query: where would phase contrast microscopy improve image quality

pos: Phase-contrast microscopy sensitive to amplitude variations. Without special arrangements, phase changes are therefore invisible. Yet, phase changes often carry important information. Phase-contrast microscopy is particularly important in biology. It reveals many cellular structures that are not visible with a simpler bright-field microscope, as exemplified in the figure. These structures were made visible to earlier microscopists by staining, but this required additional preparation and thus killing the cells. The phase-contrast microscope made it possible for biologists to study living cells and how they proliferate through cell division. After its invention in the early 1930s, phase-contrast microscopy proved to be such an advancement in

neg: Transmission electron microscopy a Beer's law effect). Instead, the sample can be modeled as an object that does not change the amplitude of the incoming electron wave function, but instead modifies the phase of the incoming wave; in this model, the sample is known as a pure phase object. For sufficiently thin specimens, phase effects dominate the image, complicating analysis of the observed intensities. To improve the contrast in the image, the TEM may be operated at a slight defocus to enhance contrast, owing to convolution by the contrast transfer function of the TEM, which would normally decrease contrast if the sample was

neg: Phase-contrast microscopy polarizing plastic containers in cell biology, DIC microscopy is increasingly replaced by Hoffman modulation contrast microscopy, invented by Robert Hoffman in 1975. Traditional phase-contrast methods enhance contrast optically, blending brightness and phase information in single image. Since the introduction of the digital camera in the mid-1990s, several new digital phase-imaging methods have been developed, collectively known as quantitative phase-contrast microscopy. These methods digitally create two separate images, an ordinary bright-field image and a so-called "phase-shift image". In each image point, the phase-shift image displays the "quantified" phase shift induced by the object, which is proportional to the optical thickness of

neg: Quantitative phase-contrast microscopy as digital holographic microscopy, holographic interference microscopy and digital in-line holographic microscopy. Common to these methods is that an interference pattern (hologram) is recorded by a digital image sensor. From the recorded interference pattern, the intensity and the phase shift image is numerically created by a computer algorithm. Conventional phase contrast microscopy is primarily used to observed unstained living cells. Measuring the phase delay images of biological cells provides quantitative information about the morphology and the drymass of individual cells. Contrary to conventional phase contrast images, phase shift images of living cells are suitable to be processed by image analysis

neg: Digital holographic microscopy same way as traditional light microscopy. However, DHM offers a superb axial (depth) resolution. An axial accuracy of approximately 5 nm has been reported. "Phase shift images" Besides the ordinary bright field image, a phase shift image is created as well. The phase shift image is unique for digital holographic microscopy and gives quantifiable information about optical distance. In reflection DHM, the phase shift image forms a topography image of the object. Transparent objects, like living biological cells, are traditionally viewed in a phase contrast microscope or in a differential interference contrast microscope. These methods visualize phase shifting transparent objects

neg: Digital holographic microscopy by distorting the bright field image with phase shift information. Instead of distorting the bright field image, transmission DHM creates a separate phase shift image showing the optical thickness of the object. Digital holographic microscopy thus makes it possible to visualize and quantify transparent objects and is therefore also referred to as quantitative phase contrast microscopy. Traditional phase contrast or bright field images of living unstained biological cells, Figure 3 (right), have proved themselves to be very difficult to analyze with image analysis software. On the contrary, phase shift images, Figure 3 (left), are readily segmented and analyzed by image

neg: Live cell imaging phototoxic, invasive and bleach when observed. This limits their use when observing living cells over extended periods of time. Non-invasive phase contrast techniques are therefore often used as a vital complement to fluorescent microscopy in live cell imaging applications. As a result of the rapid increase in pixel density of digital image sensors, quantitative phase contrast microscopy has emerged as an alternative microscopy method for live cell imaging. Quantitative phase contrast microscopy has an advantage over fluorescent and phase contrast microscopy in that it is both non-invasive and quantitative in its nature. Contrary to phase contrast images, quantitative phase contrast

neg: Refractive index is done using Zernike phase-contrast microscopy, differential interference contrast microscopy (DIC) or interferometry. Zernike phase-contrast microscopy introduces a phase shift to the low spatial frequency components of the image with a phase-shifting annulus in the Fourier plane of the sample, so that high-spatial-frequency parts of the image can interfere with the low-frequency reference beam. In DIC the illumination is split up into two beams that are given different polarizations, are phase shifted differently, and are shifted transversely with slightly different amounts. After the specimen, the two parts are made to interfere, giving an image of the derivative of the optical

neg: Quantitative phase-contrast microscopy transforming phase shift gradients into intensity variations. These intensity variations are mixed with other intensity variations, making it difficult to extract quantitative information. Quantitative phase contrast methods are distinguished from other phase contrast methods in that they create a second so-called "phase shift image" or "phase image", independent of the intensity (bright field) image. Phase unwrapping methods are generally applied to the phase shift image to give absolute phase shift values in each pixel, as exemplified by Figure 1. The principal methods for measuring and visualizing phase shifts include ptychography, Fourier ptychography, and various types of holographic microscopy methods such

neg: Phase-contrast microscopy light will then be subtracted from the background light to form an image with a darker foreground and a lighter background, as shown in the first figure. The success of the phase-contrast microscope has led to a number of subsequent phase-imaging methods. In 1952 Georges Nomarski patented what is today known as differential interference contrast (DIC) microscopy. It enhances contrast by creating artificial shadows, as if the object is illuminated from the side. But DIC microscopy and phase contrast microscopy both use polarized light, which is unsuitable when the object or its container alter polarization. With the growing use of

neg: Phase-contrast microscopy the object. Phase-contrast microscopy Phase-contrast microscopy is an optical microscopy technique that converts phase shifts in light passing through a transparent specimen to brightness changes in the image. Phase shifts themselves are invisible, but become visible when shown as brightness variations. When light waves travel through a medium other than vacuum, interaction with the medium causes the wave amplitude and phase to change in a manner dependent on properties of the medium. Changes in amplitude (brightness) arise from the scattering and absorption of light, which is often wavelength-dependent and may give rise to colors. Photographic equipment and the human eye

neg: Phase-contrast microscopy Phase-contrast microscopy Phase-contrast microscopy is an optical microscopy technique that converts phase shifts in light passing through a transparent specimen to brightness changes in the image. Phase shifts themselves are invisible, but become visible when shown as brightness variations. When light waves travel through a medium other than vacuum, interaction with the medium causes the wave amplitude and phase to change in a manner dependent on properties of the medium. Changes in amplitude (brightness) arise from the scattering and absorption of light, which is often wavelength-dependent and may give rise to colors. Photographic equipment and the human eye are only

