An optical head that can be easily assembled is for reading an image of an object and includes a housing, a diffuser, a light source module and a light sensing module. The diffuser is connected to the housing. The light source module has a substrate and a first light source mounted on a front side of the substrate. The front side of the substrate is fixed to an external surface of the diffuser. The first light source provides an initial light ray incident to the diffuser. The diffuser processes the initial light ray into uniform light for output. The light sensing module fixed in the housing senses reflected light, which is generated from the uniform light reflected by the object.