Laser Focal Point Calibration Using Two-Photon Reflection Sensing
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Solution Overview
Problem
In ophthalmological laser surgery, precise calibration of the laser beam's focal point is crucial to avoid trauma and ensure consistent, high-quality results, but existing methods lack the necessary precision, particularly in procedures like LASIK and SMILE, where the focal point needs to be calibrated within a few micrometers.
Innovation Solution
A system comprising a laser, focusing optics, detector optics, and a computer uses a two-photon absorption detector to sense the peak intensity of the reflected laser beam, adjusting the focal point along the z-axis until maximum peak intensity is achieved, indicating precise calibration at the zero-surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods are used, then the calibration process is simple, but the measurement precision of focal point position is insufficient (cannot achieve micrometer-level precision)
Solution Approach 1:
A two-photon absorption detector is introduced as an intermediary component to detect the reflected laser beam intensity. This detector serves as a mediator between the laser system and the calibration process, enabling precise focal point positioning through intensity measurement without requiring direct mechanical measurement of the focal point position.
Solution Approach 2:
The patent replaces mechanical measurement methods with optical detection. Instead of using mechanical stages or physical rulers to measure focal point position, the system uses optical intensity detection via two-photon absorption, substituting mechanical measurement with optical field-based measurement to achieve micrometer-level precision.
2Manufacturing precision
If the focal point position is not precisely calibrated, then the calibration process is faster and simpler, but the manufacturing precision of laser cuts deteriorates (inconsistent cutting depths, potential trauma to Bowman's layer)
Solution Approach 1:
The system implements a feedback mechanism where the two-photon absorption detector continuously monitors the reflected laser beam intensity, and this intensity information is fed back to adjust the focal point position. The computer analyzes the intensity signal and automatically adjusts the focusing optics to maximize intensity, creating a closed-loop feedback system that ensures precise focal point calibration.
Solution Approach 2:
The calibration procedure is performed as a preliminary action before the actual laser surgery. By completing the focal point calibration in advance using the intensity-based method, the system ensures that subsequent surgical procedures can be performed with high precision without requiring repeated calibration during the surgery itself.
3Reliability
If existing calibration methods are used, then the device complexity is low, but the reliability of surgical outcomes is insufficient (cannot guarantee consistent high-quality results)
Solution Approach 1:
The patent replaces mechanical measurement methods with optical detection. Instead of using mechanical stages or physical rulers to measure focal point position, the system uses optical intensity detection via two-photon absorption, substituting mechanical measurement with optical field-based measurement to achieve micrometer-level precision.
Solution Approach 2:
A two-photon absorption detector is introduced as an intermediary component to detect the reflected laser beam intensity. This detector serves as a mediator between the laser system and the calibration process, enabling precise focal point positioning through intensity measurement without requiring direct mechanical measurement of the focal point position.
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 method enables precise calibration of the laser beam's focal point, ensuring accurate and consistent cutting depths in ophthalmological procedures, improving the quality and safety of surgeries like LASIK and SMILE by maintaining the focal point's position within precise micrometer ranges.
Implementation Method 1
a two-photon absorption (TPA) detector senses the peak intensity of the reflected portion
Implementation Method 2
receive a portion of the laser beam reflected by the zero-surface
Data Source
AI summary
In certain embodiments, a system for calibrating the focal point of a laser beam comprises a laser, focusing optics, detector optics, a two-photon absorption (TPA) detector, and a computer. The laser generates the laser beam. The focusing optics direct the focal point of the laser beam along a z-axis towards a zero-surface corresponding to a zero-plane, and receives a portion of the laser beam reflected by the zero-surface. The detector optics receive the reflected portion from the focusing optics, and directs the reflected portion towards a TPA detector. The TPA detector senses the peak intensity of the reflected portion, which indicates a proximity of the focal point to the zero-surface, and generates a signal representing the peak intensity of the reflected portion. The computer determines whether the focal point of the laser beam is calibrated in response to the signal representing the peak intensity.