Improvement of spectroscopic method for determining refractive index of filament sample material for 3D printing in terahertz range
Keywords:method, spectroscopy, coefficient, refraction, terahertz, effect, Fabry Perot, model, interference, number, compensation, system of equations
The article considers the topical problem of non-destructive filament defectoscopy for 3D printing. The subject of the research is the process of determining the refractive index of the filament material for 3D printing taking into account the reflections from sample opposite walls, which is studied by terahertz spectroscopy in the time domain. Reflections from opposite walls are called the Fabry-Perot effect, and interference members resulting from reflections from walls are traditionally taken into account by summation and represented as a series. The disadvantage of the model in the form of a simple summation is the rejection of the members of the series above the fourth, which leads to inaccuracies in the model. The main problem with terahertz spectroscopy and this study in particular is the contradiction between the rapid development of terahertz spectroscopy and the slow development of models used in terahertz spectroscopy, while the adjacent microwave region has a set of ready-made models. Models based on the description of a standing wave in the microwave tract with refinements, transferred to a new region of terahertz spectroscopy in the time domain. The scientific novelty lies in increasing accuracy by taking into account previously unaccounted for interference members. The analogy between the Fabry-Perot effect used in terahertz spectroscopy and the reflections in a microwave multiprobe multimeter suggested the following recommendations. First, because the phase distance between the sensors in the microwave multimeter is similar to the thickness of the sample in terahertz spectroscopy, therefore, there was choosen such a sample thickness that the interference members are compensated, and secondly, instead of simple sum up it is possibility apply algorithmic processing, the condition for this is the existence in addition to the main signal in the time domain of the recorded echo signals of much smaller amplitude, therefore, one can build a system of equations and by solving it to determine the desired refractive index parameters of the filament sample material.
Mohtashemi L., Westlun, P., Sahota D. G., Lea G. B., Bushfield I., Mousavi P., Dodge J. S. Maximum-likelihood parameter estimation in terahertz time-domain spectroscopy // Optics Express. 2021. Vol. 29, No. 4. P. 4912-4926.
Naftaly M., Savvides G., Alsharee, F., Flanigan P., Lui G., Florescu M. Mullen R. A. Non-Destructive Porosity Measurements of 3D Printed Polymer by Terahertz Time-Domain Spectroscopy// Applied Sciences. 2022. Vol.12, No. 2. P. 927-938.
Klokkou N., Gorecki J., Wilkinson J. S. Apostolopoulos V. Artificial neural networks for material parameter extraction in terahertz time-domain spectroscopy // Optics Express. 2022, Vol. 30, No. 9. P. 15583-15595.
Withayachumnankul W., Naftaly M. Fundamentals of measurement in terahertz time-domain spectroscopy // Journal of Infrared, Millimeter, and Terahertz Waves. 2014. Vol. 35, No.8. P. 610-637.
Dorney T. D., Baraniuk R. G., Mittleman D. M. Material parameter estimation with terahertz time-domain spectroscopy // JOSA A. 2001. Vol. 18, No. 7. P.1562-1571.
Duvillaret L., Garet F., Coutaz J. L. Highly precise determination of optical constants and sample thickness in terahertz time-domain spectroscopy // Applied optics. 1999. 199938(2). P.409-415.
Oberto L., Bisi M., Kazemipour A., Steiger A., Kleine-Ostmann T., Schrader T. Measurement comparison among time-domain, FTIR and VNA-based spectrometers in the THz frequency range // Metrologia. 2017. Vol.54, No.1. P. 77-84.
Билько М. И., Томашевский А. К. Измерение мощности СВЧ. Москва : Радио и связь, 1976. 168 c.
Силаев М. А., Брянцев С. Ф. Приложение матриц и графов к анализу СВЧ устройств. Москва : Сов. радио, 1970. 248 c.
Somlo P. I., Hunter J. D. Microwave impedance measurement. Peter Peregrinus Ltd. 1985 207 p.
Zaichenko O., Miroshnyk M., Galkin, P. Signal Flow Graph for Optimizing of Mutual Sensors Reflection in the Multiprobe Microwave Multimeter // 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON). 2019. P. 200-203.
Zaichenko O., Galkin P., Zaichenko N., Miroshnyk M. Six-port Reflectometer with Kalman Filter Processing of Sensor Signals Proceedings / 15th International Conference on Advanced Trends in Radioelectronics // Telecommunications and Computer Engineering, TCSET 2020. 2020. P. 55–58.
Zaichenko O., Miroshnyk M., Zaichenko N., Miroshnyk A. A. Multiprobe microwave multimeter signals iterative processing // 30th International Scientific Symposium Metrology and Metrology Assurance, MMA. 2020. 2020. P. 1-4.
Zaichenko O., Galkin P., Miroshnyk M., Zaichenko N., Miroshnyk A. Application of Six-Port for Distance Measurement // 2020 IEEE International Conference on Problems of Infocommunications Science and Technology, PICST 2020 Proceedings. 2020. Р. 97-100.
Zaichenko O. B., Zaichenko, N. Y. Systematization of the Formulas of Resonant Ferrite Isolator Loss // Radio Electronics, Computer Science, Control. 2022. Vol. 1. P.20-29.
Bilik V. Six-port measurement technique: principles, impact, applications // Invited paper at the International Conference Radioelectronika. 2002. P. 1-32.
How to Cite
Authors who publish with this journal agree to the following terms:
1. Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
2. Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.3. Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).