Terahertz Inspection Estimating Device Boundary Position Accuracy
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Solution Overview
Problem
Terahertz wave inspection apparatuses struggle to accurately estimate the position of boundary surfaces in laminated samples when the amplitude of the pulse waveform corresponding to the reflected wave from the boundary surface is small, leading to potential burial in noise and reduced estimation accuracy.
Innovation Solution
The apparatus employs an estimating device that uses a second boundary surface pulse wave, which is farther from the outer surface, to estimate the position of the first boundary surface without relying on the first boundary surface pulse wave, utilizing a library of estimated waveforms to improve clarity and similarity degrees for accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the first boundary surface pulse wave is used to estimate the position of the first boundary surface, then the estimation can be performed using the direct reflected wave, but the amplitude of the pulse waveform may be small causing it to be buried in noise and reducing estimation accuracy
Solution Approach 1:
The patent uses the second boundary surface pulse wave as an intermediary to indirectly estimate the position of the first boundary surface. Instead of relying on the weak first boundary surface pulse wave that gets buried in noise, the system uses the clearer second boundary surface pulse wave (which has traveled through the first boundary surface) as a mediator to infer the position of the first boundary surface, thereby resolving the contradiction between measurement precision and signal reliability
Solution Approach 2:
The patent performs preliminary estimation of the first boundary surface position using the second boundary surface pulse wave before attempting to use the first boundary surface pulse wave. By establishing an initial estimate through the more reliable second boundary surface signal, the system can then refine or validate this estimate, ensuring accurate position determination even when the direct first boundary surface pulse wave is unclear
2Measurement precision
If the pulse waveform amplitude is increased to improve signal clarity, then the boundary surface position can be estimated more accurately, but the system may require higher terahertz wave intensity which could damage the sample
Solution Approach 1:
The patent transitions from using a single-dimensional approach (direct first boundary surface pulse wave) to a multi-dimensional approach by incorporating the second boundary surface pulse wave. This dimensional shift allows the system to achieve accurate position estimation through alternative signal paths without increasing the intensity of the original terahertz wave, thereby avoiding sample damage while maintaining 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
This approach enables proper estimation of boundary surface positions even when the first boundary surface pulse wave is unclear or buried in noise, maintaining high accuracy by leveraging the clarity and similarity of the second boundary surface pulse wave.
Implementation Method 1
a pump light (in other words, an excitation light) is irradiated to a terahertz wave generating element to which a bias voltage is applied, wherein the pump light is one laser light that is obtained by branching an ultrashort pulse laser light (for example, a femtosecond pulse laser light). As a result, the terahertz wave generating element generates the terahertz.
Implementation Method 2
The terahertz wave generated by the terahertz wave generating element is irradiated to the sample. The terahertz wave irradiated to the sample is irradiated, as a reflected terahertz wave (alternatively, a transmitted terahertz wave) from the sample, to a terahertz wave detecting element to which a probe light (in other words, an excitation light) is irradiated. As a result, the terahertz wave detecting element detects the terahertz wave reflected by or transmitted through the sample.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An inspection apparatus 100 is provided with: an irradiating device 110 configured to irradiate a sample S in which a plurality of layers L are laminated with a terahertz wave THz; a detecting device 130 configured to detect the terahertz wave from the sample to obtain a detected waveform DW; and an estimating device 1523 configured to estimate a position of a first boundary surface on the basis of a second boundary surface pulse wave PW2 and a library 1522a, the second boundary surface pulse wave appearing in the detected waveform to correspond to a second boundary surface B2 that is farther from an outer surface B0 than the first boundary surface B1, the library representing an estimated waveform EW of the terahertz wave from the sample.