Optoelectronic Filter Stack for Stray Light Suppression
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Solution Overview
Problem
Existing optoelectronic apparatuses face challenges in achieving high signal-to-noise ratios and minimizing stray light interference, particularly in spectroscopic applications with low light signals and varying angles of incidence, which affect measurement accuracy.
Innovation Solution
An optoelectronic apparatus is designed with a filter and material layers that have specific threshold wavelengths and high absorbance properties, combined with a darkened outer wall, to minimize unwanted light detection and reduce angle-dependent transmittance variations, enhancing signal-to-noise ratio and reducing stray light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a filter is used to maximize optical transmission in the wavelength range of interest, then signal transmission is improved, but stray light at other wavelengths is not sufficiently minimized
Solution Approach 1:
The optical filtering function is segmented into multiple independent layers: a dielectric filter layer for wavelength selection and an absorbing material layer for stray light absorption. Each layer performs a specific function, and their combination achieves superior overall filtering performance compared to a single filter layer.
Solution Approach 2:
The patent combines different materials with complementary optical properties: a dielectric filter material with high wavelength selectivity and an absorbing material (such as black paint or carbon-based material) with broad-spectrum light absorption. This composite structure achieves both high transmission in the passband and strong rejection in the stopband.
2Measurement precision
If conventional filters are used, then wavelength selection is achieved, but angle-dependent transmittance variations affect measurement accuracy
Solution Approach 1:
The absorbing material layer acts as an intermediary between the dielectric filter and the detector. It absorbs stray light that reflects off the dielectric filter at oblique angles, preventing this light from reaching the detector and thus eliminating the angle-dependent artifacts that would otherwise degrade measurement accuracy.
3Measurement precision
If high-performance filtering is implemented, then signal-to-noise ratio is improved, but device complexity increases
Solution Approach 1:
The patent uses materials with distinct optical absorption characteristics - the dielectric filter with its wavelength-dependent transmission (appearing colored or transparent at specific wavelengths) and the absorbing material with broad-spectrum absorption (appearing black or dark). This approach achieves high performance filtering using materials whose optical properties are defined by their absorption characteristics rather than complex structural arrangements.
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 apparatus achieves improved signal-to-noise ratio and reduced stray light interference, ensuring accurate measurements across a wide range of angles and wavelengths, suitable for miniaturized consumer applications.
Implementation Method 1
The filter has a first threshold wavelength separating a first wavelength region from an adjacent second wavelength region. Furthermore, the filter has a lower transmittance for light at wavelengths in the first wavelength region than for light at wavelengths in the second wavelength region.
Implementation Method 2
The first material layer is configured to have a higher absorbance for light at wavelengths in a third wavelength region than for light at wavelengths in an adjacent fourth wavelength region.
Implementation Method 3
an optoelectronic apparatus comprises a light detector having a bottom side, an upper side and at least one sidewall
Data Source
AI summary
In an embodiment an optoelectronic apparatus includes a light detector having a bottom side, an upper side and at least one sidewall that extends between the upper side and the bottom side, a carrier having an upper surface on which the light detector is arranged such that the bottom side faces the carrier, at least one outer wall which is arranged on the surface of the carrier, the outer wall and the carrier forming a cavity with an opening in which the light detector resides, a filter covering the upper side of the light detector, the filter having a first threshold wavelength separating a first wavelength region from an adjacent second wavelength region, wherein the filter has a lower transmittance for light at wavelengths in the first wavelength region than for light at wavelengths in the second wavelength region and a first material layer covering the filter.