Fiber-Optic Pyrometry for Broad-Range Non-Contact Temperature Sensing
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Solution Overview
Problem
Existing temperature measurement systems, such as thermocouples, face challenges in maintaining bond integrity and managing wiring harnesses during high dynamic loads and extreme temperatures, leading to assembly difficulties and potential damage, especially in spacecraft applications.
Innovation Solution
A non-contact temperature measurement system using a multimode fiber optic cable with a fixture and optical detector to collect and convert radiant energy into a single-order-magnitude electrical signal, eliminating the need for bonding and reducing the risk of damage from high temperatures and dynamic loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermocouples are bonded to surface regions of vehicle structure, then temperature measurement is achieved, but bond integrity becomes difficult to maintain under extreme temperatures and high dynamic loads
Solution Approach 1:
The patent replaces the mechanical bonding system (thermocouples bonded to surface) with an optical measurement system (pyrometric sensors that measure radiant energy). This substitution eliminates the need for physical attachment, thereby resolving the bond integrity issue while maintaining temperature measurement capability through non-contact radiant energy detection.
Solution Approach 2:
The patent introduces radiant energy as an intermediary medium between the temperature measurement system and the vehicle structure. Instead of direct contact measurement, the system measures the radiant energy emitted by the structure, which carries temperature information without requiring physical contact or bonding.
2Ease of manufacture
If wiring harnesses are run along the inside of aeroshell, then thermocouples can be coupled to electronics, but assembly becomes challenging and wiring harnesses are subject to EMI and potential damage
Solution Approach 1:
The patent replaces the electrical wiring harness system with an optical fiber system. Optical fibers transmit measurement data without requiring complex wiring connections, eliminating EMI susceptibility and simplifying assembly. The optical fibers can be routed more easily and do not present the same vulnerability to electromagnetic interference or connection failures.
3Measurement precision
If thermocouples are used for temperature measurement, then temperature data can be obtained, but the system is vulnerable to damage from high temperatures and dynamic loads
Solution Approach 1:
The patent uses radiant energy as an intermediary to transfer temperature information from the vehicle structure to the measurement system. The pyrometric sensors measure the radiant energy emitted by the structure, allowing temperature data acquisition without exposing the sensors to the extreme thermal and mechanical environment that would damage conventional thermocouples.
Solution Approach 2:
The patent substitutes contact-based thermocouple measurement with non-contact pyrometric measurement. This replacement enables temperature data acquisition in high-temperature and high-dynamic-load environments without subjecting the measurement system to damaging physical conditions.
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
Provides reliable temperature measurements over a broad range without the need for bonding and wiring, simplifying assembly and reducing the risk of damage, while being compatible with modern spacecraft designs.
Implementation Method 1
An optical detector, coupled to the second end of the fiber optic cable, converts the radiant energy to a first electrical signal indicative thereof
Implementation Method 2
The radiant energy emanating from the object is collected at the fiber optic cable's first end and is transmitted to its second end
Implementation Method 3
The radiant energy emanating from the object is collected at the fiber optic cable's first end
Data Source
AI summary
A temperature measurement system includes a multimode fiber optic cable having a first end and a second end. A fixture positions the first end in non-contact proximity to a refractory-material object configured to experience temperatures in a temperature range from ambient atmospheric temperature to approximately 3300° K. The radiant energy emanating from the object is collected at the fiber optic cable's first end and is transmitted to its second end. An optical detector, coupled to the second end of the fiber optic cable, converts the radiant energy to a first electrical signal having an amplitude spanning multiple orders of magnitude. A logarithmic converter coupled to the optical detector compresses the first electrical signal to generate a second electrical signal having an amplitude spanning a single order of magnitude.