| 摘要 |
The invention relates to a lighting apparatus comprising a conversion material (2) for converting primary light (4) into secondary light (5), wherein the conversion material (2) comprises converting photolummescent material (15), which degrades to non-converting photolummescent material over time when the conversion material (2) is illuminated by the primary light (4). The conversion material (2) is adapted such that, when the conversion material (2) is illuminated by the primary light (4), the relative decrease in concentration of the converting photolummescent material (15) within the conversion material (2) is larger than the relative decrease in intensity of the secondary light (5). This allows the lighting apparatus to provide an only slightly reduced absorbance of the primary light, even if a large part of the photolummescent material has been bleached, and thus a longer lifetime, with the same or a slightly reduced intensity of the secondary light.
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