an improved multiple circular array (mca) configuration is proposed for sparse aperture (sa) optical imaging systems. using genetic algorithms, the practical cutoff frequency (pcof), based on the modulation transfer function for the array, is selected as the fitness function. moreover, the parameters, such as diameters of aperture sets, spacing between the aperture sets, and relative rotation angles between aperture sets on different concentric circles, are calculated. improved mca configurations, with aperture numbers of 6, 9, 12, 10, 15, 11, and 13, are given. golay arrays, mcas, a single annular aperture, and improved arrays with the same fill factor are compared. the results show that the improved array has highest pcof of all the sa arrays, smoother coverage in fourier space, and better midfrequency contrast than mcas. consequently, the improved array is a promising aperture configuration that can approximate a single annular aperture. © 2017 society of photo-optical instrumentation engineers (spie).