Attenuating filter for ultraviolet light

US7196842B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Bernhard Weigl · Seattle, US
• Hans-Jochen Paul · Aalen, DE
• Eric Eva · Aalen, DE

Key dates

• Filing date: Nov 29, 2004
• Grant date: Mar 27, 2007
• Expiry date: Nov 29, 2024

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B5/208
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An attenuating filter provides a prescribed attenuation of the intensity of transmitted, short-wavelength, ultraviolet light, in particular, at wavelengths below 200 nm, that is governed by a predefinable spatial distribution of its spectral transmittance. The filter has a transparent substrate (3), e.g. fabricated from crystalline calcium fluoride. A filter coating (5) fabricated from a dielectric material that absorbs over a predefined wavelength range is applied to at least one surface (4) of the substrate. In the case of operating wavelengths of about 193 nm, the filter coating consists largely of tantalum pentoxide. Filters of the type, which may be inexpensively fabricated with high yields, are noted for their high abilities to withstand laser radiation and may be effectively antireflection coated employing simply designed antireflection coatings.