Asymmetric Optical Concentrator for Spectrometer Light Throughput
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Solution Overview
Problem
Existing spectrometer devices for infrared (IR) spectral region, particularly near-infrared (NIR), face challenges with low light throughput and poor signal-to-noise ratio due to the use of baffles that restrict light incidence to normal angles, limiting their efficiency and resolution.
Innovation Solution
The spectrometer device incorporates an optical element with an asymmetric light path to the linearly variable filter, utilizing an inversely-operated optical concentrator with a non-conical shape and reflective sidewalls to enhance light concentration and transmission, allowing more light to be directed to the detector array while maintaining high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a baffle is used to make light impinge the LVF normal to the receiving surface, then the spectral resolution is improved, but the light throughput decreases and signal-to-noise ratio deteriorates
Solution Approach 1:
The patent applies asymmetry by using a non-conical optical concentrator with asymmetric reflective surfaces. The concentrator has a first reflective surface with a first angle of incidence and a second reflective surface with a second angle of incidence, creating an asymmetric light path that directs light at non-normal angles to the LVF receiving surface. This asymmetric design increases light throughput while maintaining spectral resolution by optimizing the light distribution across the detector array.
Solution Approach 2:
The patent inverts the conventional approach by operating the optical concentrator in reverse mode. Instead of using a conventional conical concentrator that focuses light to a point, the inverted non-conical concentrator spreads light over an extended focal line, allowing more light to reach the LVF without requiring normal incidence. This inversion enables high light throughput while maintaining spectral analysis capability.
2Device complexity
If a conventional conical optical concentrator is used, then the device complexity is reduced, but the concentration efficiency decreases due to Fresnel reflection and total internal reflection losses
Solution Approach 1:
The patent replaces the symmetric conical shape with an asymmetric non-conical optical concentrator. The asymmetric geometry with different reflective surface angles optimizes the light path to minimize Fresnel reflection and total internal reflection losses. This asymmetric design maintains relatively simple device structure while significantly improving concentration efficiency by reducing optical losses at the interfaces.
3Device complexity
If the optical concentrator operates in conventional direction, then the structural simplicity is maintained, but the angular spread of captured light increases reducing resolution
Solution Approach 1:
The patent inverts the conventional operation mode of the optical concentrator. By operating the non-conical concentrator in reverse, the device takes light with large angular spread from the environment and transforms it into a collimated beam with small angular spread that impinges on the LVF. This inversion maintains structural simplicity while achieving precise angular control necessary for high-resolution spectral analysis.
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 configuration significantly improves light throughput and signal-to-noise ratio, enabling higher concentration efficiency and more accurate spectral analysis in the IR and NIR ranges, particularly for detecting heat, flames, or smoke.
Implementation Method 1
the optical concentrator device is operated in reverse direction for spreading out the captured light and reducing an angular spread of the captured light
Implementation Method 2
an inversely-operated optical concentrator with a non-conical shape and reflective sidewalls to enhance light concentration and transmission
Implementation Method 3
a linearly variable filter (LVF) and a detector array... the LVF is designated for separating light captured from an object into a spectrum of constituent wavelength signals
Data Source
Figure 1A
Figure 1B~2A
Figure 2B~3D
AI summary
A spectrometer system (110) and a spectrometer device (112) are disclosed, which are suited for investigation or monitoring purposes, in particular, in the infrared (IR) spectral region, and for a detection of heat, flames, fire, or smoke. Herein, the spectrometer device (112) comprises: - an optical element (122) designed for receiving incident light (114) from an object (116) and transferring the incident light (114) to a length variable filter (118), wherein the optical element (122) is arranged in a manner that the incident light (114) is transferred to the length variable (118) filter along a light path which is asymmetric with respect to an optical axis (123) of the spectrometer device (112); - the length variable filter (118) which is designated for separating the incident light (114) into a spectrum of constituent wavelength signals; and - a detector array (120) comprising a plurality of pixelated sensors (144), wherein each of the pixelated sensors (144) is adapted to receive at least a portion of one of the constituent wavelength signals, wherein each of the constituent wavelength signals is related to an intensity of each constituent wavelength. The spectrometer device (112) allows capturing incident light (114) from the object (116) and transferring the incident light (114) to the length variable filter (118) with a particularly high concentration efficiency. Apart from the spectrometer device (112), the spectrometer system (110) further comprises an evaluation unit (150) designated for determining information related to a spectrum of an object (116) by evaluating the detector signals (172, 172', 172'') provided by the spectrometer device (112).