| doublet | <microscopy> Two simple lens elements cemented together, for the purpose of giving spherical and chromatic corrections. An achromatic doublet may be composed of a positive crown-glass lens and a negative flint-glass lens. The errors of one element are made to compensate those of the other element. (05 Aug 1998) |
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| doublet microtubule | <cell biology> Microtubules of the axoneme. The outer nine sets are often referred to as doublet microtubules, although only one the A tubule) is complete and has 13 protofilaments. The B tubule has only 10 or 11 protofilaments and shares the remainder with the A tubule. A and B tubules differ in their stability and in the other proteins attached periodically to them, it is the dynein affixed to the A tubule attaching and detaching from the B tubule of the adjacent doublet that generates sliding movement in the axoneme. (18 Nov 1997) |
| doublethreaded | 1. Consisting of two threads twisted together; using two threads. 2. <mechanics> Having two screw threads instead of one; said of a screw in which the pitch is equal to twice the distance between the centers of adjacent threads. Source: Websters Dictionary (01 Mar 1998) |
| Wollaston's doublet | A combination of two planoconvex lenses in the eyepiece of a microscope designed to correct the chromatic aberration. (05 Mar 2000) |
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