Optical Sensor Baffle Enclosure for Cross-Talk-Free Doppler Sensing
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Solution Overview
Problem
Optical cross-talk between optical receivers and transmitters in aircraft optical sensing systems can cause unwanted zero Doppler-shift components, biasing measurement results due to reflections from interface glass.
Innovation Solution
An optical sensor unit with a transmit baffle enclosure structure extending from transmit optics to a transmit interface window without open space, and a receive baffle structure, if present, to prevent reflections from reaching receive optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensors are used on aircraft to measure air data, then measurement accuracy is improved compared to traditional pitot-probes, but optical cross-talk from interface glass reflections causes unwanted zero Doppler-shift components that bias measurement results
Solution Approach 1:
A baffle structure is introduced as an intermediary element between the transmit and receive optics to block the direct optical path from the interface window to the receive optics. This baffle acts as a physical mediator that prevents harmful reflections from reaching the detector while allowing the desired scattered light from air molecules to reach the receive optics, thus eliminating the zero Doppler-shift component without affecting the measurement of actual air data
Solution Approach 2:
The harmful reflection path is extracted and separated from the desired optical measurement path by using the baffle structure to block only the direct reflection from the interface window. This allows the system to maintain the optical measurement capability for air data while removing the specific harmful component (interface glass reflections) that causes measurement bias
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
Mitigates optical cross-talk, ensuring accurate Doppler-shift measurements by preventing unwanted reflections, thereby enhancing measurement precision.
Implementation Method 1
The transmit optics are configured to direct a light beam from a light source to the transmit interface window, through the transmit baffle enclosure structure, for transmission of the light beam to an interrogation region outside of the vehicle
Implementation Method 2
The receive interface window and the set of receive optics are configured to receive and collect a scattered portion of the transmitted light beam from molecules and/or aerosol particles in the interrogation region
Implementation Method 3
The transmit baffle enclosure structure is configured to substantially prevent reflections of the light beam from the transmit interface window from reaching the receive optics
Data Source
AI summary
An optical sensor unit for a vehicle comprises transmit optics, a transmit interface window on the vehicle, and a transmit baffle enclosure structure located in an optical path between the transmit optics and the transmit interface window. The baffle enclosure structure extends from the transmit optics to the transmit interface window without any open space. The optical sensor unit also comprises a receive interface window on the vehicle, and a set of receive optics. The transmit optics directs a light beam from a light source to the transmit interface window, through the baffle enclosure structure, for transmission of the beam to an interrogation region outside the vehicle. The receive interface window and receive optics collect a scattered portion of the beam from molecules and/or aerosol particles in the interrogation region. The baffle enclosure structure prevents reflections of the beam from the transmit interface window from reaching the receive optics.