Resonant Scanner Beam Blocking for Ophthalmic Laser Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Femtosecond ophthalmic laser systems using high pulse repetition rates require fast scanning systems, but existing systems like multi-facet polygon mirrors induce vibrations and wavefront aberrations, while resonant scanning mirrors can result in excessive gas bubbles and redundant laser pulse deposition due to high focus spot density at the ends of the scanline.
Innovation Solution
The implementation of a femtosecond ophthalmic laser system that employs a resonant scanner with a beam blocking member positioned near the internal focal plane to eliminate laser focus spots at the ends of the scanline, thereby improving uniformity and reducing unwanted effects like bubble layers and redundant pulse deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a resonant scanning mirror is used to scan the laser beam back and forth at high speed, then the scanning speed and productivity are improved, but the focus spot density at the ends of the scanline becomes excessively high, causing harmful effects like gas bubbles and redundant pulse deposition
Solution Approach 1:
The patent extracts and removes the harmful portion of the laser scanline by using a beam blocking member to eliminate focus spots at the ends of the scanline where excessive density occurs, while preserving the useful portion in the middle section
Solution Approach 2:
The patent applies different treatment to different portions of the scanline: the ends are blocked to reduce spot density, while the middle portion is allowed to maintain high spot density for effective cutting, creating local quality variation along the scanline
2Speed
If a multi-facet polygon mirror is used for high-speed scanning, then the scanning capability is improved, but the system induces vibrations and wavefront aberrations that reduce manufacturing precision
Solution Approach 1:
The patent replaces the mechanical multi-facet polygon mirror system with a resonant scanning mirror system that uses resonant vibration at lower speeds, eliminating the need for high-speed rotating mechanical components and their associated vibrations and aberrations
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 solution enhances the spatial uniformity of laser spot distribution, reduces the formation of undesirable opaque bubble layers, and minimizes redundant laser pulse deposition during ophthalmic surgeries, leading to more precise and effective tissue incisions.
Implementation Method 1
a high frequency scanner configured to scan the laser beam back and forth at a predefined frequency
Implementation Method 2
configured to focus the scanned laser beams through an internal focal plane located between the first and second sets of optical elements to a plurality of external focus spots
Data Source
AI summary
In a femtosecond ophthalmic laser system which employs a high frequency resonant scanner to produce a laser scanline and XY and Z scanners to move the scanline in a patient's eye to perform eye surgery, a beam blocking member is placed near an internal focus plane of the optical system to block some of the beam paths to truncate the laser scanline at the two ends. This eliminates the closely spaced or overlapping laser focus spots near the ends of the scanline. The beam blocking member has a plate shape with one or more apertures of different shapes or sizes, and is movable in the transverse direction to different positions to block different amounts of the scanline.