noun
ordinary ray
Technical term in optics; refers to the ray in a birefringent crystal that obeys Snell's law. Contrasts with 異常光線 (extraordinary ray).
See also: 異常光線
方解石に入射した光は常光線と異常光線に分かれる。
Light entering calcite splits into an ordinary ray and an extraordinary ray.
Compound of 常 (じょう, 'ordinary, normal') + 光線 (こうせん, 'light ray'). A calque from English 'ordinary ray'.