A light emitting device and an image capturing device using the light emitting device. The light emitting device includes a light emitting element, a digital micro mirror (DMD), a reflecting prism, and a housing. The light from the light emitting element is modulated by the DMD into structured light. The reflecting prism is on an optical path of the source light. The reflecting prism guides the source light to the DMD. The housing defines a receiving cavity. The light emitting element, the reflecting prism, and the DMD are received in the receiving cavity. The housing defines a light exit opening, the structured light exits from the light exit opening.