Fault Injection Attacks (FIA) have received a lot of attention in recent years. An adversary launches such an attack to abusively take control over the system or to leak sensitive data. Laser illumination has been considered as an effective technique to launch FIA. The laser-based FIAs are mainly used when the adversary opts to target a specific location in the target circuit. However, thanks to the miniaturization of transistors and moving towards smaller feature size, even small laser spots may illuminate more than one gate; making the attack more detectable when the circuitries are equipped with embedded fault detection mechanisms such as digital sensors. In this paper, we use time-to-digital convertors, aka digital sensors, to detect the laser shots. We show that by embedding these digital sensors in the target circuitry, the IR drop caused by the laser illumination can be sensed with a high accuracy. An alarm will be raised when the fault is detected. The simulation results show the high accuracy of the proposed scheme in detecting laser-based FIAs