Optical Sensor Interrogation System Diffractive Element
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Solution Overview
Problem
Current optical sensor interrogation systems are limited by high costs, limited bandwidth, and sensitivity to distance variations between sensors and interrogators, making them inefficient for remote deployments and requiring extensive calibration.
Innovation Solution
An optical sensor interrogation system utilizing a diffractive optical element and data processing to determine wavelengths with high accuracy, independent of distance variations, featuring a scanning assembly with a rotating mirror and a data processor that calculates wavelengths using diffraction conditions and detector data, allowing for efficient and fast signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a narrow-band scanning source is used to determine the optical path length, then the wavelength can be determined with high precision, but the system becomes sensitive to distance variations between the interrogator and remote sensors
Solution Approach 1:
The patent introduces a reference fiber Bragg grating as an intermediary element to establish a reference wavelength that is independent of distance variations. This reference grating serves as a mediator between the scanning source and the measurement process, providing a stable reference point that compensates for path length differences and enables accurate wavelength determination of remote sensors regardless of their distance from the interrogator.
2Measurement precision
If high accuracy electronics are used to control the sweep, then the relation between time and wavelength is well-defined, but the system cost increases significantly
Solution Approach 1:
The patent replaces complex electronic control systems with a mechanically simple rotating polygon mirror that has equally spaced facets. The mirror's rotation at a constant speed naturally provides the time-wavelength relationship through its geometric structure, eliminating the need for complex electronic control while maintaining accurate correlation between time and wavelength. The facet spacing and rotation speed together define the wavelength scanning pattern.
Solution Approach 2:
The patent changes the control parameter from complex electronic signals to simple mechanical rotation parameters (rotation speed and facet spacing). By using a rotating polygon mirror with fixed geometric parameters, the system achieves well-defined time-wavelength relationships through physical constants rather than electronic control, simplifying the overall system while maintaining precision.
3Measurement precision
If a narrow bandwidth sweeping filter is used, then the wavelength can be scanned, but the bandwidth is limited to around 1000 Hz making it difficult to monitor dynamic sensor behavior
Solution Approach 1:
The patent employs a dynamically rotating polygon mirror instead of a static narrow-band filter. The rotation of the mirror allows the system to rapidly sweep through a broad wavelength range, effectively increasing the bandwidth available for monitoring dynamic sensor behavior. The constant rotation speed and equally spaced facets enable high-speed wavelength scanning that can capture fast-changing sensor responses while maintaining the precision of narrow-band measurement.
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 system enables accurate and efficient wavelength determination for optical sensors, reducing the need for precise angle measurements and allowing for higher interrogation frequencies, while minimizing the impact of distance variations and temperature fluctuations, thus enhancing the deployment of optical sensors in remote locations.
Implementation Method 1
a diffractive optical element and a scanning assembly, wherein the collimated light beam is directed at the diffractive optical element at different angles of incidence. The diffractive optical element diffracts the collimated light beam into a wavelength dependent spatial distribution of the light beam.
Implementation Method 2
a scanning assembly with a rotating mirror... The diffractive optical element and a scanning assembly, wherein the collimated light beam is directed at the diffractive optical element at different angles of incidence
Data Source
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AI summary
The invention relates to an optical sensor interrogation system (12) comprising a light source (1) arranged for emitting light; a first optical arrangement (2) arranged for intercepting said light and to forward the light to an optical sensor and to receive light therefrom, wherein the wavelength reference is adapted to provide the a reference wavelength; the system (12) further comprising a second optical arrangement (5) adapted to receive reflected light from the optical sensor (4), the system (12) still further comprising a lens system for transferring the light into a beam and a scanning assembly comprising a scanning unit (8) and/or a diffractive optical element (7), the system (12) still further comprising a detector for receiving optical response from the scanning assembly and a data processing system. The invention further relates to method of manufacturing an optical sensor interrogation system.