An optical device includes a light shielding wall including a light shielding portion that shields light from a light source, a first through-hole and a second through-hole that allow passage of light from the light source, the second through-hole having a smaller diameter than the first through-hole, and a cutout portion that forms the second through-hole, a microlens array configurated by a plurality of lenses that condenses light having passed through the first through-hole and the second through-hole, and an image sensor that reads the light condensed by the microlens array.

An image reading device includes: a sensor module having a light source and a plurality of sensors; a white reference plate; and an image processor that generates correction data to be used for shading correction and performs the shading correction on image signals, using the correction data. The light source is configured to switch between at least a first luminous intensity and a second luminous intensity lower than the first luminous intensity. The image processor acquires intermediate data by causing the plurality of sensors to acquire an image signal of the white reference plate illuminated with the second luminous intensity, generates black correction data, based on the intermediate data, and performs the shading correction, using the black correction data, so that a density unevenness, in an image, caused by interference between image signals from the plurality of sensors.

An image reading device includes an image processor that generates correction data to be used for shading correction and perform the shading correction using the correction data, and a memory that stores first black correction data to be used for the shading correction in a main scanning direction in a predetermined first position in a predetermined sub-scanning direction. The image processor generates third black data based on an image signal of a second reference plate extending in the sub-scanning direction in a predetermined second position in the main scanning direction, generates black correction data according to the sub-scanning direction based on the first black correction data and the third black data, and performs the shading correction using the black correction data so as to correct density unevenness in the main scanning direction and the sub-scanning direction caused by an interference between image signals from a plurality of sensors.

An image reading device has an image processor that generates correction data to be used for shading correction and performs the shading correction using the correction data. The image processor generates intermediate data with a predetermined density level, generates intermediate data in different positions in the sub-scanning direction based on image signals of a first reference plate and a second reference plate disposed in the different positions, generates first and second black correction data based on the respective intermediate data, generates black correction data according to the sub-scanning direction based on both the black correction data, and performs the shading correction using the black correction data in the respective positions in the sub-scanning direction.

An image reading device includes a board including a plurality of imaging elements arranged along a scanning direction, and a housing including a plurality of optical components that are arranged along the scanning direction and a plurality of housing components that are arranged along the scanning direction. Each of the plurality of optical components focuses light reflected by a reading target onto a corresponding imaging element, and each of the plurality of housing components holds at least one optical component. The plurality of housing components are arranged to have a clearance therebetween and each of the plurality of housing components is fixed to the board at a position to transmit light through the optical components to focus onto the corresponding imaging element.

An image reading device includes a board including a plurality of imaging elements arranged along a scanning direction, and a housing including a plurality of optical components that are arranged along the scanning direction and a plurality of housing components that are arranged along the scanning direction. Each of the plurality of optical components focuses light reflected by a reading target onto a corresponding imaging element, and each of the plurality of housing components holds at least one optical component. The plurality of housing components are arranged to have a clearance therebetween and each of the plurality of housing components is fixed to the board at a position to transmit light through the optical components to focus onto the corresponding imaging element.

An optical element of a lens mirror array according to an embodiment includes an incident-side lens surface, a first reflection surface, a second reflection surface, an emission-side lens surface, a first positioning surface, and a second positioning surface. The incident-side lens surface refracts and converges incident light. The first reflection surface reflects light made incident via the incident-side lens surface. The second reflection surface reflects the light reflected by the first reflection surface. The emission-side lens surface emits the light reflected by the second reflection surface. The lens mirror array is a lens mirror array in which a plurality of optical elements are arrayed in a direction orthogonal to optical axes of the incident light and the reflected light and parallel to the first positioning surface.

An optical line sensor reads an inspection object conveyed in a sub-scanning direction by a reading line L extending in a main scanning direction and includes a plurality of light-receiving lenses 11 and a plurality of light-receiving elements. The plurality of light-receiving lenses 11 are arranged along the main scanning direction. The plurality of light-receiving elements are arranged linearly along the main scanning direction, and receive light transmitted through the plurality of light-receiving lenses 11. The plurality of light-receiving lenses 11 are arranged to be separated from each other by a diameter of the light-receiving lens 11 or longer. A plurality of light-receiving elements 121 form at least one row or more of the reading lines L.