A biometric system may include an ultrasonic sensor array, a light source system and a control system. Some implementations may include an ultrasonic transmitter. The control system may be capable of controlling the light source system to emit light and of receiving signals from the ultrasonic sensor array corresponding to acoustic waves emitted from portions of a target object in response to being illuminated with the light emitted by the light source system. The control system may be capable of performing a user authentication process that is based, at least in part, on the signals from the ultrasonic sensor array.