Speckle Interferometric Detection for Ophthalmic Laser Dosimetry
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Solution Overview
Problem
Existing methods for detecting surface movement under coherent light irradiation, particularly in ophthalmology, face challenges in accurately measuring small variations and adjusting laser therapy parameters due to individual patient variations and tissue characteristics, leading to potential damage from excessive pulse energy.
Innovation Solution
A method and system that utilize a coherent light beam to detect variations in the speckle pattern reflected from the surface, specifically selecting a single speckle and using a photo-detector to measure phase-sensitive changes, allowing for precise dosimetry and energy adjustment during selective retina therapy (SRT) by correlating frequency variations with surface movement, enabling immediate detection of bubble formation and thermal expansions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a detector measures the entire speckle pattern from the irradiated surface, then surface movement variations can be detected, but the device complexity and technical expenditure increase
Solution Approach 1:
The patent extracts and isolates a single speckle from the entire speckle pattern for detection. Instead of measuring all speckles across the pattern, the system selects one specific speckle location and monitors only that region, thereby simplifying the detector requirements while maintaining the ability to detect surface movement variations through phase-sensitive detection of the selected speckle's intensity variations
Solution Approach 2:
The detection process is segmented by dividing the speckle pattern into individual speckles and selecting a single representative speckle for measurement. This segmentation approach allows the system to focus computational and detection resources on one specific region rather than processing the entire pattern, reducing overall system complexity
2Productivity
If high pulse energy is used for laser therapy, then treatment effectiveness improves, but tissue damage risk increases due to excessive energy
Solution Approach 1:
The patent implements real-time feedback by continuously monitoring the speckle pattern variations during laser pulse delivery. The detected surface movement and bubble formation provide immediate feedback about tissue response, allowing the system to adjust subsequent pulse energy levels to remain within the therapeutic window and prevent excessive energy delivery that would cause damage
Solution Approach 2:
The system performs preliminary detection of surface characteristics and bubble formation thresholds before delivering full therapeutic energy. By monitoring speckle variations in advance and establishing baseline tissue response, the system can predict when threshold energies are approaching and adjust parameters proactively to avoid harmful effects
3Productivity
If multiple laser pulses are applied to achieve therapeutic effect, then treatment efficacy improves, but the risk of visible damage recurrence increases
Solution Approach 1:
Real-time monitoring of speckle pattern changes during pulse sequences provides continuous feedback on tissue response and bubble formation. This allows the system to detect when cumulative effects are approaching damaging thresholds, enabling adjustment of pulse energy or interval parameters to maintain therapeutic effectiveness while preventing visible damage recurrence
Solution Approach 2:
The laser therapy parameters are made dynamic rather than static. The system continuously adapts pulse energy, duration, or interval based on real-time speckle detection data, allowing the treatment protocol to evolve during delivery to optimize therapeutic effect while avoiding the fixed-parameter limitations that lead to damage recurrence
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
Enables accurate and real-time dosimetry for SRT, preventing tissue damage by adjusting laser energy based on detected variations, and provides a high-resolution measurement of thermal expansions during photocoagulation, ensuring effective and safe treatment.
Implementation Method 1
detecting variations caused by said movement in a speckle pattern produced by reflections of said light beam at said surface
Implementation Method 2
a coherent light beam emitted especially from a laser wherein variations caused by said movement in a speckle pattern of the reflected light beam are detected
Implementation Method 3
detecting said variations at the selected speckle... a photo-detector adapted to detect variations caused by said movement of the surface at a single speckle selected from a speckle pattern
Implementation Method 4
approximately 50% of the incident light in the green spectral range is absorbed by the pigment granules (melanosomes) in the RPE cells. High temperatures occur in the RPE
Implementation Method 5
The variation of the speckle corresponds to changes at the irradiated area. The measurement of the speckle variations is performed phase-sensitively... enabling immediate detection of bubble formation and thermal expansions
Data Source
AI summary
A method and a system for detecting a movement of a surface on an irradiated sample involves a light source for irradiating the surface with a coherent light beam, a detector for detecting variations caused by the movement in a speckle pattern produced by reflections of the light beam at the surface, selecting a single speckle from the speckle pattern, and detecting the variations at the selected speckle.