Trumpf LASERCELL 1005, Operator'S Manual

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B337EN01.DOC
Laser processing
1-33
5.6 Hazards from thermal decomposition
of ZnSe lenses
Lenses made of zinc selenide (ZnSe) are inserted on the machine
in the output mirror of the laser unit and as a focusing lens in the
cutting head.
Lens characteristics
Chemical
composition Zinc selenide (ZnSe)
Coating contains thorium fluoride (thorium content of a
lens with * 1": approx. 1 mg)
Form Disc (lens)
Color Orange, transparent
Odor -
Melting point 1520°C
Vapor pressure Negligible
Solubility
•
soluble in powerful acids and lyes
•
Insoluble in water
Combustibility -
Special
precautionary
measures None under normal storage and operating conditions
Thermal decomposition
Thermal decomposition of the lens by absorption of laser radiation,
e.g. due to contamination or pits on the lens.
Note
If a laser power of >2500 watts is used for operations, make
absolutely sure that the lens in the cutting head is clean. Other-
wise, there is an increased possibility that the lens will be
destroyed by power absorption.
Zinc oxide, zinc hydrates, selenium, selenium oxides, hydrogen
selenide (H
2
Se), thorium.
Toxicology information
Selenium and selenium compounds release toxic products in the
event of thermal decomposition. These compounds are a health
hazard as selenium replaces sulfur in body substances. At room
temperature, hydrogen selenite is a colorless gas which stinks of
rotten vegetables. Even in low volumes (MAK value of 0.2 mg/m
3
),
it can be very irritating to mucous membranes of the nose and
eyes ("selenium cold").
Table 1-6
Cause
Decomposition products
Selenium