Laser Selective Cutting by Impulsive Heat Deposition
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Solution Overview
Problem
Conventional laser surgery methods cause significant collateral damage to surrounding tissue due to excessive heat transfer and ionization, limiting their use in medical and dental applications.
Innovation Solution
The method employs impulsive heat deposition (IHD) using short IR laser pulses tuned to specific vibrational modes, ensuring energy is directly converted to heat within the ablated volume without ionization or thermal accumulation, minimizing damage to adjacent material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If long laser pulses are used for material ablation, then sufficient energy is delivered to remove material, but significant heat transfer occurs to surrounding material causing collateral damage
Solution Approach 1:
The patent employs periodic pulsed laser action with carefully controlled pulse duration (shorter than thermal diffusion time) to deliver energy in discrete intervals. This allows the irradiated volume to be heated and ablated while the surrounding material remains relatively cool, as heat does not have sufficient time to diffuse outward during each pulse cycle.
Solution Approach 2:
The patent changes the temporal parameter (pulse duration) to be shorter than the thermal diffusion time constant of the material. This parameter optimization ensures that energy is deposited faster than heat can spread, confining thermal effects to the irradiated volume and preventing collateral damage to surrounding tissue.
2Productivity
If high energy is deposited quickly to achieve fast ablation, then material removal efficiency increases, but ionization occurs causing additional damage
Solution Approach 1:
The patent optimizes the pulse duration parameter to fall within a specific window: long enough to avoid peak intensities that cause ionization, but short enough to be shorter than thermal diffusion time. This parameter tuning enables fast ablation through rapid energy deposition while maintaining peak intensities below the ionization threshold.
Solution Approach 2:
The patent dynamically adjusts the pulse characteristics to match the material's thermal response time. By making the pulse duration adaptive to the thermal diffusion time constant of the specific material being ablated, the system achieves maximum ablation efficiency without crossing into the ionization regime.
3Object-affected harmful factors
If laser energy is converted to heat slowly, then ionization is avoided, but thermal diffusion transfers energy to surrounding material reducing ablation efficiency
Solution Approach 1:
The patent changes the pulse duration parameter to a specific optimal value that is shorter than the thermal diffusion time constant. This ensures that energy conversion to heat occurs rapidly enough to prevent thermal diffusion losses, while the total pulse energy remains below the ionization threshold, avoiding ionization damage.
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 enables precise, minimally invasive material removal with reduced collateral damage, facilitating efficient and selective ablation while promoting healing in medical and dental procedures.
Implementation Method 1
impulsive heat deposition (IHD) through direct excitation of mechanical degrees of freedom (short lived vibrations or phonons) of the target material
Implementation Method 2
direct excitation of mechanical degrees of freedom (short lived vibrations or phonons) of the target material
Implementation Method 3
enough energy must be deposited to superheat the irradiated volume above the vaporization temperature of the material, leading to homogeneous nucleation and ejection of the material
Implementation Method 4
the energy deposited must not exceed the vaporization threshold, and must be deposited quickly enough that shockwaves due to sudden thermal expansion lead to mechanical breakdown and ejection of the material
Implementation Method 5
shockwaves due to sudden thermal expansion lead to mechanical breakdown and ejection of the material
Data Source
AI summary
The present invention provides a method of laser processing of materials, specifically laser induced ablation processes for laser removal of material particularly important in medical and dental applications in which the laser removal of material should be done in such a way as to not damage any of the surrounding soft or hard biomaterial. The ablation process is achieved by impulsive heat deposition (IHD) by direct and specific excitation of short lived vibrations or phonons of the material in such a way as to not generate highly reactive and damaging ions through multiphoton absorption. The heat deposition and ensuing ablation process under prescribed time and wavelength conditions for laser irradiation is achieved faster than heat transfer to surrounding tissue by either acoustic or thermal expansion or thermal diffusion that otherwise would lead to excess heat related damage. The result is that all the deposited laser energy is optimally channelled into the ablation process in which the inertially confined stresses from both photomechanical expansion forces and thermally driven phase transitions and associated volume changes constructively interfere to drive the most efficient ablation process possible with minimal damage to surrounding areas by either ionizing radiation or heat effects. By choosing a specific range of wavelengths, spatial and temporal shaping of infrared laser pulses, the energy can be optimally deposited in a manner that further increases the efficiency of the ablation process with respect to minimizing collateral damage.