| AD | accident dispensary; acetate dialysis; active disease; acute dermatomyositis; addict, addiction; ade... |
|---|---|
| AE | above-elbow [amputation]; acrodermatitis enteropathica; activation energy; adult erythrocyte; advers... |
| AFM | aflatoxin M; after fatty meal; American Federation of Musicians |
| AH | abdominal hysterectomy; absorptive hypercalciuria; accidental hypothermia; acetohexamide; acid hydro... |
| AHP | accountable health plan or partnership; acute hemorrhagic pancreatitis; after hyperpolarization; air... |
| negative image | Continuation of visual impression after cessation of stimuli causing the original image. (12 Dec 1998) |
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| direct image | <microscopy> Such as seen in a mirror or through a magnifier. A virtual image has no real existence in space as does a real image from a lens. It does have a definite location, however, caused by the angles of divergence of the rays received by the eye. This can be shown by the common school experiment of placing a pin coincident with its mirror image behind a sheet of glass acting as a partial mirror. Its location can also be placed in design by extrapolating backwards to a focus. If a magnifier is used as it should be, with the object at its focus, the virtual image is at infinity. The same is true for a microscope focused for the relaxed eye. See: distance of virtual image. (05 Aug 1998) |
| distance of virtual image | <physics> When a simple lens is used as a magnifier for visual observation the eye becomes part of the optical system. A virtual image can be formulated by construction and its apparent distance will vary with the focus of the eye. This will vary among individuals. In a rather arbitrary but standardised assumption, the normal distance for close observation, or reading has been set at 10 inches (250 mm). The optics for the compound microscope have been designed to furnish parallel light from the eyepiece so that the eyes are relaxed for distant viewing. This makes the virtual image lie at infinity. Tests showed that the average observer accommodates somewhat, placing the virtual image rather variably, often about 20 - 25 feet. (05 Aug 1998) |
| image | <microscopy> A representation of an object produced by means of radiation usually with a lens or mirror system. (05 Aug 1998) |
| image amplifier | A device for converting a low light level fluoroscopic image to one that can be seen by the eye in a lighted environment; usually consists of an electronic light amplifier chained to a television tube. Synonym: image intensifier. (05 Mar 2000) |
| image cytometry | A technique encompassing morphometry, densitometry, neural networks, and expert systems that has numerous clinical and research applications and is particularly useful in anatomic pathology for the study of malignant lesions. The most common current application of image cytometry is for DNA analysis, followed by quantitation of immunohistochemical staining. (12 Dec 1998) |
| image enhancement | Improvement of the quality of a picture by various techniques, including computer processing, digital filtering, echocardiographic techniques, light and ultrastructural microscopy, fluorescence spectrometry and microscopy, scintigraphy, and in vitro image processing at the molecular level. (12 Dec 1998) |
| image field | <microscopy> Any field showing a focused image. There are a number of such fields in the complete microscopical system. The term may also denote the field of view, or the image field at the focal plane of the camera, generally the field where the final image is formed. (05 Aug 1998) |
| image intensifier | A device for converting a low light level fluoroscopic image to one that can be seen by the eye in a lighted environment; usually consists of an electronic light amplifier chained to a television tube. Synonym: image intensifier. (05 Mar 2000) |
| image interpretation, computer-assisted | Computer systems developed to aid in the interpretation of ultrasound, radiographic images, etc. (12 Dec 1998) |
| image processing, computer-assisted | A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer. (12 Dec 1998) |
| image real | <microscopy> An image as formed by a lens on a screen, plate or any plane surface. See: image, virtual. (05 Aug 1998) |
| image space | <microscopy> The space about an optical system each point of which is conjugate to some point in the object space. (05 Aug 1998) |
| image virtual | <microscopy> A virtual image has no real existence. It is the image seen when looking into a mirror. The field of view of the microscope is a good example of a virtual image. When the eye operates in conjunction with a lens to form an image on the retina, the visual sensation is as if the image existed in space. That its apparent location is very definite is proved when a pin can be made to coincide with the mirror (virtual) image of another pin that is seen by looking at a sheet of glass acting as a mirror. With a lens system a virtual image can be definitely located as by graphically tracing rays back to a focus. In a microscope, if the eye is relaxed as it should be, the virtual image will be at infinity. Measurements show that most observers place the aerial image at 20-25 feet, some as close as seven, because of partial accommodation. (11 Mar 1998) |
| intermediate image plane | <microscopy> In a light microscope, the plane into which the objective lens directly focuses the image of the specimen. The plane is usually located a set distance (commonly 10 mm) below the shoulder for the ocular and another fixed distance (generally 160 mm) behind the rear focal plane of the objective lens. The ocular forms a virtual image of the intermediate image for visual observation, or projects a real image for photography and video microscopy. Note: The objective lens, combined with the coverslip of proper thickness, is corrected for projecting the primary image to the specified intermediate image plane only. (05 Aug 1998) |