Terahertz Wall Thickness Measurement Using Dual-Frequency Segmentation
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Solution Overview
Problem
Existing methods for determining the wall thickness of flat or elongated objects using terahertz radiation are costly and complex, particularly when measuring thin walls or objects in motion, due to signal interference, limited bandwidth, and high absorption, which complicates unambiguous frequency determination.
Innovation Solution
A method using two terahertz transmitters and receivers operating at different frequencies to determine periodic reference curves, comparing these curves with the signal curves from both receivers to identify the best matching curve, allowing for unambiguous wall thickness determination using relatively simple and cost-effective devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the bandwidth of the terahertz radiation is increased to enable clear frequency determination, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent divides the measurement task into two separate measuring devices, each operating in different frequency ranges with limited bandwidth. The first device operates in a lower frequency range and the second in a higher frequency range. By segmenting the measurement process across multiple devices with narrower bandwidths, the patent avoids the need for a single complex high-bandwidth device while achieving accurate wall thickness determination through combined evaluation of both measurements.
2Adaptability or versatility
If the center frequency is increased to achieve higher bandwidth, then measurement range is improved, but absorption increases and measurement reliability deteriorates
Solution Approach 1:
The patent segments the frequency range into two separate measurement ranges: a first lower frequency range and a second higher frequency range. Each measuring device operates in its optimized frequency range with appropriate bandwidth. This segmentation allows the system to achieve versatile measurement capability across different wall thicknesses while maintaining reliability in each frequency band, as each device can be optimized for its specific range without suffering from the absorption problems of higher frequencies.
Solution Approach 2:
The patent changes the frequency parameter by using two different center frequencies for the two measuring devices. The first device uses a lower center frequency suitable for certain measurement conditions, while the second device uses a higher center frequency for other conditions. This parameter change allows the system to adapt to different measurement requirements while avoiding the absorption issues that would occur if a single high-frequency device were used throughout.
3Measurement precision
If a single high-bandwidth device is used, then measurement precision is improved, but cost increases significantly
Solution Approach 1:
The patent segments the measurement function into two separate devices, each with moderate bandwidth requirements. Instead of requiring one expensive high-bandwidth device, the system uses two less expensive devices with narrower bandwidths that operate in different frequency ranges. The combined information from both devices achieves the same measurement precision as a single high-bandwidth device would provide, but at lower individual device costs.
4Device complexity
If the bandwidth is limited, then device complexity is reduced, but the ability to determine unambiguous frequency is worsened
Solution Approach 1:
The patent segments the frequency determination task across two devices with limited bandwidths. The first device provides frequency information in a lower range and the second device provides frequency information in a higher range. By combining the measurements from both devices, the system achieves unambiguous frequency determination without requiring either individual device to have large bandwidth, thus maintaining low device complexity while achieving high measurement precision.
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
Enables clear and cost-effective measurement of thin wall thicknesses in moving objects by simplifying the evaluation process and reducing device complexity, while being less sensitive to measurement deviations.
Implementation Method 1
the first receiver receives terahertz radiation reflected from boundary surfaces of the object and emitted by the first transmitter
Implementation Method 2
the second receiver receives terahertz radiation reflected from boundary surfaces of the object and emitted by the second transmitter
Implementation Method 3
higher frequencies of terahertz radiation lead to increased absorption of the radiation signal in many materials
Data Source
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AI summary
The invention relates to a device for determining the wall thickness of a particularly flat or elongated object, comprising a first measuring device comprising a first terahertz radiation transmitter and a first terahertz radiation receiver, and comprising a second measuring device comprising a second terahertz radiation transmitter and a second terahertz radiation receiver, wherein the first measuring device is arranged such that the first transmitter emits terahertz radiation onto the object and the first receiver receives terahertz radiation emitted by the first transmitter that is reflected from interfaces of the object, and wherein the second measuring device is arranged such that the second transmitter emits terahertz radiation onto the object and the second receiver receives terahertz radiation emitted by the second transmitter that is reflected from interfaces of the object, and comprising an evaluation device.where the measured values of the first and second receivers are applied for determining the wall thickness of the object, wherein the first transmitter emits terahertz radiation in a first frequency range with a first bandwidth around a first center frequency and the second transmitter emits terahertz radiation in a second frequency range with a second bandwidth around a second center frequency different from the first center frequency, and wherein the evaluation device is configured to determine several periodic reference waveforms approximating a signal waveform of the measured values of the first receiver, to compare the determined periodic reference waveforms with a signal waveform of the measured values of the second receiver and to identify the periodic reference waveform that best corresponds to the signal waveform of the measured values of the second receiver, and wherein the evaluation device is further configured toThe invention relates to the determination of the wall thickness of the object based on the identified reference curve. It also relates to a corresponding method.