| conoscopic image | <microscopy> The interference pattern and diffraction image seen at the back aperture of the objective lens. The conoscopic image provides a two-dimensional projection of the rays travelling in three dimensions in the specimen space. (05 Aug 1998) |
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| positive image | <microscopy> A developed image in which dark areas correspond to dark areas of the original subject. (05 Aug 1998) |
| heteronymous image | A double image in physiological diplopia, when fixation is directed beyond an object; the right image arises from the left eye, while the left image arises from the right eye; i.e., there is a crossed diplopia. (05 Mar 2000) |
| sensory image | An image based on one or more types of sensation. (05 Mar 2000) |
| hypnagogic image | Imagery occurring between wakefulness and sleep. (05 Mar 2000) |
| hypnopompic image | <psychology> Imagery occurring after the sleeping state and before complete wakefulness; similar to hypnagogic imagery except for the time of occurrence. (05 Mar 2000) |
| specular image | The image of a source of light made visible by the reflection from a mirror. (05 Mar 2000) |
| negative image | Continuation of visual impression after cessation of stimuli causing the original image. (12 Dec 1998) |
| 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) |