Optical Stops for Infrared Spectrometer Signal Noise
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Solution Overview
Problem
In optical systems, especially infrared imaging spectrometers, diffraction leads to significant leakage of unwanted background radiation and loss of signal radiation, compromising radiometric accuracy and sensitivity, particularly in compact systems like those used in UAVs or man-portable devices.
Innovation Solution
The introduction of an optical element that blocks unwanted diffracted background radiation and the use of two optical stops in the imaging spectrometer design, one to block background radiation and the other to capture more diffracted scene radiation, enhancing throughput and reducing background noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If detecting elements and slit apertures are made smaller to reduce system size, then the system becomes more compact and portable, but diffraction effects increase causing leakage of unwanted background radiation and loss of signal radiation
Solution Approach 1:
The patent divides the optical path into multiple segments by introducing additional optical elements (diffracted light mirrors, beam splitters, and detectors) that separately handle diffracted background radiation and signal radiation. This segmentation allows independent control of unwanted radiation and useful signal, resolving the contradiction between compact size and radiometric accuracy.
Solution Approach 2:
The patent introduces intermediary optical elements (diffracted light mirrors and beam splitters) that mediate between the slit aperture and the detector. These intermediaries capture and redirect diffracted radiation, preventing it from reaching the detector as noise while preserving the direct geometric ray path for signal transmission, thus maintaining accuracy in compact systems.
2Volume of moving object
If detecting elements and slit apertures are made smaller to reduce system size, then the system becomes more compact and portable, but signal radiation is lost due to diffraction outside the geometric ray bundle
Solution Approach 1:
The patent addresses signal loss in the angular dimension by placing diffracted light mirrors at specific angles to intercept diffracted signal radiation that would otherwise be lost. This dimensional approach to capturing diffracted light complements the spatial compacting, allowing smaller apertures without proportional signal loss.
3Volume of moving object
If diffraction effects are allowed to occur with smaller apertures, then the system remains compact, but unwanted background radiation leaks through to the detecting element
Solution Approach 1:
The patent extracts unwanted diffracted background radiation from the optical path by using diffracted light mirrors and beam splitters to separate and redirect this radiation away from the detector. This extraction removes the harmful effect of background radiation leakage while preserving the compact aperture design.
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 approach significantly improves radiometric accuracy by reducing unwanted background radiation and increasing the amount of usable signal radiation, thereby enhancing the sensitivity and reliability of imaging systems.
Implementation Method 1
the effects of the diffraction of light become more significant, leading to the leakage of unwanted background radiation from outside the geometric rays to pass through to the detecting element
Implementation Method 2
leading to the loss of signal radiation that is diffracted outside of the geometric ray bundle and vignette by the optical elements or stop of the system
Data Source
AI summary
Systems and methods for increasing the overall throughput, decreasing the overall background radiation, or a combination thereof for imaging systems.