Performance comparison of quasi-optical phased arrays using micro lens array with different structures

Abstract

Large aperture, compact, lightweight beam scanning systems operating in the infrared atmospheric window are attractive for aerial-based applications such as long-range lidar and countermeasures. The multiple micro lens arrays based micro lens array scanner (MLAS) with compact structure and low weight, which can be seemed as a quasi-optical phased array, is capable of large-aperture infrared beam scanning. The incident laser beam with a large aperture is separated into an array of multiple sub-beams by the MLAS, and the tip/tilt phases of the exiting sub-beams are controlled simultaneously by a relative translation (in micrometer level) of the micro lens arrays without a complex and large control circuit. In this paper, complete mathematical models have been established to describe the characteristics of MLAS with Kepler structure, Galileo structure and Modified-Kepler structure respectively. The performance of three type of MLAS, such as the maximum scanning angle and the main spot energy, etc., are theoretically analyzed and compared. The comparison presented in this paper is expected to be helpful to the designs of infrared optical systems with light beam deflectors and to provide guidelines for practical developments of MLAS.