A system and method for optical detection in autonomous vehicles includes modulating an optical signal from a laser to generate a modulated optical signal and transmitting the modulated optical signal toward an object. The system and method include receiving, responsive to transmitting the modulated optical signal, a returned optical signal and mixing the returned optical signal with a reference optical signal associated with the optical signal from the laser to generate a mixed optical signal and detecting the mixed optical signal to generate an electrical signal. Based on the electrical signal and the modulated optical signal, a parameter of an internal reflection of the returned optical signal from one or more optical components is determined, which may be used to operate a vehicle.