Spectrograph Housing Alignment and Stray-Light Reduction
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Solution Overview
Problem
Existing spectrographs require sophisticated active alignment, such as mounting a diffraction element on an adjustable mount and orientation under a microscope, which is time-consuming and prone to misalignment.
Innovation Solution
A spectrograph design with a housing that includes projections and openings to fix the orientation of the dispersive element relative to the entrance slit, using complementary dimensional parameters and tolerance parameters to ensure precise alignment, and a detector with separate light-sensitive regions to minimize stray light and redundant alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dispersive element is mounted on an adjustable mount for alignment, then the orientation precision can be improved, but the device complexity and alignment time increase
Solution Approach 1:
The housing is pre-configured with projections and openings during manufacturing, establishing the precise geometric relationship between the dispersive element mounting position and the optical axis before the dispersive element is installed. This preliminary action eliminates the need for complex post-assembly alignment procedures.
Solution Approach 2:
The complementary dimensional parameters and tolerance parameters of the projections and dispersive element contour create a self-aligning mechanism. When the dispersive element is inserted, the geometry automatically ensures proper orientation relative to the optical axis without requiring external alignment tools or procedures.
2Manufacturing precision
If active alignment procedures are performed under a microscope, then the alignment precision is improved, but the alignment time and operational complexity increase
Solution Approach 1:
The geometric relationship between the entrance slit and dispersive element is predetermined during housing manufacturing through the configuration of projections and openings. This eliminates the need for time-consuming alignment procedures under a microscope, as the components are pre-positioned to work together correctly.
Solution Approach 2:
The patent replaces complex mechanical alignment procedures (requiring microscopes and manual adjustment) with a geometric constraint system built into the housing. The complementary dimensional parameters and tolerance parameters create an automatic mechanical guidance system that ensures proper alignment without requiring optical measurement tools.
3Ease of manufacture
If the housing interior is left with standard reflective surfaces, then manufacturing simplicity is maintained, but stray light increases reducing measurement quality
Solution Approach 1:
The housing interior is treated with a selectively applied black, non-reflective coating on specific surfaces where stray light would be generated, while other surfaces maintain their standard finish. This localized treatment reduces stray light only where necessary without requiring complete repainting or treatment of the entire housing interior.
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
Enhances light energy in desired spectral ranges, reduces stray light, and minimizes the need for redundant alignment, resulting in improved overall performance and focused light measurement.
Implementation Method 1
a dispersive element located at the second opening and configured to receive light from the entrance slit along the first portion of the light path and direct light along a second portion of the light path
Implementation Method 2
The interior of the housing is coated with a black, non-reflective material to minimize stray light
Implementation Method 3
a detector located at the third opening and configured to receive light from the dispersive element along the second portion of the light path
Data Source
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AI summary
A spectrograph (100) as disclosed includes a housing (102), wherein a wall (104) of the housing includes first, second and third openings (106, 108, 110), an entrance slit (112) located at the first opening (106) and configured to direct light along a first light path portion (LP1) in the interior of the housing, a dispersive element (114) located at the second opening (108) and configured to receive light from the entrance slit along the first light path portion and direct light along a second light path portion (LP2) in the interior of the housing, a detector (116) located at the third opening (110) and configured to receive light from the dispersive element along the second light path portion. The detector can include first and second groups of light-sensitive regions (118, 120). A cover (105) can be positioned to separate the first group of light-sensitive regions from the light path, the second group of light-sensitive regions being exposed to the light path.