This paper investigates the impact of incident beam inhomogeneity on the quality of THz imaging based on the compressed sensing (CS) method. Image sampling and reconstructions under point and Gaussian beams with various geometric parameters are compared with the standard one. The simulation results show that the geometric parameters of beams strongly affect the peak signal-to-noise ratio (PSNR) of the reconstructed images. Especially for the Gaussian one, expanding the beam size at the position of the mask (BZPM) dramatically increases the PSNR. To achieve high sensitivity and resolution, new measurement matrices correlating to the incident beam distribution are proposed and the simulation results are demonstrated. Experiments under VDI THz source reveal that by using the new matrices, the PSNR of CS-based imaging at 100 GHz is evidently improved from 6 dB to 13 dB, informing the new measurement matrices are highly efficient and accurate in removing the beam effect on CS-based THz imaging. Our results may provide a new way for the high-quality CS-based THz imaging for target recognition.INDEX TERMS terahertz imaging, compressed sensing, beam inhomogeneity, beam noise removal

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The resistive microbolometer fabricated by using CMOS technology can be monolithically integrated with the readout circuit but usually performs poorly in responsivity and detectivity. In this paper, the poly-Si microbolometer with Al grating structure is demonstrated in the standard CMOS process. The simulation results show that not only are surface plasmon polaritons generated at the interface of the Al grating and SiO2, Al grating also provides the infrared resonant cavity required for the absorber, which improves the responsivity of the microbolometer. According to the experimental results, the maximum detectivity of the microbolometer with the grating structure reaches up to 2.2610 9 cmHz 1/2 /W at 10 μm, which means an increase by 27.8% compared to the one without the Al grating. Moreover, the average detectivity of the microbolometer is also improved when the wavelength ranges from 7 μm to 13 μm. It is effortless to implement the proposed high-performance microbolometer in a unit structure based on CMOS technology, which is favorable to high-density array integration.