ABSTRACT
The Fabry–Pérot Filter (FPF) is comprised of two flat and highly reflective mirrors with an air gap between them. Thus, the FPF can be considered to be a system with three media. The individual media can first be considered as shown in Figure 6.1. For an incoming beam from Medium 1 striking on the interface between Medium 1 and Medium 2, the beam can be characterized with complex reflection amplitude, r 1 , and complex transmission amplitude t 1 . Likewise, for an incoming beam from Medium 2 incident on the interface between Medium 1 and Medium 2, the beam is undergoing reflection back into Medium 2 with complex reflection amplitude, https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315151557/9c6f3136-e015-45c5-9876-1c866d2ad4d4/content/inline-math6_3.jpg"/> r 1 ′ and transmission into Medium 1 with complex transmission amplitude https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315151557/9c6f3136-e015-45c5-9876-1c866d2ad4d4/content/inline-math6_4.jpg"/> t 1 ′ . Finally, when a beam from Medium 2 strikes the interface between Medium 2 and Medium 3, the complex reflection amplitude is r2 and the complex transmission amplitude is t 2 .
