US 7,256,887 B2Granted

Determining the suitability of an optical material for the production of optical elements, corresponding device, and use of said material

AssigneeSchott AG

InventorsChristian Muehlig, Wolfgang Triebel, Jochen Alkemper, Regina Martin

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Abstract

The method tests the suitability of an optical material having a radiation-induced absorption, especially of an alkali or alkaline earth halide, for production of an optical element exposed to high-energy irradiation. The method includes pre-irradiating the optical material with laser radiation until rapid damage induced in the optical material with the laser radiation is saturated; subsequently measuring fluorescence of the optical material during and/or immediately after irradiating the optical material with excitation radiation and determining the non-intrinsic fluorescence and intrinsic fluorescence present in the measured fluorescence. Suitability may be preferably determined according to a ratio of the amount of non-intrinsic fluorescence to intrinsic fluorescence. A device for performing the method including a barrier device for blocking scattered excitation radiation is also provided.

Claims17

Dependent claims

A method of determining suitability of a crystalline optical material for production of an optical element, particularly for high-energy irradiation, wherein radiation-induced absorption is detected or identified in the optical material, said method comprising the steps of:

a) pre-irradiating the crystalline optical material with laser radiation until rapid damage induced in the crystalline optical material with the laser radiation is saturated;
b) after the pre-irradiating of step a), measuring total fluorescence produced in the crystalline optical material by excitation radiation during and/or immediately after irradiating the crystalline optical material with the excitation radiation, said total fluorescence being composed of intrinsic fluorescence and non-intrinsic fluorescence;
c) determining the non-intrinsic fluorescence of the crystalline optical material in the total fluorescence measured during and/or immediately after irradiating with the excitation radiation;
d) determining the intrinsic fluorescence of the crystalline optical material, said intrinsic fluorescence being a constant of said crystalline optical material;
e) determining an amount ratio of said non-intrinsic fluorescence to said intrinsic fluorescence in said total fluorescence measured in step b);
f) ascertaining whether or not said optical material is suitable for making said optical element according to said amount ratio determined in step e);
and
g) outputting whether or not said optical material is suitable for making said optical element according to said amount ratio.

5 more elements

A method of determining suitability of an alkaline or alkaline earth fluoride monocrystal for making an optical element for high-energy irradiation, wherein radiation-induced absorption is detected or identified in the monocrystal, said method comprising the steps of:

a) pre-irradiating the alkaline or alkaline earth fluoride monocrystal with laser radiation until rapid damage induced in the alkaline or alkaline earth fluoride monocrystal with the laser radiation is saturated;
b) after the pre-irradiating of step a), measuring total fluorescence produced in the alkaline or alkaline earth fluoride monocrystal by excitation radiation at an excitation radiation wavelength below 200 nm by means of a fluorescence measuring device during and/or immediately after irradiating the alkaline or alkaline earth fluoride monocrystal with the excitation radiation, said total fluorescence being composed of intrinsic fluorescence and non-intrinsic fluorescence;
c) during the measuring of the total fluorescence, preventing ultraviolet radiation at the excitation radiation wavelength propadated toward the fluorescence measuring device from reaching the measuring device by means of a barrier device;
d) determining the non-intrinsic fluorescence of the alkaline or alkaline earth fluoride monocrystal in the total fluorescence measured during and/or immediately after irradiating with the excitation radiation;
e) determining the intrinsic fluorescence of the alkaline or alkaline earth fluoride monocrystal, said intrinsic fluorescence being a constant of said alkaline or alkaline earth fluoride monocrystal;
f) determining an amount ratio of said non-intrinsic fluorescence to said intrinsic fluorescence in said total fluorescence measured in step b);
g) ascertaining whether or not said alkaline or alkaline earth fluoride monocrystal is suitable for making said optical element according to said amount ratio determined in step e);
and
h) outputting whether or not said optical material is suitable for making said optical element according to said amount ratio.

6 more elements

Dependencies are inferred from the claim text.