Abstract: In a surface potential distribution measurement method and device, a sample having a surface with a surface potential distribution is scanned using a charged particle beam in a two-dimensional manner. A detection signal caused by the two-dimensional scanning is obtained to measure the surface potential distribution. Charged particles, other than charged particles of the charged particle beam incident to the sample surface by the two-dimensional scanning, with which components of an incidence velocity vector of the charged particles in a direction perpendicular to the sample surface are reversed, are detected so that a detection signal indicating an intensity according to the detected charged particles is obtained in correspondence with a position on the sample surface.

Abstract: An optical scanning lens used in a scanning and imaging optical system in which a beam deflected by a light deflector is condensed on or in the vicinity of a surface to be scanned. The optical scanning lens is formed through plastic mold, and a distribution of the refractive indexes ?n(x) inside of the optical scanning lens has a local maximum within a range through which the beam passes through the lens.

Abstract: An optical scanning lens used in a scanning and imaging optical system in which a beam deflected by a light deflector is condensed on or in the vicinity of a surface to be scanned. The optical scanning lens is formed through plastic mold, and a distribution of the refractive indexes ?n(x) inside of the optical scanning lens has a local maximum within a range through which the beam passes through the lens.

Abstract: An optical scanning lens is used in a scanning and image forming optical system which gathers a light flux deflected by a light deflector in the vicinity of a surface to be scanned. The lens is formed by plastic molding of polyolefin resin, and the following condition is satisfied: 0<|?n(x)?min[?n(x)]|<34×10?5, where ?n(x) denotes a refractive-index distribution existing inside the lens, in a range which the light flux passes through, in the lens, and min[?n(x)] denotes the minimum value of the ?n(x).

Abstract: An optical scanner which performs optical scanning of a surface to be scanned by deflecting a luminous flux having a wavelength ? from a light source by means of an optical deflector, and condensing the deflected flux toward the surface to be scanned through a scanning image forming optical system, thereby forming an optical spot on the surface to be scanned. The scanning image forming optical system has at least one lens, and when the focal length f? in the main scanning direction at a surface accuracy ?i is defined as follows: f?={2.

Abstract: An optical scanning device includes: a light source; a deflector deflecting light beam from the light source; a coupling lens carrying out coupling of the light beam from the light source; a first optical system leading the light beam from the coupling lens to the deflector; a scanning optical system leading the light beam deflected by the deflector to a to-be-scanned surface; and a phase-modulatable liquid crystal device disposed on a light path lying from the light source through the to-be-scanned surface and driven by an electric signal, wherein: the first optical system at least comprises an optical device having: a surface having power positive in a sub-scanning direction; and a surface having power positive in a main scanning direction.

Abstract: In a surface potential distribution measurement method and device, a sample having a surface with a surface potential distribution is scanned using a charged particle beam in a two-dimensional manner. A detection signal caused by the two-dimensional scanning is obtained to measure the surface potential distribution. Charged particles, other than charged particles of the charged particle beam incident to the sample surface by the two-dimensional scanning, with which components of an incidence velocity vector of the charged particles in a direction perpendicular to the sample surface are reversed, are detected so that a detection signal indicating an intensity according to the detected charged particles is obtained in correspondence with a position on the sample surface.

Abstract: An optical scanning lens is used in a scanning and image forming optical system which gathers a light flux deflected by a light deflector in the vicinity of a surface to be scanned. The lens is formed by plastic molding of polyolefin resin, and the following condition is satisfied: 0<|?n(x)?min[?n(x)]|<34×10?5, where ?n(x) denotes a refractive-index distribution existing inside the lens, in a range which the light flux passes through, in the lens, and min[?n(x)] denotes the minimum value of the ?n(x).

Abstract: A lens for optical scanning condenses luminous flux deflected by an optical deflector to a plane to be scanned in a scanning image forming optical system. The lens is made of a plastic material by molding. A reference axis of an N-th order approximating curve of refractive index distribution ?n(x) of the lens is away from a center of a passing area, through which the luminous flux passes in the lens, by equal to or more than 10% of the width of the passing area.

Abstract: An optical scanning lens which is used in a scanning and age forming optical system which gathers a light flux deflected by a light deflector in the vicinity of a surface to be scanned. The lens is formed by plastic molding of polyolefin resin, and the following condition is satisfied: 0<|?n(x)?min[?n(x)]|<34×10?5, where ?n(x) denotes a refractive-index distribution existing inside the lens, in a range which the light flux passes through, in the lens, and min[?n(x)] denotes the minimum value of the ?n(x).

