|
Hoffman Modulation Contrast Microscopy
Hoffman modulation contrast microscopy (HMC microscopy) is an optical microscopy Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ... 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 particularly suitable for optical sectioning at lower magnifications.Douglas B. M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Microscopy
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties. Most optical phenomena can be accounted for by using the classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice. Practical optics is usually done using simplified models. The most common of these, geometric optics, treats light as a collection of rays that travel in straight lines and bend when they pass through or reflect from surfaces. Physical optics is a more comprehensive model of light, which includes wave effects such as diffraction and interference that cannot be ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 Nomarski in 1952. DIC works by separating a polarized light source into two orthogonally polarized mutually coherent parts which are spatially displaced (sheared) at the sample plane, and recombined before observation. The interference of the two parts at recombination is sensitive to their optical path difference (i.e. the product ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
In-vitro Fertilisation
In vitro fertilisation (IVF) is a process of fertilisation where an egg is combined with sperm in vitro ("in glass"). The process involves monitoring and stimulating an individual's ovulatory process, removing an ovum or ova (egg or eggs) from their ovaries and letting sperm fertilise them in a culture medium in a laboratory. After the fertilised egg (zygote) undergoes embryo culture for 2–6 days, it is transferred by catheter into the uterus, with the intention of establishing a successful pregnancy. IVF is a type of assisted reproductive technology used for infertility treatment, gestational surrogacy, and, in combination with pre-implantation genetic testing, avoiding transmission of genetic conditions. A fertilised egg from a donor may implant into a surrogate's uterus, and the resulting child is genetically unrelated to the surrogate. Some countries have banned or otherwise regulate the availability of IVF treatment, giving rise to fertility tourism. Restrictions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Condenser (microscope)
A condenser is an optical lens which renders a divergent beam from a point source into a parallel or converging beam to illuminate an object. Condensers are an essential part of any imaging device, such as microscopes, enlargers, slide projectors, and telescopes. The concept is applicable to all kinds of radiation undergoing optical transformation, such as electrons in electron microscopy, neutron radiation and synchrotron radiation optics. Microscope condenser Condensers are located above the light source and under the sample in an upright microscope, and above the stage and below the light source in an inverted microscope. They act to gather light from the microscope's light source and concentrate it into a cone of light that illuminates the specimen. The aperture and angle of the light cone must be adjusted (via the size of the diaphragm) for each different objective lens with different numerical apertures. Condensers typically consist of a variable-aperture diaphragm an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Objective (optics)
In optical engineering, the objective is the optical element that gathers light from the object being observed and focuses the light rays to produce a real image. Objectives can be a single lens or mirror, or combinations of several optical elements. They are used in microscopes, binoculars, telescopes, cameras, slide projectors, CD players and many other optical instruments. Objectives are also called object lenses, object glasses, or objective glasses. Microscope objectives The objective lens of a microscope is the one at the bottom near the sample. At its simplest, it is a very high-powered magnifying glass, with very short focal length. This is brought very close to the specimen being examined so that the light from the specimen comes to a focus inside the microscope tube. The objective itself is usually a cylinder containing one or more lenses that are typically made of glass; its function is to collect light from the sample. Magnification One of the most important prope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polariser
A polarizer or polariser is an optical filter that lets light waves of a specific polarization pass through while blocking light waves of other polarizations. It can filter a beam of light of undefined or mixed polarization into a beam of well-defined polarization, that is polarized light. The common types of polarizers are linear polarizers and circular polarizers. Polarizers are used in many optical techniques and instruments, and polarizing filters find applications in photography and LCD technology. Polarizers can also be made for other types of electromagnetic waves besides visible light, such as radio waves, microwaves, and X-rays. Linear polarizers ''Linear polarizers'' can be divided into two general categories: absorptive polarizers, where the unwanted polarization states are absorbed by the device, and beam-splitting polarizers, where the unpolarized beam is split into two beams with opposite polarization states. Polarizers which maintain the same axes of pola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
