Design of a simple fisheye lens.

We present a simple design of fisheye lens that consists of a pre-group optics of two negative meniscus lenses and a post-group optics of three singlet lenses. The pre-group optics is first designed according to the requirements for the compression ratio of field angle and the transverse dimension of the lens. The balance conditions of the field curvature, longitudinal and transverse chromatic aberrations between the pre-group and post-group optics, and the requirement of the total optical power of the system are used to determine the optical power and the spacing of the lenses of the post-group optics in the thin-lens model; the initial curvature radii of three lenses are then determined according to the resultant optical powers of lenses, and their thicknesses are determined according to the exact balance of field curvature and longitudinal and transverse chromatic aberrations. Finally, we apply a self-adaptive and normalized real-coded genetic algorithm to optimize the starting design of the fisheye lens obtained in the above process.