Design of non-imaging receiving system for large field of view lidar

Abstract

Lidar has been widely used in many fields due to its high precision. The system must also have a corresponding large field of view receiving capability in order to achieve effective detection of targets when imaging lidar realizes large-angle scanning. For the InGaAs-APD detector component, there is a contradiction between the high-frequency response bandwidth and the size of the photosensitive surface. This paper proposes a large surface four-quadrant InGaAs-APD detector with 2 × 2 area array structure design, which based on a small photosensitive panel detector with a unit diameter of 0.5 mm. On the basis of ensuring the cut-off frequency bandwidth of 100 MHz, it also realizes signal reception with large field of view and high sensitivity. For the receiving lens of the system, the relationship between the bin size of the detector and the receiving field of view in the non-imaging optical receiving system is studied. Under the condition that the parameters such as the size of the detector facet have been determined, the best position of the detector is optimally designed to maximize the receiving field of view. Based on theoretical foundations such as radiation angle coefficient and etendue, the non-imaging optical system lidar distance equation is established to evaluate the light-gathering ability of receiving lenses with different effective apertures and focal lengths, and to optimize optical structural parameters such as the best effective aperture and focal length of the receiving lens. Finally, the aspheric lens with the best parameters is selected as the basic receiving optical lens of the system, and an array type large field of view direct detection technology is proposed. The receiving optical system is composed of 6 aspheric single lenses, and the structure is in the form of 2 × 3 array, which finally realizes the efficient detection of echo signals with a large field of view of 48° × 26°.