Variable F/# Laser System for Ophthalmic Incisions
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Solution Overview
Problem
Current femtosecond laser systems for ophthalmic surgeries face challenges in maintaining a sharp, minimally aberrated beam focus over the full diameter and depth of the cornea and crystalline lens, due to susceptibility to optical aberrations, especially when focusing deep into the eye and crossing curved interfaces between different refractive indices.
Innovation Solution
A laser system with an optical switch that selectively routes the laser beam through either a fast path with a low F/# or a slow path with a higher F/#, combined with an afocal optical system, x-y scanner, and an aspheric patient interface device, which allows for adaptive correction of aberrations using an adaptive optic device, enabling precise incisions across a large three-dimensional working space without flattening the cornea.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a low F/# beam delivery optical system is used to obtain a small focal point and maximize spatial peak irradiance, then the precision of incisions is improved, but the system becomes very susceptible to optical aberrations that reduce peak irradiance and vary with focal point position
Solution Approach 1:
The patent employs a dynamic optical system that can switch between different F/# states (fast path with low F/# for high precision, slow path with high F/# for low aberration). The system dynamically adjusts the F/# ratio based on the specific surgical requirement, allowing optimization between precision and aberration susceptibility in real-time during procedures.
Solution Approach 2:
The system changes the F/# parameter dynamically by routing the laser beam through different optical paths (fast path for low F/1.5-2.0, slow path for high F/4-8). This parameter change allows the same system to operate in different modes: high precision mode when aberrations are acceptable, or low aberration mode when precision is compromised, thereby resolving the contradiction between these two requirements.
2Adaptability or versatility
If the laser beam is focused deep into the tissue and off-axis to cover a large three-dimensional working space, then the versatility of the system is improved, but optical aberrations increase significantly
Solution Approach 1:
The system dynamically switches between optical paths based on the depth and off-axis position of the focal point. When focusing deep into the cornea or lens, the system can select the slow path with high F/4-8 to minimize aberrations. When precision is the priority at shallower depths, the fast path with low F/1.5-2.0 is used. This dynamic adaptation allows the system to maintain reliability across the entire three-dimensional working space.
Solution Approach 2:
The F/# parameter is changed based on the focal point position within the three-dimensional working space. The system uses low F/1.5-2.0 for shallow, on-axis focusing where precision is critical, and switches to high F/4-8 for deep, off-axis focusing where aberration minimization is more important. This parameter adaptation enables the system to achieve both versatility and reliability across different working conditions.
3Object-affected harmful factors
If a low F/# system is used to maximize spatial peak irradiance and reduce laser energy requirements, then the heat transfer to adjacent tissue is reduced, but the system is more sensitive to optical aberrations
Solution Approach 1:
The system dynamically selects the appropriate F/# ratio based on the surgical task and tissue depth. For shallow corneal incisions where precision is critical and heat control is important, the system uses the fast path with low F/1.5-2.0. For deeper lens procedures where aberration sensitivity is higher, the system switches to the slow path with high F/4-8. This dynamic selection allows the system to minimize heat transfer when precision is prioritized, while accepting slightly higher heat when aberration minimization is more critical.
Solution Approach 2:
The F/number parameter is changed to balance heat transfer and aberration sensitivity based on the specific surgical requirement. The system uses low F/1.5-2.0 when maximizing spatial peak irradiance and minimizing heat transfer is the priority, and switches to high F/4-8 when reducing aberration sensitivity is more important. This parameter adaptation resolves the contradiction by allowing the system to optimize for the most critical factor in each specific surgical scenario.
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 achieves reduced aberrations and improved precision in ophthalmic incisions by dynamically adjusting the F/# of the laser beam, allowing for accurate cutting patterns across the cornea and crystalline lens with minimal collateral damage and heat transfer, enhancing the accuracy and effectiveness of ophthalmic surgeries.
Implementation Method 1
focusing ultrashort laser pulses to a very fine focus, causing a plasma mediated photodisruption of the tissue at the points of focus
Implementation Method 2
focusing ultrashort laser pulses to a very fine focus
Implementation Method 3
crossing curved interfaces between two transparent materials of different refractive indices
Implementation Method 4
aspheric patient interface device that receives a laser beam from the scan lens system
Data Source
AI summary
A laser system including a laser source that generates a laser beam and an optical switch that receives the laser beam and selectively sends the laser beam to either a fast path or a slow path, wherein in the fast path the laser beam has a first F/# and in the slow path the laser beam has a second F/# that is higher in value that of the first F/#. The laser system further including an afocal optical system that is in the slow path and receives the laser beam from the optical switch and an x-y scanner that receives either a first laser beam from the slow path or a second laser beam from the fast path. The laser system including a scan lens system that receives a scanning laser beam from the x-y scanner and performs a z-scan for the scanning laser beam only in the case wherein the scanning laser beam is generated from the laser beam in the fast path. The laser system further including an aspheric patient interface device that receives a laser beam from the scan lens system.