Reflector for excimer laser and excimer laser apparatus using the reflector
First Claim
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1. A reflector for an excimer laser comprising:
- a substrate made of a material having a high thermal conductivity and a low coefficient of linear expansion,an aluminium layer formed on one surface of said substrate, anddielectric multilayers formed on said aluminium layer,said dielectric multilayers being essentially composed of at least two pairs of a layer of high refractive index material and a layer of low refractive index material, and an optical thickness of each layer except for an outer pair of layers is λ
/4, and an optical thickness of each layer of said outer pair of layers is deviated from λ
/4, and total optical thickness of said outer pair of layers is λ
/2.
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Abstract
A reflector for an excimer laser is composed of an aluminum layer deposited on a substrate and at least two pairs of dielectric multilayers of high refractive index material and low refractive index material alternately piled on the aluminum layer, and optical thickness of the respective layers of an outer pair of the dielectric multilayers are deviated from λ/4 and total optical thickness of the outer pair is made to be λ/2.
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Citations
12 Claims
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1. A reflector for an excimer laser comprising:
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a substrate made of a material having a high thermal conductivity and a low coefficient of linear expansion, an aluminium layer formed on one surface of said substrate, and dielectric multilayers formed on said aluminium layer, said dielectric multilayers being essentially composed of at least two pairs of a layer of high refractive index material and a layer of low refractive index material, and an optical thickness of each layer except for an outer pair of layers is λ
/4, and an optical thickness of each layer of said outer pair of layers is deviated from λ
/4, and total optical thickness of said outer pair of layers is λ
/2. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An excimer laser apparatus comprising:
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a pair of longitudinally extending bar-shaped main discharge electrodes enclosed in a chamber in a spaced parallel relationship relative one another and defining a gap therebetween having a longitudinally directed laser axis therein, a plurality of pre-discharge electrodes in said chamber extending along and adjacent to the gap defined between said pair of main discharge electrodes, a laser gas including an excimer laser active medium enclosed in said chamber, a total reflector positioned in proximity to one end of said pair of main discharge electrodes for reflecting energy along the laser axis, said total reflector being composed of an aluminium layer and dielectirc multilayers formed on a substrate made of a material having a high thermal conductivity and a low coefficient of linear expansion, and an output coupling reflector positioned in proximity to the other end of said pair of main discharge electrodes and facing said first-mentioned end for reflecting energy along the laser axis, wherein said dielectric multilayers are composed of at least two pairs of a layer of high refractive index material and a layer of low refractive index material, the optical thickness of each layer other than the outer pair of layers being λ
/4, the optical thickness of each layer of the outer pair of layers being deviated from λ
/4, and the total optical thickness of the layers of the outer pair of layers being λ
/2. - View Dependent Claims (9)
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10. An excimer laser apparatus comprising:
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a pair of longitudinally extending bar-shaped main discharge electrodes enclosed in a chamber in a spaced parallel relationship relative one another and defining a gap therebetween having a longitudinally directed laser axis therein, a plurality of pre-discharge electrodes in said chamber extending along and adjacent to the gap defined between said pair of main discharge electrodes, a laser gas including an excimer laser active medium enclosed in said chamber, a total reflector positioned in proximity to one end of said pair of main discharge electrodes for reflecting energy along the laser axis, said total reflector being composed of of an aluminum layer, dielectric multilayers and a single crystal plate made of a material selected from the group consisting of calcium flouride and magnesium flouride on a substrate made of a material having a high thermal conductivity and a low coefficient of linear expansion, and an output coupling reflector positioned in proximity to the other end of said pair of main discharge electrodes and facing said first-mentioned end for reflecting energy along the laser axis, wherein said dielectric multilayers are composed of at least two pairs of a layer of high refractive index material and a layer of low refractive index material, the optical thickness of each layer other than the outer pair of layers being λ
/4, the optical thickness of each layer of the outer pair of layers being deviated from λ
/4, and the total optical thickness of the layers of the outer pair of layers being λ
/2. - View Dependent Claims (11)
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12. A reflector for an excimer laser comprising:
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a substrate having a precisely polished surface, an aluminium layer formed on said surface of said substrate, dielectric multilayers formed on said aluminium layer, and a protecting plate made of a single crystal plate of material selected from the group consisting of calcium flouride and magnesium flouride, and formed on said dielectric multilayers, wherein said dielectric multilayers are composed of at least two pairs of a layer of high refractive index material and a layer of low refractive index material, an optical thickness of each layer other than the outer pair of layers is λ
/4, and an optical thickness of each layer of the outer pair of layers is deviated from λ
/4 and the total optical thickness of the layers of the outer pair of layers is λ
/2.
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Specification