An optical device includes: a restriction member that restricts part of reflected light from a target object, the restriction member being formed from resin, the restriction member having an opening and a hole, the opening extending in a first direction crossing a propagation direction of the reflected light and formed at an upstream end in the propagation direction, the hole extending through the restriction member in the propagation direction; an optical member that transmits the reflected light that has passed through the opening; and a correction member that holds the optical member, and that comes into contact with part of an inner circumferential surface of the hole to correct a width of the opening.

A surface-emitting laser includes an active layer on which a spacer layer is disposed, and a reflection mirror disposed on the spacer layer, including a current constriction layer that is a selectively-oxidized layer having been selectively oxidized. The current constriction layer is disposed at a position of a node of a standing-wave of an electric field of light oscillated at the active layer and is disposed away from an interface between the spacer layer and the reflection mirror by an optical distance of one-fourth of an oscillation wavelength at the active layer. The selectively-oxidized layer is made of AlGaAs. The reflection mirror includes at least one AlGaInP layer contacting the selectively-oxidized layer.

A light guide includes a first exit portion emitting first exiting light, a second exit portion emitting second exiting light in a different direction than the first exiting light, and a reflecting portion reflecting light entering the light guide to each of the first and second exit portions. The first and second exit portions respectively have first and second curved surfaces each having a convex cross section perpendicular to the long axis direction. The second exit portion is connected to the first exit portion in the direction perpendicular to the long axis direction. The reflecting portion is provided, in a plane facing the first exit portion and the second exit portion, at a position shifted in the direction perpendicular to the long axis direction from a position where a normal to the plane passes through a connection portion between the first and second exit portions.

A light-guide member includes a light-incident surface formed at an end portion of the light-guide member in a first direction, a light-emitting surface that is elongated in the first direction and that includes first and second light-emitting regions, which cause light to be emitted in different directions in a first cross section that is perpendicular to the first direction, a common deflecting portion that deflects light from the light-incident surface and causes the light to be emitted from the first and second light-emitting regions to the outside, and first and second protruding portions each of which is located on one of two sides of the deflecting portion in the first cross section, the first and second protruding portions protruding in a direction away from the light-emitting surface with respect to the deflecting portion.

A light irradiation device includes a light source, a light guide member, and a holding member. The light guide member includes an incident surface, an exit surface, and a held surface. The incident surface has an elongated shape in a main scanning direction and faces a light emitting surface of the light source. The light guide member includes a securing structure in each of both end portions in the main scanning direction, which are out of a light guide area of the light guide member. The securing structure in one end portion is an engagement lug structure protruding to penetrate into a through-hole of the holding member, including a lug on a leading end, and engaging the holding member. The securing structure on another end portion is a fastening structure having a fastening hole penetrated with a fastening member and being secured to the holding member with the fastening member.

An illumination device includes a light guide member having a bar-like shape and a light source disposed so as to face an end surface of the light guide member. The illumination device guides light from the light source in the light guide member and emits the light from a light emission surface of the light guide member formed in a longitudinal direction of the light guide member. The light emission surface includes a first light diffusing portion that is formed in a first portion near the light source and that has a protruding/recessed shape, and a second light diffusing portion that is formed in a second portion adjacent to an end of the first light diffusing portion, the end being away from the light source. The second light diffusing portion has a protruding/recessed shape and has lower light diffusivity than the first light diffusing portion.

A first reflection light guide includes an axial part as an end part, and a main body part, has a linear rod-like shape including the end part and the main body part, and allows light from a first reflection light source to enter the end part and to be emitted from the main body part. The end part of the first reflection light guide is narrower than the main body part, and includes a contact surface in contact with a cap. The cap includes a light source side opening. A first reflection light source is arranged at the light source side opening. The first reflection light source faces the end part.

A light guide includes a first exit portion emitting first exiting light, a second exit portion emitting second exiting light in a different direction than the first exiting light, and a reflecting portion reflecting light entering the light guide to each of the first and second exit portions. The first and second exit portions respectively have first and second curved surfaces each having a convex cross section perpendicular to the long axis direction. The second exit portion is connected to the first exit portion in the direction perpendicular to the long axis direction. The reflecting portion is provided, in a plane facing the first exit portion and the second exit portion, at a position shifted in the direction perpendicular to the long axis direction from a position where a normal to the plane passes through a connection portion between the first and second exit portions.

A light-guide member includes a light-incident surface formed at an end portion of the light-guide member in a first direction, a light-emitting surface that is elongated in the first direction and that includes first and second light-emitting regions, which cause light to be emitted in different directions in a first cross section that is perpendicular to the first direction, a common deflecting portion that deflects light from the light-incident surface and causes the light to be emitted from the first and second light-emitting regions to the outside, and first and second protruding portions each of which is located on one of two sides of the deflecting portion in the first cross section, the first and second protruding portions protruding in a direction away from the light-emitting surface with respect to the deflecting portion.

A surface-emitting laser includes an active layer on which a spacer layer is disposed, and a reflection mirror disposed on the spacer layer, including a current constriction layer that is a selectively-oxidized layer having been selectively oxidized. The current constriction layer is disposed at a position of a node of a standing-wave of an electric field of light oscillated at the active layer and is disposed away from an interface between the spacer layer and the reflection mirror by an optical distance of one-fourth of an oscillation wavelength at the active layer. The selectively-oxidized layer is made of AlGaAs. The reflection mirror includes at least one AlGaInP layer contacting the selectively-oxidized layer.