Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye. There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy.
A microscope is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisible to the eye unless aided by a microscope.
A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample. The electron beam is scanned in a raster scan pattern, and the position of the beam is combined with the intensity of the detected signal to produce an image. In the most common SEM mode, secondary electrons emitted by atoms excited by the electron beam are detected using a secondary electron detector. The number of secondary electrons that can be detected, and thus the signal intensity, depends, among other things, on specimen topography. Some SEMs can achieve resolutions better than 1 nanometer.
The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century. Basic optical microscopes can be very simple, although many complex designs aim to improve resolution and sample contrast.
Atomic force microscopy (AFM) or scanning force microscopy (SFM) is a very-high-resolution type of scanning probe microscopy (SPM), with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit.
A synchrotron light source is a source of electromagnetic radiation (EM) usually produced by a storage ring, for scientific and technical purposes. First observed in synchrotrons, synchrotron light is now produced by storage rings and other specialized particle accelerators, typically accelerating electrons. Once the high-energy electron beam has been generated, it is directed into auxiliary components such as bending magnets and insertion devices in storage rings and free electron lasers. These supply the strong magnetic fields perpendicular to the beam that are needed to stimulate the high energy electrons to emit photons.
Photoemission electron microscopy is a type of electron microscopy that utilizes local variations in electron emission to generate image contrast. The excitation is usually produced by ultraviolet light, synchrotron radiation or X-ray sources. PEEM measures the coefficient indirectly by collecting the emitted secondary electrons generated in the electron cascade that follows the creation of the primary core hole in the absorption process. PEEM is a surface sensitive technique because the emitted electrons originate from a shallow layer. In physics, this technique is referred to as PEEM, which goes together naturally with low-energy electron diffraction (LEED), and low-energy electron microscopy (LEEM). In biology, it is called photoelectron microscopy (PEM), which fits with photoelectron spectroscopy (PES), transmission electron microscopy (TEM), and scanning electron microscopy (SEM).
An X-ray microscope uses electromagnetic radiation in the X-ray band to produce magnified images of objects. Since X-rays penetrate most objects, there is no need to specially prepare them for X-ray microscopy observations.
Focused ion beam, also known as FIB, is a technique used particularly in the semiconductor industry, materials science and increasingly in the biological field for site-specific analysis, deposition, and ablation of materials. A FIB setup is a scientific instrument that resembles a scanning electron microscope (SEM). However, while the SEM uses a focused beam of electrons to image the sample in the chamber, a FIB setup uses a focused beam of ions instead. FIB can also be incorporated in a system with both electron and ion beam columns, allowing the same feature to be investigated using either of the beams. FIB should not be confused with using a beam of focused ions for direct write lithography. These are generally quite different systems where the material is modified by other mechanisms.
X-ray optics is the branch of optics that manipulates X-rays instead of visible light. It deals with focusing and other ways of manipulating the X-ray beams for research techniques such as X-ray diffraction, X-ray crystallography, X-ray fluorescence, small-angle X-ray scattering, X-ray microscopy, X-ray phase-contrast imaging, and X-ray astronomy.
ALBA is a 3 GeV, third-generation synchrotron light source facility located in the Barcelona Synchrotron Park in Cerdanyola del Vallès near Barcelona, in Catalonia (Spain). It was constructed and is operated by CELLS, and co-financed by the Spanish central administration and regional Catalan Government.
High-resolution transmission electron microscopy is an imaging mode of specialized transmission electron microscopes that allows for direct imaging of the atomic structure of samples. It is a powerful tool to study properties of materials on the atomic scale, such as semiconductors, metals, nanoparticles and sp2-bonded carbon. While this term is often also used to refer to high resolution scanning transmission electron microscopy, mostly in high angle annular dark field mode, this article describes mainly the imaging of an object by recording the two-dimensional spatial wave amplitude distribution in the image plane, similar to a "classic" light microscope. For disambiguation, the technique is also often referred to as phase contrast transmission electron microscopy, although this term is less appropriate. At present, the highest point resolution realised in high resolution transmission electron microscopy is around 0.5 ångströms (0.050 nm). At these small scales, individual atoms of a crystal and defects can be resolved. For 3-dimensional crystals, it is necessary to combine several views, taken from different angles, into a 3D map. This technique is called electron tomography.
