Laser Beam Apodizator for Low-Diffraction Amplifier Filling
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Solution Overview
Problem
High-energy laser systems face challenges in achieving efficient beam propagation through optical elements and free space while minimizing diffraction and intensity modulation, leading to potential damage and reduced energy utilization due to nonlinear interactions and finite aperture constraints.
Innovation Solution
A laser beam apodizator that modifies the beam profile to a cosN-type function, ensuring intensity decreases nonlinearly with radial distance and maintains low diffraction, allowing the beam to propagate several meters without image relaying, with intensity modulation not exceeding 10%, and achieving at least 70% beam shaping efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a Gaussian beam profile is used, then diffraction is minimized during propagation, but the active media are poorly filled and population inversion cannot be fully utilized
Solution Approach 1:
The patent modifies the beam profile parameters by applying an apodization function that transforms the Gaussian profile into a super-Gaussian profile. This changes the intensity distribution parameters while maintaining the overall Gaussian character, allowing the beam to fill the active media more effectively without excessive diffraction. The apodization function adjusts the radial intensity distribution to optimize both propagation stability and media utilization.
2Productivity
If a super-Gaussian beam profile is used to improve population inversion utilization, then beam shaping efficiency increases, but the beam diffracts strongly and intensity peaks appear causing optical element damage
Solution Approach 1:
The patent applies local quality modification by using an apodization function that creates a super-Gaussian profile with a flat top region and controlled edges. This local modification of the intensity distribution allows high utilization of the active media in the central region while controlling the intensity at the edges to prevent diffraction-induced peaks that could damage optical elements. The apodization function specifically shapes the radial intensity distribution to balance these competing requirements.
3Stability of the object's composition
If image relaying optical elements are added to preserve super-Gaussian beam profile, then beam profile is maintained, but system size and complexity increase
Solution Approach 1:
The patent applies preliminary action by shaping the beam profile at the very beginning of the optical system using an apodization function. This preliminary shaping creates a beam that is inherently more resistant to diffraction and profile degradation during propagation. By establishing the desired super-Gaussian profile early in the beam path, the system eliminates the need for subsequent image relaying optical elements that would otherwise be required to maintain the profile, thereby reducing overall system complexity.
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 apodizator enables efficient beam propagation and energy utilization in high-energy laser systems by reducing diffraction and intensity modulation, simplifying the system design, and maintaining power without the need for image relaying, thus reducing costs and complexity.
Implementation Method 1
to minimize the modifications of the laser beam spatial profile, especially, to minimize the modulation of the profile due to diffraction effect on the edges of the active media apertures
Implementation Method 2
Nonlinear interaction with optical elements can lead to undesirable effects such as self-focusing (also known as spatial self-phase modulation), which can focus the beam as a whole
Data Source
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AI summary
The invention relates to laser beam apodizators for use in high-energy laser systems with at least one laser or parametric amplification module. The invention also relates to high-energy laser systems and high-energy laser radiation generation methods. It is aimed to form a laser beam of a modified profile in order to achieve the highest possible efficiency of the amplifiers of the laser system and at the same time to ensure low diffraction of the beam when it propagates through the optical elements and in free space inside and outside the laser system. A particular focus is paid to beam propagation through optical elements of a finite diameter in order to minimize the modulation of the beam spatial profile due to diffraction effect on the edges of the active media apertures. A family of functions suitable for laser beam profiles is proposed. The solution allows to increase the efficiency of the laser system of several amplification stages, compared to identical systems in which the Gaussian beam propagates. At the same time, the solution allows to build a laser system of a simpler design and lower price, compared to systems in which the super-Gaussian beam with the flat top is formed.