neg: Differential interference contrast microscopy Differential interference contrast microscopy Differential interference contrast (DIC) microscopy, also known as Nomarski interference contrast (NIC) or Nomarski microscopy, is an optical microscopy technique used to enhance the contrast in unstained, transparent samples. DIC works on the principle of interferometry to gain information about the optical path length of the sample, to see otherwise invisible features. A relatively complex optical system produces an image with the object appearing black to white on a grey background. This image is similar to that obtained by phase contrast microscopy but without the bright diffraction halo. The technique was developed by Polish physicist Georges

neg: Holographic interference microscopy interference microscopy were worked out and applied for phase micro-object study in the 1980s. In the late 1990s, a computer began to be used for 3D imaging of phase micro-objects by their interferograms. 3D images were obtained for the first time when investigating blood erythrocytes. And from the beginning of the 21st century, holographic interference microscopy has become digital holographic interference microscopy. Digital holographic interference microscopy (DHIM) is a combination of the holographic interference microscopy with digital methods of image processing for 3D imaging of phase micro-objects. The holographic phase-contrast or interference-contrast images (interferograms) are recorded by a digital camera

neg: Dark-field microscopy and hence phase gradients, which provide quantitative information on vector lattice strain. Dark-field microscopy Dark-field microscopy (also called dark-ground microscopy) describes microscopy methods, in both light and electron microscopy, which exclude the unscattered beam from the image. As a result, the field around the specimen (i.e., where there is no specimen to scatter the beam) is generally dark. In optical microscopy, dark-field describes an illumination technique used to enhance the contrast in unstained samples. It works by illuminating the sample with light that will not be collected by the objective lens and thus will not form part of the image.

neg: Hoffman modulation contrast microscopy Nikon Advanced Modulation Contrast (NAMC), Olympus Relief Contrast (RC) and Leica's integrated Hoffman Modulation Contrast (iMC). Hoffman modulation contrast microscopy Hoffman modulation contrast microscopy (HMC microscopy) is an optical microscopy technique for enhancing the contrast in unstained biological specimens. The technique was invented by Robert Hoffman in 1975. Like differential interference contrast microscopy (DIC microscopy), contrast is increased by using components in the light path which convert phase gradients in the specimen into differences in light intensity that are rendered in an image that appears three-dimensional. The 3D appearance may be misleading, as a feature which appears to cast a

neg: Hoffman modulation contrast microscopy Hoffman modulation contrast microscopy Hoffman modulation contrast microscopy (HMC microscopy) is an optical microscopy technique for enhancing the contrast in unstained biological specimens. The technique was invented by Robert Hoffman in 1975. Like differential interference contrast microscopy (DIC microscopy), contrast is increased by using components in the light path which convert phase gradients in the specimen into differences in light intensity that are rendered in an image that appears three-dimensional. The 3D appearance may be misleading, as a feature which appears to cast a shadow may not necessarily have a distinct physical geometry corresponding to the shadow. The technique is

neg: Holographic interference microscopy phase-contrast method is the holographic interference microscopy technique for phase micro-object visualization that converts the phase shifts inserted by the micro-object to the wave of light passed through it into intensity changes in the image. The method is based on the holographic addition (constructive interference) or holographic subtraction (destructive interference) of the “empty” wave reconstructed from the hologram, and the object wave disturbed by the phase micro-objects under study. The image can be considered as interferogram in interference fringes of infinite width. The method solves the same problem as does F. Zernike phase contrast method. But in comparison with F.

neg: Holographic interference microscopy quality control. Holographic interference microscopy Holographic interference microscopy (HIM) is holographic interferometry applied for microscopy for visualization of phase micro-objects. Phase micro-objects are invisible because they do not change intensity of light, they insert only invisible phase shifts. The holographic interference microscopy distinguishes itself from other microscopy methods by using a hologram and the interference for converting invisible phase shifts into intensity changes. Other related microscopy method to holographic interference microscopy are phase contrast microscopy, holographic interferometry. Holography was born as "new microscopy principle". D. Gabor invented holography for electron microscopy.For some reasons his idea is not applied in this

neg: Contrast transfer function Contrast transfer function The contrast transfer function (CTF) mathematically describes how aberrations in a transmission electron microscope (TEM) modify the image of a sample. This contrast transfer function (CTF) sets the resolution of high-resolution transmission electron microscopy (HRTEM), also known as phase contrast TEM. By considering the recorded image as a CTF-degraded true object, describing the CTF allows the true object to be reverse-engineered. This is typically denoted CTF-correction, and is vital to obtain high resolution structures in three-dimensional electron microscopy, especially cryo-electron microscopy. Its equivalent in light-based optics is the optical transfer function. The contrast in HRTEM comes from

neg: Phase-contrast imaging Phase-contrast imaging Phase-contrast imaging is a method of imaging that has a range of different applications. It exploits differences in the refractive index of different materials to differentiate between structures under analysis. In conventional light microscopy, phase contrast can be employed to distinguish between structures of similar transparency, and to examine crystals on the basis of their double refraction. This has uses in biological, medical and geological science. In X-ray tomography, the same physical principles can be used to increase image contrast by highlighting small details of differing refractive index within structures that are otherwise uniform. In transmission electron microscopy

neg: Differential interference contrast microscopy phase contrast. However analysis of DIC images must always take into account the orientation of the Wollaston prisms and the apparent lighting direction, as features parallel to this will not be visible. This is, however, easily overcome by simply rotating the sample and observing changes in the image. Differential interference contrast microscopy Differential interference contrast (DIC) microscopy, also known as Nomarski interference contrast (NIC) or Nomarski microscopy, is an optical microscopy technique used to enhance the contrast in unstained, transparent samples. DIC works on the principle of interferometry to gain information about the optical path length of the sample, to

neg: Optical microscope to manage the quality and intensity of the illumination. For illumination techniques like dark field, phase contrast and differential interference contrast microscopy additional optical components must be precisely aligned in the light path. The actual power or magnification of a compound optical microscope is the product of the powers of the ocular (eyepiece) and the objective lens. The maximum normal magnifications of the ocular and objective are 10× and 100× respectively, giving a final magnification of 1,000×. When using a camera to capture a micrograph the effective magnification of the image must take into account the size of the image.

