The Coatings folder contains default and user-defined Coatings that can be applied to any surface in a FRED document. When used in conjunction with Raytrace Controls, coatings specify the relative reflection and transmission for the specular component of the ray interaction at a surface. The default coatings are:
100% Absorb 100% Reflect %100 Transmit Standard Coating (96% transmitting, 4% reflecting) Uncoated (Bare substrate)
Users can edit any one of the default coating types except Uncoated, which requires no user input. NOTE: Changing the default Coatings can have unexpected consequences if the user forgets that a change has been made. It is recommended that the user create a new coating if different functionality is required. The default Absorb, Reflect, Transmit, and Standard coatings are Sampled Coating types. Other FRED coating types are:
Quarter Wave Single Layered Coating
NOTE: FRED allows the user to change the coating parameters for an existing coating but does not allow the user to change the Coating type once it has been defined.
The Coatings object tree folder Coatings have their own dedicated folder on the object tree labeled "Coatings", which can be expanded by clicking on the "+" icon and collapsed by clicking on the "-" symbol. Default and user defined coatings are stored in this folder and can be applied to any surface in the FRED document.
Edit/View an existing coating To edit an existing coating, right mouse click on the coating in the object tree and select "Edit/View Coating". The coating type cannot be changed once a coating has been defined, but the coating parameters can be modified.
Coating Detailed/Summary Reports The coating Detailed/Summary Reports can be accessed by right mouse clicking on the Coatings folder in the object tree and selecting "Summary Report" or "Detailed Report" from the list menu.
Adding a new coating to a FRED document There are several methods for adding a new coating to a FRED model. Read about them at this help topic.
The following table describes the options available in the coating dialog.
Coatings and raytrace controls When a ray interacts with a surface, the Raytrace Control is evaluated first to see which components are allowed to propagate. If the Raytrace Control allows specular transmission and/or specular reflection, the coating property is checked to determine how much power should be generated into each component. For more on ray power assignments, please see this help topic.
When a ray is incident on a surface, the TIR condition is triggered by an evaluation of the refractive index values for the materials assigned to the surface and the ray's current immersion material. If the ray is determined to be in a TIR condition, then no transmitted ray is generated and the following rules apply for the reflected ray: Uncoated, Thin Film and Quarter Wave Coatings: The coating is evaluated and the resulting magnitude and phase is applied to the ray.
Sampled, General Sampled, Polarizer/Waveplate and Scripted Coatings: The coating is not evaluated. The magnitude is set to unity, the phase is set to zero, and then applied to the ray.
Default coatings for a new lens element The default coatings for a lens that was imported from a catalog or entered as a element are 100% Transmitting coatings on the front and back surfaces and 100% Absorbing on the edges and bevels (if any).
Default coatings for a new prism element The surface coating types for a prism imported from a catalog or entered as a primitive will vary according to function, but the coatings will be selected from the default set.
Default coatings for a new mirror element The default coatings for a Mirror element are 100% Reflective on the reflecting surface and 100% Absorbing on the back surface, edge, and bevels.
Copies between FRED models will always transfer new material and coating information.
Summary and detailed coating reports Summary and detailed reports containing information about the coatings currently available in the FRED document can be printed to the output window by right mouse clicking on the Coatings folder in the object tree and selecting either "Summary Report" or "Detailed Report" from the list menu.
The summary report prints a list of the coating names and descriptions to the output window.
The detailed report prints a summary of the coating properties (wavelength, reflection and transmission coefficients, etc.) for each coating type defined in the FRED document.
Coatings - General Sampled Coating Coatings - Polarizer / Waveplate Coating Coatings - Quarter Wave Single Layer Coatings - Thin Film Layered Coating
For details about Raytrace Controls, select the following link.
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