Imaging characteristics of logarithmic axicon for application in compound eye system

Logarithmic axicon (LA) was proposed to overcome the defocus in the spherical compound eye imaging utilizing its focal line. The depth of field of LA was designed to meet the requirements of all the channels of the compound eye. On-axis and off-axis characteristics of LA were studied based on numerical simulation. Mass production of LA was achieved by diamond cutting and molding technology. Experimental results show that the on-axis point spread function(PSF) keeps constant along the propagation, while the off-axis PSF is cross-shaped. The intersection of the cross can be extracted and used to determine the spot centroid in off-axis imaging. The proposed method is helpful to eliminate the intrinsic defocus effects of spherical lens and improve the positioning accuracy and imaging quality of the spherical compound eye system.