OPTICAL DEVICE AND PROJECTING DEVICE

An optical device according to an embodiment includes a first birefringent element on which coherent incident light is incident, a transmissive diffusing element on which light emitted from the first birefringent element is incident, and a second birefringent element on which light emitted from the transmissive diffusing element is incident. Light emitted by a laser light source is incident on the first birefringent element and the incident light is separated into two lights by birefringence to be incident on the diffusing element. The diffusing element diffuses the two lights to emit. The second birefringent element synthesizes the two lights emitted from the diffusing element into one light to emit.