This coating defines a single l/4 layer thin film coating. FRED uses the characteristic matrix of the coating layer to determine reflection and transmission properties as a function of wavelength and angle of incidence. Only those materials defined in the Materials folder of the object tree can be used to define the quarter wave coating. Once defined, the coating type cannot be changed.
The Quarter Wave Single Layer coating can be created in the following ways: •Open a new coating dialog and select "Quarter Wave Single Layer Coating" as the coating type.
Only the materials contained in the Materials folder can be used to define a coating. The material entry must be completed first.
Coatings and raytrace controls Coatings are used in conjunction with the Raytrace Controls to determine ray propagation. •To continue propagating a reflected ray, both the Raytrace Control and the Coating must allow the reflection •To continue propagating a transmitted ray, both the Raytrace Control and the Coating must allow the transmission •Scattered rays are subject to the same limitations. Currently, an absorbing surface cannot generate scattered rays.
Copies between FRED models will always transfer new material and coating information.
A single layer quarter wave thickness magnesium fluoride (n = 1.38) to be used as an anti-reflection coating is sometimes referred to as V-coat, describing the shape reflectance curve as a function of wavelength. For this example, minimum reflectance is achieved at a wavelength of 0.55 microns at a 45-degree angle of incidence. Note that the Wavelength and Angle settings are used by FRED to calculate the physical thickness of the layer. The following values would be entered into the coating dialog: WAVELENGTH = 0.55 ANGLE = 45 MATERIAL = MgF2
Coatings - General Sampled Coating Coatings - Polarizer / Waveplate Coating Coatings - Thin Film Layered Coating
For details about Raytrace Controls, select the following link.
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