An apparatus, comprising: an ultrasonic sensor array ; a light source system ; a substrate, wherein the ultrasonic sensor array is disposed in or on the substrate and the light source system is coupled to the substrate; and a control system configured to: control the light source system to emit light having a pulse duration in a range of 10 nanoseconds to 500 nanoseconds, wherein the light induces acoustic wave emissions inside a target object; select a first acquisition time delay for the reception of acoustic wave emissions primarily from a first depth inside the target object; acquire first ultrasonic image data from the acoustic wave emissions received by the ultrasonic sensor array during a first acquisition time window that is initiated at an end time of the first acquisition time delay; select second through Nth acquisition time delays; acquire second through Nth ultrasonic image data during second through Nth acquisition time windows after the second through Nth acquisition time delays, each of the second through Nth acquisition time delays corresponding to a second through an Nth depth inside the target object; obtain attribute information corresponding to sub-epidermal features from the ultrasonic image data. an ultrasonic sensor array ; a light source system ; a substrate, wherein the ultrasonic sensor array is disposed in or on the substrate and the light source system is coupled to the substrate; and a control system configured to: control the light source system to emit light having a pulse duration in a range of 10 nanoseconds to 500 nanoseconds, wherein the light induces acoustic wave emissions inside a target object; select a first acquisition time delay for the reception of acoustic wave emissions primarily from a first depth inside the target object; acquire first ultrasonic image data from the acoustic wave emissions received by the ultrasonic sensor array during a first acquisition time window that is initiated at an end time of the first acquisition time delay; select second through Nth acquisition time delays; acquire second through Nth ultrasonic image data during second through Nth acquisition time windows after the second through Nth acquisition time delays, each of the second through Nth acquisition time delays corresponding to a second through an Nth depth inside the target object; obtain attribute information corresponding to sub-epidermal features from the ultrasonic image data. control the light source system to emit light having a pulse duration in a range of 10 nanoseconds to 500 nanoseconds, wherein the light induces acoustic wave emissions inside a target object; select a first acquisition time delay for the reception of acoustic wave emissions primarily from a first depth inside the target object; acquire first ultrasonic image data from the acoustic wave emissions received by the ultrasonic sensor array during a first acquisition time window that is initiated at an end time of the first acquisition time delay; select second through Nth acquisition time delays; acquire second through Nth ultrasonic image data during second through Nth acquisition time windows after the second through Nth acquisition time delays, each of the second through Nth acquisition time delays corresponding to a second through an Nth depth inside the target object; obtain attribute information corresponding to sub-epidermal features from the ultrasonic image data. <EOS>