Q-Switched Alexandrite Laser for Vascular and Pigmented Lesion Treatment
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Solution Overview
Problem
Current laser technologies for treating vascular and pigmented lesions, such as pulsed dye lasers and frequency-doubled Nd:YAG lasers, face challenges with limited dye lifespan, high costs, and difficulties in achieving high energy millisecond pulse durations, making them less accessible and effective for comprehensive skin treatments.
Innovation Solution
A method and apparatus utilizing a free-running alexandrite laser to pump a Neodymium-doped laser rod, combined with a passive Q-switch and second harmonic generator, delivering a train of sub-pulses with wavelengths between 500nm and 600nm, specifically 524nm, to effectively treat both vascular and pigmented lesions, with pulse durations ranging from 5ns to 200ns and macro pulses from 0.1ms to 100ms, optimizing absorption coefficients for oxyhemoglobin and melanosomes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pulsed dye laser is used for treating vascular lesions, then treatment effectiveness is improved, but dye lifespan is limited due to photo degradation
Solution Approach 1:
The patent replaces the expensive, limited-life dye in pulsed dye lasers with a solid-state laser medium (Nd:YAG or Nd:YLF crystal) that does not degrade. The solid-state gain medium can operate indefinitely without replacement, eliminating the periodic maintenance requirement while maintaining effective vascular lesion treatment through the 532nm or 524nm wavelength output.
Solution Approach 2:
The patent changes the physical state of the laser medium from liquid dye to solid-state crystal, and adjusts the wavelength output (532nm or 524nm) to achieve comparable or superior blood absorption while eliminating photo degradation. This parameter change transforms a consumable medium into a permanent one.
2Duration of action of stationary object
If frequency-doubled Nd:YAG laser is used for vascular lesion treatment, then dye replacement is eliminated, but achieving high energy millisecond pulse durations becomes difficult
Solution Approach 1:
The patent changes the pulse duration parameter from the difficult-to-control millisecond regime in frequency-doubled lasers to the well-established nanosecond regime (5-200ns) using Q-switched technology. This provides precise, reproducible pulse durations that are optimal for vascular lesion treatment while simplifying the overall system design.
Solution Approach 2:
The patent employs Q-switching, a periodic modulation technique, to generate high-energy nanosecond pulses from the solid-state laser medium. The Q-switch periodically builds up energy in the gain medium and then releases it in controlled nanosecond bursts, providing reliable pulse duration control.
3Manufacturing precision
If Q-switched laser pulses are used for pigmented lesion treatment, then thermal relaxation time matching is improved, but treatment of vascular lesions simultaneously becomes challenging
Solution Approach 1:
The patent creates a universal laser system that can treat both pigmented and vascular lesions effectively. By using a Q-switched solid-state laser with adjustable wavelength (532nm or 524nm) and the ability to deliver pulse trains, the single device performs multiple functions that previously required separate specialized lasers.
Solution Approach 2:
The patent segments the treatment approach by using pulse trains consisting of multiple nanosecond sub-pulses within an envelope pulse. This segmentation allows different portions of the pulse train to target different lesion types: the nanosecond sub-pulses treat pigmented lesions by matching melanosome thermal relaxation time, while the overall pulse train structure enables vascular lesion treatment.
4Reliability
If multiple specialized lasers are used for different lesion types, then treatment specificity is improved, but device cost and complexity increase
Solution Approach 1:
The patent consolidates multiple specialized laser functions into a single Q-switched solid-state laser system. The device can treat pigmented lesions, vascular lesions, and perform skin toning/rejuvenation using the same laser medium and delivery system, eliminating the need for multiple separate laser devices while maintaining treatment specificity through wavelength and pulse parameter control.
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 provides a cost-effective, efficient treatment for vascular and pigmented lesions, offering deeper penetration and thermal confinement, reducing tissue damage and improving treatment outcomes for both lesion types, while also supporting skin toning and rejuvenation procedures in a single treatment pass.
Implementation Method 1
a free-running alexandrite laser to pump a Neodymium-doped laser rod
Implementation Method 2
combined with a passive Q-switch
Implementation Method 3
second harmonic generator, delivering a train of sub-pulses with wavelengths between 500nm and 600nm, specifically 524nm
Implementation Method 4
optimizing absorption coefficients for oxyhemoglobin and melanosomes
Data Source
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AI summary
An apparatus and method for treating pigmented lesions and vascular lesions by a wavelength between 500nm and 600nm applied to the segment of skin as a train of pulses. In some examples, a wavelength of 1048nm is applied sequentially or simultaneously with the wavelength between 500nm and 600nm.