Scanning optical system
First Claim
1. A scanning optical system, comprising:
- a light source;
a deflector, said deflector deflecting a beam emitted from said light source; and
a scanning lens having a positive refractive power, said scanning lens converging the beam deflected by said deflector onto a surface to be scanned, wherein said scanning lens comprises at least one refractive lens element and a diffractive lens structure which is formed on at least one surface of said refractive lens element, said diffractive lens structure compensating a lateral chromatic aberration caused by the refractive power of said scanning lens, said diffractive lens structure satisfying the following relationship;
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Accused Products
Abstract
A scanning optical system is provided with a light source, a deflector, which deflects a beam emitted from said light source, and a scanning lens for converging the beam deflected by the deflector onto a surface to be scanned. The scanning lens has a positive power as a whole, and includes a diffraction lens structure that is formed on at least one surface of one of the lens element. The diffractive lens structure compensates a lateral chromatic aberration caused by the refraction lens elements. The diffraction lens structure satisfies the following condition (1);
where, m is the number of periodic patterns of the diffraction lens structure struck by the incident light beam having the maximum scan angle W (unit: degrees).
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Citations
22 Claims
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1. A scanning optical system, comprising:
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a light source;
a deflector, said deflector deflecting a beam emitted from said light source; and
a scanning lens having a positive refractive power, said scanning lens converging the beam deflected by said deflector onto a surface to be scanned, wherein said scanning lens comprises at least one refractive lens element and a diffractive lens structure which is formed on at least one surface of said refractive lens element, said diffractive lens structure compensating a lateral chromatic aberration caused by the refractive power of said scanning lens, said diffractive lens structure satisfying the following relationship;
- View Dependent Claims (2, 3, 4, 5, 6)
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7. A scanning optical system, comprising:
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a light source;
a deflector, said deflector deflecting a beam emitted from said light source; and
a scanning lens having positive refractive power, said scanning lens converging the beam deflected by said deflector onto a surface to be scanned, wherein said scanning lens comprises at least one refractive lens element and a diffractive lens structure having a plurality of rings that compensate a lateral chromatic aberration caused by the refractive power of said scanning lens, said diffractive lens structure being formed on one surface of said at least one refractive lens element where the width of the incident light beam having the maximum scan angle in a main scanning direction is maximized, whereby a loss of light at a boundary between adjacent rings is reduced by a step between adjacent rings. - View Dependent Claims (10, 11, 12)
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8. A scanning optical system, comprising:
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a light source;
a deflector, said deflector deflecting a beam emitted from said light source; and
a scanning lens having positive refractive power that converges the beam deflected by said deflector onto a surface to be scanned, wherein said scanning lens comprises at least one refractive lens element and a diffractive lens structure having a plurality of rings that compensate a lateral chromatic aberration caused by the refractive power of said scanning lens, said diffractive lens structure being formed on the surface that is closest to said deflector of the surfaces having positive refractive power whereby a loss of light at a boundary between adjacent rings is reduced by a step between adjacent rings. - View Dependent Claims (13, 14, 15)
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9. A scanning optical system, comprising:
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a light source;
a deflector, said deflector deflecting a beam emitted from said light source; and
a scanning lens having positive refractive power that converges the beam deflected by said deflector onto a surface to be scanned, wherein said scanning lens comprises at least one refractive lens element and a diffractive lens structure having a plurality of rings that compensates a lateral chromatic aberration caused by the refractive power of said scanning lens, said diffractive lens structure being formed on one surface of said refractive lens element where the incident angle of the incident light beam having the maximum scan angle in a main scanning direction is maximized, whereby a loss of light at a boundary between adjacent rings is reduced be a step between adjacent rings. - View Dependent Claims (16, 17, 18)
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19. A scanning optical system, comprising:
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a light source;
a deflector, said deflector deflecting a beam emitted from said light source; and
a scanning lens having positive refractive power that converges the beam deflected by said deflector onto a surface to be scanned, wherein said scanning lens comprises at least one refractive lens element and a diffractive lens structure including a plurality of rings that compensate a lateral chromatic aberration caused by the refractive power of said scanning lens, said diffractive lens structure being formed on the surface having non-positive power that is closer to said deflector than said closest surface having positive power, whereby a loss of light at a boundary between adjacent rings is reduced by a step between adjacent rings. - View Dependent Claims (20, 21, 22)
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Specification