neg: Quantitative phase-contrast microscopy Quantitative phase-contrast microscopy Quantitative phase contrast microscopy is the collective name for a group of microscopy methods that quantify the phase shift that occurs when light waves pass through a more optically dense object. Translucent objects, like a living human cell, absorb and scatter small amounts of light. This makes translucent objects difficult to observe in ordinary light microscopes. Such objects do, however, induce a phase shift that can be observed using a phase contrast microscope. Conventional phase contrast microscopy and related methods, such as differential interference contrast microscopy, quantitative phase microscopy, or digital holographic microscopy, visualize phase shifts by

neg: Classical interference microscopy Classical interference microscopy Classical interference microscopy (also referred to as quantitative interference microscopy) uses two separate light beams with much greater lateral separation than that used in phase contrast microscopy or in differential interference microscopy (DIC). In variants of the interference microscope where object and reference beam pass through the same objective, two images are produced of every object (one being the "ghost image"). The two images are separated either laterally within the visual field or at different focal planes, as determined by the optical principles employed. These two images can be a nuisance when they overlap, since they can

neg: High-resolution transmission electron microscopy image plane, in analogy to a "classic" light microscope. For disambiguation, the technique is also often referred to as phase contrast TEM. At present, the highest point resolution realised in phase contrast TEM is around . At these small scales, individual atoms of a crystal and its defects can be resolved. For 3-dimensional crystals, it may be necessary to combine several views, taken from different angles, into a 3D map. This technique is called electron crystallography. One of the difficulties with HRTEM is that image formation relies on phase contrast. In phase-contrast imaging, contrast is not necessarily intuitively interpretable, as

neg: Phase-contrast microscopy is weak and typically phase-shifted by −90° (due to both the typical thickness of specimens and the refractive index difference between biological tissue and the surrounding medium) relative to the background light. This leads to the foreground (blue vector) and background (red vector) having nearly the same intensity, resulting in low image contrast. In a phase-contrast microscope, image contrast is increased in two ways: by generating constructive interference between scattered and background light rays in regions of the field of view that contain the specimen, and by reducing the amount of background light that reaches the image plane. First, the

neg: Microscope viewing by eye or with specifically sensitive cameras. Phase contrast microscopy is an optical microscopy illumination technique in which small phase shifts in the light passing through a transparent specimen are converted into amplitude or contrast changes in the image. The use of phase contrast does not require staining to view the slide. This microscope technique made it possible to study the cell cycle in live cells. The traditional optical microscope has more recently evolved into the digital microscope. In addition to, or instead of, directly viewing the object through the eyepieces, a type of sensor similar to those used

neg: Microscopy occurs, resulting in the phase contrast image. One disadvantage of phase-contrast microscopy is halo formation (halo-light ring). Superior and much more expensive is the use of interference contrast. Differences in optical density will show up as differences in relief. A nucleus within a cell will actually show up as a globule in the most often used differential interference contrast system according to Georges Nomarski. However, it has to be kept in mind that this is an "optical effect", and the relief does not necessarily resemble the true shape. Contrast is very good and the condenser aperture can be used fully

neg: Holographic interference microscopy wave disturbed by the phase micro-objects so the system of straight interference fringes is obtained, which are deviated in the image of the micro-object. The image can be considered as an interferogram in the fringes of finite width. The deviation formula_11 of the interference fringe in a point of the image is linearly dependent on the phase shift formula_12 inserted in the corresponding point of the micro-object : formula_13, where formula_14 is the set period of the system of interference fringes.So, the interference-contrast image (interferogram) visualizes phase silhouette of the micro-object in the form of the deviated lines; and the

neg: Holographic interference microscopy allows measuring the phase shifts, and 3D images of the phase micro-objects can be reconstructed under computer processing of their phase-contrast images. The high sensitivity to vibrations is the main backgrounds of the method. It requires developing the hologram in its place. So, the method remains "exotic", and it is not widely applied. Holographic interference-contrast method is the holographic interference microscopy technique for phase micro-object visualization that converts the phase shifts inserted by the micro-object to the passed light wave light into deviations of interference fringes in its image. A certain angle is introduced between the “empty” wave and the

neg: Microscopy glass window: one sees not the glass but merely the dirt on the glass. There is a difference, as glass is a denser material, and this creates a difference in phase of the light passing through. The human eye is not sensitive to this difference in phase, but clever optical solutions have been devised to change this difference in phase into a difference in amplitude (light intensity). In order to improve specimen contrast or highlight certain structures in a sample, special techniques must be used. A huge selection of microscopy techniques are available to increase contrast or label a sample.

neg: Holographic interference microscopy wave disturbed by the phase micro-objects under study. The hologram of the "empty" object wave is recorded using a reference beam, and it is used as an optical element of the holographic interference microscope. In the dependence on conditions of the interference two methods of the holographic interference microscopy can be realized: the holographic phase-contrast method and the holographic interference-contrast method. In the first case, the phase shifts inserted by the phase micro-object into the light wave passing through it are converted into intensity changes in its image; and in the second case – into deviations of interference fringes. Holographic

neg: Imagine Optic mirrors to specifically address the phase correction in laser systems. Key points of this technology are the optical quality, the capacity of correction, great stability and linearity and simplified maintenance requirements. Aberrations induced by optical elements of a microscope and by biological samples distort the point spread function of the optical setup and significantly reduce the quality of the acquired images. Adaptive optics can correct these aberrations and considerably improve the contrast and resolution in different types of microscopy. The benefits of the use of Imagine Optic’s products have been demonstrated in single molecule super resolution methods, such as PALM/STORM

neg: Microscopy due to out of focus objects). Dark field microscopy is a technique for improving the contrast of unstained, transparent specimens. Dark field illumination uses a carefully aligned light source to minimize the quantity of directly transmitted (unscattered) light entering the image plane, collecting only the light scattered by the sample. Dark field can dramatically improve image contrast – especially of transparent objects – while requiring little equipment setup or sample preparation. However, the technique suffers from low light intensity in final image of many biological samples and continues to be affected by low apparent resolution. "Rheinberg illumination" is a special

neg: Microscopy employed. The image contrast is related to the sample's absorption coefficient formula_2. This is in contrast to bright or dark field microscopy, where the image contrast is due to transmittance or scattering. In principle, the contrast of fluorescence microscopy is proportional to the sample's absorption too. However, in fluorescence microscopy the fluorescence quantum yield formula_3 needs to be unequal to zero in order that a signal can be detected. In photoacoustic microscopy, however, every absorbing substance gives a photoacoustic signal formula_4 which is proportional to formula_5 Here formula_6 is the Grüneisen coefficient, formula_7 is the laser's photon energy and formula_8

neg: Quantitative phase-contrast microscopy software. This has led to the development of non-invasive live cell imaging and automated cell culture analysis systems based on quantitative phase contrast microscopy. Quantitative phase-contrast microscopy Quantitative phase contrast microscopy is the collective name for a group of microscopy methods that quantify the phase shift that occurs when light waves pass through a more optically dense object. Translucent objects, like a living human cell, absorb and scatter small amounts of light. This makes translucent objects difficult to observe in ordinary light microscopes. Such objects do, however, induce a phase shift that can be observed using a phase contrast microscope.

