This part is a kind of semiconductor called L6565.

Function of this product has The best light source is supported by the best electrode technology.

Manufacturers : Hamamatsu Corporation

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Some of the text within the PDF file :

LAMPS DEUTERIUM LAMPS L2D2 The best light source is supported by the best electrode technology. PATENTS L2D2 Lamps (Deuterium Lamps ) LONG LIFE : 4000 HOURS 4 times longer guaranteed life I Life Characteristics The L2-4000 series lamps assure an operating life of 4000 hours-4 times longer than conventional lamps. This is the longest operating life of any deuterium lamp. HIGH LIGHT OUTPUT : 1.3 TIMES HIGHER 1.1 times higher (L2-4000 series) The L2-2000 series lamps produce 1.3 times higher light output than conventional lamps. The L2-4000 series lamps even offer light output 1.1 times higher than conventional lamps. (L2-2000 Series) I Radiant Output Intensity 4 100 LIGHT INTENSITY (%) LIGHT INTENSITY (A.U.) 3 L2D2LAM PL 1.3 TIMES 2-200 [ ... ]

L6565 PDF Datasheet Download