Compact Spectrometer Using Cascaded Diffraction Gratings
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Solution Overview
Problem
Existing spectrometer designs fail to achieve a balance between high sensitivity and spectral resolution while maintaining compactness and portability, making them unsuitable for industrial applications that require accurate elemental analysis.
Innovation Solution
A spectrometer design featuring a primary and secondary diffraction grating configuration with collimating and imaging transmissive optics, including a collimating lens, beam folding mirrors, and a wavelength tuning refractive plate, which allows for high resolution and throughput in a compact form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a long focal length spectrometer (Czerny-Turner or echelle) is used to achieve high sensitivity and resolution, then spectral resolution and sensitivity are improved, but the device becomes heavy, bulky, and not portable
Solution Approach 1:
The patent implements a folded optical path where light reflects multiple times between mirrors arranged in a compact configuration. The optical components are nested within each other, with the light path folding back on itself to achieve an effective long focal length within a physically compact housing, making the spectrometer portable while maintaining high spectral resolution
Solution Approach 2:
The patent transitions from a linear optical path to a three-dimensional folded path using multiple mirrors at specific angles. By utilizing vertical and lateral spatial dimensions, the optical path length is extended without increasing the device's footprint, achieving long focal length performance in a compact form factor
2Volume of moving object
If a compact spectrometer design is used to achieve portability, then device size is reduced, but spectral resolution and sensitivity are limited
Solution Approach 1:
The patent employs adjustable mirrors and a movable wavelength tuning plate that can be positioned to optimize the optical path for different wavelength ranges. This dynamic adjustment capability allows the compact spectrometer to achieve high spectral resolution across multiple spectral regions by optimizing the effective focal length for each measurement
3Measurement precision
If traditional Czerny-Turner design is used to achieve high resolution, then spectral resolution is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses a single grating that serves multiple functions: it diffracts light into the spectrometer, provides wavelength dispersion, and works in conjunction with the tunable mirror system to cover multiple spectral regions. The wavelength tuning plate further enhances versatility by allowing selection of different spectral windows, reducing the need for multiple specialized components
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 design achieves high spectral resolution and sensitivity while maintaining a portable and compact form, enhancing the performance of analytical systems like LIBS by optimizing focal length and spectral resolution, and reducing costs compared to traditional Czerny-Turner designs.
Implementation Method 1
The spectrometer includes a primary diffraction grating configured to receive the light beam and diffract the light beam into a plurality of primary diffracted beams, each comprising a different wavelength of the light beam. Each secondary diffraction channel includes a secondary diffraction grating configured to receive a corresponding primary diffracted beam and diffract the primary diffracted beam into a twice diffracted beam
Implementation Method 2
The collimating input optics may include one or more transmissive optical components collimating the light beam. For example, the collimating input optics may include a collimating lens disposed in front of the primary diffraction grating. The imaging output optics of each secondary diffraction channel may include transmissive optical components imaging the corresponding twice diffracted beam
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
Spectrometer designs are provided. The spectrometer includes two planar diffraction gratings disposed in a cascade, without intervening optics therebetween. Advantageously, the described configurations may promote both a high throughput and a high resolution, enabling the design of a portable device having sufficient resolution for on-site use or in the laboratory. In some implementations, two different secondary diffraction channels may be provided.