VCSEL Optical Proximity Sensing for Non-Metal Targets in Space
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Solution Overview
Problem
Existing proximity sensors, such as inductive, capacitive, and magnetic sensors, are ineffective in detecting non-metallic or non-magnetic objects in space environments due to their reliance on specific materials or fields, limiting their applicability in terrestrial applications.
Innovation Solution
An optical proximity sensor system utilizing a vertical-cavity surface-emitting laser (VCSEL) that generates an optical beam with linear polarization, forming an external optical cavity with a target object, where the polarization switching frequency is used to determine distance, enabling effective detection in space environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inductive proximity sensors are used to detect metallic objects, then detection capability for metallic objects is improved, but applicability is limited to metallic objects only
Solution Approach 1:
The patent applies universality by developing an optical proximity sensor that can detect both metallic and non-metallic objects using the same device. The sensor uses optical radiation instead of electromagnetic induction, enabling it to detect objects regardless of their electrical conductivity properties, thus achieving multi-functionality across different object types.
Solution Approach 2:
The patent replaces the electromagnetic induction mechanism with an optical detection mechanism. Instead of using electromagnetic fields to detect metallic objects, the system uses optical radiation that reflects off the target object's surface, substituting the detection principle to overcome material limitations.
2Measurement precision
If capacitive proximity sensors are used for non-metallic object detection, then detection capability for non-metallic objects is improved, but effectiveness in space environment is lost
Solution Approach 1:
The patent replaces the capacitive sensing mechanism that relies on dielectric properties with an optical detection system. The optical sensor measures the round-trip time of optical radiation, which does not depend on the presence of a dielectric medium, making it reliable in space environments where vacuum conditions eliminate the air gap required for capacitive sensing.
Solution Approach 2:
The patent changes the detection parameter from electrical capacitance (which requires a dielectric) to optical time-of-flight measurement. This parameter change allows the sensor to function in vacuum conditions by measuring the speed of light in different media, including vacuum, without requiring atmospheric presence.
3Measurement precision
If magnetic proximity sensors are used to detect magnetic objects, then detection capability for magnetic objects is improved, but applicability is limited to magnetic objects only
Solution Approach 1:
The patent replaces magnetic field detection with optical radiation detection. Instead of sensing magnetic fields generated by magnetic objects, the system uses optical radiation that reflects from any object surface, substituting the detection mechanism to achieve universal applicability across magnetic and non-magnetic objects.
Solution Approach 2:
The patent achieves universality by creating a single optical sensor system that can detect all types of objects regardless of their magnetic properties. The optical time-of-flight measurement principle works with any object that reflects or interacts with optical radiation, making the sensor universally applicable.
4Adaptability or versatility
If optical proximity sensor system is used in space environment, then versatility for detecting all object types is improved, but signal-to-noise ratio may be reduced
Solution Approach 1:
The patent introduces a collimating lens as an intermediary optical element in the detection path. The lens collects and directs optical radiation that has traveled through the vacuum of space, improving the concentration and quality of the returned signal at the detector, thereby maintaining signal-to-noise ratio despite the challenging space environment.
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 optical proximity sensor system effectively calculates the distance to a target object in space environments, providing a non-contact, reliable method for positioning or coupling objects without damaging them, and enhances the signal-to-noise ratio with a collimating lens for extended range.
Implementation Method 1
a laser, which could be configured as a vertical-cavity surface-emitting laser (VCSEL), that is configured to generate an optical beam
Implementation Method 2
The target object can correspond to that to which proximity is being measured as a function of distance... the reflected optical beam can thus stimulate the gain region of the laser to periodically oscillate between emitting the optical beam at the first linear polarization and the second linear polarization
Implementation Method 3
enhances the signal-to-noise ratio with a collimating lens for extended range
Data Source
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AI summary
An optical proximity sensor system to detect a distance to a target object is provided. The optical proximity sensor system includes a laser that generates an emitted optical beam at a linear polarization and an optical cavity system that includes an optical cavity defined by a distance between the laser and the target object. The target object reflects the emitted optical beam to generate a reflected optical beam. A partially reflective mirror diverts a portion of the emitted optical beam and/or the reflected optical beam. A photodetector receives the diverted optical beam and generates a proximity signal that has a frequency that is indicative of the distance to the target object based on the diverted portion of the at least one of the emitted optical beam and the reflected optical beam. A proximity processor calculates the distance to the target object based on the frequency of the proximity signal.