Optical scanning system with diffractive optics
First Claim
1. An optical system for scanning a beam comprising:
- a laser source for emitting a beam along a first path;
a deflector intersecting said first path for translating said beam into a scanning beam which moves along a second path in a scan plane;
a F-θ
lens system in said second path comprising first and second elements for focusing said scanning beam onto an image plane transverse to said scan plane;
said first and second elements each comprising at least one body having a non-toric lens; and
the body of at least one of said first and second elements also provides a diffractive element which corrects optical aberrations of said scanning beam, wherein said diffractive element corrects optical aberrations in said scanning beam which includes at least correcting of astigmatic aberrations of said scanning beam.
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Accused Products
Abstract
An improved optical system having diffractive optic elements is provided for scanning a beam. This optical system includes a laser source for emitting a laser beam along a first path. A deflector, such as a rotating polygonal mirror, intersects the first path and translates the beam into a scanning beam which moves along a second path in a scan plane. A lens system (F-θ lens) in the second path has first and second elements for focusing the scanning beam onto an image plane transverse to the scan plane. The first and second elements each have a cylindrical, non-toric lens. One or both of the first and second elements also provide a diffractive element, which provides not only astigmatic correction, but may further provide chromatic aberration correction of the scanning beam. This astigmatic correction is achieved without the presence of any lens having a toroidal (toric) surface. The system may further have a third element in the first path of the beam prior to the deflector. This third element provides a lens having another diffractive element. This diffractive element can correct chromatic and spherical aberration of the scanning beam in the cross-scan plane, a plane perpendicular to the scan plane.
49 Citations
18 Claims
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1. An optical system for scanning a beam comprising:
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a laser source for emitting a beam along a first path; a deflector intersecting said first path for translating said beam into a scanning beam which moves along a second path in a scan plane; a F-θ
lens system in said second path comprising first and second elements for focusing said scanning beam onto an image plane transverse to said scan plane;said first and second elements each comprising at least one body having a non-toric lens; and the body of at least one of said first and second elements also provides a diffractive element which corrects optical aberrations of said scanning beam, wherein said diffractive element corrects optical aberrations in said scanning beam which includes at least correcting of astigmatic aberrations of said scanning beam. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An optical system for scanning a beam comprising:
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a laser source for emitting a beam along a first path; a deflector intersecting said first path for translating said beam into a scanning beam which moves along a second path in a scan plane; a lens system in said second path comprising first and second elements for focusing said scanning beam onto an image plane transverse to said scan plane; said first and second elements each comprising at least one body having a non-toric lens; and the body of at least one of said first and second elements also provides a diffractive element wherein said body of said first and second elements providing said non-toric lens defines a first cylindrical surface and a second spherical surface. - View Dependent Claims (8)
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9. An optical system for scanning a beam comprising:
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a laser source for emitting a beam along a first path; a deflector intersecting said first path for translating said beam into a scanning beam which moves along a second path in a scan plane; a lens system in said second path comprising first and second elements for focusing said scanning beam onto an image plane transverse to said scan plane; said first and second elements each comprising at least one body having a non-toric lens; and the body of at least one of said first and second elements also provides a diffractive element wherein said body of said first and second elements is a cylindrical lens.
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10. An optical system for scanning a beam comprising:
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a laser source for emitting a beam along a first path; a deflector intersecting said first path for translating said beam into a scanning beam which moves along a second path in a scan plane; a lens system in said second path comprising first and second elements for focusing said scanning beam onto an image plane transverse to said scan plane; said first and second elements each comprising at least one body having a non-toric lens; and the body of at least one of said first and second elements also provides a diffractive element, and wherein the body of both said first and second elements provides a diffractive element.
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11. An optical system for scanning a beam comprising:
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a laser source for emitting a beam along a first path; a deflector intersecting said first path for translating said beam into a scanning beam which moves along a second path in a scan plane; a lens system in said second path comprising first and second elements for focusing said scanning beam onto an image plane transverse to said scan plane; said first and second elements each comprising at least one body having a non-toric lens; the body of at least one of said first and second elements also provides a diffractive element; and a third lens element in said first path of said beam prior to said deflector for focusing said beam such that said second path of said beam is focused in a cross-scan plane substantially perpendicular to said scan plane. - View Dependent Claims (12, 13, 14)
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15. An optical system for scanning a beam comprising:
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a laser source for emitting a beam along a first path; a deflector intersecting said first path for translating said beam into a scanning beam which moves along a second path in a scan plane; a F-θ
lens system in said second path comprising first and second elements for focusing said scanning beam onto an image plane transverse to said scan plane;said first and second elements each comprising at least one body having a non-toric lens; and the body of at least one of said first and second elements also provides a diffractive element which corrects optical aberrations of said scanning beam, wherein said F-θ
lens system has an optical axis and a focal length F in the scan plane, said deflector moves said beam along said second path at a varying angle θ
with respect to said optical axis, and said F-θ
lens system focuses said scanning beam into a nearly diffraction-limited spot having a lateral position from said optical axis in said scan plane approximately equal to F multiplied by θ
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16. A method for scanning a beam comprising the steps of:
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emitting a beam from a laser source along a first path; translating said beam from said first path into a scanning beam which moves along a second path in a scan plane; and directing said scanning beam through a F-θ
lens system in said second path for focusing said scanning beam onto an image plane transverse to said scan plane, wherein said first and second elements each comprise at least one body having a non-toric lens, and the body of at least one of said first and second elements also provides a diffractive element which corrects at least astigmatic aberrations of said scanning beam. - View Dependent Claims (17, 18)
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Specification