US Patent 8000181 Beam irradiation device and laser radar

A beam irradiation device includes a light source for emitting laser light, an actuator for displacing a propagation direction of the laser light in accordance with a control signal, and a scan expansion lens for increasing a swing width of the laser light to be generated by the actuator. A spectral element is arranged between the actuator and the scan expansion lens. The spectral element allows at least a part of the laser light to be incident from the actuator to transmit, and reflects at least a part of the laser light to be incident from the scan expansion lens. The beam irradiation device further includes a light detector for receiving the laser light to be reflected on the spectral element to output an electrical signal.