| solid state laser | <radiobiology> A laser using a transparent substance (crystalline or glass) as the active medium, doped to provide the energy states necessary for lasing. The pumping mechanism is the radiation from a powerful light source, such as a flashlamp. The ruby, Nd-YAG, and Nd:glass lasers are solid-state lasers. (09 Oct 1997) |
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| spectrometry, mass, matrix-assisted laser desorption-ionization | A mass spectrometric technique that is used for the analysis of large biomolecules. Analyte molecules are embedded in an excess matrix of small organic molecules that show a high resonant absorption at the laser wavelength used. The matrix absorbs the laser energy, thus inducing a soft disintegration of the sample-matrix mixture into free (gas phase) matrix and analyte molecules and molecular ions. In general, only molecular ions of the analyte molecules are produced, and almost no fragmentation occurs. This makes the method well suited for molecular weight determinations and mixture analysis. (12 Dec 1998) |
| dye laser | <radiobiology> A type of laser in which the active material (the material which emits the laser light) is a dye. These lasers are tunable when the dye has very large molecules (such as acridine red or esculin) and the laser action takes place between the first excited and ground electronic states, because each of these states contains a broad continuum band of vibrational-rotational levels. (09 Oct 1997) |
| yag laser surgery | <ophthalmology, procedure, surgery> The use of laser light to punch a hole in the iris to relieve intraocular pressure within the eye (for example glaucoma). This surgery is painless and requires no anaesthesia. (27 Sep 1997) |
| keratectomy, photorefractive, excimer laser | A type of refractive surgery of the cornea to correct myopia and astigmatism, using an excimer laser. An excimer laser is a laser containing a noble gas, such as helium or neon, which is based on a transition between an excited state in which a metastable bond exists between two gas atoms and a rapidly dissociating ground state. The extremely precise laser light reshapes the surface of the cornea without making an incision. This procedure can reduce much higher degrees of myopia than radial keratotomy (keratotomy, radial), although it generally takes longer for vision to clear. (12 Dec 1998) |
| laser | A medical instrument that produces a powerful beam of light and can produce intense heat when focused at close range. Lasers are often used in surgery to vaporize damaged cell tissue. (16 Dec 1997) |
| laser angioplasty | <cardiology, procedure> A technique utilizing a laser coupled to a catheter which is used in the dilatation of occluded blood vessels. This includes laser thermal angioplasty where the laser energy heats up a metal tip, and direct laser angioplasty where the laser energy directly ablates the occlusion. One form of the latter approach uses an excimer laser which creates microscopically precise cuts without thermal injury. When laser angioplasty is performed in combination with balloon angioplasty it is called laser-assisted balloon angioplasty (angioplasty, balloon, laser-assisted). (05 Mar 2000) |
| laser-assisted balloon angioplasty | <cardiology, procedure> Techniques using laser energy in combination with a balloon catheter to perform angioplasty. These procedures can take several forms including: 1. Laser fibre delivering the energy while the inflated balloon centres the fibre and occludes the blood flow. 2. Balloon angioplasty immediately following laser angioplasty. 3. Laser energy transmitted through angioplasty balloons that contain an internal fibre. (05 Mar 2000) |
| laser coagulation | The coagulation of tissues using lasers. These lasers produce light in the visible green wavelength that is selectively absorbed by haemoglobin, and thus it is possible to seal bleeding blood vessels. (12 Dec 1998) |
| laser-doppler flowmetry | A method of non-invasive, continuous measurement of microcirculation. The technique is based on the values of the doppler effect of low-power laser light scattered randomly by static structures and moving tissue particulates. (12 Dec 1998) |
| laser fusion | <radiobiology> Form of inertial confinement fusion where laser beams are used to compress and heat the fuel pellet. (09 Oct 1997) |
| laser interferometer | <radiobiology> An interferometer which uses a laser as a light source. Because of the monochromatic nature and high brightness of laser light, laser interferometers can operate with much longer beam paths and path differences than conventional interferometers. (09 Oct 1997) |
| laser iridotomy | Peripheral iridectomy as performed by laser.This is a refinement of the surgical technique devised in 1858 by von Graefe. In acute glaucoma the aqueous humor cannot flow freely around the lens and through the pupil to be absorbed in the angle of the anterior chamber. Laser peripheral iridectomy corrects this problem by producing a small hole in the iris to permit aqueous flow. The procedure takes only a few seconds and employs a laser attached to a slit lamp. (05 Mar 2000) |
| laser microscope | <instrument> A microscope in which a laser beam is focused on a microscopic field, causing it to vaporise; the emitted radiation is analyzed by means of a microspectrophotometer; at a low intensity the laser is employed as the light source in an interference microscope. (05 Mar 2000) |
| laser surgery | A type of operation using the cutting powers of laser beams from various sources. The use of a laser either to vaporise surface lesions or to make bloodless cuts in tissue. It does not include the coagulation of tissue by laser (laser coagulation). (12 Dec 1998) |