achromasia ach·ro·ma·si·a (āk’rō-mā’zē-ə, -zhə)
Pallor associated with the hippocratic facies of extremely severe and chronic illness.
. noun Also called achromatic lens. a lens designed to bring light of two chosen wavelengths to the same focal point, thus reducing chromatic aberration Compare apochromat a person who has no colour vision at all and can distinguish only black, white, and grey. The condition is very rare
a person unable to perceive color.
Optics. free from color. able to emit, transmit, or receive light without separating it into colors. Biology. (of a cell structure) difficult to stain. Music. without accidentals or changes in key. Historical Examples achromatic lenses are used in all high-grade optical instruments such as telescopes and microscopes. Physics Willis Eugene Tower If not, the substitution […]
- Achromatic colour
noun (physics) colour, such as white, black, and grey, that is devoid of hue See colour (sense 2)
- Achromatic lens
a system of two or more lenses that is substantially free from chromatic aberration and in which the lenses are made of different substances so that the focal length of the system is the same for two or three wavelengths of light. Historical Examples The achromatic lens consists of a double convex lens of crown […]