## 5 Conclusions  
Versatile operation of universal, convenient and easy-to-use antenna coupled sensitive titanium-based microbolometers dedicated to the precise alignment and the control of spatial mode profiles without additional focusing optical components of weak power THz sources are demonstrated. Spatial mode profile control and polarization-resolved mode structures are recorded for different type THz emitters--electronic multiplier sources, optical THz mixers-based frequency domain and femtosecond optoelectronic THz time-domain spectrometers as well as optically pumped molecular THz laser--operating either in continuous wave or pulsed modes. Features of the microbolometers coupled with resonant antennas within 0.15-0.6 THz range are exposed and discussed, and their ability to detect spatial mode profiles far above the antennas resonances, up to 2.54 THz, are explored as well. It is found that a broadband antenna (below 1 THz) coupled microbolometer reproduces well the spatial mode profile of time-domain spectrometer. Polarization-sensitive mode control possibilities are examined in details; suitability of the resonant antenna-coupled bolometers to resolve low-absorbing objects at 0.3 THz is revealed via direct, dark field and phase contrast imaging techniques. The microbolometer, for instance, coupled with a 0.3 THz frequency dipole antenna exhibits the response time of 1 \(\upmu\)s range, sensitivity of 300 V/W, and noise-equivalent power of 14 pW/\(\sqrt{Hz}\). Microbolometers display corresponding values of 200 kV/W and less then 20 pW/\(\sqrt{Hz}\), respectively, and the response time in the 5 \(\upmu\)s range. These parameters make the devices promising for real-time fine adjustment of THz spectroscopic and imaging systems as well as imaging applications and inspection of low-absorbing objects.  
Conceptualization of the research, G.V. and L.M.; methodology, G.V., L.M. and A.S. ([PERSON]); software, D.J.; development of antenna-coupled Ti-microbolometers, A.S. ([PERSON]), A.S., I.K., and J.T.; investigation using electronic sources, L.M., A.S. ([PERSON]), L.Q. and D.J.; investigation using frequency domain spectrometer, D.S.; investigation using THz time-domain spectrometer, I.K.; investigation using optically-pumped molecular THz laser, D.S., L.Q., and L.M.; data acquisition, L.M. and G.V.; experimental data analysis, L.M., A.S. ([PERSON]), L.Q., and G.V.; writing--original draft preparation, G.V.; writing--review and editing, L.M., A.S. ([PERSON]), I.K, and G.V.; visualization, L.M., A.S. ([PERSON]), L.Q., and D.J.; supervision and coordination, G.V.; project administration, G.V. All authors have read and agreed to the published version of the manuscript.  
L.M. and I.K. acknowledge financial support from \"KOTERA-PLAZA\" project supported from European Regional Development Fund (Grant No. 01.2.2-LMT-K-718-01-0047).  
Authors are very grateful to [PERSON] and [PERSON] for their kind assistance in experiments with femtosecond optoelectronic THz emitters and for illuminating discussions.  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} THz & Terahertz \\ THz ELS & Terahertz electronic multiplier source \\ THz FDS & Terahertz frequency domain spectrometer \\ THz TDS & Terahertz time domain spectrometer \\ THz OPML & Optically pumped molecular THz laser \\ Ti-mB & titanium-based microbolometer \\ CW & continuous wave \\ SNR & Signal-to-noise ratio \\ Ksps & Kilo samples per second \\ \end{tabular}