Abstract: An optical material for lithographic applications is selected from crystal materials by a testing method. The crystal materials are preferably quartz and/or alkali or alkaline earth halides, especially fluorides, or mixed crystals. The testing method includes three tests to measure irreversible radiation damage: 1) the optical material is irradiated with ultraviolet radiation at 193 nm and the non-intrinsic fluorescence intensity at 740 nm is measured; 2) the optical material is irradiated with high energy density laser light and a change in respective absorptions before and after irradiation at 385 nm is measured; and 3) the optical material is irradiated with an X-ray or radioactive source to form all possible color centers and a difference of respective surface integrals of corresponding absorption spectra in ultraviolet spectral and/or visible spectral regions is measured before and after irradiation.

Abstract: An optical material for lithographic applications is selected from crystal materials by a testing method. The crystal materials are preferably quartz and/or alkali or alkaline earth halides, especially fluorides, or mixed crystals. The testing method includes three tests to measure irreversible radiation damage: 1) the optical material is irradiated with ultraviolet radiation at 193 nm and the non-intrinsic fluorescence intensity at 740 nm is measured; 2) the optical material is irradiated with high energy density laser light and a change in respective absorptions before and after irradiation at 385 nm is measured; and 3) the optical material is irradiated with an X-ray or radioactive source to form all possible color centers and a difference of respective surface integrals of corresponding absorption spectra in ultraviolet spectral and/or visible spectral regions is measured before and after irradiation.

Abstract: Single crystals with low scattering, small refractive index differences and few small angle grain boundaries have a bi-directional scattering distribution function value (BSDF) of less than 1.5*10?6 or 5*10?7.

Abstract: The method determines the extent of irreversible radiation damage of an optical material. The method includes the following three tests to determine the extent of irreversible radiation damage: 1) the optical material is irradiated with ultraviolet radiation at a wavelength of 193 nm and the non-intrinsic fluorescence intensity at a wavelength of 740 nm is measured; 2) the optical material is irradiated with high energy laser light and a change in respective absorptions at a wavelength of 385 nm is determined before and after irradiation; and 3) the optical material is irradiated with an energetic radiation source to form all possible color centers and a difference of respective surface integrals of corresponding absorption spectra in ultraviolet spectral and/or visible spectral regions is measured before and after irradiation.

Abstract: The method provides CaF2 single crystals with low scattering, small refractive index differences and few small angle grain boundaries, which can be tempered at elevated temperatures. In the method a CaF2 starting material is heat-treated for at least five hours at temperatures between 1000° C. and 1250° C. and then vaporized at a temperature of at least 1100° C. in a vacuum of at most 5*10?4 mbar to form a vapor. The vapor is condensed at a temperature between 500° C. to 1280° C. to form a condensate. Then a melt formed from the condensate is cooled in a controlled manner to obtain the single crystal, which is subsequently tempered. The method is preferably performed with a CaF2 starting material including waste material and cuttings from previously used melts.

Abstract: The method provides CaF2 single crystals with low scattering, small refractive index differences and few small angle grain boundaries, which can be tempered at elevated temperatures. In the method a CaF2 starting material is heat-treated for at least five hours at temperatures between 1000° C. and 1250° C. and then sublimed at a sublimation temperature of at least 1100° C. in a vacuum of at most 5*10?4 mbar to form a vapor. The vapor is condensed at a condensation temperature of at least 500° C., which is at least 20° C. below the sublimitation temperature, to form a condensate. Then a melt formed from the condensate is cooled in a controlled manner to obtain the single crystal, which is subsequently tempered. The method is preferably performed with a CaF2 starting material including waste material and cuttings from previously used melts.

Abstract: A calcium fluoride single crystal with increased radiation resistance can be prepared by growing under controlled conditions of solidification from a melt of a crystal raw material containing a dopant affording ions of Al and/or Ga and/or In and/or Tl. Such a single crystal after irra-diation with at least 5×108 laser pulses having a pulse energy of at least 10 mJ/cm2 shows at a wavelength of 193 nm an absorption of less than 0.1%/cm.

Abstract: The invention relates to the loading of quartz glass objects with hydrogen in an annealing process in a furnace for improving the homogeneity of the refractive index and the laser resistance while, at the same time, maintaining a specified stress birefringence of each of the glass objects. Initially, the distribution of the refractive index, the stress birefringence, the distribution of the hydrogen and the differences in refractive index, which are to the equalized, are determined in the respective glass object, after which the hydrogen change, which is necessary for equalizing the refractive index, is determined. Furthermore, the annealing temperature and its holding time, as well as the hydrogen concentration and the hydrogen pressure in the furnace are adjusted to achieve a sufficiently equalized distribution of refractive index.

Abstract: The invention relates to a synthetic quartz glass that can be produced by direct precipitation by means of flame hydrolysis of a silicon precursor, especially a chlorine-containing silicon precursor, which quartz glass when irradiated with laser pulses at a wavelength of 193 nm at an energy density (H) of up to H=1.5 mJ/cm2 and at a repetition frequency of the laser pulses of up to R=4 kHz is characterized by the following properties: in the range of energy densities of up to 1.5 mJ/cm2, the equilibrium absorption of quartz glass rises sublinearly with the energy density for all repetition frequencies of the laser pulses; the dependency of the equilibrium absorption on the repetition frequency of the laser pulses is sublinear; and the relationship of equilibrium absorption and energy density (H) can be described as a function of H1.7; the H2 content being at least 0.2·1018 molecules/cm3. Other aspects of the invention relate to a process for producing such a synthetic quartz glass.