Abstract: An optical scanning lens which is used in a scanning and age forming optical system which gathers a light flux deflected by a light deflector in the vicinity of a surface to be scanned. The lens is formed by plastic molding of polyolefin resin, and the following condition is satisfied: 0<|&Dgr;n(x)−min [&Dgr;n(x)]|<34×10−5, where &Dgr;n(x) denotes a refractive-index distribution existing inside the lens, in a range which the light flux passes through, in the lens, and min [&Dgr;n(x)] denotes the minimum value of the &Dgr;n(x).

Abstract: A lens for optical scanning condenses luminous flux deflected by an optical deflector to a plane to be scanned in a scanning image forming optical system. The lens is made of a plastic material by molding. A reference axis of an N-th order approximating curve of refractive index distribution &Dgr;n(x) of the lens is away from a center of a passing area, through which the luminous flux passes in the lens, by equal to or more than 10% of the width of the passing area.

Abstract: An optical scanning lens is used in a scanning and image forming optical system which gathers a light flux deflected by a light deflector in the vicinity of a surface to be scanned. The lens is formed by plastic molding of polyolefin resin, and the following condition is satisfied: 0<|&Dgr;n(x)−min[&Dgr;n(x)]|<34×10−5, where &Dgr;n(x) denotes a refractive-index distribution existing inside the lens, in a range which the light flux passes through, in the lens, and min[&Dgr;n(x)] denotes the minimum value of the &Dgr;n(x).

Abstract: An optical scanning device includes a plurality of optical scanning, units each including a light source emitting a light flux, a scanning input optical system directing the light flux emitted from the light source to a deflector. The deflector deflects the light flux so as to cause the light flux to scan a surface to be scanned. A scanning and imaging optical system condenses the light flux deflected by the deflector so as to form a beam spot thereof on the surface to be scanned. The optical scanning device scans the surface to be scanned continuously through coordinated movements of the plurality of optical scanning units, and the respective scanning and imaging optical systems of adjacent at least two of the plurality of optical scanning units have one lens in common.

Abstract: An optical scanning lens used in a scanning and imaging optical system in which a beam deflected by a light deflector is condensed on or in the vicinity of a surface to be scanned. The optical scanning lens is formed through plastic mold, and a distribution of the refractive indexes &Dgr;n(x) inside of the optical scanning lens has a local maximum within a range through which the beam passes through the lens.

Abstract: An optical scanning lens used in a scanning and imaging optical system in which a beam deflected by a light deflector is condensed on or in the vicinity of a surface to be scanned. The optical scanning lens is formed through plastic mold, and a distribution of the refractive indexes &Dgr;n(x) inside of the optical scanning lens has a local maximum within a range through which the beam passes through the lens.

Abstract: An optical scanning lens is used in a scanning and image forming optical system which gathers a light flux deflected by a light deflector in the vicinity of a surface to be scanned. The lens is formed by plastic molding of polyolefin resin, and the following condition is satisfied: 0<|&Dgr;n(x)−min[&Dgr;n(x)]|<34×10−5, where &Dgr;n(x) denotes a refractive-index distribution existing inside the lens, in a range which the light flux passes through, in the lens, and min[&Dgr;n(x)] denotes the minimum value of the &Dgr;n(x).

Abstract: An optical scanner which performs optical scanning of a surface to be scanned by deflecting a luminous flux having a wavelength &lgr; from a light source by means of an optical deflector, and condensing the deflected flux toward the surface to be scanned through a scanning image forming optical system, thereby forming an optical spot on the surface to be scanned. The scanning image forming optical system has at least one lens, and when the focal length f&sgr; in the main scanning direction at a surface accuracy &sgr;i is defined as follows: f&sgr;={2.

Abstract: An optical scanning lens is used in a scanning and image forming optical system which gathers a light flux deflected by a light deflector in the vicinity of a surface to be scanned. The lens is formed by plastic molding of polyolefin resin, and the following condition is satisfied: 0<|&Dgr;n(x)−min[&Dgr;n(x)]|<34×10−5, where &Dgr;n(x) denotes a refractive-index distribution existing inside the lens, in a range which the light flux passes through, in the lens, and min[&Dgr;n(x)] denotes the minimum value of the &Dgr;n(x).

Abstract: An optical scanning apparatus is constructed to detect one or more defective or damaged light emitting devices of a light source unit and forms images having substantially the same quality as that of the images formed when all of a plurality of light emitting devices of a light source of the apparatus are functioning normally even when any one of the plurality of light emitting devices are damaged or broken, without decreasing the image forming performance of the apparatus. The optical scanning apparatus detects one or more damaged or broken light emitting devices and then compensates for the light omitted due to the damaged or broken light emitting devices using the normally functioning light emitting devices without decreasing the image forming speed or quality of the optical scanning apparatus.