Optical properties
Among the optical properties of the surface which are most often influenced by layers are transmittance, absorbance and reflectance. In addition to primarily nanometer specialized layers for optical components, there are micrometer options associated with, for example, unique combinations with large absorption and extreme heat resistance.
PVD coatings: LUBRIK G,
Transmittance is one of the optical properties of surfaces most often influenced by the application of PVD layers. This determines the amount of radiation that passes through the given material. Furthermore absorbance (absorbance) indicates how much radiation a given material absorbs and reflectance (Reflectance) affects the amount of radiation reflected from the surface in proportion to the amount falling on the material.
There are very thin specialized layers for optical purposes and components that are not expected to be exposed to high temperatures. It is possible to prepare PVD outside this category with micrometer-thick layers uniquely optimized to create a combination of great absorbency and heat resistance to levels of 500 – 650°C, with a focus on laser power optics.
Measurement
One method of performing measurements is that of using reflectometers. An example of measuring absorption curves in the 500-1100 nm range of two versions of coatings (calottes in Fig. 2) on three textured base materials – dural 7075, copper and steel ČSN 19830 is given in Fig. 1. In the areas above 800 nm, the coatings achieve very attractive absorbance with values greater than 98 or 95%.
Spherical spheres are also commonly used to measure absorbance. The absorbances of the aforementioned coatings were measured with a laser at two wavelengths of 1064 and 1550 nm. The graph in Fig. 3 shows a comparison of the effect of the texture and the effect of the subsequent coating. Both coatings achieve absorbance values above 94%. The values confirm the trend from the previous reflectometric measurement in the range of 500-1100 nm.
