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

Thank you for reading principles of optics electromagnetic theory of propagation interference and diffraction of light. As you may know, people have search hundreds times for their favorite novels like this principles of optics electromagnetic theory of propagation interference and diffraction of light, but end up in harmful downloads. Rather than enjoying a good book with a cup of coffee in the afternoon, instead they are facing with some infectious bugs inside their computer.

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

Two-photon excitation provides a means of activating chemical or physical processes with high spatial resolution in three dimensions and has made possible the development of three-dimensional fluorescence imaging, optical data storage, and lithographic microfabrication. These applications take advantage of the fact that the two-photon absorption probability depends quadratically on intensity, so under tight-focusing conditions, the absorption is confined at the focus to a volume of order λ3 (where λ is the laser wavelength). Any subsequent process, such as fluorescence or a photoinduced chemical reaction, is also localized in this small volume. Although three-dimensional data storage and microfabrication have been illustrated using two-photon-initiated polymerization of resins incorporating conventional ultraviolet-absorbing initiators, such photopolymer systems exhibit low photosensitivity as the initiators have small two-photon absorption cross-sections (δ). Consequently, this approach requires high laser power, and its widespread use remains impractical. Here we report on a class of π;-conjugated compounds that exhibit large δ (as high as 1, 250 × 10−50 cm4 s per photon) and enhanced two-photon sensitivity relative to ultraviolet initiators. Two-photon excitable resins based on these new initiators have been developed and used to demonstrate a scheme for three-dimensional data storage which permits fluorescent and refractive read-out, and the fabrication of three-dimensional micro-optical and micromechanical structures, including photonic-bandgap-type structures.

Two-photon polymerization initiators for three-dimensional optical data storage and microfabrication

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

Course Description This is an advanced course in which we explore the field of Statistical Optics. Topics covered include such subjects as the statistical properties of natural (thermal) and laser light, spatial and temporal coherence, effects of partial coherence on optical imaging instruments, effects on imaging due to randomly inhomogeneous media, and a statistical treatment of the detection of light. Development of this more comprehensive model of the behavior of light draws upon the use of tools traditionally available to the electrical engineer, such as linear system theory and the theory of stochastic processes.

http://ieeexplore.ieee.org/iel5/3/23094/01073023.pdf

Statistical optics

An optical arrangement has an imaging system between an array space and object space, in which the imaging system has at least one separate array objective (8) with a focusing plane in the face facing away from the array space, and an object axis. The arrangement in the array space has a line or matrix with at least two light detecting and/or light emitting elements or sub-matrices with light detecting and/or light emitting or illuminating elements. In the focusing plane on the side of the array objective facing away from the array space, or in a plane conjugated to this focus plane, at least one further optical element is arranged which is designed as a detractive optical element (DOE) and which combines and/or divides bundles of rays from the light detecting and/or light emitting elements in the array space, which is located in the array space in different lateral positions, by light diffraction in different orders. An independent claim is included for an optical imaging method.

Arrangement for simultaneous multi-focal optical imaging e.g. for microscopy, macroscopy and digital photography, use imaging system with single array objective having focus plane in array space

Modern products are becoming more miniaturised, more complex and have an increasing number of functionalities. The critical dimensions of structures written in silicon are becoming considerably smaller than the wavelength of the applied light source and this trend is to be sustained for the coming years until the next-generation patterning using extreme UV is implemented. As the feature sizes are decreasing, so the theoretical and practical constraints of making them and ensuring their quality are increasing. The same holds true for other industrial branches such as machine construction and automotive engineering where the surface-quality requirements of critical components and the overall complexity of the products have dramatically grown over the past few years. Consequently, modern production and inspection technologies are confronted with a bundle of challenges. In this paper at first the mentioned challenges and the physical limitations are addressed. Afterwards some modern approaches are discussed such as active wave front control, model based metrology and intelligent sensor fusion. On example of the inspection of non-resolved semiconductor structures and micro components new practical ways to cope with the mentioned challenges are presented.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Different approaches to overcome existing limits in optical micro- and nano-metrology

The measurement of aspheres and freeforms poses several challenges to interferometric and other optical testing methods which are well established for spherical surfaces. Accuracy, measurement time and flexibility are requirements encountered in a production environment. The approach of tilted-wave-interferometry is to illuminate the specimen with a whole ensemble of wavefronts. Each of these wavefronts has a different amount of tilt with respect to the optical axis. The surface under test is completely covered by interferogram patches where rays from one source hit the surface such that resolvable fringe densities result. Yet, one still deviates from the null setup which requires that the interferometer is calibrated precisely. This is obtained by recording interferograms of a known reference object placed in the test space. The aberrations of the interferometer are described within a black box model. A sophisticated set of algorithms is used to reconstruct these coefficients with high accuracy. The non-null configuration prohibits a direct evaluation of the measurement from the interferograms. Instead, the surface is reconstructed by the solution of an inverse problem. A second step gives access to the remaining high-frequency errors. The key ideas and implementations in the process of measurement and calibration are explained and the differences to other common concepts in optical testing are elaborated. As an example, results of a freeform measurement, including both form and high-frequent deviations from design, are discussed.

The tilted-wave-interferometer: freeform surface reconstruction in a non-null setup

In microscopy it is customary to use a wide variety of imaging methods. Unfortunately, for most of these it is
necessary to physically change the setup (filters, special objectives, etc.). We present a programmable microscope
in which an integrated spatial light modulator (SLM) is incorporated in order to realize a number of otherwise
physically intricate modifications. We employ a HDTV LCOS SLM (Holoeye Pluto, 1920x1080 pixel, 8 μm pixel
pitch), 2 different LED illuminations in reflection and transmission, an Olympus UmPlanFl 50x objective with
a NA of 0.8 and a CCD camera (SVS-Vistek eco204 1/3") with 1024x768 resolution. By the use of computer
generated holograms (CGHs) we are able to recreate a number of classical phase contrast imaging techniques
such as Zernike phase contrast or DIC, and modify them in unconventional ways. Additionally, the SLM enables
us to compensate various kinds of aberrations. Other imaging methods like stereovision for three dimensional
object reconstruction on a microscopic scale, structured illumination or confocal microscopy are also possible if
the setup is extended to a state in which not only the imaging light but also the illumination light is propagated
over an SLM with a CGH.

SLM-based microscopy

We present an optically addressed non-pixelated spatial light modulator. The system is based on reversible photoalignment of a LC cell using a red light sensitive novel azobenzene photoalignment layer. It is an electrode-free device that manipulates the liquid crystal orientation and consequently the polarization via light without artifacts caused by electrodes. The capability to miniaturize the spatial light modulator allows the integration into a microscope objective. This includes a miniaturized 200 channel optical addressing system based on a VCSEL array and hybrid refractive-diffractive beam shapers. As an application example, the utilization as a microscope objective integrated analog phase contrast modulator is shown.

Wolfgang Osten

Papers

Arrangement for simultaneous multi-focal optical imaging e.g. for microscopy, macroscopy and digital photography, use imaging system with single array objective having focus plane in array space

Different approaches to overcome existing limits in optical micro- and nano-metrology

The tilted-wave-interferometer: freeform surface reconstruction in a non-null setup

SLM-based microscopy

Optically addressed modulator for tunable spatial polarization control