noun
crown glass
A type of optical glass with low dispersion, historically used for window panes and lenses.
クラウンガラスはフリントガラスと組み合わせて色収差を補正するのに使われる。
Crown glass is used in combination with flint glass to correct chromatic aberration.
Alternate kana spelling with a middle dot.
Kanji form using 硝子 for glass; rarely used.
Flint glass has higher dispersion and refractive index, often paired with crown glass in achromatic lenses.
From English 'crown glass'. The term 'crown' refers to the traditional manufacturing method where the glass was blown and spun into a flat disk with a thicker center (the 'crown').