The non-destructive behavior of terahertz (THz) radiation is used in a wide variety of applications in industry and research and has inspired researchers to explore different configurations of THz-based measurement systems to bring such systems from the laboratory to the field. In this work, an optical system is presented for terahertz reflectivity measurement based on refractive optical elements. The optical arrangement is housed in a handheld THz scanner head unit that is realized using additive manufacturing. The THz scanner head is modular, compact, lightweight, and easy to handle, making it field deployable and suitable for outdoor measurements. Further, the applicability of this THz scanner head is demonstrated in applications such as hydration sensing, surface roughness characterization, and interface detection in multilayered structures, which play key roles in industrial environment for non-contact quality control and assessment of consumer products.