对于给定的观察者位置，和给定的光源位置或者与光源相关的发光表面来说，该表面或曲线上各点的亮度相同。

Locus of points on a surface at which the luminance is the same, for given positions of the observer and of the source or sources in relation to the surface.

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And, when zinc sulfide is hit by particles or by anything, by radiation or by particles of greater than a certain critical energy, there is a glow.

当粒子或其他东西,通过辐射或粒子的方式，并且能量高于临界值,撞击到硫化锌的表面上的时候，就会发光。

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