Imaging Modes In Force Regulated Near Field Scanning Optical Microscopy

"This dissertation describes the force regulated near-field scanning optical microscope (NSOM) and two important adaptations: one for imaging polarization contrast with a linear response, and the other for interference imaging. An introduction to near- field optics is first presented, followed by a description of the background to this work that includes the relevant references to the literature and previous results. A simple theoretical description of the NSOM in terms of scalar fields is then presented, followed by an exposition of an early but relevant rigorous vectorial interpretation of the experiment. The basic force regulated NSOM is presented: its parts, operation, and construction is described and discussed, and its imaging capabilities are shown and discussed with results from different samples. In particular, the ability of the system to simultaneously image topographical and optical characteristics of the samples is described, and the importance of separating the optical and topographical information for the correct operation of the microscope is stressed. An adaptation to the basic NSOM that permits imaging sample-dependent polarization variations with sub-wavelength resolution and with a linear sensitivity is then discussed and analyzed. Results are shown for several samples that include metal on quartz, magneto-optic media, and polymers. Lastly, an interferometric arrangement of the NSOM is presented that allows imaging of phase variations, as well as polarization variations, with a significant signal enhancement achieved with the use of a pseudo-heterodyning technique."--Abstract.

Scanning near-field optical microscopy (SNOM, also known as NSOM) is a new local probe technique with a resolving power of 10--50 nm. Not being limited by diffraction, near-field optics (NFO) opens new perspectives for optical characterization and the understanding of optical phenomena, in particular in biology, microelectronics and materials science. SNOM, after first demonstrations in '83/'84, has undergone a rapid development in the past two to four years. The increased interest has been largely stimulated by the wealth of optical properties that can be investigated and the growing importance of characterization on the nanometer scale in general. Examples include the use of fluorescence, birefrigence and plasmon effects for applications in particular in biology, microelectronics and materials science, to name just a few. This volume emerged from the first international meeting devoted exclusively to NFO, and comprises a complete survey of the 1992 activities in the field, in particular the variety of instrumental techniques that are currently being explored, the demonstration of the imaging capabilities as well as theoretical interpretations - a highly nontrivial task. The comprehensive collection of papers devoted to these and related subjects make the book a valuable tool for anybody interested in near-field optics.

For more than a century, microscopy has been a centerpiece of extraordinary discoveries in biology. Along the way, remarkable imaging tools have been developed allowing scientists to dissect the complexity of cellular processes at the nano length molecular scales. Nanoimaging: Methods and Protocols presents a diverse collection of microscopy techniques and methodologies that provides guidance to successfully image cellular molecular complexes at nanometer spatial resolution. The book's four parts cover: (1) light microscopy techniques with a special emphasis on methods that go beyond the classic diffraction-limited imaging; (2) electron microscopy techniques for high-resolution imaging of molecules, cells and tissues, in both two and three dimensions; (3) scanning probe microscopy techniques for imaging and probing macromolecular complexes and membrane surface topography; and (4) complementary techniques on correlative microscopy, soft x-ray tomography and secondary ion mass spectrometry imaging. Written in the successful format of the Methods in Molecular BiologyTM series, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step protocols, and notes on troubleshooting and avoiding known pitfalls. Authoritative and accessible, Nanoimaging: Methods and Protocols highlights many of the most exciting possibilities in microscopy for the investigation of biological structures at the nano length molecular scales.

Making a clear distinction is made between nano- and micro-mechanical testing for physical reasons, this monograph describes the basics and applications of the supermicroscopies AFM and SNOM, and of the nanomechanical testing on rough and technical natural surfaces in the submicron range down to a lateral resolution of a few nm. New or improved instrumentation, new physical laws and unforeseen new applications in all branches of natural sciences (around physics, chemistry, mineralogy, materials science, biology and medicine) and nanotechnology are covered as well as the sources for pitfalls and errors. It outlines the handling of natural and technical samples in relation to those of flat standard samples and emphasizes new special features. Pitfalls and sources of errors are clearly demonstrated as well as their efficient remedy when going from molecularly flat to rough surfaces. The academic or industrial scientist learns how to apply the principles for tackling their scientific or manufacturing tasks that include roughness far away from standard samples.

ABSTRACT: A technique allowing for phase contrast imaging with a near-field scanning optical microscope is discussed. Background theory relating to near-field scanning optical microscopy (NSOM) is presented, in addition to relevant aspects of interferometry. A brief discussion of currently available methods for phase contrast imaging in both near-field and far-field microscopy is presented. Theory regarding the proposed technique, which exploits the interference of electrooptically modulated light and a conventional NSOM signal, is discussed in detail. Phase data using the proposed technique in a simplified configuration is presented to validate its effectiveness. The experimental arrangement used for data collection is specified. Finally, phase data obtained using the proposed technique in conjunction with a near-field microscope is examined and assessed in comparison with the results expected from prior knowledge of the sample under study.

This book contains the most recent information on optical nanoscopy. Far-Field and Near-Field properties on e.m. waves are presented which illustrate how optical images can be obtained from sub-micron objects. Scanning Probe techniques and computer processing are covered here. An explanation is given on how propagating photons or evanescent waves can behave over distances shorter than the wavelength, taking into account the presence of small objects. Quantum tunneling of photons is explained comparatively with the electron mechanism. Technical details are given on photon tunneling microscopes. Typical results already obtained with these techniques are also described.

Scientists and engineers have long relied on the power of imaging techniques to help see objects invisible to the naked eye, and thus, to advance scientific knowledge. These experts are constantly pushing the limits of technology in pursuit of chemical imagingâ€"the ability to visualize molecular structures and chemical composition in time and space as actual events unfoldâ€"from the smallest dimension of a biological system to the widest expanse of a distant galaxy. Chemical imaging has a variety of applications for almost every facet of our daily lives, ranging from medical diagnosis and treatment to the study and design of material properties in new products. In addition to highlighting advances in chemical imaging that could have the greatest impact on critical problems in science and technology, Visualizing Chemistry reviews the current state of chemical imaging technology, identifies promising future developments and their applications, and suggests a research and educational agenda to enable breakthrough improvements.

Conventional optical science and technology have been restricted by the diffraction limit from reducing the sizes of optical and photoruc devices to nanometric dimensions. Thus, the size of optical integrated circuits has been incompatible with that of their counterpart, integrated electronic circuits, which have much smaller dimensions. This book provides potential ideas and methods to overcome this difficulty. Near-field optics has developed very rapidly from around the middle 1980s after preliminary trials in the microwave frequency region, as proposed as early as 1928. At the early stages of this development, most technical efforts were devoted to realizing super-high-resolution optical microscopy beyond the diffraction limit. However, the possibility of exploiting the optical near-field, phenomenon of quasistatic electromagnetic interaction at subwavelength distances between nanometric particles has opened new ways to nanometric optical science and technology, and many applications to nanometric fabrication and manipulation have been proposed and implemented. Building on this historical background, this book describes recent progress in near-field optical science and technology, mainly using research of the author's groups. The title of this book, Near-Field Nano-Optics-From Basic Principles to Nano-Fabrication and Nano-Photonics, implies capabilities of the optical near field not only for imaging/microscopy, but also for fabrication/manipulation/proc essing on a nanometric scale.