Abstract-Spectroscopic Terahertz Imaging at Room Temperature Employing Microbolometer Terahertz Sensors and Its Application to the Study of Carcinoma Tissues

Irmantas Kašalynas 1,* , Rimvydas Venckevičius 1

, Linas Minkevičius 1

, Aleksander Sešek 2

,Faustino Wahaia 3

, Vincas Tamošiūnas 1

, Bogdan Voisiat 1

, Dalius Seliuta 1

, Gintaras Valušis 1

,Andrej Švigelj 2

 and Janez Trontelj 2

1 Department of Optoelectronics, Center for Physical Sciences and Technology, Savanoriu Ave. 231, Vilnius 02300, Lithuania2 Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, Ljubljana 1000, Slovenia3 Instituto de Investigacao e Inovacao em Saudeand, Instituto de Engenharia Biomedica, University of Porto, Rua do Campo Alegre, 823, Porto 4150-180, Portugal

* Author to whom correspondence should be addressed.

Academic Editors: Dragan Indjin and Vincenzo Spagnolo

Received: 6 February 2016 / Revised: 4 March 2016 / Accepted: 18 March 2016 / Published: 25 March 2016

http://www.mdpi.com/1424-8220/16/4/432

A terahertz (THz) imaging system based on narrow band microbolometer sensors (NBMS) and a novel diffractive lens was developed for spectroscopic microscopy applications. The frequency response characteristics of the THz antenna-coupled NBMS were determined employing Fourier transform spectroscopy. The NBMS was found to be a very sensitive frequency selective sensor which was used to develop a compact all-electronic system for multispectral THz measurements. This system was successfully applied for principal components analysis of optically opaque packed samples. A thin diffractive lens with a numerical aperture of 0.62 was proposed for the reduction of system dimensions. The THz imaging system enhanced with novel optics was used to image for the first time non-neoplastic and neoplastic human colon tissues with close to wavelength-limited spatial resolution at 584 GHz frequency. The results demonstrated the new potential of compact RT THz imaging systems in the fields of spectroscopic analysis of materials and medical diagnostics.