Femtosecond Corneal Cutting With Spatial Light Beam Shaping
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Solution Overview
Problem
Femtosecond lasers used in ophthalmological surgery for cutting corneas or lenses are slow and inefficient due to the need for multiple pulses and tedious beam displacement, leading to prolonged surgical times and increased costs, with existing methods to enhance speed either compromising cut quality or being difficult to implement.
Innovation Solution
A cutting device that modulates the phase of the femtosecond laser beam using a liquid crystal spatial light modulator to distribute energy into multiple distinct points in the focal plane, allowing for simultaneous generation of multiple cutting points with controlled positions, thereby improving cutting speed and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the laser frequency is increased to optimize cutting time, then the cutting speed improves, but the cost of the installation increases due to the need for high-frequency beam displacement systems
Solution Approach 1:
The invention segments the laser beam into multiple separate beams using beam splitting optics. Each beam can be independently directed to different locations on the tissue, allowing simultaneous cutting at multiple points. This segmentation enables parallel processing of the cutting task, significantly reducing total cutting time without requiring high-frequency beam displacement systems or scanners.
Solution Approach 2:
The invention combines multiple lower-frequency laser beams into a coordinated multi-point cutting system. By synchronizing the operation of multiple beams that are split from a single laser source, the system achieves high productivity equivalent to high-frequency single-beam systems but with simpler, lower-cost hardware.
2Area of stationary object
If beam displacement systems (scanners and stages) are used to move the laser beam, then the cutting coverage area increases, but the cutting operation becomes slower and more tedious
Solution Approach 1:
The laser beam is divided into multiple segments (separate beams) that can be simultaneously directed to different areas of the tissue. This allows the system to cover a large cutting area through spatial distribution of multiple beams rather than sequential scanning, dramatically reducing the time required to treat the entire area.
Solution Approach 2:
The invention transitions from one-dimensional sequential beam scanning to two-dimensional parallel beam processing. By distributing multiple beams across the cutting plane simultaneously, the system exploits the spatial dimension to achieve area coverage without the time penalty of sequential scanning.
3Productivity
If the spacing between laser impacts is increased to reduce processing time, then the cutting speed improves, but the quality of the cut deteriorates
Solution Approach 1:
The laser beam is segmented into multiple beams with controlled spacing and positioning. Each beam can be precisely directed to create optimally spaced cavitation bubbles along the cutting path. This segmentation allows simultaneous achievement of adequate spacing (for speed) and precise positioning (for quality), as each beam can be independently optimized for its specific cutting location.
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 significantly reduces cutting time, enhances surface quality, and reduces endothelial mortality, while being compatible with existing beam displacement techniques, offering a more efficient and cost-effective method for ophthalmological surgeries.
Implementation Method 1
modulating the phase of the wavefront of the L.A.S.E.R. beam
Implementation Method 2
a liquid crystal spatial light modulator
Implementation Method 3
a plasma is generated by non-linear ionization when the intensity of the laser exceeds a threshold value, called the optical breakdown threshold
Implementation Method 4
A cavitation bubble then forms, causing a very localized disruption of the surrounding tissues
Implementation Method 5
The zone cut by the laser at each pulse is very small, of the order of a micron or ten microns
Data Source
Figure 1~3
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AI summary
The invention relates to a device (1) for cutting human or animal tissue, such as a cornea (3), or a crystalline lens, said device comprising a femtosecond laser (2) that can emit a L.A.S.E.R. beam (4) in the form of impulses, and means for directing and focusing said beam onto or into the tissue for the cutting thereof as such. According to the invention, the device comprises means (9) for shaping the L.A.S.E.R. beam (4), which are positioned in the trajectory of said beam, and can modulate the energy distribution of the L.A.S.E.R. beam (4) in the focal plane thereof, corresponding to the cutting plane.