Greek 'a-' (without) + 'chroma' (colour) — coined in the 1760s for lenses that correct colour distortion.
Without colour; transmitting light without separating it into constituent colours; relating to achromatic colours (black, white, and grey).
From Greek 'akhrōmatistos' (uncoloured), from 'a-' (without, not) and 'khrōma' (colour). The word entered English in the 1760s as a technical term in optics, specifically to describe lenses designed to minimize chromatic aberration — the rainbow-fringing effect caused by a lens's inability to focus all wavelengths of light to the same point. The achromatic lens, independently developed by Chester Moore Hall (c. 1733) and John Dollond (1758), was a breakthrough in telescope and microscope
Newton believed it was impossible to build a lens that did not produce chromatic aberration, because he assumed all transparent materials dispersed light equally. This error — one of Newton's rare scientific mistakes — delayed the development of the achromatic lens by decades. Chester Moore Hall proved Newton wrong in the 1730s by combining crown glass and flint glass, which have different dispersive properties, in a single lens that focused
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