Xing Zhao

Bio: Xing Zhao is an academic researcher from Nankai University. The author has contributed to research in topic(s): Integral imaging & Image processing. The author has an hindex of 11, co-authored 39 publication(s) receiving 259 citation(s). Previous affiliations of Xing Zhao include Hong Kong Polytechnic University.

Illumination system using LED sources for pocket-size projectors

Abstract: An illumination system using LED sources for pocket-size projectors is designed. Its color gamut is much larger than the sRGB standard. The maximum theoretical efficiency of this system is 29.98% by non-imaging theory-based calculations. To analyze the system model, 1.5 × 106 rays are traced by using the LightTools software. The total light flux that illuminates the digital micromirror device is 44 lm and the American National Standards Institute 13-point uniformity on the surface is 91.55%, −91.15% with a system efficiency of 28.3%. The calculations are in good agreement with the simulation results. The illumination system can be used for personal pocket-size projectors providing a 15-20 in. (38-51 cm) color display with the brightness comparable with a laptop.

Enhancement of depth-of-field in a direct projection-type integral imaging system by a negative lens array

Abstract: We propose a method for enhancing depth-of-field, in which the spot size on a marginal depth plane is reduced. This method is implemented in a projection-type integral imaging system using a negative lens array without a diffuser. Numerical simulation results show that the spot size is merely 5.7% of that in a conventional system. Thus, the depth-of-field in the proposed system is enhanced by 17.5 times over that in a conventional system. Optical experiments confirm good agreement between the results and numerical predictions.

A theoretical and experimental investigation of material removal characteristics and surface generation in bonnet polishing

Abstract: This paper presents a theoretical and experimental investigation which attempts to provide a better scientific understanding of the material removal characteristics and surface generation in bonnet polishing. The experimental results reveal that the material removal is shared by the polishing pad and the abrasives trapped in the pad-workpiece interface, and the abrasive wear is dominated significantly by plastic removal mode of abrasive particles, while the material removal caused by the polishing pad should be mitigated in order to obtain super mirror finished surfaces. The surface generation is found to be a linearly cumulative effect of dwell time together with the constant material removal rate under the identical polishing condition. Hence, a multi-scale material removal model and a surface generation model have been built based on the contact mechanics, kinematics theory, abrasive wear mechanism, as well as the relative and cumulative removal process of surface generation in bonnet polishing. The models are verified through a series of spot and pattern polishing experiments. Based on the results of spot polishing experiments, the multi-scale material removal model is found to predict well for the material removal characteristics under various polishing conditions. The simulated patterns by the surface generation model are found to agree well with the measured patterns in the pattern polishing experiments which substantiate that the relative and cumulative removal process is a key surface generation mechanism in bonnet polishing.

Generalized approach to modifying optical vortices with suppressed sidelobes using Bessel-like functions

Abstract: We propose a generalized approach to producing optical vortices with suppressed sidelobes using a variable Bessel-like function added to the conventional spiral phase plate. Experimental verifications are implemented by a phase-only spatial light modulator. It is demonstrated that the method is valid for optical vortex beams with arbitrary topological charges and without changing the primary ring size as a unique property among the existing techniques.

Autostereoscopy-based three-dimensional on-machine measuring system for micro-structured surfaces

Abstract: Traditional off-line measuring systems find it difficult to measure micro-structured workpieces which have a large volume and heavy weight, such as micro-structured patterned precision roller drums. This paper proposes an autostereoscopy-based three-dimensional (3D) measuring method and develops an innovative measuring system for the 3D on-machine measurement of the micro-structured surfaces, an Autostereoscopy-based Three-Dimensional On-machine Measuring (ATDOM) system. The ATDOM system is compact and capable of fast data acquisition and high accuracy in 3D computational reconstruction of complex surfaces under different measuring environments. A prototype ATDOM system is experimentally verified through a series of measurement experiments conducted on a precision machine tool. The results indicate that the ATDOM system provides an important means for efficient and reliable on-machine measurement of micro-structured surfaces.

I and i

Abstract: 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 …

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

Abstract: 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.

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

Abstract: On-machine and in-process surface metrology are important for quality control in manufacturing of precision surfaces. The classifications, requirements and tasks of on-machine and in-process surface metrology are addressed. The state-of-the-art on-machine and in-process measurement systems and sensor technologies are presented. Error separation algorithms for removing machine tool errors, which is specially required in on-machine and in-process surface metrology, are overviewed, followed by a discussion on calibration and traceability. Advanced techniques on sampling strategies, measurement systems-machine tools interface, data flow and analysis as well as feedbacks for compensation manufacturing are then demonstrated. Future challenges and developing trends are also discussed.

Rapid fabrication of large-area concave microlens arrays on PDMS by a femtosecond laser.

Abstract: A fast and single-step process is developed for the fabrication of low-cost, high-quality, and large-area concave microlens arrays (MLAs) by the high-speed line-scanning of femtosecond laser pulses. Each concave microlens can be generated by a single laser pulse, and over 2.78 million microlenses were fabricated on a 2 × 2 cm2 polydimethylsiloxane (PDMS) sheet within 50 min, which greatly enhances the processing efficiency compared to the classical laser direct writing method. The mechanical pressure induced by the expansion of the laser-induced plasmas as well as a long resolidifing time is the reason for the formation of smooth concave spherical microstructures. We show that uniform microlenses with different diameters and depths can be controlled by adjusting the power of laser pulses. Their high-quality optical performance is also demonstrated in this work.

Simple technique for generating the perfect optical vortex

Abstract: We propose an improved technique for generating the perfect optical vortex. This technique is notable for the simplicity of its practical realization and high quality of the results. The efficiency of the proposed technique is illustrated with the results of physical experiments and an example of its application in optical trapping of small particles.