Wavelength Selective Mirror for Optical Sensor Crosstalk Reduction
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Solution Overview
Problem
Optical crosstalk in proximity sensors due to the close proximity of emitting and detecting devices through a common aperture leads to reduced detection range and performance, and is aesthetically undesirable as the optoelectronic devices are visible to the user.
Innovation Solution
An optical sensor arrangement with a wavelength selective mirror placed between the optoelectronic device and the aperture, which directs only specific wavelengths (e.g., infrared radiation) through the aperture while reflecting or preventing visible light from reaching the optoelectronic device, thereby disguising the aperture and optoelectronic devices from an observer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common aperture is used for both emitting and detecting devices, then the device complexity is reduced, but optical crosstalk increases and detection performance deteriorates
Solution Approach 1:
The aperture is segmented into wavelength-specific transmission zones. The cover arrangement includes a first aperture for infrared radiation and a second aperture for visible light, allowing spatial separation of optical paths while maintaining a unified structural design. This reduces optical crosstalk between emitting and detecting devices while preserving structural simplicity.
Solution Approach 2:
A reflective arrangement acts as an intermediary optical element between the emitting and detecting devices. This mirror or reflective surface redirects infrared radiation from the emitting device to the detecting device through the aperture, enabling functional separation without physical separation of components, thus reducing optical crosstalk while maintaining compact structure.
2Volume of moving object
If the optoelectronic devices are positioned close to each other through a common aperture, then the device size is reduced, but optical crosstalk increases and detection range decreases
Solution Approach 1:
The optical paths are separated in angular/directional space rather than linear space. The reflective arrangement directs infrared radiation along a specific angular path from the emitting device to the detecting device, allowing close positioning of components while maintaining sufficient optical path separation to reduce crosstalk and preserve detection range.
Solution Approach 2:
The reflective arrangement serves as an intermediary that enables long detection range despite compact component positioning. By redirecting infrared radiation through the aperture at optimized angles, the reflective arrangement allows the detecting device to receive signals from distant objects even when positioned close to the emitting device.
3Device complexity
If the aperture and optoelectronic devices are made visible, then the optical path is simplified, but cosmetic appearance deteriorates
Solution Approach 1:
The cover arrangement includes a translucent or transparent cover layer with printed patterns or coloration that visually camouflages the aperture and optoelectronic devices. The printed information or decorative patterns on the cover arrangement hide the underlying optical components and aperture from user view, improving cosmetic appearance while maintaining optical functionality through the translucent/transparent cover material.
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
This configuration reduces optical crosstalk and enhances detection range while making the optoelectronic devices and apertures invisible to the user, addressing both performance and cosmetic concerns.
Implementation Method 1
The mirror arrangement comprises a wavelength selective mirror, in particular a hot or a cold mirror, having a passband and a stopband and being arranged to direct only electromagnetic radiation with certain wavelengths, in particular infrared radiation, from the optoelectronic device to the aperture and vice versa
Implementation Method 2
The passband includes a first wavelength range including the first wavelength, while the stopband includes a second wavelength range corresponding to visible light
Data Source
AI summary
An optical sensor arrangement comprises an optoelectronic device covered by a cover arrangement and being configured to emit or detect at least electromagnetic radiation with a first wavelength through an aperture of the cover arrangement. The optical sensor arrangement further comprises a mirror arrangement arranged between the optoelectronic device and the aperture and comprising a wavelength selective mirror with a passband and a stopband. The passband includes a first wavelength range including the first wavelength, the stopband includes a second wavelength range corresponding to visible light or vice versa.