A laser is a device that emits light (electromagnetic radiation) through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation.The emitted laser light is notable for its high degree of spatial and temporal coherence, unattainable using other technologies.
The main relevance of lasers in the OBD is that they travel at the speed of light (or rather, slightly slower than the speed of light in an atmosphere, but the difference is negligible). Thus, any character capable of actually reacting to, dodging, or outrunning one can be said to have reactions or speed at a lightspeed or FTL level. However, attempting to claim "laser-timing" feats is not nearly as simple as it sounds, as there are many complications regarding lasers in fiction.
The word "laser", similar to the word "quantum", has been a sci-fi buzzword practically ever since lasers were invented. This means that it is often used incorrectly in fiction, to describe devices that bear no resemblance to real-world lasers, and often move much more slowly. An example are the blaster weapons from Star Wars. Therefore, something merely being called a laser does not mean we should assume it moves at lightspeed. In order to establish that a given fictional "laser" travels at lightspeed, the following considerations must be taken:
1. Is the speed ever stated? If it is stated to move at the speed of light, that is one piece of evidence in its favor. Of course, like any other statement, it must be evaluated based on reliability of the source and whether it matches visual evidence instead of just blindly accepted.
2. Does it behave like a real laser? Some guidelines for determining this:
a. If you can see the beam visually (without some kind of super sensing equipment or such), and it is not moving through a diffuse medium (examples: a cloud of dust or fog), then it is not a real laser, as real lasers are only visible at the emitter, the target, or if you are standing in between them.
b. If the laser is fired in discrete "bolts" or "pulses" instead of a continuous beam, it is not a real laser.
c. If the laser curves or changes direction (without hitting any reflective surfaces or there being another explanation for this), it is not a real laser.
d. If the setting in which the laser appears is more scientifically accurate or based on real - world physics, then a laser is more likely to be a real laser.
3. If the speed of the laser can be established or calculated to be lightspeed (as in, shown to travel the same amount of distance in a given amount of time that light would). Of course, if this can be determined, it kind of undermines the point of claiming something is fast merely because it dodged a laser, since you have concrete numbers.
Keep in mind that even if a laser is determined to travel at lightspeed, it is still possible to aimdodge it, so a scene of the beam heading towards something and someone moving before it hits are required.