neg: Transmission electron microscopy By changing the strength of Intermediate lens, the Diffraction pattern is projected on a screen. Diffraction is a very powerful tool for doing a cell reconstruction and crystal orientation determination. The contrast between two adjacent areas in a TEM image can be defined as the difference in the electron densities in image plane. Due to the scattering of the incident beam by the sample, the amplitude and phase of the electron wave change, which results in amplitude contrast and phase contrast, correspondingly. Most of images have both contrast components. Amplitude–contrast is obtained due to removal of some electrons before the

neg: Optical microscope image of the sample. The Nobel Prize in physics was awarded to Dutch physicist Frits Zernike in 1953 for his development of phase contrast illumination which allows imaging of transparent samples. By using interference rather than absorption of light, extremely transparent samples, such as live mammalian cells, can be imaged without having to use staining techniques. Just two years later, in 1955, Georges Nomarski published the theory for differential interference contrast microscopy, another interference-based imaging technique. Modern biological microscopy depends heavily on the development of fluorescent probes for specific structures within a cell. In contrast to normal transilluminated light microscopy,

neg: Electron tomography secondary and tertiary structure of an individual protein or polypeptide. In the field of biology, bright-field transmission electron microscopy (BF-TEM) and high-resolution TEM (HRTEM) are the primary imaging methods for tomography tilt series acquisition. However, there are two issues associated with BF-TEM and HRTEM. First, acquiring an interpretable 3-D tomogram requires that the projected image intensities vary monotonically with material thickness. This condition is difficult to guarantee in BF/HRTEM, where image intensities are dominated by phase-contrast with the potential for multiple contrast reversals with thickness, making it difficult to distinguish voids from high-density inclusions. Second, the contrast transfer function of

neg: Phase-contrast imaging correction have enabled a new generation of HRTEMs to reach resolutions once thought impossible. Phase-contrast imaging Phase-contrast imaging is a method of imaging that has a range of different applications. It exploits differences in the refractive index of different materials to differentiate between structures under analysis. In conventional light microscopy, phase contrast can be employed to distinguish between structures of similar transparency, and to examine crystals on the basis of their double refraction. This has uses in biological, medical and geological science. In X-ray tomography, the same physical principles can be used to increase image contrast by highlighting small details

neg: Holographic interference microscopy Zernike phase contrast method, the method has some advantages. Due to equal intensities of the interfering waves, the holographic phase-contrast method allows obtaining maximal contrast of images. The sizes of the micro-object do not restrict the application of the method, though F. Zernike phase contrast method works the more successfully, the smaller the micro-object in thick and sizes. The image in the holographic phase-contrast method is the result of interaction of two identical waves, and it is free of aberrations. The method can be realized as the method of holographic addition and subtraction in an interference fringe. A small angle

neg: Digital holographic microscopy use of a reference wave front to obtain amplitude (intensity) "and" phase information. The information is recorded on a digital image sensor or by a photodetector from which an image of the object is created (reconstructed) by a computer. In traditional microscopy, which do not use a reference wave front, only intensity information is recorded and essential information about the object is lost. Holography was invented by Dennis Gabor to improve electron microscopy. Nevertheless, it never found many concrete and industrial applications in this field. Actually, DHM has mostly been applied to light microscopy. In this field, it has shown

neg: Phase telescope Phase telescope A phase telescope or Bertrand lens is an optical device used in aligning the various optical components of a light microscope. In particular it allows observation of the back focal plane of the objective lens and its conjugated focal planes. The phase telescope/Bertrand lens is inserted into the microscope in place of an eyepiece to move the intermediate image plane to a point where it can be observed. Phase telescopes are primarily used for aligning the optical components required for Köhler illumination and phase contrast microscopy. For Köhler illumination the light source and condenser diaphragm should appear in

neg: Differential interference contrast microscopy in complete destructive interference and an anomalous dark region; if the phase difference reached 360° (a full wavelength), it would produce complete constructive interference, creating an anomalous bright region. The image can be approximated (neglecting refraction and absorption due to the sample and the resolution limit of beam separation) as the differential of optical path length with respect to position across the sample along the shear, and so the differential of the refractive index (optical density) of the sample. The contrast can be adjusted using the offset phase, either by translating the objective Nomarski prism, or by a lambda/4 waveplate

neg: Microscopy image contrast on "flat" areas of interest where AFM images are limited in contrast. The combination of AFM-UFM allows a near field acoustic microscopic image to be generated. The AFM tip is used to detect the ultrasonic waves and overcomes the limitation of wavelength that occurs in acoustic microscopy. By using the elastic changes under the AFM tip, an image of much greater detail than the AFM topography can be generated. Ultrasonic force microscopy allows the local mapping of elasticity in atomic force microscopy by the application of ultrasonic vibration to the cantilever or sample. In an attempt to analyze

neg: Phase-contrast imaging Precambrian metazoan embryos from the Doushantuo Formation in China, allowing the internal structure of delicate microfossils to be imaged without destroying the original specimen. In the field of transmission electron microscopy, phase-contrast imaging may be employed to image columns of individual atoms. This ability arises from the fact that the atoms in a material diffract electrons as the electrons pass through them (the relative phases of the electrons change upon transmission through the sample), causing diffraction contrast in addition to the already present contrast in the transmitted beam. Phase-contrast imaging is the highest resolution imaging technique ever developed, and can

neg: Optical sectioning the wavelength, n the refractive index of the objective lens immersion media and NA the numerical aperture. In comparison, the lateral resolution can be approximated as: formula_2 Beyond increasing numerical aperture, there are few techniques available to improve optical sectioning in bright-field light microscopy. Most microscopes with oil immersion objectives are reaching the limits of numerical aperture possible due to refraction limits. Differential interference contrast (DIC) provides modest improvements to optical sectioning. In DIC the sample is effectively illuminated by two slightly offset light sources which then interfere to produce an image resulting from the phase differences of the two

neg: High-resolution transmission electron microscopy it undergoes further phase change and interferes as the image wave in the imaging plane (mostly a digital pixel detector like a CCD camera). It is important to realize, that the recorded image is NOT a direct representation of the samples crystallographic structure. For instance, high intensity might or might not indicate the presence of an atom column in that precise location (see simulation). The relationship between the exit wave and the image wave is a highly nonlinear one and is a function of the aberrations of the microscope. It is described by the "contrast transfer function". The phase contrast

neg: Köhler illumination condenser diaphragm (e.g. the annulus for phase contrast microscopy) should also appear in focus. Köhler illumination Köhler illumination is a method of specimen illumination used for transmitted and reflected light (trans- and epi-illuminated) optical microscopy. Köhler illumination acts to generate an extremely even illumination of the sample and ensures that an image of the illumination source (for example a halogen lamp filament) is not visible in the resulting image. Köhler illumination is the predominant technique for sample illumination in modern scientific light microscopy. It requires additional optical elements which are more expensive and may not be present in more basic

neg: Phase-contrast microscopy background light is phase-shifted by −90° by passing it through a phase-shift ring, which eliminates the phase difference between the background and the scattered light rays.When the light is then focused on the image plane (where a camera or eyepiece is placed), this phase shift causes background and scattered light rays originating from regions of the field of view that contain the sample (i.e., the foreground) to constructively interfere, resulting in an increase in the brightness of these areas compared to regions that do not contain the sample. Finally, the background is dimmed ~70-90% by a gray filter ring—this method

