Fiber Optic Temperature Probe for RF Noise Immunity
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Solution Overview
Problem
Existing temperature sensors like thermocouples and thermistors are prone to noise and safety hazards in RF environments, requiring redundant systems to ensure accurate temperature measurement in applications like plasma deposition processes, which increases complexity and cost.
Innovation Solution
A fiber optic temperature sensing system with a phosphor or GaAs based fiber optic sensor as a primary sensor, accompanied by a secondary redundant sensor, using solid-state electronics to generate outputs mimicking thermocouple or thermistor signals, thereby providing accurate feedback without additional control system changes and meeting safety standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermocouples or thermistors are used as temperature sensors in RF environments, then they can provide temperature feedback for control systems, but they act as antennas that pick up electrical noise and RF interference, resulting in noisy and inaccurate signals
Solution Approach 1:
The patent replaces electrical temperature sensing systems (thermocouples, thermistors) with an optical sensing system using fiber optic cables and phosphor materials. The optical system is immune to electrical noise and RF interference, eliminating the antenna effect while maintaining temperature measurement capability through photodetector-based detection of phosphor luminescence decay
Solution Approach 2:
The patent introduces phosphor material as an intermediary between the temperature sensing point and the detection system. The phosphor converts temperature information into luminescence decay characteristics, which are then detected by photodetectors. This intermediary approach allows accurate temperature sensing in electrical environments by converting the measurement to the optical domain
2Reliability
If redundant temperature sensors are implemented to meet safety standards, then safety specifications for over-temperature conditions are satisfied, but the system complexity and cost increase
Solution Approach 1:
The patent makes the fiber optic temperature sensor system universally applicable to both primary control functions and safety-critical monitoring functions. A single optical sensor can serve dual purposes: providing temperature feedback for closed-loop control and simultaneously providing redundant safety monitoring, eliminating the need for separate electrical sensor channels for each function
Solution Approach 2:
The patent changes the fundamental measurement parameter from electrical signals (voltage, resistance) to optical parameters (luminescence intensity, decay time). This parameter change allows the same sensor to be used for both control and safety functions without the electrical noise and interference issues that previously required separate redundant electrical sensor channels
3Measurement precision
If fiber optic sensors are used for temperature measurement, then they are immune to electrical noise and provide accurate readings, but they require safety-rated software or solid-state electronics to meet applicable safety standards
Solution Approach 1:
The patent employs simple, robust solid-state electronic components for signal processing that do not require complex safety-rated software or sophisticated processing systems. The approach uses basic photodetectors and simple decay-time measurement circuitry that are inherently reliable and easier to certify for safety applications, replacing the need for complex programmable safety systems
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 ensures accurate temperature measurement in noisy electrical environments, reduces safety hazards, and simplifies compliance with safety standards by using optical sensors that are less susceptible to electrical noise, while maintaining redundancy for critical temperature control.
Implementation Method 1
a phosphor based fiber optic sensor as a primary temperature sensor for reading a temperature of a measured object
Implementation Method 2
The signal fluctuates according to a decay rate responsive to the temperature
Implementation Method 3
The fiber optic technology may be used in conjunction with a secondary sensor to provide measurements for over temperature conditions
Data Source
AI summary
An optical temperature sensing system is disclosed which includes a fiber optic sensor as a primary temperature sensor for reading a temperature of a measured object or a measured environment. The temperature probe is coupled to a converter which generates using solid-state electronic components without software, a temperature output. A temperature sensing system is also disclosed that includes a temperature sensor for reading a temperature of a measured object, and a dual converter module comprising a first converter to provide a primary temperature sensor signal, and a second converter to generate a secondary temperature sensor signal from a signal provided by the first converter. An optical temperature sensor is also described, with a conversion module that generates an output that mimics the output of a thermistor or a thermocouple.