Multiplanar imaging properties of Theon sieves.

Greek ladders with diffraction-limited array foci provide a probability to realize array imaging with equal intensity. Here, taking the ancient Theon sequence as an example, we design the optical structure and have measured the focusing properties by digital holography. Then, we verify the multiplanar imaging with different magnifications by experiment. The experimental results agree well with the theoretical analysis. In addition, bi-Fourier planes filtering technology is proposed to solve the problem of crosstalk between different imaging planes to further improve the imaging resolution. Therefore, we can freely design the focal length of the bifocal lens to achieve high-quality imaging at different resolutions. As a kind of amplitude-only diffractive lens, multifocal imaging provides a possibility of application in array biological imaging, ophthalmology, and an optical zoom system.