Konica Minolta Opto, Inc.

Daisuke Tanahashi

Yayoi Eguro

Shoji Kogo

A scanning optical system is provided with a light source device (), a deflection optical system () that deflects the light flux from the light source device () to carry our a scan in a main-scanning direction (y), and a scanning and image-forming optical system () that forms the light flux deflected by the deflection optical system () into an image on a scanning surface (H). The scanning and image-forming optical system () includes at least a first lens (). The scanning optical system satisfies a predetermined condition relating to a numerical aperture of a light flux entering the deflection optical system () in a sub-scanning direction (z), and a distance between the deflection optical system () and the first lens (). The first lens () is a plastic lens made of a predetermined resin as a base material.

Scanning optical system, optical scanning device, and image forming device

An imaging lens good in mass-productivity, compact, low in manufacturing cost, good in aberration performance is provided by effectively correcting aberrations without greatly varying the variation of the thickness of a curing resin. An imaging device having such an imaging lens and a portable terminal are also provided. A third lens (L) has a flat surface on the object side, a convex surface near the optical axis on the image side, and a concave aspheric surface around the peripheral portion within the region where a light beam passes. Therefore, it is possible to reduce the other optical aberrations such as distortion and simultaneously to design the imaging lens so that the astigmatism takes on a maximum value at the outermost portion. Hence, the resolutions at low to middle image heights are high. In addition, such a shape does not cause a large variation of the thickness of the third lens (L) from the region along the axis to the periphery. Therefore, the thickness of the third lens (L) can be small, and the material cost can be reduced.

Scan optical system, light scan device, and image formation device

A scanning optical system includes: a light source for emitting a light flux with a wavelength &#x3bb;; a polygon mirror comprising a plurality of reflection surfaces for deflecting the light flux emitted from the light source for scanning the scanning surface; a light-converging lens group in a two-element structure. The light-converging lens group is arranged between the polygon mirror and the scanning surface and forms a light spot on the scanning surface. In the scanning optical system, the wavelength &#x3bb; is not larger than 600 nm, and the scanning optical system satisfies a conditional expression relating to a number of the reflection surfaces of the polygon mirror, a scanning width of the scanning optical system, and a focal length of the light-converging lens group in a main scanning direction.

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Hachioji, Japan

Daisuke Tanahashi