Fresnel is a simple texture map that allows you to blend two colors or maps based on the angle of view and an index of refraction. For example you can connect the Fresnel texture to the specular color of a normal material in order to create a Fesnel reflection.
Perpendicular – Specifies the color for the texture when viewed frontally.
Parallel – Specifies the color for the texture when viewed at a grazing angle.
IOR – Specifies the index of refraction to use when calculating the Fresnel term.
Mode – Specifies the multiplication mode of the colors.
Multiplier – Multiplies the RGB numbers for each pixel of the top layer with the RGB number of the corresponding pixel from the bottom layer. The result is a darker picture.
Blend Amount– Takes each pixel from the top layer if present. Otherwise the bottom layer is used.
Perpendicular – Controls the intensity of the perpendicular color.
Parallel – Controls the intensity of the parallel color.