Achromatic

Lead oxide is used in producing fine "crystal glass" and "flint glass" of a high index of refraction for achromatic lenses. The nitrate and the acetate are soluble salts. Lead salts such as lead arsenate have been used as insecticides, but their use in recent years has been practically eliminated in favor of less harmful organic compounds. 

Acheson process Achlorhydria Achondrites Achromatic hologram Achromobacter sp. Achromycin Achromycin [60-54-8]... 

Spectroscopic ellipsometers that measure A in the whole data range require an achromatic compensator with a phase shift close to 90° over a large spectral range. The compensator can be located between polarizer and sample or between sample and analyzer. 

Achromat, m. achromatic lens, achromat, achromatisch, a. achromatic, achromatisieren, v.t. achromatize. Achromatismus, m. achromatism. 

Farbe-kiife, -ktipe, /. dyeing vat, dye vat, dye beck, -lack, m. lac dye. farbelos, a. colorless achromatic. 

Through a curious set of circumstances, Newton failed to solve the problem of chromatic aberration, and so, he abandoned the attempt to construct a refracting telescope which should be achromatic, and instead designed a reflecting telescope, probably on the model of a small one that he had constructed in 1668. The form he used is known by his name today. 

Information on the hue of whiteness is provided by dividing CIE colour space, in the neighbourhood of the D65 achromatic point, into a series of parallel strips corresponding to variations in hue of whiteness. The principle is illustrated in Figure 11.4. According to this... 

Microscopists were not entirely idle, however, and after Giovanni Battista Amici (1786-1863) introduced achromatic lenses in France in 1827, the cell theory was not far behind. Henri Dutrochet (1776-1847) had already proposed that animal and plant tissues were constituted of cells, a view reiterated by many, notably Jan Evangelista Purkyne (1787-1869), Johannes Muller (1801 -1858), andjacob Henle (1809-1885). Felix Dujardin... 

The least expensive (and most common) objectives are the achromatic objectives that are designed to limit the effects of chromatic and spherical aberration. Achromatic objectives are corrected to bring two wavelengths of light (typically red and blue) into focus in the same plane. The limited correction of achromatic objectives leads to problems with color microscopy and photomicrography. 

Apochromat Microscope objective that has better color correction than the much more common achromat objectives corrected chromatically for two wavelengths of light (red and blue). Apochromatic objectives are corrected chromatically for three colors (red, green and blue) and spherically for two colors, which practically eliminates chromatic aberration. 

Neofluar objectives are chromatically better corrected than the achromatic objectives (fluorite), but worse than the plan-apochromat objectives. The contrast of the neofluar objectives is however larger than with the plan-apochromat objectives. 

Fig. 6. The Sofica LS photometer 1 - Hg Pump cooled by high pressure water, 2 - total reflection prism, 3 - achromatic condensing lens, 4 - wavelength filters, 5 - glass diffuser,...

Achromatic colours resemble only black and white (grey). 

Chroma is the attribute of a colour that expresses the degree by which it differs from an achromatic colour of the same lighmess. 

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