This application provides an optical device, including an emitting assembly configured to emit an outgoing light signal, a beam splitting assembly configured to pass the outgoing light signal from the emitting assembly to a detection region, receive a reflected light signal from the detection region, and modify a transmission direction of the reflected light signal, a receiving assembly configured to receive the reflected light signal from the beam splitting assembly after the direction modification and generate an electrical signal in response to the reflected light signal. Also disclosed is a method of adjusting an optical device as described herein.