Y-Toric Diffraction Element for Spectrometer Precision
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Solution Overview
Problem
Conventional spectrometers with concave diffraction elements face issues with intensity decrease and flare due to the anamorphic toric surface, leading to deteriorated precision in spectroscopy, as the diffraction gratings formed on such surfaces have varying pitch and are not parallel, affecting diffraction efficiency and imaging performance.
Innovation Solution
A diffraction element with a curved surface having a y-toric shape, where the curvature radius in the arrangement direction of gratings is larger than in the extending direction, and a blazed grating is used, processed by rotating a working tool about a rotation axis within a finite radius, ensuring the gratings are formed orthogonally and maintaining diffraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional anamorphic toric surface is used for the diffraction element, then the curvature radius in the spectral direction can be optimized for Rowland circle imaging, but the diffraction gratings have varying pitch and are not parallel, causing intensity decrease and flare that deteriorate spectroscopy precision
Solution Approach 1:
The patent applies asymmetry by using a y-toric surface with different curvature radii in orthogonal directions (R in spectral direction, r in orthogonal direction where R > r), creating an asymmetric curved surface that optimizes both Rowland circle imaging and grating uniformity. This asymmetric design resolves the contradiction by allowing the spectral direction to be optimized for precision while the orthogonal direction compensates for intensity maintenance.
Solution Approach 2:
The patent changes the geometric parameters of the diffraction element surface from a conventional toric shape to a y-toric shape with specific curvature radius relationships (R > r). By adjusting these parameters, the patent achieves both precise spectroscopy measurement and reliable imaging performance, eliminating the intensity decrease and flare problems.
2Measurement precision
If the curvature radius in the spectral direction is optimized for high precision spectroscopy, then measurement accuracy improves, but the light beam intensity decreases and flare occurs due to non-parallel gratings
Solution Approach 1:
The asymmetric y-toric surface design with R > r creates different optical paths in orthogonal directions. The spectral direction (radius R) is optimized for precise wavelength separation, while the orthogonal direction (radius r) maintains grating parallelism and uniform pitch, preventing intensity decrease and flare while preserving measurement accuracy.
Solution Approach 2:
The patent applies local quality by optimizing different regions of the diffraction element for different functions: the spectral direction is optimized for high precision measurement, while the orthogonal direction is optimized for maintaining uniform light distribution and preventing flare, achieving both goals simultaneously through localized optimization.
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 y-toric diffraction element prevents intensity decrease and flare, maintaining high diffraction efficiency and achieving accurate spectral analysis without compromising imaging performance in both spectral and orthogonal directions.
Implementation Method 1
a light beam entering through an incident slit is diffracted by a concave diffraction element having fine grooves formed in a direction perpendicular to the paper face in different angles for respective wavelengths
Implementation Method 2
The light beam entering through the incident slit on the Rowland circle is reflected and diffracted by the concave diffraction element, and then forms an image on the Rowland circle
Data Source
AI summary
Objects are to obtain a highly accurate diffraction element that may prevent an intensity decrease of a light beam entering a light receiving unit without a decrease in diffraction efficiency and without a problem of flare or the like, a manufacturing method for the diffraction element, and a spectrometer using the same. A diffraction element (2) includes a diffraction grating formed on a substrate having a curved surface. In the diffraction element (2), the curved surface (3) has an anamorphic shape formed by pivoting a curved line (I) in a plane about a straight line (II) in the same plane serving as a rotation axis, and gratings (10a) of the diffraction grating (10) exist in cross sections orthogonal to the rotation axis.