Ricoh Company, Ltd.

Kenichiro Saisho

Yoshinori Hayashi

Kohji Sakai

Toshiaki Tokita

Nobuaki Kubo

Naoto Watanabe

Daisuke Ichii

Takeshi Ueda

A polarization-separation device includes: a beam splitter that includes a beam-separating surface, on which a light beam that contains a first light beam and a second light beam impinges, wherein polarization direction of the first light beam and polarization direction of the second light beam are perpendicular to each other, and incident angle of the first light beam and incident angle of the second beam vary independently while incident into the beam-separating surface; a first polarizer arranged in an optical path of light beams having transmitted through the beam splitter, and allows the first light beam to transmit therethrough; and a second polarizer arranged in an optical path of light beams reflected from the beam splitter, and allows the second light beam to transmit therethrough.

Polarization-separation device, optical scanning apparatus, and image forming apparatus

An optical scanning device includes four light sources, a pre-deflector optical system, a polygon mirror, an optical scanning system, etc. The optical scanning system includes deflector-side scanning lenses made of glass, imaging-surface-side scanning lenses made of resin, polarized light splitters, and reflecting mirrors. The deflector-side scanning lenses, the imaging-surface-side scanning lenses, the polarized light splitters, and the reflecting mirrors are arranged in this order on an optical path of light going from the polygon mirror toward drum-shaped photosensitive elements.

Optical scanning device and image forming apparatus

An optical scanning device includes a light source, a light-beam splitting unit, a deflector, and a scanning optical system. The light-beam splitting unit splits a light beam from the light source into a plurality of light beams, so that the light beams are each incident to any one of reflecting surfaces of the deflector while having a phase difference of approximately &#x3c0;/2. The scanning optical system receives the light beams from the deflector and projects each of the light beams onto a corresponding target surface.

A diffractive-optical element that is transparent includes a diffraction surface that is formed by a step. A width of the step is set substantially equal to a common multiple of &#x3bb;/{n(&#x3bb;)&#x2212;1} for two or more wavelengths, where &#x3bb;(i=1, 2, . . . ) is a wavelength and n(&#x3bb;) is a refractive index with respect to the wavelength &#x3bb;.

Diffractive-optical element, scanning optical system, optical scanner, and image forming apparatus

An optical scanning device includes a light source having light emitting points for emitting light beams, a coupling optical element that couples the light beams, a deflecting unit that deflects and scans the light beams, and a scanning optical system that focus the light beams to form an image. The optical scanning device satisfies the following condition: F tan(&#x3b8;/2)+A&#x3c;D/0.7 where A is the maximum distance between the light emitting points and an optical axis of the coupling optical element, &#x3b8; is a divergence angle (full-width half-maximum) of the light beams, F is a focal length of. the coupling optical element, and D is an effective radius of the coupling optical element.

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Kanagawa, Japan

Kenichiro Saisho