Compact VUV Spectrometer Using Concave Grating
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Solution Overview
Problem
Current compact spectrometers for vacuum ultraviolet (VUV) radiation spectrum measurement have limitations in recording range and spectral resolution, with transmissive gratings being fragile and prone to contamination, and existing designs either compromise on spectral range or suffer from low resolution and detector efficiency issues.
Innovation Solution
A compact VUV spectrometer with a flat, relief-type diffraction grating having flat reflective faces and non-reflective grooves, capable of recording spectra in both -1st and +1st diffraction orders, with a grazing angle of 4 to 6 degrees, and a multi-element detector for enhanced sensitivity and calibration, allowing for wide spectral range recording and absolute intensity measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transmissive gratings are used in VUV spectrometers, then spectral range and luminosity are improved, but reliability deteriorates due to fragility and contaminant deposition
Solution Approach 1:
The patent replaces fragile transmissive gratings with robust reflective gratings that have a reflective coating on a substrate. This reflective design is much more resistant to damage and contamination, effectively creating a durable, long-lasting component that eliminates the reliability issues of transmissive gratings while maintaining spectral performance.
Solution Approach 2:
The grating is constructed as a composite structure with a substrate (providing mechanical strength and stability) and a reflective coating layer (providing optical functionality). This composite approach combines the advantages of structural integrity with optical performance, resolving the contradiction between reliability and spectral range.
2Measurement precision
If phase reflection diffraction gratings with beam grazing incidence are used, then spectral resolution is improved, but device complexity increases due to precise alignment requirements
Solution Approach 1:
The patent employs a concave grating geometry where the grating surface is curved rather than flat. This curvature is specifically designed to focus diffracted rays onto the detector, automatically providing the precise alignment needed for high spectral resolution without requiring complex external alignment mechanisms. The curved surface acts as both the diffraction element and the focusing element.
Solution Approach 2:
The patent combines the diffraction function and the focusing function into a single grating element. The concave grating simultaneously diffracts the incoming radiation and focuses the diffracted orders onto the detector plane, eliminating the need for separate alignment of multiple optical components and thereby reducing device complexity while maintaining high spectral resolution.
3Adaptability or versatility
If multiple spectrometers are used to cover wide spectral range, then spectral range is improved, but device complexity and measurement procedure complexity increase
Solution Approach 1:
The patent designs a single spectrometer system that can simultaneously record multiple diffraction orders (+1st, -1st, and higher orders) on a single detector. By optimizing the grating parameters and detector positioning, the system achieves wide spectral coverage across different diffraction orders, making one spectrometer as versatile as multiple spectrometers would be, thereby reducing device complexity while maintaining broad spectral range.
Solution Approach 2:
The patent utilizes the diffraction order dimension to extend the spectral range. Instead of using multiple spectrometers to cover different wavelength ranges, the system records spectra in different diffraction orders (+1st, -1st, etc.) simultaneously, effectively using the order number as an additional dimension for spectral coverage. This allows a single device to achieve the spectral range that would otherwise require multiple instruments.
4Measurement precision
If detector is illuminated with grazing incidence, then spectral resolution is improved, but detector quantum efficiency deteriorates and noise increases
Solution Approach 1:
The patent uses a concave grating geometry that focuses diffracted radiation onto the detector at more favorable angles. The curved grating surface directs the diffracted beams to converge on the detector plane, reducing the grazing incidence angle at which radiation strikes the detector. This improves quantum efficiency and reduces noise while maintaining the spectral resolution benefits of grazing incidence diffraction.
Solution Approach 2:
The patent optimizes the grating parameters (curvature radius, groove density, illumination angle) to control the diffraction geometry. By carefully selecting these parameters, the system achieves a balance where the diffracted radiation reaches the detector at angles that provide both adequate spectral resolution and acceptable quantum efficiency, thereby changing the operational parameters to resolve the contradiction between resolution and efficiency.
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 spectrometer achieves a wide spectral range of 3-200 nm with moderate to high spectral resolution, enabling absolute radiation yield measurements and maintaining a compact size, while the flat grating design improves robustness and reduces production costs.
Implementation Method 1
a diffraction grating with period d, on which a radiation beam is incident at a grazing angle θ, and a detector
Implementation Method 2
the diffraction grating is designed to be flat, with a relief, with flat reflective working faces which lie in a grating plane
Data Source
AI summary
The invention relates to a compact wideband vacuum ultraviolet (VUV) and soft X-ray grazing incidence spectrometer based on a plane amplitude diffraction grating. The spectrometer enables simultaneous detection of a VUV spectrum in a positive first order of diffraction and a negative first order of diffraction. The technical result of the invention is that of recording a spectrum in a wide spectral range (3-200 nm) with a moderate spectral resolution (λ/δλ˜15-30) and with a significantly higher spectral resolution (λ/δλ˜100-200) in a narrow soft X-ray or extreme ultraviolet range with the possibility of measuring the absolute radiation output in these regions of the spectrum.