neg: Phase-contrast microscopy maximizes the amount of scattered light generated by the illumination (i.e., background) light, while minimizing the amount of illumination light that reaches the image plane. Some of the scattered light (which illuminates the entire surface of the filter) will be phase-shifted and dimmed by the rings, but to a much lesser extent than the background light (which only illuminates the phase-shift and gray filter rings). The above describes "negative phase contrast". In its "positive" form, the background light is instead phase-shifted by +90°. The background light will thus be 180° out of phase relative to the scattered light. The scattered

neg: Contrast transfer function not only interfere with the transmitted beam, but will also interfere with each other. This will produce second order diffraction intensities. Non-linear imaging theory is required to model these additional interference effects. Contrast transfer function The contrast transfer function (CTF) mathematically describes how aberrations in a transmission electron microscope (TEM) modify the image of a sample. This contrast transfer function (CTF) sets the resolution of high-resolution transmission electron microscopy (HRTEM), also known as phase contrast TEM. By considering the recorded image as a CTF-degraded true object, describing the CTF allows the true object to be reverse-engineered. This is typically denoted

neg: Live cell imaging microscopy. The phase contrast microscope was popularized through a series of time-lapse movies (Video 1), recorded using a photographic film camera. Its inventor, Frits Zernike, was awarded the Nobel Prize in 1953. Other later phase contrast techniques used to observe unstained cells are Hoffman modulation and differential interference contrast microscopy. Phase contrast microscopy does not have the capacity to observe specific proteins or other organic chemical compounds which form the complex machinery of a cell. Synthetic and organic fluorescent stains have therefore been developed to label such compounds, making them observable by fluorescent microscopy (Video 2). Fluorescent stains are, however,

neg: Hypomyces hyalinus this, various forms of microscopy including bright-field microscopy, fluorescence microscopy, interference contrast microscopy, and phase contrast microscopy have been used to observe the pathogen. "H. hyalinus" has a large geographic distribution and has been recorded in Eastern Canada, Northwestern U.S.A., North-Central U.S.A., Northeastern U.S.A., Southeastern U.S.A., China,and Eastern Asia. This parasite has very minimal citations in scientific literature. Further research would be useful to form a more complete picture of life cycle of "H. hyalinus" which would allow researchers to better understand the mode of transmission of this disease. Furthermore, due to the specificity of "H. hyalinus" to parasitize the

neg: Phase-contrast imaging (TEM), phase contrast enables very high resolution (HR) imaging, making it possible to distinguish features a few Angstrom apart (at this point highest resolution is 60 pm). "See also: Phase contrast microscopy and Quantitative phase contrast microscopy" Phase contrast takes advantage of the fact that different structures have different refractive indices, and so bend light and delay its passage through the sample by different amounts. The retardation of the light results in some waves being 'out of phase' with others, and so to the human eye a microscope in phase contrast mode effectively darkens or brightens particular areas to reflect

neg: High-resolution transmission electron microscopy The CTF now becomes a function that oscillates quickly with "Cu". What this means is that for certain diffracted beams with a given spatial frequency "u" the contribution to contrast in the recorded image will be reversed, thus making interpretation of the image difficult. In Scherzer defocus, one aims to counter the term in "u" with the parabolic term Δ"fu" of "χ"("u"). Thus by choosing the right defocus value "Δf" one flattens "χ"("u") and creates a wide band where low spatial frequencies "u" are transferred into image intensity with a similar phase. In 1949, Scherzer found that the optimum defocus

neg: Differential interference contrast microscopy between polarizer and the condenser Normarski prism (De-Senarmont Compensation). The resulting contrast is going from dark-field for zero phase offset (intensity proportional to the square of the shear differential), to the typical relief seen for phase of ~5–90 degrees, to optical staining at 360 degrees, where the extinguished wavelength shifts with the phase differential. DIC is used for imaging live and unstained biological samples, such as a smear from a tissue culture or individual water borne single-celled organisms. Its resolution and clarity in conditions such as this are unrivaled among standard optical microscopy techniques. One non-biological area where DIC is

neg: Digital holographic microscopy high-pixel-count sensors. As of 2010, affordable image sensors can have up to 60 megapixels. In addition, the CD and DVD-player market has driven development of affordable diode lasers and optics. The first reports of using digital holography for light microscopy came in the mid 1990s. However, it was not until the early 2000s that image sensor technology had progressed far enough to allow images of a reasonable quality. During this time, the first commercial digital holographic microscopy companies, 4Deep inwater imaging, Lyncée tec, and Phase Holographic Imaging, were founded. With increased computing power and use of inexpensive high-resolution sensors and

neg: Transillumination used to verify egg yolks are intact, as the yolk is opaque while the albumin is transparent. Transillumination Transillumination is the technique of sample illumination by transmission of light through the sample. Transillumination is used in a variety of methods of imaging. In microscopy transillumination refers to the illumination of a sample by transmitted light. In its most basic form it generates a bright field image, and is commonly used with transillumination techniques such as phase contrast and differential interference contrast microscopy. In medicine transillumination generally refers to the transmission of light through tissues of the body. A common example

neg: Transillumination Transillumination Transillumination is the technique of sample illumination by transmission of light through the sample. Transillumination is used in a variety of methods of imaging. In microscopy transillumination refers to the illumination of a sample by transmitted light. In its most basic form it generates a bright field image, and is commonly used with transillumination techniques such as phase contrast and differential interference contrast microscopy. In medicine transillumination generally refers to the transmission of light through tissues of the body. A common example is the transmission of light through fingers, producing a red glow due to red blood cells absorbing

neg: Phase stretch transform applications. The software is protected under a US patent. Phase stretch transform Phase stretch transform (PST) is a computational approach to signal and image processing. One of its utilities is for feature detection and classification. PST is related to time stretch dispersive Fourier transform. It transforms the image by emulating propagation through a diffractive medium with engineered 3D dispersive property (refractive index). The operation relies on symmetry of the dispersion profile and can be understood in terms of dispersive eigenfunctions or stretch modes. PST performs similar functionality as phase-contrast microscopy, but on digital images. PST can be applied to digital

neg: Phase stretch transform Phase stretch transform Phase stretch transform (PST) is a computational approach to signal and image processing. One of its utilities is for feature detection and classification. PST is related to time stretch dispersive Fourier transform. It transforms the image by emulating propagation through a diffractive medium with engineered 3D dispersive property (refractive index). The operation relies on symmetry of the dispersion profile and can be understood in terms of dispersive eigenfunctions or stretch modes. PST performs similar functionality as phase-contrast microscopy, but on digital images. PST can be applied to digital images and temporal (time series) data. Here the principle

