Non-diffracting linear-shift point-spread function by focus-multiplexed computer-generated hologram

An Airy beam can be used to implement a non-diffracting self-bending point-spread function (PSF), which can be utilized for computational 3D imaging. However, the parabolic depth-dependent spot trajectory limits the range and resolution in rangefinding. In this Letter, we propose a novel pupil-phase-modulation method to realize a non-diffracting linear-shift PSF. For the modulation, we use a focus-multiplexed computer-generated hologram, which is calculated by multiplexing multiple lens-function holograms with 2D sweeping of the foci. With this method, the depth-dependent trajectory of the non-diffracting spot is straightened, which improves the range and resolution in rangefinding. The proposed method was verified by numerical simulations and optical experiments. The method can be applied to laser-based microscopy, time-of-flight rangefinding, and so on.