There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

We introduce the concept of the perfect optical vortex whose dark hollow radius does not depend on the topological charge. It is shown analytically and experimentally that such a vortex can be approximately generated in the Fourier transforming optical system with a computer-controlled liquid-crystal spatial light modulator.

Generation of the "perfect" optical vortex using a liquid-crystal spatial light modulator

On-machine and in-process surface metrology for precision manufacturing

Micro-structured functional surfaces have achieved widespread applications in various advanced scientific, technological, industrial, and engineered fields due to their excellent performances, which are vitally limited by their feasible fabrication. Currently, ultra-precision machining, typically including ultra-precision diamond turning, ultra-precision diamond milling, ultra-precision diamond scratching, ultra-precision grinding, and ultra-precision polishing, is developed as a very-promising solution for the micro-structured functional surface fabrication with high quality, high efficiency, high flexibility, and low cost. Therefore, this paper aims to briefly review the current state of the art in the investigation into ultra-precision machining characteristics of micro-structured functional surfaces with a focus on their typical advanced applications as the significant achievements of their ultra-precision machining fabrication, discuss the key challenges, and further provide new insights into ultra-precision machining of micro-structured functional surfaces for the future research and their further advanced applications.

Advances in ultra-precision machining of micro-structured functional surfaces and their typical applications

Low-power integrated projection technology can play a key role in development of low-cost mobile devices with built-in high-resolution projectors. Low-cost 3D imaging and holography systems are also among applications of such a technology. In this paper, an integrated projection system based on a two-dimensional optical phased array with fast beam steering capability is reported. Forward biased p-i-n phase modulators with 200MHz bandwidth are used per each array element for rapid phase control. An optimization algorithm is implemented to compensate for the phase dependent attenuation of the p-i-n modulators. Using rapid vector scanning technique, images were formed and recorded within a single snapshot of the IR camera.

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Nanophotonic projection system.

A reconstruction method of axially moving lenslet array (AMLA) was proposed. First, the dot-pattern reconstructed image was generated from a set of AMLA-recorded EIs using pixel-to-pixel mapping. Then, the empty pixels of dot-pattern reconstructed image can be filled by the average of the intensity values of all pixels that are corresponding to the empty pixels in each EI and determined through back projection. Using this proposed method, not only can the empty pixels be eliminated, but also the image quality is higher than conventional interpolation. Moreover, the axially moving gap can also be arbitrary, which breaks the limitation of the strict interpolation-free condition of the conventional reconstruction method. The feasibility of this method was verified by simulations and optical experiments.

Xing Zhao

Papers

Hybrid pixel mapping reconstruction method of axially moving lenslet array in integral imaging with arbitrary moving gap