Optical Detector with Linear Variable Filtering for Stray-Light Reduction
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Solution Overview
Problem
Spectroscopic measurement devices face issues with stray light due to multiple reflections of light inside or between filter members and optical detectors, which affect the accuracy of spectral data generation.
Innovation Solution
An optical detector with a window containing a light transmitting member and a linear variable filter coat on one surface, allowing only the predetermined order of light to transmit, suppressing stray light and multiple reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a filter member is disposed at an upstream side of the optical detector to remove higher-order light, then the predetermined order of light can be detected, but stray light increases due to multiple reflections inside the filter member or between the filter member and the window
Solution Approach 1:
The patent applies local quality by making the filter coat's transmitted wavelength position variable along the dispersion direction. Different regions of the filter coat have different transmitted wavelengths, allowing each wavelength component to be filtered locally without requiring a separate filter member for each wavelength, thereby reducing multiple reflections while maintaining detection accuracy.
Solution Approach 2:
The patent changes the parameter of transmitted wavelength from a fixed value to a variable value that changes along the dispersion direction. This allows the filter characteristic to adapt to different wavelength components of light, enabling effective suppression of higher-order light across the entire spectral range without introducing additional reflection interfaces.
2Measurement precision
If filter coats are formed on both the light incident surface and light exit surface to block higher-order light, then filtering effectiveness improves, but multiple reflections increase between the two filter coats
Solution Approach 1:
The patent extracts the filtering function from a dual-filter-coat structure and concentrates it into a single linear variable filter coat. By removing one of the two filter coats and replacing it with a variable wavelength filter, the patent eliminates the reflection interface between two fixed-wavelength filter coats while maintaining comprehensive filtering effectiveness across all wavelengths.
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 detects the predetermined order of light, reducing stray light and enhancing the S/N ratio of spectral data by blocking higher-order light, thus improving data accuracy.
Implementation Method 1
a linear variable filter coat formed on one of the light incident surface and the light exit surface, and having a transmitted wavelength changing along the predetermined direction
Implementation Method 2
there is concern that stray light may increase due to multiple reflections of light to be measured inside the filter member or between the filter member and a window of the optical detector
Data Source
AI summary
An optical detector detects primary light in light to be measured dispersed in an X-axis direction. The optical detector includes a package having an opening, a window closing the opening and allowing the predetermined order of light to transmit, and a light detection element disposed inside the package, including a light receiving region facing the window, and configured to detect the predetermined order of light. The light receiving region includes a plurality of light detection channels arranged in the X-axis direction. The window includes a light transmitting member having a light incident surface and a light exit surface, and a linear variable filter coat formed on one of the light incident surface and the light exit surface, and having a transmitted wavelength changing along the X-axis direction.