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Wave Theory of Image Formation and Resolution
Published in Bethe A. Scalettar, James R. Abney, Cyan Cowap, Introductory Biomedical Imaging, 2022
Bethe A. Scalettar, James R. Abney, Cyan Cowap
Diffraction in optical microscopy can have two distinct origins: (1) apertures, such as those in the objective, and (2) wavelength-sized structures in the specimen (Fig. 4.1). Apertures inevitably give rise to wave spreading that degrades image quality. Thus, when aberrations are negligible, resolution in optical microscopy is said to be “diffraction limited.” Specimen details can give rise to diffraction “spots,” or “orders,” that encode information about the structure of the specimen, similar to the case of crystallography. We consider effects of apertures first and discuss specimen-derived diffraction in the context of Abbe Theory in Section 4.2.
Metrology for Nanolithography
Published in Bruce W. Smith, Kazuaki Suzuki, Microlithography, 2020
As suggested previously in the discussion on “super-resolution” image processing techniques and as E.H. Singhe indeed suggested over 75 years ago, the diffraction limit in optical microscopy is not fundamental; rather, it arises from the assumption that a lens is used to focus a spot of light onto an object surface. If one introduces a spot of light onto an object’s surface by using a sub-wavelength aperture instead of a lens, the classical far-field diffraction limit does not apply and imaging beyond the Rayleigh limit is possible if the spacing between the aperture and the surface is much less than the illumination wavelength. For many years, it has been assumed that imaging could only occur with classical propagating mode solutions to Maxwell’s equations. However, imaging with the so-called “non-propagating” exponential (evanescent) modes is also possible. This rather non-conventional technique is referred to as “near-field” optical microscopy. In near-field optics, the evanescent decay of intensity with distance from a highly localized source or detector (i.e. tiny aperture) is utilized for the transduction of super-resolution information to far-field propagating modes that are detected.
Photoluminescence Spectroscopy of Single Semiconductor Quantum Dots
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Nowadays, the term super-resolution microscopy encompasses a class of methods with many acronyms derived from the two original wide-field methods of photo-activated localization microscopy, or PALM, and stochastic optical reconstruction microscopy, or STORM. The trick leading to “breaking” the diffraction limit lies in resolving the spatially unresolvable objects in time. A series of images, or frames, of the set of objects under study is taken, and in each frame, only some of these objects emit light, whereas the rest are off. Dedicated algorithms are then used to track the individual studied objects in the separate frames, and their position is determined with sub-diffraction-limit precision using a fitting procedure. Thus, as long as the areal density of the momentarily emitting objects is kept low, a super-resolved image can be superposed from the individual frames with spatial resolution typically in tens of nanometers, see Figure 21.15c,d.
Light, the universe and everything – 12 Herculean tasks for quantum cowboys and black diamond skiers
Published in Journal of Modern Optics, 2018
Girish Agarwal, Roland E. Allen, Iva Bezděková, Robert W. Boyd, Goong Chen, Ronald Hanson, Dean L. Hawthorne, Philip Hemmer, Moochan B. Kim, Olga Kocharovskaya, David M. Lee, Sebastian K. Lidström, Suzy Lidström, Harald Losert, Helmut Maier, John W. Neuberger, Miles J. Padgett, Mark Raizen, Surjeet Rajendran, Ernst Rasel, Wolfgang P. Schleich, Marlan O. Scully, Gavriil Shchedrin, Gennady Shvets, Alexei V. Sokolov, Anatoly Svidzinsky, Ronald L. Walsworth, Rainer Weiss, Frank Wilczek, Alan E. Willner, Eli Yablonovitch, Nikolay Zheludev
There is a second limitation on atom optics, which may seem surprising given the great advances in this area and its application towards atom interferometry. However, one key element has been missing: an aberration-corrected lens for atoms. This is a crucial component in optical imaging and in the electron microscope, providing diffraction-limited resolution. Recent work on a pulsed magnetic hexapole offers a solution to aberration-corrected atom imaging, and may enable the development of a neutral atom microscope with atomic resolution [52]. Imaging of atoms with this new approach is illustrated in Figure 24. The combination of nanoscale imaging with increased flux may also make it worth revisiting atom lithography.