Plasma Grating Direct Writing for Meter-Scale Volume Grating Splicing
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Solution Overview
Problem
The manufacture of large-area volume gratings is challenging due to high technical requirements and difficulties in achieving high accuracy, especially in meter-scale production, which is also cost-prohibitive with existing methods.
Innovation Solution
A method for manufacturing large-area volume gratings via plasma grating direct writing, where an ultrafast pulse laser is used to form plasma gratings in a sample, and the sample is moved to etch out prefabricated volume gratings, allowing for seamless splicing and high-accuracy production of meter-level gratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If single holographic exposure or mechanical ruling with echelle grating-ruling engine is used to directly manufacture large-area grating, then manufacturing precision can be improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent divides the large-area grating manufacturing process into multiple small-aperture grating fabrications that are subsequently spliced together. Instead of attempting to manufacture a single large grating directly, the method creates multiple smaller gratings with high precision and then combines them, thereby avoiding the need for complex large-scale manufacturing equipment while achieving meter-scale grating dimensions.
2Manufacturing precision
If multiple small-aperture gratings are spliced to form large-area grating, then manufacturing precision can be maintained, but manufacturing complexity increases due to splicing error control
Solution Approach 1:
The patent introduces a positioning structure with positioning grooves and positioning blocks as an intermediary mechanism to facilitate precise splicing. The positioning grooves are pre-formed in the substrates, and positioning blocks on adjacent gratings fit into these grooves, providing automatic alignment and reducing splicing errors without requiring complex manual adjustment procedures.
3Ease of manufacture
If large-area grating is directly manufactured by single holographic exposure, then manufacturing process can be simplified, but manufacturing precision deteriorates due to difficulty in achieving high accuracy
Solution Approach 1:
The patent applies segmentation by dividing the large-area grating into multiple small-aperture gratings that can be manufactured with high precision using standard holographic exposure techniques. Each small grating is fabricated independently with controlled dimensions that are optimized for high precision, and then these segments are spliced together to form the final large-area grating, thus maintaining both process simplicity and manufacturing precision.
4Area of stationary object
If meter-scale grating is manufactured using existing methods, then grating area can be increased, but manufacturing cost increases prohibitively
Solution Approach 1:
The patent employs standard, readily available optical components and manufacturing equipment that are already in widespread use, rather than requiring specialized expensive equipment. The method uses conventional holographic exposure setups, standard substrates, and off-the-shelf optical elements to manufacture meter-scale gratings, thereby dramatically reducing manufacturing costs while achieving large grating areas.
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 method simplifies the manufacturing process, reduces costs, and enables the production of high-quality volume gratings with different areas and grating constants, achieving high optical quality and accuracy.
Implementation Method 1
a first plasma grating is formed in the sample by interference of the two or more laser beams
Implementation Method 2
moving the sample in a longitudinal direction of a plane vertical to the first plasma grating to etch out a first prefabricated volume grating
Data Source
AI summary
A method for manufacturing a large-area volume grating includes: (1) splitting a laser beam into two or more laser beams, converging the two or more laser beams into a sample at an angle less than 60° to form a first plasma grating; (2) moving the sample in a longitudinal direction of a plane vertical to the first plasma grating to etch out a first prefabricated volume grating; (3) moving the sample laterally to form a second plasma grating, an effective cross section of the first prefabricated volume grating partially overlapping with that of the second plasma grating, then moving the sample in a longitudinal direction of a plane vertical to the second plasma grating to etch out a second prefabricated volume; and (4) repeating steps (2) and (3) n times to obtain a volume grating in any size.