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

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.

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)
glass
spectacle crown1.5232.54
dense barium crown1.6203.71
dense flint1.7063.20
dense barium flint1.7004.10
titanium oxide1.7012.99
plastics
PMMA1.4901.19
CR-391.4981.32
polycarbonate1.5861.2
cellulose acetate butyrate1.481.2
cellulose propionate1.461.2

Table D2 Relationship between optical density D and light transmission T of optical filters
DT (%)
0.0100
0.179.4
0.263.1
0.350.1
0.439.8
0.531.6
0.625.1
0.720.0
0.815.8
0.912.6
1.010.0
1.53.16
2.01.0
2.50.32
3.00.1
4.00.01
References in periodicals archive ?
Because optical density is essentially a log function, the chart is effectively a log-log graph.
The smoke optical density values were compared in Figure 12 with respect to the distance from the fire.
The advantage of using the reflection mode of operation is that the optical density ad is doubled without having to increase the time of doping and depoping of the anion.
The optical density was measured using a spectrophotometer (Stratagene, Strasbourg, France) at 560 nm for test and 640 nm for reference.
In later stages, when the optical density of the film was significant, heat evolution began to play a role in initiating thermal reactions in the film.
Solsperse 78000 provides improved print gloss and optical density, superior mill base viscosity and increased color strength.
The rate of increase in macular pigment optical density was correlated with the plateau concentration of carotenoids in the serum (r = 0.
The coproantigen test showed a significant reduction in the optical density value for both dogs, which can be interpreted as effective deworming for Echinococcus.
The optical density of each sample was determined at a wavelength of 450 nm and a reference wavelength of 540 nm by a microplate reader (OpsysMR, DYNEX, Minneapolis, MN, USA).
Typical applications for the new densitometer include determining the concentration of cells (bacterial and yeast) in fermentation processes, detecting the susceptibility of micro-organisms to antibiotics, identifying micro-organisms with various test systems, and measuring optical density at fixed wavelength.
Samples were considered positive with an optical density [greater than or equal to] 0.
These attributes have been achieved by incorporating a unique surface chemistry technique allowing for other favorable properties such as increased optical density, excellent lightfastness, improved wet smear resistance on photographic substrates, sharp resolution in printed images, less color bleeding, high levels of formulation flexibility and improved chroma.

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