China March non-ferrous metal production data at a glance

Beijing April 18 news, the latest published statistics of non-ferrous metal production by the National Bureau of Statistics in March 2005 are as follows: (Monthly data are preliminary data) Changes in year-on-year changes in March % Change from January to March, year-on-year % Refined copper 186,000 10.5 546,000 17.5 Aluminium 568,100 12.9 1,656,700 14.3 Alumina 682,900 20.0 1,911,200 16.4 Zinc 230,000 8.6 613,500 2.8 Lead 167,000 6.2 460,100 12.7 Tin 9,150 19.2 24,716 13.5 Newly released February 2005 revised list of non-ferrous metals by the National Bureau of Statistics: (tons) Revision After the revised estimate of the value of the former value of copper 186,300 184,800 aluminum 557,000 557,300 alumina 593,600 593,700 zinc 211,000 194,600 lead 145,200 144,200 tin 6,944 8,347 (Mandarin Finance compiled)

Achromatic Lens

An achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths (typically red and blue) into focus in the same plane.

The most common type of achromat is the achromatic doublet, which is composed of two individual lenses made fromglasses with different amounts of dispersion. Typically, one element is a negative (concave) element made out of flint glasssuch as F2, which has relatively high dispersion, and the other is a positive (convex) element made of crown glass such as BK7, which has lower dispersion. The lens elements are mounted next to each other, often cemented together, and shaped so that the chromatic aberration of one is counterbalanced by that of the other.

In the most common type (shown), the positive power of the crown lens element is not quite equalled by the negative power of the flint lens element. Together they form a weak positive lens that will bring two different wavelengths of light to a common focus. Negative doublets, in which the negative-power element predominates, are also made.

Achromatic Lens,Achromatic Objective Lens,Achromatic Condenser Lens,Achromatic Doublet Lenses

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