Doyen's Mirror

The doyen mirror is one of the most famous and frequently used lenses in the physics of optics. This is a special optical instrument that is used to measure various parameters of light.

A doyen mirror is also a flat lens, which consists of two identical concave surfaces located at an angle of 90°. The mirror is made of glass or plastic. The main element of this lens is a thin film of dielectric material (such as silicon) that sits between two glass surfaces and helps focus light. This type of mirror can have different shapes, including round, oval, rectangular and others.

**Principle of operation of the Doyen mirror**

A Doualien mirror is a type of thin plane mirror that has two concave surfaces located at a distance s from each other. This creates the effect of changing the direction of light as it exits the mirror. The reflected light passes through the polarizer and enters