Echelle Spectrometer Reflective Dispersion Assembly
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Solution Overview
Problem
Existing Echelle spectrometers with internal order separation suffer from limited light throughput due to the need for small slit heights to prevent order overlap, resulting in significant light loss compared to spectrometers using diffraction gratings in the first order.
Innovation Solution
A compact spectrometer design featuring a reflective dispersion assembly that reflects and re-passes the parallel radiation bundle through an Echelle grating, allowing for high dispersion and separation of orders with a large entrance slit, utilizing a prism or grism for lateral dispersion, and operating in autocollimation mode to minimize optical components and material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a prism is used for generating lateral dispersion, then orders are separated in the spectral wavelength range with short wavelengths, but larger gaps are generated compared to the spectral range with larger wavelengths
Solution Approach 1:
The patent combines a prism and a diffraction grating in a compound dispersion assembly. The prism provides initial lateral dispersion that pre-separates different wavelength ranges, while the Echelle grating subsequently disperses each wavelength range into its spectral orders. This merging of two dispersion mechanisms allows for effective order separation across the entire spectral range while maintaining high light throughput through the optimized path.
Solution Approach 2:
The prism performs preliminary dispersion of the incoming radiation bundle before it reaches the Echelle grating. By pre-separating the radiation into different wavelength ranges laterally, the prism enables the grating to work more efficiently on each separated range, reducing the need for excessive angular dispersion and allowing for a larger entrance slit height while maintaining order separation.
2Quantity of substance
If the entrance slit height is increased to improve light throughput, then more light enters the spectrometer, but orders overlap in the focal plane
Solution Approach 1:
The compound dispersion assembly merges prism-based lateral dispersion with grating-based spectral dispersion. This combination creates a two-dimensional dispersion pattern where the prism separates wavelengths laterally and the grating separates orders angularly, allowing larger slit heights without order overlap while maintaining spectral resolution.
Solution Approach 2:
The patent introduces a second dimension of dispersion by combining lateral dispersion (prism) with angular dispersion (grating). This two-dimensional separation strategy allows the system to accommodate larger entrance slit heights by utilizing both spatial dimensions for order separation, thereby increasing light throughput without sacrificing spectral resolution.
3Measurement precision
If diffraction gratings are used for lateral dispersion, then the situation is reversed compared to prisms, but the fundamental problem of order overlap persists
Solution Approach 1:
The patent merges the advantages of both prism and diffraction grating dispersion mechanisms in a compound assembly. By combining lateral dispersion (from either prism or grating) with angular dispersion from the Echelle grating, the system achieves effective order separation across the entire spectral range while maintaining high light throughput, overcoming the limitations of using either mechanism alone.
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 resolution and large light throughput by effectively separating orders over the entire spectral range with minimal optical components, reducing material costs and maintaining high imaging quality, while allowing for easy adjustment and low production costs.
Implementation Method 1
a collimator optics for generating a parallel bundle of rays from radiation entering the spectrometer assembly
Implementation Method 2
an Echelle grating for dispersing radiation entering the spectrometer assembly in a main dispersion direction
Implementation Method 3
the dispersion assembly is reflective, and the dispersion assembly is arranged along the optical path before the Echelle grating in such a way that parallel radiation bundle is reflected in the direction of the Echelle grating
Data Source
AI summary
A spectrometer assembly (10), comprising an Echelle grating (18; 46) for dispersing radiation entering the spectrometer assembly (10) in a main dispersion direction, and a dispersion assembly (16; 40) for dispersing a parallel radiation bundle generated from the radiation entering the spectrometer assembly in a lateral dispersion direction, is characterized in that the dispersion assembly (16; 40) is reflective, and the dispersion assembly (16; 40) is arranged relative to the Echelle grating (18; 46) in such a way that the parallel radiation bundle is reflected in the direction of the Echelle grating. The Echelle grating (18; 46) may be arranged in such a way that the dispersed radiation is reflected back to the dispersion assembly (16; 40).