Due to its outstanding characteristics the brand LITHOTEC describes these kind of ZERODUR which is being used in lithographic and metrology applications.
ZERODUR is an inorganic, non-porous glass ceramic, characterized by a phase of evenly distributed nanocrystals within a residual glass phase. ZERODUR contains about 70-78 weight percent crystalline phase with a high quartz structure. This crystalline phase has a negative linear thermal expansion, while that of the glass phase is positive. The crystals have an average size of about 50 nm.
LITHOTEC® i-line glass is offered with the following outstanding properties:
* High refractive index homogeneity values (<0.5 ppm at 200 mm diameter)
* Excellent internal quality
* Negligible stress birefringence due to a well-defined annealing process
* Variation of absolute refractive index values per lot of less than 5 x 10-5
* Availability of a wide range of high transmission glass types FK5HT to F14 HT ensures high flexibility in optical designs
LITHOTEC® i-line glasses are most often used in applications such as:
* Projection lenses and illumination systems for use in i-line wafer steppers and scanners
* Standard optical applications requiring high transmission in the UV region