Laser Focal Point Calibration Using Reflected TPA Peak Intensity
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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, ensuring precise calibration of the focal point at the zero-surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional focal point calibration methods are used, then the calibration process is simple, but the calibration precision is insufficient for ophthalmological procedures requiring micrometer-level accuracy
Solution Approach 1:
A reflective surface is introduced as an intermediary element between the laser beam and the detection system. The reflective surface captures the laser beam at the zero-surface location and redirects it to the detector, enabling indirect measurement of focal point position with high precision without requiring direct access to the focal point itself
Solution Approach 2:
The patent replaces mechanical measurement methods with optical detection. Instead of using physical probes or mechanical gauges to determine focal point position, the system uses optical detection of the reflected laser beam characteristics (intensity, position) to non-contactively and precisely measure the focal point location
2Manufacturing precision
If the focal point is positioned too close to the Bowman's layer, then the cut depth is sufficient, but trauma is caused by pulling back the flap
Solution Approach 1:
The calibration system provides real-time feedback on the focal point position relative to the zero-surface and Bowman's layer. By continuously monitoring the reflected beam characteristics and comparing them against calibration data, the system enables precise control of cut depth to achieve the optimal range (80-500 μm) without causing trauma to the flap
Solution Approach 2:
The focal point calibration is performed in advance before the actual surgical procedure. The zero-surface is calibrated and stored as reference data, allowing the surgical system to pre-determine the correct focal point position that will achieve the desired cut depth and avoid trauma during the actual surgery
3Object-affected harmful factors
If the focal point is positioned too far from the Bowman's layer, then trauma is avoided, but the Bowman's layer may be breached
Solution Approach 1:
The calibration system provides real-time feedback on the focal point position relative to the zero-surface and Bowman's layer. By continuously monitoring the reflected beam characteristics and comparing them against calibration data, the system enables precise control of cut depth to achieve the optimal range (80-500 μm) without causing trauma to the flap
Solution Approach 2:
The focal point calibration is performed in advance before the actual surgical procedure. The zero-surface is calibrated and stored as reference data, allowing the surgical system to pre-determine the correct focal point position that will achieve the desired cut depth and avoid trauma during the actual surgery
4Ease of operation
If the lenticule cut is not precisely calibrated, then the procedure is simpler, but the corneal curvature and refractive correction are compromised
Solution Approach 1:
The patent replaces mechanical measurement methods with optical detection. Instead of using physical probes or mechanical gauges to determine focal point position, the system uses optical detection of the reflected laser beam characteristics (intensity, position) to non-contactively and precisely measure the focal point location
Solution Approach 2:
A reflective surface is introduced as an intermediary element between the laser beam and the detection system. The reflective surface captures the laser beam at the zero-surface location and redirects it to the detector, enabling indirect measurement of focal point position with high precision without requiring direct access to the focal point itself
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 allows for precise calibration of the laser beam's focal point, enhancing the accuracy and consistency of ophthalmological procedures by minimizing the focal point's deviation from the intended position, thereby improving surgical outcomes.
Implementation Method 1
The TPA detector senses the peak intensity of the reflected portion, which indicates a proximity of the position of the focal point to 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.