THz-TDS Techniques of Thickness Measurements in Thin Shim Stock Films and Composite Materials
Abstract
:1. Introduction
2. Fundamental Theory
2.1. Measurement of Refractive Index
2.2. Measurement of Refractive Index
3. Experiment System and Measurement
3.1. Measurement System
3.2. Measurement Method
4. Results and Discussion
4.1. Measurement of Terahertz Refractive Index
4.2. Electric Field Evaluation of Carbon Fiber
4.3. Measurement of Thickness Using the Reflection Mode
4.4. Relation between Nominal Thickness and Thickness Measured from T-ray Techniques
5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Materials | Refractive Index (n) * | Refractive Index (n) |
---|---|---|
Reflection Mode | ||
PMMA | 1.60 ± 0.08 | 1.59 ± 0.07 |
Shim Stock films | - | 1.52 ± 0.03 |
Fused quartz | 1.95 ± 0.05 | 1.94 ± 0.09 |
GFRP | - | 2.17 ± 0.05 |
Sample No. | Delay Time (Δt, ps) | Resonance Frequency (Δf) | T-ray Measure ment (mm) | Reference Thickness (mm) | Others |
---|---|---|---|---|---|
1 | 1.322 | 0.750 | 0.137 | 0.127 | Shim stock Co., Ltd. (Edenvale, South Africa) |
2 | 2.551 | 0.392 | 0.250 | 0.254 | |
3 | 3.846 | 0.260 | 0.396 | 0.381 | |
4 | 5.881 | 0.170 | 0.539 | 0.508 | |
5 | 8.600 | 0.115 | 0.789 | 0.762 |
Sample No. | Delay Time (Δt, ps) | Resonance Frequency (Δf) | T-ray Measurement (mm) | Reference Thickness (mm) | Others |
---|---|---|---|---|---|
1 | 24.480 | 0.041 | 2.000 | 2.020 | Shim Stock Co., Ltd. |
2 | 50.000 | 0.020 | 3.180 | 3.080 | |
3 | 75.130 | 0.013 | 5.600 | 5.740 | |
4 | 83.30 | 0.012 | 5.920 | 5.920 |
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Im, K.-H.; Kim, S.-K.; Cho, Y.-T.; Woo, Y.-D.; Chiou, C.-P. THz-TDS Techniques of Thickness Measurements in Thin Shim Stock Films and Composite Materials. Appl. Sci. 2021, 11, 8889. https://doi.org/10.3390/app11198889
Im K-H, Kim S-K, Cho Y-T, Woo Y-D, Chiou C-P. THz-TDS Techniques of Thickness Measurements in Thin Shim Stock Films and Composite Materials. Applied Sciences. 2021; 11(19):8889. https://doi.org/10.3390/app11198889
Chicago/Turabian StyleIm, Kwang-Hee, Sun-Kyu Kim, Young-Tae Cho, Yong-Deuck Woo, and Chien-Ping Chiou. 2021. "THz-TDS Techniques of Thickness Measurements in Thin Shim Stock Films and Composite Materials" Applied Sciences 11, no. 19: 8889. https://doi.org/10.3390/app11198889