Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Patent
1993-01-22
1993-09-21
Arnold, Bruce Y.
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
359206, 359662, G02B 2608, G02B 300
Patent
active
052473856
ABSTRACT:
In an optical scanner, a light beam emitted from a semiconductor laser is changed to a parallel light beam by a collimator lens and the parallel light beam is formed by a first optical system as a linear image extending in a main scan-corresponding direction. The image-formed parallel light beam is deflected at an equal angular velocity by a rotary polygon mirror having a deflection reflecting face in the vicinity of the linear image. The deflected light beam is formed as a light spot on a scanned face by a second optical system to perform an optical scanning operation. An f.theta. lens in the optical scanner is used as the second optical system. The f.theta. lens has an f.theta. function in the main scan-corresponding direction and a function for setting the scanned face and a deflecting start point on the deflection reflecting face in an approximately conjugate relation in geometrical optics in a cross scan-corresponding direction. The f.theta. lens has a first lens having a concave spherical face on an object side of the f.theta. lens and a cylindrical face on an image side of the f.theta. lens; a second lens having a concave spherical face on the object side and a convex spherical face on the image side; and a third lens having a flat face on the object side and a toric face on the image side. The f.theta. lens may be constructed by two lenses.
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Arnold Bruce Y.
Nguyen Thong
Ricoh & Company, Ltd.
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