Variable Stage Optical System for Ophthalmic Laser Surgery
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Solution Overview
Problem
Current laser surgery techniques for the anterior segment of the eye face challenges in precision and control due to significant optical distortions and aberrations, particularly when performing lens surgery, as existing systems are optimized for corneal procedures and struggle with the deeper focal depths required for lens surgery.
Innovation Solution
The implementation of a femtosecond laser system with variable scanning control, incorporating a Z scanner that allows incremental and continuous scanning along the Z axis, along with a precompensator to manage aberrations, ensuring the Strehl ratio and focal spot radius meet specific threshold values across the surgical target region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser system is optimized for corneal procedures with fixed focal depth, then corneal surgery precision is improved, but lens surgery capability deteriorates due to insufficient Z-axis scanning range
Solution Approach 1:
The patent implements a dynamic Z-axis scanning system with variable stages that can adjust focal depth continuously or in incremental steps. This transforms the previously fixed focal depth system into a dynamic one capable of adapting to different surgical targets (cornea or lens) by moving optical elements along the Z-axis to achieve the required focal ranges.
Solution Approach 2:
The laser system is designed with multi-functionality to perform both corneal and lens surgeries using the same equipment. By incorporating a variable Z-axis scanning mechanism with sufficient travel range and precision control, the system can serve multiple surgical purposes, eliminating the need for separate optimized systems for different ocular structures.
2Adaptability or versatility
If Z-axis scanning range is extended for lens surgery, then lens surgery capability is improved, but optical aberrations and distortion increase
Solution Approach 1:
The system applies pre-compensation for optical aberrations by calculating and applying correction values before the actual laser delivery. Wavefront sensing is performed to measure aberrations, and correction patterns are pre-computed and applied through the scanning control system to counteract the expected aberrations from extended Z-axis scanning, thereby maintaining beam quality across the full scanning range.
3Measurement precision
If continuous Z-scanning is implemented for deep focal depths, then lens surgery precision is improved, but optical distortion increases
Solution Approach 1:
The system incorporates wavefront sensing and real-time feedback control to monitor and correct optical distortions during continuous Z-scanning. The feedback loop measures actual beam deviations and adjusts scanning parameters or applies dynamic compensation to maintain precision despite the extended scanning range and associated optical distortions.
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 enhances precision and control in laser surgery by minimizing optical distortions and aberrations, allowing for effective photodisruption and tissue ablation within the anterior segment, particularly for lens surgery, by maintaining a high Strehl ratio and controlling focal spot size across the surgical area.
Implementation Method 1
laser surgery via photodisruption caused by laser pulses
Implementation Method 2
a Z scanner to scan a focal point of the laser beam in a direction essentially along a Z axis
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Systems and techniques for providing variable scanning control in delivering a laser beam of laser pulses to a surgical target are provided. The described systems and techniques can be used for laser surgery within the anterior segment of the eye and the crystalline lens via photodisruption caused by laser pulses from a femtosecond laser.