Contrary to the well known diffraction limit, the fluorescence microscope is in principle capable of unlimited resolution. The necessary elements are spatially structured illumination light and a nonlinear dependence of the fluorescence emission rate on the illumination intensity. As an example of this concept, this article experimentally demonstrates saturated structured-illumination microscopy, a recently proposed method in which the nonlinearity arisesfromsaturationoftheexcitedstate.Thismethodcanbeused in a simple, wide-field (nonscanning) microscope, uses only a single, inexpensive laser, and requires no unusual photophysical properties of the fluorophore. The practical resolving power is determined by the signal-to-noise ratio, which in turn is limited by photobleaching. Experimental results show that a 2D point resolution of <50 nm is possible on sufficiently bright and photostable samples.

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Nonlinear structured-illumination microscopy: Wide-field fluorescence imaging with theoretically unlimited resolution

We review 20 years of development in the field of 3-D laser imaging. An overview of 3-D digitizing techniques is presented with an emphasis on commercial techniques and systems currently available. It covers some of the most important methods that have been developed, both at the National Research Council of Canada (NRC) and elsewhere, with a focus on commercial systems that are considered good representations of the key technologies that have survived the test of years. © 2004 SPIE and IS&T.

Review of 20 years of range sensor development

The Leap Motion Controller is a new device for hand gesture controlled user interfaces with declared sub-millimeter accuracy However, up to this point its capabilities in real environments have not been analyzed Therefore, this paper presents a first study of a Leap Motion Controller The main focus of attention is on the evaluation of the accuracy and repeatability For an appropriate evaluation, a novel experimental setup was developed making use of an industrial robot with a reference pen allowing a position accuracy of 02 mm Thereby, a deviation between a desired 3D position and the average measured positions below 02mmhas been obtained for static setups and of 12mmfor dynamic setups Using the conclusion of this analysis can improve the development of applications for the Leap Motion controller in the field of Human-Computer Interaction

Analysis of the Accuracy and Robustness of the Leap Motion Controller

Phase shifting algorithms for fringe projection profilometry: A review

Temporal phase unwrapping algorithms for fringe projection profilometry: A comparative review

We first provide an overview of 3-D shape measurement us- ing various optical methods. Then we focus on structured light tech- niques where various optical configurations, image acquisition tech- niques, data postprocessing and analysis methods and advantages and limitations are presented. Several industrial application examples are presented. Important areas requiring further R&D are discussed. Finally, a comprehensive bibliography on 3-D shape measurement is included, although it is not intended to be exhaustive. © 2000 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(00)00101-X)

Overview of three-dimensional shape measurement using optical methods

This paper reviews numerical methods and analysis procedures used in the study of automotive disc brake squeal. It covers two major approaches used in the automotive industry, the complex eigenvalue analysis and the transient analysis. The advantages and limitations of each approach are examined. This review can help analysts to choose right methods and make decisions on new areas of method development. It points out some outstanding issues in modelling and analysis of disc brake squeal and proposes new research topics. It is found that the complex eigenvalue analysis is still the approach favoured by the automotive industry and the transient analysis is gaining increasing popularity.

Numerical analysis of automotive disc brake squeal: a review

Chapters written by professional and academic experts in the field cover: analytical modeling and analysis, CEA modeling and numerical methods, techniques for dynamometer and road test evaluation, critical parameters that contribute to brake squeal, robust design processes to reduce/prevent brake squeal via up-front design, and more.

Disc Brake Squeal: Mechanism, Analysis, Evaluation, and Reduction/Prevention

In industry, there is a need for accurately measuring the 3-D shape of objects to speed up and ensure product development and manufacturing quality. There are a variety of applications of 3-D shape measurement, such as: control for intelligent robots, obstacle detection for vehicle guidance, dimension measurement for die development, stamping panel geometry checking, and accurate stress/ strain and vibration measurement. Moreover, automatic online inspection and recognition issues can be reduced to the 3-D shape measurement of, for example, body panel paint defects and dent inspection. The principles of triangulation, structured light, and interferometry have been in existence for decades. However, it is only with the recent availability of advanced and low cost computers, electro-optical elements, and lasers that such techniques have reached the breakthrough point to be commercialized, and ever increasingly be applied in industry. To make it even more acceptable in industry and to strive to achieve 10 to 10 accuracy, there are still some challenges that need to be addressed, such as: the shading issue, the specular surface headache, accurate data patching from different view directions, geometric parameter determination and calibration, absolute phase measurement, local and global coordinates tracking and transforming, real-time computing, sensor planing, and optimization. This special section is designed to promote research activity and to serve as a forum both for academia and industry. This special section includes a variety of development and application examples such as: optimization of an optical system which results in one part in 20,000 accuracy, new techniques using a diffraction grating or defocus to overcome the shading issue, direct digital wavefront reconstruction combined with wavelength scanning to attack the absolute phase measurement issue, and develop-

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Guest Editorial: Special Section on Optical Methods for Shape Measurement

Squeal simulation and analysis methods have been significantly advanced. Evaluation and testing technologies have been noticeably improved, and reduction remedies and prevention measures have become more mature. Brakes have become much quieter. However, the recurring occurrence of disk brake squeal indicates that there are still many challenges ahead, and brake squeal is still an elusive quality issue. This overview provides a summary of some recent and current developments and discusses remaining challenges along with future technologies. In addition, it emphasises the real-world counter-measures for squeal reduction, elimination and prevention.

Frank Chen

Papers

Overview of three-dimensional shape measurement using optical methods

Numerical analysis of automotive disc brake squeal: a review

Disc Brake Squeal: Mechanism, Analysis, Evaluation, and Reduction/Prevention

Guest Editorial: Special Section on Optical Methods for Shape Measurement

Automotive disk brake squeal: an overview