The optical properties of a metal are revisited. Starting from Maxwell’s equations, a rigorous calculation on the reflection and refraction of light at the interface between two metallic plates, A and B, is made. A complex conductivity \(\sigma = \sigma ^{\mathrm {Re}} + i\sigma ^{\mathrm {Im}}\) derived from the Drude-Zener treatment of the conduction electrons is incorporated into the equations, thereby introducing the effects of dispersion in the optical properties. Thereafter, we consider the case when medium A is either air or vacuum by setting the dielectric constant and magnetic permeability to unity, and by taking the limit \(\sigma \rightarrow 0\). The present theory provides a good account of published optical measurements on elemental aluminium.

重新审视了金属的光学特性。从麦克斯韦方程组出发，对光在两块金属板 A 和 B 之间的界面处的反射和折射进行了严格的计算。由传导电子的 Drude-Zener 处理导出的复电导率\(\sigma = \sigma ^{\mathrm {Re}} + i\sigma ^{\mathrm {Im}}\)被纳入方程，从而在光学特性中引入色散的影响。此后，我们通过将介电常数和磁导率设置为单位并取极限\(\sigma \rightarrow 0\)来考虑介质 A 是空气或真空的情况。本理论很好地说明了已发表的关于元素铝的光学测量。