The European X-Ray Free-Electron Laser Facility is an X-ray research laser facility commissioned during 2017. The first laser pulses were produced in May 2017 and the facility started user operation in September 2017. The international project with twelve participating countries; nine shareholders at the time of commissioning, later joined by three other partners, is located in the German federal states of Hamburg and Schleswig-Holstein. A free-electron laser generates high-intensity electromagnetic radiation by accelerating electrons to relativistic speeds and directing them through special magnetic structures. The European XFEL is constructed such that the electrons produce X-ray light in synchronisation, resulting in high-intensity X-ray pulses with the properties of laser light and at intensities much brighter than those produced by conventional synchrotron light sources.
Ptychography is a computational method of microscopic imaging. It generates images by processing many coherent interference patterns that have been scattered from an object of interest. Its defining characteristic is translational invariance, which means that the interference patterns are generated by one constant function moving laterally by a known amount with respect to another constant function. The interference patterns occur some distance away from these two components, so that the scattered waves spread out and "fold" into one another as shown in the figure.
A Low-voltage electron microscope (LVEM) is an electron microscope which operates at accelerating voltages of a few kiloelectronvolts (keV) or less. Traditional electron microscopes use accelerating voltages in the range of 10-1000 keV.
The technique of vibrational analysis with scanning probe microscopy allows probing vibrational properties of materials at the submicrometer scale, and even of individual molecules. This is accomplished by integrating scanning probe microscopy (SPM) and vibrational spectroscopy. This combination allows for much higher spatial resolution than can be achieved with conventional Raman/FTIR instrumentation. The technique is also nondestructive, requires non-extensive sample preparation, and provides more contrast such as intensity contrast, polarization contrast and wavelength contrast, as well as providing specific chemical information and topography images simultaneously.
Scanning transmission X-ray microscopy (STXM) is a type of X-ray microscopy in which a zone plate focuses an X-ray beam onto a small spot, a sample is scanned in the focal plane of the zone plate and the transmitted X-ray intensity is recorded as a function of the sample position. A stroboscopic scheme is used where the excitation is the pump and the synchrotron X-ray flashes are the probe. X-ray microscopes work by exposing a film or charged coupled device detector to detect X-rays that pass through the specimen. The image formed is of a thin section of specimen. Newer X-ray microscopes use X-ray absorption spectroscopy to heterogeneous materials at high spatial resolution. The essence of the technique is a combination of spectromicroscopy, imaging with spectral sensitivity, and microspectroscopy, recording spectra from very small spots.
The scanning helium microscope (SHeM) is a form of microscopy that uses low-energy (5–100 meV) neutral helium atoms to image the surface of a sample without any damage to the sample caused by the imaging process. Since helium is inert and neutral, it can be used to study delicate and insulating surfaces. Images are formed by rastering a sample underneath an atom beam and monitoring the flux of atoms that are scattered into a detector at each point.
SOLARIS is a synchrotron light source in the city of Kraków in Poland. It is the only one facility of its kind in Central-Eastern Europe. Built in 2015, under the auspices of the Jagiellonian University, it is located on the Campus of the 600th Anniversary of the Jagiellonian University Revival, in the southern part of the city. It is the central facility of the National Synchrotron Radiation Centre SOLARIS.
Carolyn Larabell is an American scientist that led the first construction and commissioning of a soft x-ray microscope to be used for biological imaging Her research primarily focuses on X-ray microtomography, a technology that allows for a 3D visualization of different cells. Larabell is a joint anatomy professor at the University of California, San Francisco and both the founder and director of the National Center for X-ray Tomography.
