Concave Diffraction Grating Transfer for Uniform Blaze Angles
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Solution Overview
Problem
Existing methods for manufacturing concave diffraction gratings face issues such as inconsistent blaze angles, shape variations, and wrinkling due to mechanical engraving or imprinting on curved surfaces, leading to non-uniform diffraction patterns and reduced diffraction efficiency.
Innovation Solution
A method involving a flat diffraction grating with stretchable, thin film, or low-friction parts is mounted on a convex substrate to form a die, which is then imprinted onto a concave substrate, ensuring uniform grating patterns and reducing wrinkling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical engraving with a ruling engine is used to manufacture a die for diffraction grating, then the engraving process can be performed with a constant angle tool, but inconsistent blaze angles are produced due to the constant angle of the engraving tool, resulting in shallow and deep parts in the serrate grating pattern at the center and edge parts of the curved substrate
Solution Approach 1:
The patent replaces the mechanical ruling engine system with an ion beam-based manufacturing system. The ion beam method uses physical sputtering to create grating grooves, eliminating the mechanical contact and constant angle tool issues inherent in ruling engines. This substitution enables precise control of the blaze angle across the entire curved substrate surface, achieving uniform diffraction efficiency without the shallow and deep pattern variations caused by mechanical engraving.
2Manufacturing precision
If ion etching is performed on a curved surface to form grating grooves, then the grating groove can be formed on the curved substrate, but shape variation of the grating groove occurs
Solution Approach 1:
The patent employs parameter changes in the ion beam irradiation process, specifically adjusting the incidence angle of the ion beam relative to the curved substrate surface. By controlling the ion beam angle and using a rotation mechanism to maintain optimal incidence angles during etching, the method achieves uniform grating groove shapes across the curved surface. This parameter control prevents the shape variation that would otherwise occur due to the varying surface normals on the curved substrate.
3Adaptability or versatility
If a flexible member such as silicone resin is used to form the grating groove on the curved surface by imprinting, then the die can be formed on the curved substrate, but the pattern of the die collapses due to tension applied during imprinting and separation, thus shortening the service life
Solution Approach 1:
The patent replaces the flexible member imprinting method with a direct ion beam etching method. Instead of using silicone resin or other flexible materials that must be stretched and separated from the curved substrate, the ion beam directly etches the grating grooves into the curved substrate or into a resist layer on the curved substrate. This eliminates the mechanical tension and pattern collapse issues entirely, as there is no flexible die to stretch and separate. The resulting gratings have intact patterns and extended service life.
4Manufacturing precision
If photolithography is used to form the grating groove in the resist on a curved substrate, then the grating groove can be formed on the curved surface, but precise formation of the grating groove is difficult
Solution Approach 1:
The patent replaces the photolithography process with direct ion beam etching. Instead of using photomasks, light exposure, and chemical development on a curved substrate, the ion beam directly writes the grating groove pattern through physical sputtering. This substitution eliminates the complexity of aligning and maintaining photomasks on curved surfaces, and the precision limitations of optical methods on non-planar substrates. The ion beam method provides direct, high-precision pattern formation that is inherently suited to curved geometries.
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 enables precise manufacturing of concave diffraction gratings with uniform blaze angles, improving diffraction efficiency and reducing stray light, suitable for optical devices like spectrophotometers.
Implementation Method 1
ion beam is irradiated on a substrate with a concave surface having formed thereon a grating photoresist pattern, to form a grating groove pattern with a serrate cross section on the concave surface
Data Source
AI summary
Provided is a feature for highly precisely manufacturing a concave diffraction grating that has a uniform diffraction grating pattern. This method for manufacturing a concave diffraction grating includes: preparing a flat diffraction grating that has a lattice groove and that also has an elongated section, a thin-film section, or a low-friction section formed outside of a region for forming a mold for the concave diffraction grating; mounting the flat diffraction grating on a convex substrate and acquiring the mold for the concave diffraction grating; and transferring the lattice groove in the mold to the concave substrate.