neg: Köhler illumination the condenser lenses and diaphragm. Finally, the field diaphragm is reopened to just beyond the field of view. In order to test the alignment of components on the light source image plane, the eyepiece must be removed to allow observation of the intermediate image plane (the position of the eyepiece diaphragm) either directly or by using a phase telescope/Bertrand lens. The light source (e.g. the bulb filament) and the edges of the condenser diaphragm should appear in focus. Any optical components at the back focal plane of the objective (e.g. the phase ring for phase contrast microscopy) and at the

neg: Interferometric microscopy neutral atom beams (see Atomic de Broglie microscope), where the Numerical aperture is usually very limited Interferometric microscopy Interferometric microscopy or Imaging interferometric microscopy is the concept of microscopy which is related to holography, synthetic-aperture imaging, and off-axis-dark-field illumination techniques. Interferometric microscopy allows enhancement of resolution of optical microscopy due to interferometric (holographic) registration of several partial images (amplitude and phase) and the numerical combining. In interferometric microscopy, the image of a micro-object is synthesized numerically as a coherent combination of partial images with registered amplitude and phase. For registration of partial images, a conventional holographic set-up is used with

neg: Dark-field microscopy Dark-field microscopy Dark-field microscopy (also called dark-ground microscopy) describes microscopy methods, in both light and electron microscopy, which exclude the unscattered beam from the image. As a result, the field around the specimen (i.e., where there is no specimen to scatter the beam) is generally dark. In optical microscopy, dark-field describes an illumination technique used to enhance the contrast in unstained samples. It works by illuminating the sample with light that will not be collected by the objective lens and thus will not form part of the image. This produces the classic appearance of a dark, almost black, background with

neg: Holographic interference microscopy Holographic interference microscopy Holographic interference microscopy (HIM) is holographic interferometry applied for microscopy for visualization of phase micro-objects. Phase micro-objects are invisible because they do not change intensity of light, they insert only invisible phase shifts. The holographic interference microscopy distinguishes itself from other microscopy methods by using a hologram and the interference for converting invisible phase shifts into intensity changes. Other related microscopy method to holographic interference microscopy are phase contrast microscopy, holographic interferometry. Holography was born as "new microscopy principle". D. Gabor invented holography for electron microscopy.For some reasons his idea is not applied in this branch of

neg: Time stretch analog-to-digital converter property (refractive index). In addition to wideband A/D conversion, photonic time-stretch (PTS) is also an enabling technology for high-throughput real-time instrumentation such as imaging and spectroscopy. The first artificial intelligence facilitated high-speed phase microscopy is demonstrated to improve the diagnosis accuracy of cancer cells out of blood cells by simultaneous measurement of phase and intensity spatial profiles. The world's fastest optical imaging method called serial time-encoded amplified microscopy (STEAM) makes use of the PTS technology to acquire image using a single-pixel photodetector and commercial ADC. Wavelength-time spectroscopy, which also relies on photonic time-stretch technique, permits real-time single-shot measurements of rapidly

neg: Low-energy electron microscopy In most electron microscopies, the contrast aperture is introduced into the back focal plan of the objective lens (where the actual diffraction plane lies). However, this is not true in the LEEM, because dark-field imaging (imaging of nonspecular beams) would not be possible because the aperture has to move laterally and would intercept the incident beam for large shifts. Therefore, researchers adjust the excitation of the objective lens so as to produce an image of the diffraction pattern in the middle of the beam separator and choose the desired spot intensity to image using a contrast aperture inserted there. This

neg: Transmission electron microscopy which is caused by specimen interaction. Image formation is given by the complex modulus of the incoming electron beams. As such, the image is not only dependent on the number of electrons hitting the screen, making direct interpretation of phase contrast images more complex. However this effect can be used to an advantage, as it can be manipulated to provide more information about the sample, such as in complex phase retrieval techniques. As previously stated, by adjusting the magnetic lenses such that the back focal plane of the lens rather than the imaging plane is placed on the imaging apparatus

neg: Super-resolution microscopy best quality in a 4Pi microscope was reached in conjunction with the STED principle in fixed cells and RESOLFT microscopy with switchable proteins in living cells. There is also the wide-field structured-illumination (SI) approach. SI enhances spatial resolution by collecting information from frequency space outside the observable region. This process is done in reciprocal space: The Fourier transform (FT) of an SI image contains superimposed additional information from different areas of reciprocal space; with several frames with the illumination shifted by some phase, it is possible to computationally separate and reconstruct the FT image, which has much more resolution information.

neg: Bright-field microscopy illumination, sample contrast comes from absorbance of light in the sample Image:Paper_Micrograph_Cross-Polarised.png|Cross-polarized light illumination, sample contrast comes from the rotation of polarized light through the sample Image:Paper_Micrograph_Dark.png|Dark-field illumination, sample contrast comes from light scattered by the sample Image:Paper_Micrograph_Phase.png|Phase-contrast illumination, sample contrast comes from interference of different path lengths of light through the sample </gallery> Bright-field microscopy is a standard light-microscopy technique, and therefore magnification is limited by the resolving power possible with the wavelength of visible light. Bright-field microscopy Bright-field microscopy is the simplest of all the optical microscopy illumination techniques. Sample illumination is transmitted (i.e., illuminated from below and

neg: Köhler illumination primary advantage of Köhler illumination is the even illumination of the sample. This reduces image artifacts and provides high sample contrast. Even illumination of the sample is also critical for advanced illumination techniques such as phase contrast and differential interference contrast microscopy. Adjusting the condenser diaphragm alters sample contrast. Furthermore, altering the size of the condenser diaphragm allows adjustment of sample depth of field by altering the effective numerical aperture of the microscope. The role of the condenser diaphragm is analogous to the aperture in photography although the condenser diaphragm of a microscope functions by controlling illumination of the specimen,

neg: Embryo quality puts more focus on the genome, and where there is a risk of a genetic disorder it more often involves cell sampling from the embryo for preimplantation genetic diagnosis. Embryo quality is mainly evaluated by microscopy at certain time points using a morphological scoring system. This has shown to significantly improve pregnancy rates. Time-lapse microscopy is an expansion of microscopy wherein the morphology of embryos is studied over time. As of 2014, time-lapse microscopy for embryo quality assessment is emerging from the experimental stage to something with enough evidence for broader clinical use. Studies using the EmbryoScope(tm) time-lapse incubator have

neg: Differential interference contrast microscopy according to the optical path difference." The image has the appearance of a three-dimensional object under very oblique illumination, causing strong light and dark shadows on the corresponding faces. The direction of apparent illumination is defined by the orientation of the Wollaston prisms. As explained above, the image is generated from two identical bright field images being overlaid slightly offset from each other (typically around 0.2 μm), and the subsequent interference due to phase difference converting changes in phase (and so optical path length) to a visible change in darkness. This interference may be either constructive or destructive, giving rise

