurement.
Solution Approach 2:
The optical filter acts as an intermediary that selectively transmits only the frequency components relevant to speckle patterns. This filtering action in the optical domain before detection eliminates noise from subsequent measurement, providing a cleaner signal with higher precision.
4Measurement precision
If conventional methods are used to analyze speckle patterns, then measurement precision is improved, but data processing complexity increases
Solution Approach 1:
The patent performs the essential filtering and transformation actions in the optical domain before detection. The Fourier transform element and spatial frequency filter prepare the light signal in advance, extracting the relevant information physically so that simple detection and minimal processing are sufficient afterward, rather than requiring complex processing of complete image data.
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 device provides a compact, cost-effective means to analyze speckle patterns, reducing noise sensitivity and eliminating the need for complex data processing, while directly determining speckle contrast for applications such as monitoring vital signs.
Implementation Method 1
Speckles are interference patterns generated when a coherent light source, such as a laser, is used to illuminate a surface
Implementation Method 2
the light is scattered by the biological tissue and forms the speckle pattern
Implementation Method 3
a Fourier transform element configured to collect the light scattered by the biological tissue and to transform the collected light into a spatial Fourier domain at a Fourier plane of the Fourier transform element
Implementation Method 4
a spatial bandpass filter arranged at the Fourier plane, the spatial bandpass filter being configured to selectively transmit light at a spatial position of the Fourier plane, the spatial position corresponding to a band of speckle sizes of the speckle pattern
Implementation Method 5
a photosensitive detector configured to detect the light transmitted through the bandpass filter, wherein a signal output from the photosensitive detector comprises information on contrast of the speckle pattern
Data Source
AI summary
According to an aspect there is provided a device for analyzing a speckle pattern from biological tissue, the device comprising:a light source configured to generate light for illuminating the biological tissue, such that the light is scattered by the biological tissue and forms the speckle pattern;a Fourier transform element configured to collect the light scattered by the biological tissue and to transform the collected light into a spatial Fourier domain at a Fourier plane of the Fourier transform element;a spatial bandpass filter arranged at the Fourier plane, the spatial bandpass filter being configured to selectively transmit light at a spatial position of the Fourier plane, the spatial position corresponding to a band of speckle sizes of the speckle pattern;a photosensitive detector configured to detect the light transmitted though the bandpass filter, wherein a signal output from the photosensitive detector comprises information on contrast of the speckle pattern.