| optical density n. See absorbance. |
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 | ||||
| n | density (g/cm3) | |||
| glass | ||||
| spectacle crown | 1.523 | 2.54 | ||
| dense barium crown | 1.620 | 3.71 | ||
| dense flint | 1.706 | 3.20 | ||
| dense barium flint | 1.700 | 4.10 | ||
| titanium oxide | 1.701 | 2.99 | ||
| plastics | ||||
| PMMA | 1.490 | 1.19 | ||
| CR-39 | 1.498 | 1.32 | ||
| polycarbonate | 1.586 | 1.2 | ||
| cellulose acetate butyrate | 1.48 | 1.2 | ||
| cellulose propionate | 1.46 | 1.2 | ||
| Table D2 Relationship between optical density D and light transmission T of optical filters | |
| D | T (%) |
| 0.0 | 100 |
| 0.1 | 79.4 |
| 0.2 | 63.1 |
| 0.3 | 50.1 |
| 0.4 | 39.8 |
| 0.5 | 31.6 |
| 0.6 | 25.1 |
| 0.7 | 20.0 |
| 0.8 | 15.8 |
| 0.9 | 12.6 |
| 1.0 | 10.0 |
| 1.5 | 3.16 |
| 2.0 | 1.0 |
| 2.5 | 0.32 |
| 3.0 | 0.1 |
| 4.0 | 0.01 |
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