Planar Grating Spectrometer with Acute Angle Alignment
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Solution Overview
Problem
Existing miniaturized spectrometers face challenges in achieving high sensitivity due to scattered light issues when using multiple optical elements and require costly components like curved gratings and small apertures.
Innovation Solution
A compact spectrometer design utilizing a planar optical grating aligned at an acute angle with a large aperture, minimizing scattered light and incorporating an objective arrangement with focusing lenses to direct higher orders of diffraction onto a sensor element, ensuring maximum radiation capture and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple optical elements (mirrors, lenses, apertures) are used in miniaturized spectrometers, then the spectrometer can be compact, but scattered light increases and sensitivity decreases
Solution Approach 1:
The patent removes intermediate optical elements (mirrors, lenses, apertures) from the optical path, extracting only the essential components: entrance aperture, planar grating, and sensor. This eliminates scattered light sources while maintaining compactness through direct optical coupling.
Solution Approach 2:
The optical system is segmented into three functional zones: illumination zone (aperture), diffraction zone (grating), and detection zone (sensor). Each zone is optimized independently with precise spatial arrangement, allowing compact integration while minimizing optical path complexity and scattered light.
2Volume of moving object
If a curved optical grating is used in miniaturized spectrometers, then the spectrometer can be compact, but the cost increases significantly
Solution Approach 1:
Instead of using a curved grating to achieve compactness, the patent inverts the approach by using a planar grating with a specific tilt angle (less than 45°). This planar configuration is much easier and cheaper to manufacture while still achieving compact spectrometer design through angular optimization.
Solution Approach 2:
The patent changes the critical parameter from grating curvature to grating tilt angle. By optimizing the tilt angle to be less than 45°, the system achieves compact form factor without requiring expensive curved gratings, thereby reducing manufacturing costs while maintaining performance.
3Volume of moving object
If a small aperture is used in miniaturized spectrometers, then the spectrometer can be compact, but the sensitivity decreases
Solution Approach 1:
The patent resolves the aperture size conflict by transitioning from a single-dimension constraint to a two-dimensional optimization: a large aperture area (for sensitivity) combined with a shallow optical path depth (for compactness). The planar grating tilted at less than 45° enables this dimensional transition, allowing large aperture without increasing overall spectrometer volume.
4Reliability
If the optical grating is aligned at a large angle with respect to the normal, then the diffraction efficiency may improve, but the construction complexity and space requirement increase
Solution Approach 1:
The patent optimizes the grating angle parameter to be less than 45° (specifically 7.5°-15°), finding the optimal balance between diffraction efficiency and construction simplicity. This angular parameter optimization reduces the required space for light propagation while maintaining sufficient diffraction efficiency, thereby simplifying the overall construction.
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
The design achieves high sensitivity and compactness with reduced scattered light, enabling efficient electromagnetic radiation capture and analysis, while maintaining a simple and cost-effective construction.
Implementation Method 1
only a first order of diffraction or higher orders of diffraction of the electromagnetic radiation that is diffracted by the optical grating is/are directed onto the objective arrangement and the sensor element
Implementation Method 2
For focusing the incident electromagnetic radiation onto the sensor element, the objective arrangement is arranged between the optical grating and the sensor element
Data Source
AI summary
The invention relates to a spectrometer comprising a housing (11) equipped with a planar optical grating (2), which is arranged opposite an aperture (1) of the housing (11) and which is aligned at an angle of less than 45° to a normal of the aperture (1), a lens assembly (6), and a sensor element (7). The aperture (1) is dimensioned such that electromagnetic radiation incident parallel to the normal of the aperture (1) completely irradiates the surface of the optical grating (2). The lens assembly (6) is arranged between the optical grating (2) and the sensor element (7) in order to focus the electromagnetic radiation onto the sensor element (7) such that solely a first order of diffraction or higher orders of diffraction of the electromagnetic radiation diffracted by the optical grating (2) is directed towards the lens assembly (6) and the sensor element (7).