optical density

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optical density

The ability of a laboratory specimen to absorb or block the passage of light. The optical density of a laboratory sample can be used as an indicator of the concentration of specific components in the sample.
Synonym: optical absorbance
See also: density
Medical Dictionary, © 2009 Farlex and Partners

optical density

a spectrophotometric measurement of light scattered by a suspension at a particular wavelength. Optical density measurements can be used to determine the BIOMASS concentration in a suspension, when, for instance, monitoring the GROWTH of a culture of MICROORGANISMS. It should be noted, however, that the microorganisms in the suspension will both scatter and, probably to a lesser extent, absorb the incident light, and it is the sum of these properties that is measured. It is therefore debatable what term should be applied. ABSORBANCE is sometimes used interchangeably with optical density, but this is not strictly correct. Optical density is generally accepted as the more appropriate term when measuring microbial growth.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

density, optical

A term applied to optical filters. It is equal to the logarithm to the base 10 of the reciprocal of the transmission factor T thus,
where D is the symbol for optical density. Syn. absorbance. See absorbance; absorption; spectrophotometer; transmittance.
Table D1 Density of optical lens materials
ndensity (g/cm3)
spectacle crown1.5232.54
dense barium crown1.6203.71
dense flint1.7063.20
dense barium flint1.7004.10
titanium oxide1.7012.99
cellulose acetate butyrate1.481.2
cellulose propionate1.461.2

Table D2 Relationship between optical density D and light transmission T of optical filters
DT (%)
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
References in periodicals archive ?
[c.sub.0] is a constant, in which its optical density generated other components.
Caption: Figure 5: The mean optical density for elastogenesis and degradation markers in the dermis of protruding and indented type anetoderma.
Concentration of the substance to be determined was calculated by comparing the optical density.
The optical density measurements for the full-tone area were performed with D50 illuminant using a 2[degrees] observer, 0[degrees]/45[degrees] measuring geometry and a polarization filter.
Among its benefits, digital radiology rationalized radiographic procedures, eradicated the use of the radiographic film and the need of wet chemical processing, which contributed to preservation of the environment, reduced radiation exposure without compromising image quality, enabled image manipulation based on the requirements of each medical area, even for underexposed images (BRENNAN, 2002), and made it possible to measure optical density of different materials in pixels (SABBAGH et al., 2004; CARVALHO-JUNIOR et al., 2007; BRAUN et al., 2008).
There is no statistically significant difference in cell viability, apoptosis rate, and TH optical density between the isoflavone + [MPP.sup.+] (P < 0.01), Z-YVAD-CHO + [MPP.sup.+], and Z-DEVD-CHO + [MPP.sup.+] groups (P < 0.05) and control group cells, but the [MPP.sup.+] group is lower than all the other groups, and the isoflavone group is higher than all the other groups.
Table 1: Optical density of the serial dilution of KMn[O.sub.4] Optical 1.101 0.525 0.258 0.130 0.070 0.030 0.006 Density (OD) Conc.
The compound also meets regulations for ASTM Cl 166 (flame propagation of elastomers), ASTM El62 (surface flammability of materials using a radiant heat energy source), ASTM E662 (specific optical density of smoke generated by solid materials) and ASTM El 354 (heat and visible smoke release rates for materials using an oxygen consumption calorimeter).
Injection blow moulding with Lexan HP resin provides uniform, thicker walls enabling optical density measurement capabilities with limited pH shift.
The optical density of the reference was subtracted from the optical density of the solution containing the supernatant.
Quantification of the size of lymph follicles and their germinative centers was performed on tonsil sections 4-5 [micro]m thick, stained with hematoxylin-eosin method and included the calculation of several parameters: range ([mm.sup.2]), the mean optical density, volume (mm), circularity, Feret's diameter (mm) and integrated optical density.

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