A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

비만아 부모의 돌봄 경험: q 방법론

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Principles Of Optics Electromagnetic Theory Of Propagation Interference And Diffraction Of Light

Quantitative phase imaging (QPI) has emerged as a valuable method for investigating cells and tissues. QPI operates on unlabelled specimens and, as such, is complementary to established fluorescence microscopy, exhibiting lower phototoxicity and no photobleaching. As the images represent quantitative maps of optical path length delays introduced by the specimen, QPI provides an objective measure of morphology and dynamics, free of variability due to contrast agents. Owing to the tremendous progress witnessed especially in the past 10–15 years, a number of technologies have become sufficiently reliable and translated to biomedical laboratories. Commercialization efforts are under way and, as a result, the QPI field is now transitioning from a technology-development-driven to an application-focused field. In this Review, we aim to provide a critical and objective overview of this dynamic research field by presenting the scientific context, main principles of operation and current biomedical applications. Over the past 10–15 years, quantitative phase imaging has moved from a research-driven to an application-focused field. This Review presents the main principles of operation and representative basic and clinical science applications.

Quantitative phase imaging in biomedicine

Proceedings of the National Academy of Sciences

The characteristics of photonic nanojets are analyzed by changing the parameters, such as the wavelength, refractive index of the surroundings, diameter and refractive index of the microsphere, in this paper. Quadratic functions are used to describe the relation between the above parameters and photonic nanojets’ characteristics. Several techniques are proposed to control the photonic nanojets.

Parameter optimization for photonic nanojet of dielectric microsphere

The invention discloses a 360-degree three-dimensional display device based on splicing of multiple high-speed projectors. The 360-degree three-dimensional display device comprises an orientation diffuser screen set, a rotating device set, a rotating detection module, a projection splicing integration module, image storage modules and the N high-speed projectors. An algorithm of splicing of the multiple high-speed projectors is used for calculation to obtain a two-dimensional frame image sequence projected by each high-speed projector in real time, and the two-dimensional frame image sequences are sent to all the image storage modules. Under modulation of the rotating detection module, all the high-speed projectors are controlled to be matched with rotation of one set or more sets of orientation diffuser screens, splicing and synthesizing imaging of projection areas of all the high-speed projectors are achieved, and the space resolution ratio of three-dimensional display is improved in a multiplied mode. The algorithm based on splicing of the high-speed projectors is matched with the orientation diffuser screens for imaging, the three-dimensional imaging space is enlarged, the transverse dimension, the longitudinal dimension and the field depth dimension of a three-dimensional image are increased, and spatial expansion of three-dimensional display of the large-dimension space is achieved.

360-degree three-dimensional display device and method based on splicing of multiple high-speed projectors

Utilizing the diffractive effect of the output light fields from photonic nanojets, a new scheme for a microsphere array is designed to focus an incident wave to achieve subwavelength resolution in the far field. The three-dimensional finite-difference time-domain (FDTD) method has been introduced to investigate the beam focusing phenomenon along the propagation direction. According to the numerical calculation results, we find that a focal spot with a full width at half maximum (FWHM) of 0.63λ can be achieved at a distance of 20.4λ away from the exit plane of the microsphere array with a refractive index n = 1.45. We show that the properties of the focal spot will be diverse with the changes of the refractive index, the incident wavelength, and the arrangement of the array. This potential relationship is explicitly analyzed.

http://iopscience.iop.org/article/10.1088/2040-8978/13/3/035702/pdf

Subwavelength focusing by a microsphere array

We propose a method theoretically to break the diffraction limit and to improve the resolution in all three dimensions for fluorescence emission difference microscopy. We produce two kinds of hollow focal spot by phase modulation. By incoherent superposition, these two kinds of focal spot yield a 3D hollow focal spot. The optimal proportion of these two kinds of spot is given in the paper. By employing 3D hollow focal spot, super-resolution image can be yielded by means of fluorescence emission difference microscopy, with resolution enhanced both laterally and axially. According to computation result, size of point spread function of three-dimensional super-resolution imaging is reduced by about 40% in all three spatial directions with respect to confocal imaging.

Three-dimensional super-resolution imaging for fluorescence emission difference microscopy

Super-resolution optical microscopy is a useful tool to investigate physical and biological characteristics on the sub-100-nanometer scale. Here, we develop pulsed saturated absorption competition ...

Cuifang Kuang

Papers

Parameter optimization for photonic nanojet of dielectric microsphere

360-degree three-dimensional display device and method based on splicing of multiple high-speed projectors

Subwavelength focusing by a microsphere array

Three-dimensional super-resolution imaging for fluorescence emission difference microscopy

Pulsed Saturated Absorption Competition Microscopyon Nonbleaching Nanoparticles