Optical Sensor Interrogation via Electrical Frequency Measurement
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Solution Overview
Problem
Current optical sensor interrogation systems based on wavelength encoding struggle to achieve high data decoding rates, typically limited to 10 to 1000 Hz, while applications such as control systems and structural health monitoring require rates up to tens of Megahertz, without increasing cost or complexity.
Innovation Solution
An optical sensor interrogation system utilizing a multi-frequency optical source, a photodetector to generate an electrical difference frequency signal from a reference and sensor data signal, and an electrical frequency measurement module, which includes narrow band filters or high bandwidth components to measure the difference frequency, enabling direct conversion and processing in the electrical domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical spectrum analyzer methods are used to interrogate optical sensors, then wavelength decoding can be achieved, but the data decoding rate is limited to 10 to 1000 Hz
Solution Approach 1:
The patent replaces the mechanical/optical scanning system (tunable optical filter sweeping through wavelengths) with an electrical domain system. The photodetector converts optical wavelength information directly into electrical frequency signals, which are then processed electronically to determine wavelength. This substitution enables much higher decoding rates (tens of MHz) compared to the mechanical scanning limitation.
Solution Approach 2:
The patent transforms the measurement parameter from direct optical wavelength detection to electrical frequency measurement. By converting the optical signal into an electrical signal whose frequency corresponds to the wavelength, the system can leverage high-speed electrical measurement techniques to achieve faster decoding rates while maintaining wavelength measurement accuracy.
2Measurement precision
If optical spectrum analyzers with tunable filters are used, then wavelength measurement is possible, but the system complexity and cost increase
Solution Approach 1:
The patent eliminates the need for complex optical spectrum analyzers, tunable optical filters, and spatially dispersed optical components by replacing them with a simple photodetector and electrical signal processing system. This dramatically reduces system complexity and cost while maintaining wavelength measurement capability through the electrical frequency measurement approach.
Solution Approach 2:
The patent extracts only the essential function needed for wavelength measurement - converting optical wavelength information into a measurable form - and implements it through a minimal component set (photodetector + electrical frequency meter), removing all the unnecessary complex optical components that would otherwise be required.
3Productivity
If spatial dispersion methods with arrays of photodetectors are used, then parallel wavelength detection is achieved, but the system complexity and cost increase
Solution Approach 1:
The patent makes a single photodetector perform the function that would otherwise require an entire array of photodetectors. By encoding wavelength information into the frequency domain of a single electrical signal, one photodetector can measure all wavelength information sequentially through frequency analysis, eliminating the need for multiple detectors and their associated optical routing complexity.
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 approach allows for higher data decoding rates, achieving frequencies in the Megahertz range without increased complexity or cost, and enables direct detection of the difference frequency in the electrical domain, overcoming limitations of conventional systems.
Implementation Method 1
a photodetector configured to detect a reference signal and the optical sensor data signal and generate an electrical difference frequency signal
Data Source
AI summary
An optical sensor interrogation system comprises: a multi-frequency optical source configured to generate an optical interrogation signal, at least one optical sensor configured to filter light at a wavelength corresponding to a value of a sensed parameter and generate an optical sensor data signal, a photodetector configured to detect a reference signal and the optical sensor data signal and generate an electrical difference frequency signal corresponding to a wavelength difference between the reference signal and the optical sensor data signal, and an electrical frequency measurement module configured to measure the electrical difference frequency.