Q-Switched Cavity-Dumped Laser for High-Energy Sub-Nanosecond Pulses
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Solution Overview
Problem
Current laser systems capable of producing short pulse durations and high energy outputs for treating skin pigmentations, such as tattoos, are complex and expensive, often requiring multiple lasers and amplifier stages, making them impractical for cosmetic and medical applications.
Innovation Solution
A simplified laser configuration with a sub-nanosecond cavity round trip time, incorporating Q-switching and cavity dumping features, generates high energy sub-nanosecond pulses without additional amplifier stages, using a single resonator with a Pockels cell, polarizer, and gain medium, achieving pulse energies of several hundred millijoules per pulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional laser systems are used to produce short pulse durations and high energy outputs, then the desired pulse characteristics are achieved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent combines Q-switching and cavity-dumping techniques within a single laser resonator system to achieve sub-nanosecond pulse durations. By integrating these two methods, the system produces high-energy short pulses without requiring multiple separate laser systems and amplifier stages, thus reducing device complexity while maintaining the desired pulse characteristics.
Solution Approach 2:
The patent employs dynamic control of the resonator Q-factor through Q-switching and cavity-dumping mechanisms. By dynamically adjusting the resonator properties during operation, the system can generate sub-nanosecond pulses with high energy output, achieving the desired pulse duration without the need for complex static multi-component systems.
2Use of energy by moving object
If multiple lasers and amplifier stages are used to achieve high energy output, then the energy per pulse increases, but the device complexity and cost increase
Solution Approach 1:
The patent merges Q-switching and cavity-dumping functions within a single laser resonator to achieve high energy per pulse output. This integration eliminates the need for multiple separate laser systems and amplifier stages, reducing device complexity while maintaining the capability to deliver several hundred millijoules per pulse.
Solution Approach 2:
The patent uses Q-switching to preliminarily store energy in the laser medium before cavity-dumping releases it in a sub-nanosecond pulse. This preliminary energy accumulation allows the system to achieve high energy per pulse output without requiring multiple amplifier stages, thereby reducing system complexity.
3Use of energy by moving object
If pulse duration is extended to achieve higher energy output, then energy per pulse increases, but thermal diffusion into surrounding tissues increases
Solution Approach 1:
The patent employs dynamic Q-switching and cavity-dumping to generate sub-nanosecond pulses with high energy content. By controlling the pulse duration to be extremely short (sub-nanosecond), the system delivers high energy per pulse while minimizing the time for thermal diffusion into surrounding tissues, thus reducing harmful thermal effects.
Solution Approach 2:
The patent changes the pulse duration parameter to the sub-nanosecond range while maintaining high energy per pulse through Q-switching and cavity-dumping. This parameter optimization allows the system to achieve the desired energy output while keeping pulse duration short enough to prevent significant thermal diffusion, thereby reducing harmful effects on surrounding tissues.
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
The solution provides a compact, cost-effective method for generating laser pulses with durations between 100 picoseconds and 900 picoseconds and energies of 100 mJ or more, suitable for photomechanical treatment of skin pigmentations, effectively disrupting tattoo pigment particles without the need for complex systems.
Implementation Method 1
Representative laser configurations include a Q-switching feature. Representative laser configurations include a cavity dumping feature.
Implementation Method 2
a laser configuration including a laser oscillator having dimensions suitable to produce a sub-nanosecond cavity round trip time that is used to generate laser light with a sub-nanosecond pulse duration
Implementation Method 3
The laser configuration also includes Q-switching and cavity dumping features. As a result, laser energy suitable for a number of applications, including cosmetic and medical applications
Implementation Method 4
The principle of selective photothermolysis underlies many conventional medical laser therapies to treat diverse dermatological problems. The dermal and epidermal layers containing the targeted structures are exposed to laser energy having a wavelength that is preferentially or selectively absorbed in these structures
Implementation Method 5
This leads to localized heating to a temperature (e.g., to about 70° C. or higher) that denatures constituent proteins or disperses pigment particles
Data Source
AI summary
Apparatuses and methods are disclosed for applying laser energy having desired pulse characteristics, including a sufficiently short duration and/or a sufficiently high energy for the photomechanical treatment of skin pigmentations and pigmented lesions, both naturally-occurring (e.g., birthmarks), as well as artificial (e.g., tattoos). The laser energy may be generated with an apparatus having a resonator with a sub-nanosecond round trip time.