We overview the results of research-and-development activities carried out in the “Laboratory of advanced research on millimeter-wave and terahertz radiation” (NSU, Novosibirsk, Russia) focused on improving conventional and creating novel quasi-optical components and systems of submm-wave and THz instrumentation. The main emphasis is put on considering the high-performance components based on single- and multi-layered metallized microstructures of sub-wavelength topology, which include band-pass filters, non-profiled focusing devices, thin-film phase and polarization transformers, ultra-thin resonant absorbers. The aspects of electromagnetic modeling, lithographic fabrication, and characterization of the developed structures designed both for stand-alone applications and for integration with various metrological systems are described together with their practical applications. Additionally, we present original approaches in submm-wave imaging, including bolometric and radar techniques developed in our laboratory, promising for security screening and nondestructive material quality inspection.