We present an overview of our technological achievements in the implementation of detector structures based on mercury cadmium telluride (MCT) heterostructures and nanostructures for IR and THz spectral ranges. We use a special MBE design set for the epitaxial layer growth on (013) GaAs substrates with ZnTe and CdTe buffer layers up to 3" in diameter with the precise ellipsometric monitoring in situ. The growth of MCT alloy heterostructures with the optimal composition distribution throughout the thickness allows for the realization of different types of many-layered heterostructures and quantum wells to prepare the material for fabricating single-or dual-band IR and THz detectors.We also present the two-color broad-band bolometric detectors based on the epitaxial MCT layers that are sensitive in 150-300-GHz subterahertz and infrared ranges from 3 to 10 m, which operate at the ambient or liquid nitrogen temperatures as photoconductors, as well as the detectors based on planar HgTe quantum wells. The design and dimensions of THz detector antennas are optimized for reasonable detector sensitivity values. A special diffraction limited optical system for the detector testing was designed and manufactured. We represent here the THz images of objects hidden behind a plasterboard or foam plastic packaging, obtained at the radiation frequencies of 70, 140, and 275 GHz, respectively.

Room temperature linear arrays (up to 160 detectors in array) from silicon metal- oxide-semiconductor field-effect transistors (Si-MOSFETs) have been designed for sub- THz (radiation frequency 140 GHz) close to real-time direct detection operation scanner to be used for detection and recognition of hidden objects. For this scanner, the optical system with aspherical lenses has been designed and manufactured. To estimate the quality of optical system and its resolution, the system modulation transfer function was applied. The scanner can perform real-time imaging with the spatial resolution better than 5 mm at the radiation frequency 140 GHz and contrast 0.5 for the moving object speed up to 200 mm/s and the depth of field 20 mm. The average dynamic range of real time imaging system with 160-detector linear array is close to 35 dB, when the sources with the output radiation power of 23 mW (IMPATT diodes) are used (scan speed 200 mm/s). For the system with 32-detector array, the dynamic range was about 48 dB and for the single-detector system with raster scanning 80 dB with lock-in amplifier. However, in the latter case for obtaining the image with the sizes 20×40 mm and step of 1 mm, the average scanning time close to 15 min is needed. Convolutional neural network was exploited for automatic detection and recognition of hidden items.

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We report on the development of lenses for terahertz vision systems from their design up to manufacturing. Fused deposition modeling was used for assisting the 3D printing manufacturing process. HIP (High Impact Polystyrene) used for printing has high transmittance in the terahertz region and low deformation in the manufacturing process. The comparative analysis of experimental parameters data and the designed ones showed good agreement for the aspherical lenses manufactured. Application of the lenses manufactured to get imaging of some objects at 140 GHz radiation with 32 elements linear detector array has been demonstrated.