Abstract: In a method of preparing a phosphor or scintillator layer to become deposited on a support, a vapor depositing step is applied from a crucible unit by heating as phosphor precursor raw materials present in said crucible, a Cs(X,X?) matrix compound and an activator or dopant precursor compound, wherein said crucible unit comprises at least a bottom and surrounding side walls as a container for phosphor precursor raw materials present in said crucible in liquefied form after heating said crucible, and wherein said Cs(X,X?) matrix compound has a higher vapor pressure than said activator or dopant precursor compound, said method comprising a step of providing said activator or dopant compound in form of a precursor raw material represented by the formula CsxEuyX?(x+?y), wherein x, y and ? are integers, wherein x/y is more than 0.

Abstract: A lighting apparatus is provided having a plurality N of light sources arranged annularly around the optical axis of a reflector. The efficiency of such an apparatus and its service life are improved by providing a central mirrored column which is symmetrically disposed with respect to the light sources. The column has C.sub.N or D.sub.N symmetry and reflects light emitted by the light sources away from the light sources themselves, thereby reducing the amount of light reflected back at the light sources and reducing their thermal load. The column has peaks that extend into the notional annulus on which the light sources are arranged to shield adjacent light sources from each other.