Design of Focal Plane Array with Lens for W-band Short Range Passive Imaging

A 48-channel focal plane array (FPA) with a quasioptical dielectric lens is proposed in this paper. The FPA is designed for a W-band passive imaging system which is designed for concealed contraband detection. The quasi-optical Lens is shaped in asymmetric aspheric contours with a diameter of 450mm to provide minimum focusing error and high resolution. The optical design tool ZEMAX is utilized to calculate the parameters of the lens structure, and ray tracing method is used to determine the location of each feed to improve the uniformity of the focus-spots formed on the object plane. The measured results show that the 3dB beam-spot-width of the FPA is only about 15.6mm at distance of 1720 mm, and the power level difference between beams is less than 0.8dB.