Method and apparatus for determining reflection coefficients to filter arrangement with thin layers

The invention relates to a method for determining optical properties by measuring intensities of a thin layer is irradiated with the light on an at least partially transparent substrate having the thin layer. It can be measured as a relative intensity of at least one superposition shaft, optionally with the use of appropriate filter arrangements interference on the at least one thin layer, and then the or determines the reflection and / or transmission coefficient of the reflection and / or transmission to the thin layer. Preferably, the intensity of at least two superposition of waves is measured. The light can be irradiated directly to the carrier. The invention also relates to a device for determining optical properties by measuring intensities of a thin layer. This comprises an evaluation unit in the at least a stored lookup table. The use is preferably provided in the area of ​​the home protection.