Sealed Dual-Grating Optical Assembly for Clean Spectral Beam Combining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing High Energy Laser (HEL) Spectral Beam Combining (SBC) systems face challenges with grating contamination, wavelength dispersion, and alignment sensitivity, requiring cleanroom environments for assembly and maintenance, which complicates operation and shipment.
Innovation Solution
A dual-grating fiber SBC system with transmissive gratings protected by a micro-vented tube and modular design, allowing field serviceability and alignment in a controlled atmosphere, using fused silica components for stability and alignment maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single grating is used for spectral beam combining, then the system complexity is reduced, but wavelength dispersion degrades beam quality
Solution Approach 1:
The patent combines two separate gratings into a single integrated component where the first grating disperses wavelengths and the second grating recombines them. This merging approach maintains the beam quality benefits of dual-grating dispersion compensation while reducing overall system complexity and component count.
Solution Approach 2:
The patent embeds the second grating within the structure created by the first grating, where the dispersed beams from the first grating are immediately recombined by the second grating in a compact arrangement. This nesting allows dispersion compensation without requiring separate alignment systems.
2Manufacturing precision
If two matched gratings are used for dispersion compensation, then beam quality is improved, but alignment accuracy requirements increase
Solution Approach 1:
By merging the two gratings into a single integrated component, the patent eliminates the need for precise alignment between separate gratings. The combined structure ensures that the dispersion and recombination functions are inherently aligned, removing alignment accuracy requirements while maintaining beam quality.
3Object-affected harmful factors
If HEPA filters and dry air purging are used to control airborne particles, then grating cleanliness is maintained during operation, but system complexity and operational restrictions increase
Solution Approach 1:
The patent encapsulates the gratings in a hermetically sealed environment that is evacuated to vacuum or filled with inert gas. This creates a contamination-free atmosphere that protects the gratings during operation, shipment, and storage, eliminating the need for HEPA filters and dry air purging systems.
Solution Approach 2:
The patent extracts the harmful atmosphere (air with contaminants) from the grating environment by evacuating the sealed chamber to vacuum. This removal of the harmful medium eliminates contamination risks without requiring active filtration or purging systems.
4Object-affected harmful factors
If the system is sealed to protect gratings from contamination, then grating cleanliness is maintained, but pressure equalization and thermal management become challenging
Solution Approach 1:
The patent incorporates porous materials such as sintered metal or porous ceramics in the sealed chamber design. These materials allow pressure equalization through their porous structure while maintaining the seal that protects against contamination. The porous structure permits gas flow for pressure balancing but blocks larger contaminants.
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 system maintains beam quality and alignment under varying environmental conditions, enabling field replacement and reducing operational complexity while ensuring high laser resistance and cleanliness.
Implementation Method 1
The tube can include one or more pressure-equalizing vents or orifices having filter structures, such as permeable membranes, microporous films, expanded polytetrafluoroethylene (ePTFE) membranes, or the like. The permeable filter structure in the vent is intended to allow for pressure equalization, but to prevent contaminants and moisture from entering the sealed interior 82 of the tube 80.
Implementation Method 2
The first and second diffraction gratings 70a-b deflect incident beams according to their wavelengths so that all of the incident beams will subsequently propagate in the same direction.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An apparatus is used for spectral beam combining laser wavelengths into a combined beam. The apparatus has an integrated, sealed optical assembly that can be installed and replaced in the field. The optical assembly has a housing composed of a material, such as fused silica, transparent to the laser wavelengths. Transmissive gratings are disposed on ends of the housing and have their datums facing the sealed interior. V-grooves on a shelf at one end of the housing are disposed at an angle relative to the first grating. Fiber ends of a fiber array have end caps affixed in the V-grooves and aligned to the datums of the first grating. The fiber ends transmit the laser wavelengths in an array of beams toward the first grating, which diffracts the laser wavelengths to the second grating. In turn, the second grating transmits the laser wavelengths as a combined beam from the second end of the housing.