| monocular diplopia | A double image or an extra ghost image produced in one eye, almost always by an aberration of the ocular media; for example, a corneal or lenticular irregularity, an uncorrected astigmatism or an irregularity of the vitreous or the retina. If a similar process occurs in both eyes (bilateral monocular diplopia), that is, the doubling is still present with either eye covered, the patient may still only see two images; seeing multiple images (polyopia) is rare. (05 Mar 2000) |
|---|---|
| heteronymous diplopia | crossed diplopia |
| homonymous diplopia | Double image's produced by stimuli arising from points proximal to the horopter. Synonym: homonymous diplopia, simple diplopia, uncrossed diplopia. (05 Mar 2000) |
| simple diplopia | Double image's produced by stimuli arising from points proximal to the horopter. Synonym: homonymous diplopia, simple diplopia, uncrossed diplopia. (05 Mar 2000) |
| diplopia | <ophthalmology, symptom> The perception of two images of a single object. Synonym: ambiopia, double vision, binocular polyopia. (18 Nov 1997) |
| uncrossed diplopia | Double image's produced by stimuli arising from points proximal to the horopter. Synonym: homonymous diplopia, simple diplopia, uncrossed diplopia. (05 Mar 2000) |
| auditory field | The space included within the limits of hearing of a definite sound, as of a tuning fork. (05 Mar 2000) |
| bright field illumination | <microscopy> The method of lighting the specimen with a solid cone of rays. Transmitted bright field illumination is performed by a substage condenser. Reflected bright field illumination is performed by a vertical illuminator. Compare: dark field illumination (05 Aug 1998) |
| bright field imaging | <microscopy> An imaging mode in a transmission electron microscopy that uses only unscattered Electrons to form the image. Contrast in such an image is due entirely to mass-thickness variations in amorphous samples, and may include diffraction contrast in crystalline samples. (05 Aug 1998) |
| bright field microscopy | <technique> Optical microscopy, in which absorption to a great extent and diffraction to a minor extent give rise to the image, as opposed to phase contrast or interference methods of microscopy. (18 Nov 1997) |
| Broca's field | The posterior part of the inferior frontal gyrus of the left or dominant hemisphere, corresponding approximately to Brodmann's area 44; Broca identified this region as an essential component of the motor mechanisms governing articulated speech. Synonym: Broca's area, Broca's field, motor speech centre. (05 Mar 2000) |
| cardioid dark field condenser | <microscopy> A condenser designed with two reflecting surfaces, the first, a spherical surface which reflects the rays to a second, cardioid (heart-shaped) surface. The virtue in such an arrangement is that, if the cardioid surface is of true figure, the lens is both achromatic and aplanatic. It has a limiting numerical aperture of about 1.0. Thus objectives of a greater numerical aperture cannot be used successfully with it. A true cardioid figure is the trace of a point on the circumference of a circle rolling around an equal, fixed circle. (05 Aug 1998) |
| magnetic field | The sphere of influence of a magnet. (05 Mar 2000) |
| magnetic field gradient | In magnetic resonance imaging, a magnetic field that varies with location, superimposed on the uniform field of the magnet, to alter the resonant frequency of nuclei and allow recovery of their spatial position. Synonym: field gradient. (05 Mar 2000) |
| paraboloid dark field condenser | <microscopy> A lens of parabolic shape. The vertex end is ground back so that its focus can be brought into coincidence with the specimen on the slide. A central stop is provided to block the central rays. It is used chiefly for medium- power work. (05 Aug 1998) |