定义：采用一系列四分之一波长包层的电介质反射镜。

四分之一波长反射镜，也称为布拉格反射镜，是包含交替排列的两种不同光学材料的电介质反射镜结构，每一个光学薄层的厚度都对应的是设计波长的四分之一（其中，波长是指光在材料中的波长）。对于给定波长和层数对，四分之一波长反射镜可以得到最高的反射率。 
四分之一波长叠层也是更复杂电介质反射镜结构的基本组成部分。

Definition: dielectric mirrors based on a sequence of quarter-wave layers

Alternative term: Bragg mirrors

A quarter-wave mirror, also called a Bragg mirror, is usually a dielectric mirror (or semiconductor mirror) structure which consists of an alternating sequence of layers of two different optical materials, with each optical layer thickness corresponding to one-quarter of the wavelength for which the mirror is designed. Here, the wavelength is taken to be the wavelength within the material, not the vacuum wavelength. For a given wavelength and number of layer pairs, a quarter-wave mirror is the structure which can result in the highest reflectance.

Quarter-wave stacks are also very basic building blocks of more complicated dielectric mirror structures.