Spectroscopic Module Aperture Structure for Stray-Light Suppression
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Solution Overview
Problem
Improving the spectral accuracy of spectroscopic modules using Fabry-Perot interference filters is challenging due to issues with stray light and limited resolution.
Innovation Solution
The spectroscopic unit incorporates a Fabry-Perot interference filter with variable spacing between mirrors, along with apertures that control light incidence angles and suppress stray light by using tapered portions and precise positioning, enhancing the spectral accuracy and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Fabry-Perot interference filter is applied to improve spectral accuracy, then measurement precision is improved, but stray light increases and resolution deteriorates
Solution Approach 1:
The aperture is divided into multiple sections: a first aperture in the housing wall, a second aperture in the aperture member, and multiple tapered portions within the aperture member. This segmentation allows each section to perform a specific function in controlling light paths, thereby reducing stray light while maintaining spectral accuracy through the Fabry-Perot interference filter.
Solution Approach 2:
The aperture member acts as an intermediary component between the housing and the Fabry-Perot interference filter. It includes tapered portions that serve as light-guiding structures, mediating the light path from the first aperture to the second aperture, and preventing oblique incident light from reaching the filter as stray light.
2Measurement precision
If a Fabry-Perot interference filter is applied to improve spectral accuracy, then measurement precision is improved, but resolution deteriorates due to limited angular acceptance
Solution Approach 1:
The aperture member is designed with non-uniform structure: the first tapered portion has a larger cross-sectional area at the first aperture side, and the second tapered portion has a larger cross-sectional area at the second aperture side. This local quality variation allows the aperture to accept light from a wider angular range while the Fabry-Perot filter maintains its spectral resolution by selecting only the appropriate angles for interference.
3Device complexity
If simple aperture structures are used, then device complexity is reduced, but stray light increases and spectral accuracy deteriorates
Solution Approach 1:
The aperture member is designed with tapered portions that create dynamic light-guiding effects. The tapered geometry naturally guides light rays through total internal reflection, creating a dynamic optical path that adapts to different incident angles. This reduces stray light without requiring complex mechanical adjustments or additional active components.
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 solution effectively improves spectral accuracy and reduces stray light, leading to enhanced resolution and detection capabilities in spectroscopic analysis.
Implementation Method 1
a Fabry-Perot interference filter having a first mirror part and a second mirror part in which a distance therebetween is variable
Implementation Method 2
improving the spectral accuracy by the Fabry-Perot interference filter
Implementation Method 3
light incident on the second aperture at a large incident angle becoming stray light by being incident into the housing while being reflected by an inner surface of the second aperture can be suppressed
Data Source
AI summary
A spectroscopic unit includes a housing having a wall part formed with an opening, a first aperture part formed with a first aperture, and a second aperture part formed with a second aperture, in which a length of the second aperture in the facing direction is larger than a length of the first aperture in the facing direction, an outer edge of the first aperture is positioned inside each of an outer edge of the opening and an outer edge of the second aperture, and the first aperture includes at least one of a first tapered portion reaching a first surface of the first aperture part and extending toward the first surface, and a second tapered portion reaching a second surface of the first aperture part and extending toward the second surface.