Polarizer for high-power deep UV radiation
First Claim
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1. A polarizing system for deep UV light comprising:
- a substrate having a surface normal inclined between 65° and
75°
to a direction of propagation of an unpolarized beam of light having a nominal wavelengths less than 250 nm;
an antireflective coating on the surface of the substrate that reflects no more than 2% of a first of two orthogonally related polarization components of the unpolarized beam of light;
the antireflective coating also reflects at least 80% of a second of the two orthogonally related polarization components of the unpolarized beam of light; and
an optical beam conveyor that routes a first portion of the unpolarized beam that is reflected from the antireflective coating as a substantially polarized beam intended for further propagation.
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Abstract
A polarizing effect is achieved for light having wavelengths less than 250 nm by orienting an antireflector at an incidence angle between 65° and 75°. Despite limited choices for materials, the antireflector is constructed of layers that alternate in refractive index to exploit the mechanism of interference for limiting the reflectivity of one linear polarization component of the light. The same combination of layers supports the reflectivity of an orthogonal linear polarization component. The light reflected from the antireflector is highly polarized.
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Citations
65 Claims
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1. A polarizing system for deep UV light comprising:
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a substrate having a surface normal inclined between 65° and
75°
to a direction of propagation of an unpolarized beam of light having a nominal wavelengths less than 250 nm;
an antireflective coating on the surface of the substrate that reflects no more than 2% of a first of two orthogonally related polarization components of the unpolarized beam of light;
the antireflective coating also reflects at least 80% of a second of the two orthogonally related polarization components of the unpolarized beam of light; and
an optical beam conveyor that routes a first portion of the unpolarized beam that is reflected from the antireflective coating as a substantially polarized beam intended for further propagation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A polarization-sensitive routing system for ultraviolet light comprising:
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a working optical pathway for conveying an unpolarized beam of ultraviolet light having a wavelength less than 250 nm;
an antireflector inclined to the working optical pathway such that rays within the unpolarized beam of ultraviolet light encounter the antireflector at angles of incidence above Brewster'"'"'s angle;
the antireflector including a plurality of layers that exploit a mechanism of interference for reducing reflectivity of P polarization components of the unpolarized beam that are oriented within the planes of incidence while substantially reflecting S polarization components of the unpolarized beam that are oriented normal to the planes of incidence; and
a beam conveyer that routes a first portion of the unpolarized beam that is reflected from the antireflector as a substantially S polarized beam at an extinction ratio of S polarization to P polarization of at least 40 to 1 along the working optical pathway for productive use. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A method of polarizing light having a nominal wavelength less than 250 nm and a power densities of at least five milli-joules per square centimeter per pulse comprising the steps of:
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orienting an antireflective surface with respect to an unpolarized beam of light such that individual light rays of the beam impinge upon the antireflective surface at incidence angles between 65° and
75°
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reflecting less than 2% of a first of two orthogonally related polarization components of the unpolarized beam of light from the antireflective surface;
reflecting more than 80% of a second of the two orthogonally related polarization components of the unpolarized beam of light from the antireflective surface; and
routing a first portion of the unpolarized beam that is reflected from the antireflective coating as a substantially polarized beam intended for further propagation. - View Dependent Claims (37, 38, 39, 40)
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41. A method of polarizing ultraviolet light comprising:
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conveying an unpolarized beam of ultraviolet light having a wavelength less than 250 nm along a working optical pathway;
inclining an antireflector to the working optical pathway such that rays within the unpolarized beam of ultraviolet light encounter the antireflector at angles of incidence above Brewster'"'"'s angle;
exploiting a mechanism of interference within the antireflector for reducing reflectivity of P polarization components of the unpolarized beam that are oriented within the planes of incidence while substantially reflecting S polarization components of the unpolarized beam that are oriented normal to the planes of incidence; and
routing a first portion of the unpolarized beam that is reflected from the antireflector as a substantially S polarized beam at an extinction ratio of S polarization to P polarization of at least 40 to 1 along the working optical pathway for productive use. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
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54. A polarizer for polarizing deep UV light comprising:
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a substrate having a mounting surface inclined to an optical axis along which the deep UV light is propagated, a series of layers supported on the substrate having refractive indices that vary in an alternating pattern of higher and lower refractive indicies;
the layers being adjusted in thickness for optimizing conditions of interference between reflections of the deep UV light from adjacent layers;
a normal of the layers being inclined to an optical axis through an angle of incidence at which an extinction ratio between orthogonally related polarization components in a reflected beam approaches a maximum;
the angle of incidence being within a range at which the maximum extinction ratio occurs at progressively higher angles of incidence as the refractive index of the higher refractive index layers increases; and
the number of layers being within a range at which the maximum extinction ratio occurs at progressively higher angles of incidence as the number of layers increases. - View Dependent Claims (55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65)
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Specification