Fang Zhi-liang

Generation of Optical Vortex Using a Spiral Phase Plate Fabricated in Quartz by Direct Laser Writing and Inductively Coupled Plasma Etching

A simple, economical and reliable technique is proposed for fabricating a spiral phase plate (SPP) in a quartz substrate to generate optical vortex with a unit topological charge at the wavelengths of 632.8 nm. The spiral phase plate is first formed in the photoresist by direct laser writing lithography and then transferred into the quartz substrate by inductively coupled plasma etching. The performance of the fabricated SPP is verified by using beam intensity distribution, which is in agreement with the theoretical calculation result. The interference measurement suggests that we have succeeded to generate optical vortex with a unit topological charge with the fabricated SPP.

Properties of Fraunhofer Diffraction by an Annular Spiral Phase Plate for Sidelobe Suppression

A simple and accurate method for calculating the optimal width of an annular spiral phase plate (SPP) to generate optical vortices with sidelobe suppression is proposed. The sidelobes can be sharply suppressed when the ratio of inner and outer radii of an annular SPP is equal to that of the principal ring and the first sidelobe diffracted by a circular SPP with the same topological charge n. Moreover, the ratio of the inner and outer radii of the optimal annular SPP depends only on the topological charge n and is not affected by the incident wavelength or the size of the SPP.

Continuous imaging space in three-dimensional integral imaging

We report an integral imaging method with continuous imaging space. This method simultaneously reconstructs real and virtual images in the virtual mode, with a minimum gap that separates the entire imaging space into real and virtual space. Experimental results show that the gap is reduced to 45% of that in a conventional integral imaging system with the same parameters.

Optical/digital color photography based on white-light information processing

The achievement in optical/digital color photography based on white-light information processing including the color-encoding camera, the color image decoder, the integral window Fourier algorithm of the Fourier transform in digital decoding, the color correction of the retrieval color image and the fusion of zero order diffraction is reported. This technique has found its important applications in the fields of aerial reconnaissance photography and far-distance ground photography due to its features of large information capacity, convenience in archival storage, the capability of color enhancement, particularly easy transportation by internet.