| DOS | day of surgery; deoxystreptamine; disk operating system; Doctor of Ocular Science; Doctor of Optical... |
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| IOD | injured on duty; integrated optical density; interorbital distance |
| MORD | magnetic optical rotatory dispersion |
| OCR | oculocardiac reflex; oculocerebrorenal [syndrome]; optical character recognition |
| OD | Doctor of Optometry; obtained absorbance; occipital dysplasia; occupational dermatitis; occupational... |
| dioptric aberration | <microscopy> A lens defect in which image forming rays passing through the outer zones of the lens focus at a distance from the principal plane, different from that of the rays passing through the centre of the lens. The aberration caused by (near-paraxial) monochromatic light rays or electron beams passing through different radii of a lens not coming to the same focus. (05 Aug 1998) |
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| distortion aberration | The faulty formation of an image arising because the magnification of the peripheral part of an object is different from that of the central part when viewed through a lens. (05 Mar 2000) |
| lateral aberration | In spherical aberration, the distance between paraxial focus of central rays on the optic axis. (05 Mar 2000) |
| longitudinal aberration | In spherical aberration, the distance separating the focus of paraxial and peripheral rays on the optic axis. (05 Mar 2000) |
| axis, optical | <microscopy> Usually refers to the axis on which several principal lens axes may lie. It also refers to the axis of the eye which extends through the centre of the eye lens. The line formed by the coinciding principal axes of a series of optical elements comprising an optical system. It is the line passing through the centres of curvature of the optical surfaces. (05 Aug 1998) |
| specific optical dispersion | <microscopy> The difference between the refractive indices of light of two different wavelengths, both indices measured at the same temperature, the difference being divided by the specific gravity also measured in the same medium at the test temperature. For convenience, the specific dispersion value is multiplied by ten. (05 Aug 1998) |
| optical | 1. Of or pertaining to vision or sight. "The moon, whose orb Through optic glass the Tuscan artist views." (Milton) 2. Of or pertaining to the eye; ocular; as, the optic nerves (the first pair of cranial nerves) which are distributed to the retina. 3. Relating to the science of optics; as, optical works. <optics> Optic angle, a graduated circle used for the measurement of angles in optical experiments. Optical square, a surveyor's instrument with reflectors for laying off right angles. Origin: F. Optique, Gr.; akin to sight, I have seen, I shall see, and to the two eyes, face, L. Oculus eye. See Ocular, Eye, and cf. Canopy, Ophthalmia. Source: Websters Dictionary (01 Mar 1998) |
| optical activity | The ability of a material to rotate the plane of polarized light. (09 Oct 1997) |
| optical antipode | <chemistry> A pair of chiral isomers (stereoisomers) that are direct, nonsuperimposable mirror images of each other. (09 Jan 1998) |
| optical axis | <physics> The line passing through both the centres of curvature of the optical surfaces of a lens, the optical centreline for all the centres of a lens system. (09 Oct 1997) |
| optical density | 1. <chemistry, investigation> Absorbance is defined as a logarithmic function of the percent transmission of a wavelength of light through a liquid. 2. <microbiology> This can be used as a measure of the amount of light absorbed by a suspension of bacterial cells or a solution of an organic molecule, it is measured by a colourimeter or spectrophotometer. Absorbance values are used to plot the growth of bacteria in suspension cultures and to gauge the purity and concentration of molecules (such as proteins) in solution. See: absorption. (15 Jan 1998) |
| optical diffraction | A technique used to obtain information about repeating patterns. Diffraction of visible light can be used to calculate spacings in the object. (18 Nov 1997) |
| optical flat | <microscopy> Usually, a glass or quartz plate or disk, the thickness of which should be at least 1/10 of its diameter. It is ground until any remaining unevenness can be measured only by interferometric methods. Their maximum departure from flatness usually is less than 1/10 of the sodium doublet (589.3 nm). (05 Aug 1998) |
| optical illusions | An illusion of vision usually affecting spatial relations. (12 Dec 1998) |
| optical image | An image formed by the refraction or reflection of light. (05 Mar 2000) |