neg: Digital holographic microscopy Digital holographic microscopy Digital holographic microscopy (DHM) is digital holography applied to microscopy. Digital holographic microscopy distinguishes itself from other microscopy methods by not recording the projected image of the object. Instead, the light wave front information originating from the object is digitally recorded as a hologram, from which a computer calculates the object image by using a numerical reconstruction algorithm. The image forming lens in traditional microscopy is thus replaced by a computer algorithm. Other closely related microscopy methods to digital holographic microscopy are interferometric microscopy, optical coherence tomography and diffraction phase microscopy. Common to all methods is the

neg: High-resolution transmission electron microscopy the image is influenced by aberrations of the imaging lenses in the microscope. The largest contributions for uncorrected instruments typically come from defocus and astigmatism. The latter can be estimated from the so-called Thon ring pattern appearing in the Fourier transform modulus of an image of a thin amorphous film. The contrast of a HRTEM image arises from the interference in the image plane of the electron wave with itself. Due to our inability to record the phase of an electron wave, only the amplitude in the image plane is recorded. However, a large part of the structure information of

neg: Magnetic resonance angiography create high quality contrast-enhanced MRA images without subtraction of a non-contrast enhanced mask image. This approach has been shown to improve diagnostic quality, because it prevents motion subtraction artifacts as well as an increase of image background noise, both direct results of the image subtraction. An important condition for this approach is to have excellent body fat suppression over large image areas, which is possible by using mDIXON acquisition methods. Traditional MRA suppresses signals originating from body fat during the actual image acquisition, which is a method that is sensitive to small deviations in the magnetic and electromagnetic fields and

neg: Phase-contrast X-ray imaging services he has rendered by the discovery of the remarkable rays subsequently named after him". Since then, X-rays were used as an invaluable tool to non-destructively determine the inner structure of different objects, although the information was for a long time obtained by measuring the transmitted intensity of the waves only, and the phase information was not accessible. The principle of phase-contrast imaging in general was developed by Frits Zernike during his work with diffraction gratings and visible light. The application of his knowledge to microscopy won him the Nobel Prize in Physics in 1953. Ever since, phase-contrast microscopy has

neg: Phase-contrast microscopy microscopy that its inventor Frits Zernike was awarded the Nobel Prize in Physics in 1953. The basic principle to making phase changes visible in phase-contrast microscopy is to separate the illuminating (background) light from the specimen-scattered light (which makes up the foreground details) and to manipulate these differently. The ring-shaped illuminating light (green) that passes the condenser annulus is focused on the specimen by the condenser. Some of the illuminating light is scattered by the specimen (yellow). The remaining light is unaffected by the specimen and forms the background light (red). When observing an unstained biological specimen, the scattered light

neg: Quantum microscopy interference pattern changes when the beams hit portion on the glass surface that are of a different height. The shape of the patterns can be resolved by analysing the interference pattern and phase difference. A standard optical microscope would be very unlikely to detect something so small. The difference when measured with entangled photons is precise, as one entangled photon gives information about the other. Therefore, they provide more information than independent photons, creating sharper images. Entanglement-enhancement principles can be used to vastly improve the image provided by microscopes. By enhancing with quantum entanglement, researchers are able to overcome the

neg: Polarized light microscopy <gallery caption="Comparison of transilumination techniques used to generate contrast in a sample of tissue paper. 1.559 μm/pixel." align="center"> Image:Paper_Micrograph_Cross-Polarised.png|Cross-polarized light illumination, sample contrast comes from rotation of polarized light through the sample. Image:Paper_Micrograph_Bright.png|Bright field illumination, sample contrast comes from absorbance of light in the sample. Image:Paper_Micrograph_Dark.png|Dark field illumination, sample contrast comes from light scattered by the sample. Image:Paper_Micrograph_Phase.png|Phase contrast illumination, sample contrast comes from interference of different path lengths of light through the sample. </gallery> Polarized light microscopy Polarized light microscopy can mean any of a number of optical microscopy techniques involving polarized light. Simple techniques include illumination of the

neg: Phase-contrast X-ray imaging been an important field of optical microscopy. The transfer of phase-contrast imaging from visible light to X-rays took a long time due to the slow progress in improving the quality of X-ray beams and the non-availability of X-ray optics (lenses). In the 1970s it was realized that the synchrotron radiation emitted from charged particles circulating in storage rings constructed for high-energy nuclear physics experiments was potentially a much more intense and versatile source of X-rays than X-ray tubes. The construction of synchrotrons and storage rings, explicitly aimed at the production of X-rays, and the progress in the development of optical

neg: Live cell imaging images (Video 3) can be automatically processed to extract vast amount of dynamic cellular data from time-lapse image sequences. Due to the narrow focal depth of conventional microscopy, live cell imaging is to a large extent currently limited to observing cells on a single plane. Most implementations of quantitative phase contrast microscopy allow for images to be created and focused at different focal planes from a single exposure. This opens up the future possibility of 3-dimensional live cell imaging by means of fluorescence techniques. A marker-free holographic technique that instead relies on complex deconvolution has been implemented and commercialized to

neg: Polarized light microscopy sample and so generating contrast with the background. Polarized light microscopy is used extensively in optical mineralogy. As polarised light passes through a birefringent sample, the phase difference between the fast and slow directions varies with the thickness, and wavelength of light used. The optical path difference (o.p.d.) is defined as formula_1, where t is the thickness of the sample. This then leads to a phase difference between the light passing in the two vibration directions of formula_2. For example, if the optical path difference is formula_3, then the phase difference will be formula_4, and so the polarisation will be

neg: Contrast transfer function we are given an approximation of formula_44 as From the thin-lens formula it can be shown that formula_55, yielding a final estimation of the difference in refracted angle between in-focus and off-focus rays as The contrast transfer function determines how much phase signal gets transmitted to the real space wavefunction in the image plane. As the modulus squared of the real space wavefunction gives the image signal, the contrast transfer function limits how much information can ultimately be translated into an image. The form of the contrast transfer function determines the quality of real space image formation in the TEM.

neg: Differential interference contrast microscopy The separation is normally similar to the resolution of the microscope. They will experience different optical path lengths where the areas differ in refractive index or thickness. This causes a change in phase of one ray relative to the other due to the delay experienced by the wave in the more optically dense material." 5. "The rays travel through the objective lens and are focused for the second Nomarski-modified Wollaston prism." 6. "The second prism recombines the two rays into one polarised at 135°. The combination of the rays leads to interference, brightening or darkening the image at that point

neg: Microscopy <gallery caption="Four examples of transillumination techniques used to generate contrast in a sample of tissue paper. 1.559 μm/pixel." align="center"> Image:Paper_Micrograph_Bright.png|Bright field illumination, sample contrast comes from absorbance of light in the sample. Image:Paper_Micrograph_Cross-Polarised.png|Cross-polarized light illumination, sample contrast comes from rotation of polarized light through the sample. Image:Paper_Micrograph_Dark.png|Dark field illumination, sample contrast comes from light scattered by the sample. Image:Paper_Micrograph_Phase.png|Phase contrast illumination, sample contrast comes from interference of different path lengths of light through the sample. </gallery> Bright field microscopy is the simplest of all the light microscopy techniques. Sample illumination is via transmitted white light, i.e. illuminated from below and

neg: Hybrid operating room to protect the lower body region. Even more restrictive rules apply to pregnant staff members. A very effective measure of both protection to both the staff and the patient of course is applying less radiation. There is always a trade-off between radiation dose and image quality. A higher x-ray dose leads to a clearer picture. Modern software technology can improve image quality during post-processing, such that the same image quality is reached with a lower dose. Image quality thereby is described by contrast, noise, resolution and artifacts. In general, the ALARA principle (as low as reasonably achievable) should be followed.

