A light beam propagating over an infinite anti-diffracting distance requires infinite power to preserve its shape. However, the fundamental barrier of finite power in free space has made the problem of diffraction insurmountable in recent decades. To overcome this limitation, we report an approach that employs the multiple energy oscillation mechanism, thereby permitting the creation of a light beam with an ultralong anti-diffracting distance in free space. A versatile optical pen is therefore developed to manipulate the number, amplitude, position and phase of energy oscillations for a focusing lens so that multiple energy oscillations can be realized. A light beam with a tunable number of energy oscillations is eventually generated in free space and propagates along a wavy trajectory. This work will enable the extension of non-diffractive light beams to an expanded realm and facilitate extensive developments in optics and other research fields, such as electronics and acoustics.

We propose a full color computer generated holographic near-eye display (NED) based on white light illumination. The method inspired from color rainbow holography is used for calculation of 2D and 3D color holograms. The parameters of the color hologram calculation are designed based on the parameters of the spatial light modulator (SLM) with 4K resolution. A slit type spatial filter is designed in frequency domain to extract red, green and blue frequency components for full color display. A NED system including a white light source, an achromatic collimating lens, a 4K SLM, a 4f optical filtering system, and an achromatic lens as eyepiece is designed and developed. The main contribution of this paper is the first time to apply the rainbow holography concept to the dynamic full color NED with a compact display system. The optical experiments prove the feasibility of the proposed method.

A method of optimizing and manufacturing a diffractive blazed grating array (DBA) is proposed to create a visual security feature when illuminated by a divergent light-emitting diode source. A pure phase grating array serving as the optical security component consists of blazed grating cells with the same size, 75 µm. After a divergent spherical wave is decomposed into harmonic waves, each grating cell of the DBA locally deflects the harmonic-waves into predefined directions and forms a feature pattern on the target plane. Particularly, a two-step optimization method is further developed for optimizing the period and orientation of each grating cell. The DBA sample is fabricated by using our home-built parallel direct-write photoplotter with a resolution of 0.75 µm. Both numerical simulations and optical experiments are demonstrated to validate the proposed model. Since the optical security component developed is a surface relief structure of a single polymer material, it can be replicated for mass production by using standard roll to roll nanoimprint technology. The design algorithm proposed in this work will enable the extension of the optical security elements to a broader realm and facilitate extensive developments in other research fields of the optics community, such as light-shaping, specific illumination for lithography, and microscope systems.

An optimization method of pure phase CGH for beam shaping with divergent incoherent light is proposed. The sample experiment fabricated with our home built photo-plotter shows a good agreement with the numerical simulation results.