Adaptive Laser Scanner Correction for Ophthalmic Surgery
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Solution Overview
Problem
Laser scanners used in ophthalmic surgery experience mechanical lag errors at higher scan rates, leading to distortion of scan patterns and reduced precision in corneal tissue reshaping during procedures like LASIK, which can result in errors and increased surgical time.
Innovation Solution
A method and apparatus for adaptive correction of scanning errors by modifying control signals to direct the laser scanner to produce a targeted scan pattern that compensates for characteristic positioning errors, allowing for precise control of the focal point without requiring hardware changes, using mathematical operations to adjust for distortions such as elliptical compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If scan rate is increased to reduce surgical time, then productivity is improved, but manufacturing precision deteriorates due to mechanical lag errors in focal point positioning
Solution Approach 1:
The system performs preliminary calibration to determine characteristic positioning errors at different scan rates, then uses these pre-determined error patterns to adjust the directed scan pattern in advance, compensating for mechanical lag before it affects the actual scan
Solution Approach 2:
The system changes the parameters of the directed scan pattern (such as scan line spacing, focal point distribution, or scan trajectory) based on the operating scan rate, adapting the pattern to compensate for rate-dependent mechanical lag errors
2Loss of time
If scan rate is increased to reduce surgical time, then loss of time is reduced, but reliability deteriorates due to positioning errors
Solution Approach 1:
The system uses measured positioning errors from calibration as feedback to adjust the directed scan pattern, creating a closed-loop system where error information is used to improve subsequent scanning accuracy at high scan rates
3Manufacturing precision
If hardware changes are made to eliminate mechanical lag errors, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system replaces mechanical solutions (hardware modifications to reduce lag) with a computational/software-based solution that adjusts scan patterns through mathematical corrections, avoiding increased hardware complexity while maintaining precision
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 ensures scan pattern fidelity at higher scan rates, reducing mechanical lag errors and maintaining precision in corneal tissue reshaping, thereby minimizing patient stress and surgical time while maintaining the desired shape and accuracy of corneal flaps.
Implementation Method 1
The laser emits pulses at a known frequency, and each pulse photoalters tissue at the focal point of the laser beam
Implementation Method 2
Laser scanners for ophthalmic surgical systems generally utilize a pair of scanning mirrors or other optics to angularly deflect and scan the laser beam
Implementation Method 3
Scanning mirrors driven by galvanometers may be employed, each scanning the laser along one of two orthogonal axes
Implementation Method 4
A focusing objective, whether one lens or several lenses, images the laser beam onto a focal plane of the optical system
Data Source
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AI summary
A system for adaptive laser scanning correction includes a laser scanner coupled to a controller. The controller develops control signals for the laser scanner for a directed scan pattern that is modified to compensate for a characteristic scan-pattern distortion introduced by the laser scanner. The laser scanner responds to the control signals to provide an actual scan pattern approaching a target scan-pattern shape. The system may be useful for ophthalmologic laser surgery and other applications requiring precise control over scan pattern shape and a high scanning speed.