neg: Photoacoustic microscopy blue, are used to enhance vasculature as well as to improve tumor imaging. In addition, dyes are easily filtered out of the body due to their small size (≤ 3 nm). Nanoparticles are currently being researched due to their chemical inactivity and ability to target tumor cells. These properties allow for cancer propagation to be monitored and potentially enables intraoperative cancer removal. However, more studies on short-term toxicity effects are necessary to determine if nanoparticles are suitable for clinical research. Gold nanoparticles have shown promise as a contrast agent for image-guided medicine. AuNPs have been widely used as contrast agents

neg: Photoemission electron microscopy is used to convert the electron image to a photon image. The choice of phosphor type is governed by resolution considerations. A multichannel plate detector that is imaged by a CCD camera can substitute phosphor screen. Photoemission electron microscopy Photoemission Electron microscopy (PEEM, also called photoelectron microscopy, PEM) is a widely used type of emission microscopy. PEEM utilizes local variations in electron emission to generate image contrast. The excitation is usually produced by UV 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

neg: Time-lapse microscopy During the second World War II Carl Zeiss AG released the first phase contrast microscope on the market. With this new microscope, cellular details could for the first time be observed without using lethal stains. By setting up some of the first time-lapse experiments with chicken fibroblasts and a phase contrast microscope, Michael Abercrombie described the basis of our current understanding of cell migration in 1953. With the broad introduction of the digital camera at the beginning of this century, time-lapse microscopy has been made dramatically more accessible and is currently experiencing an unrepresented raise in scientific publications. Time-lapse microscopy

neg: Interferometric microscopy Interferometric microscopy Interferometric microscopy or Imaging interferometric microscopy is the concept of microscopy which is related to holography, synthetic-aperture imaging, and off-axis-dark-field illumination techniques. Interferometric microscopy allows enhancement of resolution of optical microscopy due to interferometric (holographic) registration of several partial images (amplitude and phase) and the numerical combining. In interferometric microscopy, the image of a micro-object is synthesized numerically as a coherent combination of partial images with registered amplitude and phase. For registration of partial images, a conventional holographic set-up is used with a reference wave, as is usual in optical holography. Capturing multiple exposures allows the numerical emulation

neg: Contrast resolution Contrast detail curves, which depict the functional relationship between image resolution and contrast resolution, can be produced using this type of data. Contrast resolution Contrast resolution is the ability to distinguish between differences in intensity in an image. The measure is used in medical imaging to quantify the quality of acquired images. It is a difficult quantity to define, because it depends on the human observer as much as the quality of the actual image. For example, the size of a feature affects how easily it is detected by the observer. One definition of image contrast is: where S and

neg: Surface-conduction electron-emitter display Despite having two glass layers instead of one in a typical LCD, this reduction in overall complexity makes SEDs similar in weight and size as LCDs. Canon's 55" prototype SED offered bright images of 450 cd/m, 50,000:1 contrast ratios, and a response time of less than 1 ms. Canon has stated that production versions would improve the response time to 0.2 ms and 100,000:1 contrast ratios. SEDs can be viewed from extremely wide angles without any effect on the quality of the image. In comparison, a modern LCD televisions like the Sony KDL-52W4100 claims to offer 30,000:1 contrast ratios, but

neg: Transmission electron microscopy diffracting angle (known as the Bragg Angle), any distortion of the crystal plane that locally tilts the plane to the Bragg angle will produce particularly strong contrast variations. However, defects that produce only displacement of atoms that do not tilt the crystal to the Bragg angle (i. e. displacements parallel to the crystal plane) will not produce strong contrast. Crystal structure can also be investigated by high-resolution transmission electron microscopy (HRTEM), also known as phase contrast. When using a field emission source and a specimen of uniform thickness, the images are formed due to differences in phase of electron waves,

neg: Franz Pfeiffer (physicist) Franz Pfeiffer (physicist) Franz Pfeiffer (born 25 November 1972 in Kösching, Germany) is a German physicist known for his contributions to the development of Phase-contrast X-ray imaging and its applications in biomedical research. Pfeiffer contributed to the extension of known imaging modalities such as Differential interference contrast microscopy and Dark-field microscopy to the X-ray regime. In 2006 he demonstrated the feasibility of phase sensitive X-ray imaging with conventional, polychromatic X-ray sources and a grating interferometer . This enlarged the potential of X-ray phase imaging for clinical use as before the technique was only possible at synchrotron facilities. Pfeiffer further introduced

neg: Quantum microscopy Rayleigh criterion. This is ideal for studying biological tissues and materials that are opaque. However, a limitation is that the light intensity is lowered in order to avoid damaging the sample. Further, the use of entangled microscopy can avoid the phototoxicity and photobleaching that comes with two-photon scanning fluorescence microscopy. In addition, since the interaction region within entangled microscopy is controlled by two beams, the selection of where to image is extremely flexible, which provides enhanced axial and lateral resolution In addition to the sampling of biological tissues, high-precision optical phase measurements have additional applications such as gravitational wave detection,

neg: Low-energy electron microscopy contrast aperture to pass only those electrons that contribute to that particular spot. In the image planes after the contrast aperture it is then possible to observe where the electrons originate from in real space. This technique allows scientists to study on which areas of a specimen a structure with a certain lattice vector (periodicity) exists. In photoemission electron microscopy (PEEM), upon exposure to electromagnetic radiation (photons), secondary electrons are excited from the surface and imaged. PEEM was first developed in the early 1930s, using ultraviolet (UV) light to induce photoemission of (secondary) electrons. However, since then, this technique has

neg: Laser capture microdissection usually less than 1 µm, thus the target cells are not affected by the laser beam. Even live cells are not damaged by the laser cutting and are viable after cutting for cloning and reculturing as appropriate. The various technologies differ in the collection process, possible imaging methods (fluorescence microscopy/bright field microscopy/differential interference contrast microscopy/phase contrast microscopy/ etc.) and the types of holders and tissue preparation needed before the imaging and isolation. Most are primarily dedicated micro-dissection systems, and some can be used as research microscopes as well, only one technology (#2 here, Leica) uses an upright microscope, limiting some