An investigation on diffractive micro-lens array used in THz imaging

In this paper, micro-lens array is proposed to enhance the coupling efficiency between the diffracted field of the objective lens and the micro-bolometer array in the focal plane of THz imaging system, so as to improve the receiving sensitivity of the micro-bolometer array. Two types of micro-lens array, one is hyper-hemispherical micro-lens array and another is diffractive micro-lens array, are analyzed, and the diffracted field pattern are simulated and compared. The diffractive micro-lens array is fabricated and integrated with micro-bolometer to get a focal plane array for THz imaging. Experimental results show that the coupling between the diffracted field and micro-bolometer is enhanced much.