Terahertz Measurement Device with Adjustable Optical Axis
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Solution Overview
Problem
Terahertz measurements of layer thickness and distance in materials like plastic are hindered by the need for precise alignment of the measurement device, which is challenging, especially for soft materials and continuous production processes, leading to reduced signal strength and inaccurate results due to misalignment.
Innovation Solution
A terahertz measuring device with an adjustable optical axis that can be continuously or periodically adjusted within a range to ensure perpendicular incidence of radiation, allowing for precise alignment and maximum signal capture without requiring complex adjustments of the measurement object or intermediate stops, using mechanisms like angle adjustment motors or mirror arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measurement device is precisely aligned to the measurement object, then the signal strength and measurement precision are improved, but the positioning effort and device complexity increase significantly
Solution Approach 1:
The measurement device automatically determines its own optimal angular position by evaluating measurement signals from multiple angular positions. The system performs self-alignment through automated signal evaluation and angular position determination, eliminating the need for complex mechanical alignment mechanisms or manual positioning efforts.
2Manufacturing precision
If mechanical guides are used to ensure precise alignment, then the positioning accuracy is improved, but the device complexity and ease of operation deteriorate
Solution Approach 1:
The patent replaces mechanical alignment guides with an automated optical/electronic alignment system. Instead of using mechanical structures to physically guide and constrain the measurement device, the system uses terahertz radiation measurements and signal evaluation to automatically determine and achieve optimal alignment, significantly simplifying the mechanical structure and improving ease of operation.
3Reliability
If multiple measurements are taken at different angular positions, then the reliability of finding the optimal alignment is improved, but the measurement time and productivity decrease
Solution Approach 1:
The system performs periodic angular position adjustments and measurements within a defined angular range. By systematically varying the angular position in periodic steps and evaluating measurement signals at each position, the device reliably identifies the optimal alignment position while maintaining efficient periodic operation that balances thoroughness with measurement speed.
Solution Approach 2:
The measurement device performs preliminary angular position adjustments and measurements to determine the optimal alignment position before conducting the final production measurement. This preliminary action ensures that when the actual measurement is performed, the device is already optimally aligned, guaranteeing high reliability without requiring repeated measurements during production.
4Adaptability or versatility
If the optical axis is continuously adjusted during measurement, then the adaptability to misaligned objects is improved, but the device complexity increases
Solution Approach 1:
The measurement device incorporates dynamic angular adjustment capability that allows the optical axis to be continuously or periodically varied during the measurement process. This dynamic adjustment mechanism enables the device to adapt to objects at different angular positions by automatically finding and locking onto the optimal alignment position, providing high adaptability through controlled dynamic movement rather than complex static mechanisms.
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 reliable and precise terahertz measurements with high signal strength and minimal effort, allowing for continuous measurement during production without stopping the process, even for misaligned objects, by identifying the optimal angular position for maximum amplitude and using it directly for accurate layer thickness and distance determination.
Implementation Method 1
A portion of the incident terahertz radiation is reflected upon entering the material layer, and a portion of the terahertz radiation which has entered the material layer is reflected at a subsequent interface
Implementation Method 2
which has a significantly higher refractive index for the terahertz radiation compared to air or vacuum
Implementation Method 3
the optical axis of which can be adjusted and is adjusted during the measurement of the measurement object. In this case, the optical axis of the emitted terahertz radiation is adjusted continuously or periodically
Implementation Method 4
the time difference between the two measurement peaks can be evaluated as the transit time of the double crossing of the material layer
Data Source
Figure 1
Figure 2a~4c
Figure 5~6
AI summary
The invention relates to a method and a terahertz measuring apparatus for measuring a layer thickness and/or a distance, wherein at least one terahertz beam (7a) is radiated onto the measurement object (2) by a terahertz transmission and reception unit along an optical axis and reflected terahertz radiation that has passed through at least one layer (3) of the measurement object (2) is detected, wherein a measurement signal of the detected reflected terahertz radiation is evaluated and a layer thickness is ascertained from a propagation time difference for the radiation reflected at boundary surfaces (2a, 2b) of the layer (3). In this case, there is provision for multiple measurements to be performed using different optical axes, wherein the optical axis of the emitted terahertz radiation (7a) is adjusted during the measurements or between the measurements and one of the multiple measurements is used for ascertaining the layer thickness. Preferably, the optical axis is adjusted continuously and/or periodically within an adjustment angle range (a) and in the process the multiple measurements are recorded, the measurement therefrom with the maximum amplitude being used as the measurement for ascertaining the layer thickness.