An apparatus for covering a left eye and a right eye of a human, includes: a first eye piece configured for covering a left eye of a human； and a second eye piece configured for covering a right eye of the human； wherein the first eye piece and the second eye piece are configured for preventing transmission of visible light； and wherein at least one of the first eye piece and the second eye piece comprises a region that is transparent for electromagnetic radiation with a wavelength range outside a visible range.
