The main optical parameters of the dielectric high reflection film emitter are as follows：

Reflectivity

Through the constructive interference of multiple reflected light beams, the intensity of the reflected light is increased and the transmitted light is reduced. When the number of dielectric film layers is large enough, the reflection coefficient approaches 1 at a specific wavelength λ₀, that is, almost total reflection is achieved. Commonly used multi - layer high - reflection films are alternately coated with high - and low - refractive - index film layers with an optical thickness nd of λ/4, which can be expressed as G(HL)pHA (p = 1, 2, 3 …). Here, G and A represent the glass substrate and air respectively, H and L represent the high - and low - refractive - index film layers respectively, p represents the number of groups of alternating high - and low - refractive - index layers, and the total number of film layers is (2p + 1). 

Thickness

The thickness of the anti - reflection film is directly proportional to the wavelength. To enhance the intensity of the reflected light and make the optical path difference between the reflected light on the front and back surfaces of the film be one wavelength, the thickness of the anti - reflection film is usually half of the wavelength of the incident light in the film. 

Wavelength

In the design and application, the specific working wavelength needs to be considered to ensure high reflectivity at this wavelength. The design of multi - layer high - reflection films is aimed at a specific wavelength λ, and high - reflection effects are achieved by setting the optical thickness of the film layer to λ/4.