Angled Cloud Sensor Layout for Solar-Resistant Icing Detection
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Solution Overview
Problem
Existing optical sensors for aircraft face challenges in detecting icing conditions from clouds while minimizing interference from ambient light, particularly due to the need for high-speed, sensitive electronics to detect short pulse width laser reflections.
Innovation Solution
The use of dual detectors with complementary tilt angles and a quad detector photodiode configuration, along with a detector mask to selectively polarize and obscure light, allows for cloud detection and phase discrimination while avoiding simultaneous solar interference, enabling the use of lower-cost lasers and electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If short pulse width lasers are used to detect cloud reflections for icing conditions, then detection sensitivity is improved, but the requirement for high-speed, sensitive electronics increases
Solution Approach 1:
The patent uses periodic modulation of the laser beam at a specific frequency (e.g., 1 kHz) and detects the reflected light at the same frequency using synchronous detection. This periodic action allows the system to use lower-speed electronics while maintaining high detection sensitivity, as the signal is concentrated at a known frequency that can be easily filtered and detected
Solution Approach 2:
The patent introduces an intermediary modulation frequency as a mediator between the laser source and detector. By modulating the laser at a specific frequency and detecting at that frequency, the system converts the detection problem into a frequency-domain problem that can be solved with simpler, lower-speed electronics while maintaining high sensitivity
2Measurement precision
If optical sensors are used to detect cloud icing conditions, then detection capability is improved, but interference from ambient light increases
Solution Approach 1:
The patent modulates the laser beam periodically and detects the reflected light at the same modulation frequency. This allows the system to distinguish the modulated laser signal from ambient light, which does not share the same frequency characteristics, thereby rejecting ambient light interference while maintaining cloud detection capability
Solution Approach 2:
The patent uses synchronous detection where the detector is driven by the same modulation signal that modulates the laser. This feedback mechanism allows the system to selectively amplify signals at the modulation frequency while rejecting signals at other frequencies, effectively filtering out ambient light interference
3Measurement precision
If high-speed, sensitive electronics are used to detect short pulse width laser reflections, then detection sensitivity is improved, but system cost increases
Solution Approach 1:
The patent uses periodic modulation at a known frequency and synchronous detection, which allows the use of lower-speed, less expensive electronics while maintaining high detection sensitivity. The periodic nature of the signal allows for simple frequency-selective filtering and detection
Solution Approach 2:
The patent replaces expensive, high-speed electronics with cheaper, lower-speed electronics that can still achieve the same detection sensitivity through frequency-based signal processing. The system trades hardware complexity for signal processing simplicity
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 solution effectively reduces the risk of solar interference, allows for cloud detection and phase determination without high-speed electronics, and enables the use of lower-cost components, improving the efficiency and cost-effectiveness of cloud sensing systems.
Implementation Method 1
The first detector is configured to detect light reflected from an illumination volume and to generate a first detector signal that corresponds to a first intensity of detected light
Implementation Method 2
A detector mask and various detector masks can be used to compensate for constraints on tilt angle ranges by allowing for cloud detection and/or cloud phase discrimination while still preventing simultaneous solar interference
Data Source
AI summary
An optical sensor for an aircraft includes two detectors, a light source, and a controller. The detectors are oriented along detector paths and have tilt angles and fields of view. The detectors are configured to detect light reflected from an illumination volume and to generate detector signals that correspond to intensities of detected light. The tilt angles are equal such that each detector is oriented in an opposite direction within a plane containing a light source path and the detector paths. The light source is oriented along the light source path and is configured to illuminate the illumination volume which overlaps with the fields of view within a predetermined distance range. The controller is configured to receive the detector signals, detect whether a cloud is present based upon the detector signals, determine a cloud phase, and calculate a density of the detected cloud.