Miniature Spectrometer Mode Switching via Liquid Crystal
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Solution Overview
Problem
Conventional miniature spectrometers face challenges in switching between imaging and spectrometer modes without mechanical elements, leading to increased production costs, susceptibility to errors, and a less compact design, while also requiring complex centering and being prone to interference patterns that affect image quality.
Innovation Solution
A miniature spectrometer design incorporating a polarizer, a Savart element with birefringent crystals, and liquid crystal elements that adjust polarization axes, along with a switchable diffuser, allows for mode switching without mechanical elements, enabling independent imaging and spectrometry with improved accuracy and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical elements are used for mode switching, then reliability is improved, but device complexity and volume increase
Solution Approach 1:
The patent replaces mechanical switching elements with an optical switching mechanism based on a liquid crystal variable retarder (LCVR). The LCVR changes its optical properties (birefringence) in response to electrical signals, enabling mode switching without any moving mechanical parts. This substitution eliminates mechanical complexity while maintaining reliable mode transitions between imaging and spectrometer modes.
Solution Approach 2:
The invention utilizes parameter changes in the liquid crystal material's optical properties to achieve mode switching. By applying different voltages to the LCVR, the optical path difference between ordinary and extraordinary rays is dynamically adjusted, transforming the system between imaging mode (minimal optical path difference) and spectrometer mode (specific optical path difference for interferogram generation).
2Reliability
If mechanical elements are used for mode switching, then reliability is improved, but production costs increase
Solution Approach 1:
The patent eliminates mechanical switching components (motors, gears, moving mirrors) and replaces them with an electrically controlled liquid crystal variable retarder. This reduction in mechanical parts simplifies manufacturing processes, reduces assembly complexity, and lowers production costs while maintaining reliable mode switching functionality.
3Reliability
If mechanical elements are used for mode switching, then reliability is improved, but compactness deteriorates
Solution Approach 1:
The invention replaces bulky mechanical switching mechanisms with a compact liquid crystal variable retarder that can be integrated into the existing optical path. The LCVR requires minimal space and eliminates the need for mechanical movement, enabling a more compact overall spectrometer design while maintaining reliable mode switching.
4Adaptability or versatility
If interferogram is superimposed on image in imaging mode, then spectrometry capability is improved, but image quality deteriorates
Solution Approach 1:
The patent dynamically controls the optical path difference using a liquid crystal variable retarder to switch between two distinct operational states: imaging mode where the optical path difference is minimized to prevent interferogram superposition and maintain image quality, and spectrometer mode where a specific optical path difference is introduced to generate interferograms for spectral analysis.
Solution Approach 2:
The invention changes the optical parameters (specifically the optical path difference) by applying different voltages to the liquid crystal variable retarder. In imaging mode, the retarder is configured to minimize optical path difference, preventing interferogram formation. In spectrometer mode, it is configured to create the appropriate optical path difference for interferogram generation, thus controlling whether spectral or imaging information is prioritized.
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
Enables high-quality image acquisition and spectrometric measurements in both modes with reduced mechanical complexity, improved accuracy, and increased compactness, allowing for wider application and reduced production costs.
Implementation Method 1
a first liquid crystal element arranged in the beam path between the polarizer and the Savart element, which is designed to set a fourth polarization axis of a radiation exiting from the first liquid crystal element
Implementation Method 2
a Savart element, which comprises a first birefringent element and a second birefringent element, the first liquid crystal element is designed to set a fourth polarization axis of a radiation exiting from the first liquid crystal element in such a way that the radiation exiting from the first liquid crystal element is split into a first ordinary ray and a first extraordinary ray in the first birefringent element
Implementation Method 3
the first beam and the second beam are superimposed again at a point in the detection plane. Depending on the difference in the optical path and the resulting phase difference, the first and second beams interfere and a light spot is produced with an intensity that is dependent on the difference in the phases of the first and second beam
Data Source
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AI summary
The invention relates to a miniature spectrometer (10) for spectrometry and for image capture, comprising a detection unit (7) for detecting an optical parameter and an optical unit, comprising a polarizer (2), a Savart element (40), which comprises a first birefrigent element (4a) and a second birefrigent element (4b), and an analyzer (5), characterized in that a first liquid crystal element (3a) is arranged between the polarizer (2) and the Savart element (40), which is designed to adjust a fourth polarization axis (203) from a radiation (103) emitted from the first liquid crystal element such that, in an imaging mode of the miniature spectrometer (10), the radiation (103) emitted from the first liquid crystal element passes through the first birefrigent element (4a) without splitting and, in a spectrometer mode of the miniature spectrometer (10), the radiation (103) emitted from the first liquid crystal element is split in the first birefringent element (4a) into a first ordinary beam (500b) and a first extraordinary beam (500a) and wherein the analyzer (5) is arranged in the beam path behind the Savart element (40) and the detection unit (7) is arranged in the beam path behind the analyzer (5).