Adjustable Laser Focusing Depth for Corneal Tissue Separation
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Solution Overview
Problem
Current laser-based processing devices for corneal tissue face challenges in accurately controlling the separation depth due to variations in energy ranges, leading to deviations from the preset separation plane, as the assumed power density threshold may differ from the actual threshold, influenced by laser parameters and local material characteristics.
Innovation Solution
A method that adjusts the focusing depth of the laser pulse based on ascertained breakthrough parameters, including power density thresholds, to ensure accurate material separation by accounting for both laser and material parameters, thereby minimizing deviations in the separation depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the laser pulse energy is increased to ensure exceeding the power density threshold for optical breakthrough, then the material separation effectiveness is improved, but the separation depth accuracy deteriorates due to premature breakdown before reaching the preset separation depth
Solution Approach 1:
The patent applies dynamics by making the focusing depth adjustable rather than fixed. The focusing depth is dynamically adapted based on the actual power density threshold determined during a calibration process, allowing the system to optimize both the exceeding of the threshold for effective separation and the precision of the separation depth by compensating for threshold variations through dynamic focusing depth adjustment.
2Device complexity
If the power density threshold is assumed to be constant for calibration, then the device complexity is reduced, but the separation depth precision deteriorates due to variations in actual threshold caused by laser and material parameter changes
Solution Approach 1:
The patent applies preliminary action by performing a calibration process before actual material separation. During this calibration, the actual power density threshold is determined by identifying the focusing depth at which optical breakthrough occurs. This preliminary determination of the actual threshold allows subsequent separation operations to use accurate threshold values, improving separation depth precision without significantly increasing device complexity.
Solution Approach 2:
The patent implements feedback through the calibration process where the actual power density threshold is determined based on observed optical breakthrough behavior. This feedback information about the actual threshold is then used to adjust the focusing depth for subsequent operations, creating a closed-loop system that compensates for variations in laser and material parameters and maintains high separation depth precision.
3Manufacturing precision
If the focusing depth is adjusted to compensate for power density threshold variations, then the separation depth accuracy is improved, but the device complexity increases due to additional adaptation methods
Solution Approach 1:
The patent applies copying by using the calibration process to create a reference model of the actual power density threshold for specific laser and material conditions. This copied threshold information is then applied to adjust focusing depths for subsequent separation operations, enabling accurate depth control without requiring complex real-time measurement and adjustment systems during actual processing.
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 enhances the accuracy of material separation by precisely controlling the focusing depth, ensuring that the breakthrough reaction occurs at the intended separation depth, reducing unwanted tissue decomposition outside the desired area.
Implementation Method 1
The optical breakthrough describes a strong local ionization of the corneal tissue, wherein a critical plasma density is exceeded. The optical breakthrough may be initiated in laser-induced manner in the corneal tissue in that a power density threshold is exceeded by the laser pulse within the corneal tissue.
Implementation Method 2
Upon exceeding the critical plasma density, the local absorption capacity of the corneal tissue rises, whereby the plasma temperature is severely increased.
Implementation Method 3
Due to the temperature increase of the plasma, a Coulomb expansion of the plasma occurs, whereby a cavitation bubble arises in the corneal tissue
Implementation Method 4
The photodisruption is based on a local mechanical decomposition of the corneal tissue, which is caused by a shock wave arising in the optical breakthrough.
Implementation Method 5
The photodisruption is based on a local mechanical decomposition of the corneal tissue, which is caused by a shock wave arising in the optical breakthrough.
Implementation Method 6
the laser pulse is focused on a focusing point in the corneal tissue, in which it then has a maximum power density, which exceeds the power density threshold
Data Source
AI summary
A method for providing control data for a processing device with at least one laser and with at least one focusing optics is provided. The method comprises the following steps performed by a control device: receiving a specification for processing a material of an object in at least one preset separation point in a respective, preset separation depth of the material; ascertaining a respective focusing depth of a focusing point to be adjusted in the focusing optics of the processing device for separating the material in the respective, at least one preset separation point in the preset separation depth of the material; providing control data, wherein the control data is configured for controlling the focusing optics of the processing device for focusing at least one laser pulse on the at least one focusing point in the focusing depth of the material to be adjusted and for controlling the laser.