Abstract: An optical reader includes an imaging device and an photographing optical system for reading images of an object such as a semiconductor wafer. An LED light source is provided as a dark field illumination light source for illuminating the object at an angle of illumination that deviates from the optical axis of the photographing optical system. The LED light source is supported by a swing-type support member having both ends secured to a housing of the optical reader using screws and nuts. This allows the angle and position of the dark field illumination light source to be adjusted so as to provide a first angle of illumination for illuminating the object directly with the illuminating light from the dark field illumination light source, or a second angle of illumination for illuminating the object by reflection from a half mirror that is disposed in an illumination optical system.

Abstract: An optical reader includes an imaging device and an photographing optical system for reading images of an object such as a semiconductor wafer. An LED light source is provided as a dark field illumination light source for illuminating the object at an angle of illumination that deviates from the optical axis of the photographing optical system. The LED light source is supported by a swing-type support member having both ends secured to a housing of the optical reader using screws and nuts. This allows the angle and position of the dark field illumination light source to be adjusted so as to provide a first angle of illumination for illuminating the object directly with the illuminating light from the dark field illumination light source, or a second angle of illumination for illuminating the object by reflection from a half mirror that is disposed in an illumination optical system.