In this topic I will be debunking the common misconception and myth that LDIRCM systems can only affect one and only missile, which is wrong.
Many people think that laser beams emitted by LDIRCM systems are like ‘single photon’ wide, which is not the case.
You see, laser beams have Diameter (commonly called ‘Beam Width’). The Laser beam is not 1 photon or few millimeters wide.
In terms of LDIRCM systems, they usually have Beam Divergence from 0.1 to 5 milliRadians.
If you take 1 mrad Divergence as an example, a beam would grow by about 1 mm per meter of travel — over 1000 m that’s roughly 1 m across. Increase divergence to 5 mrad, and that spot becomes ~5 m wide at 1 km. And vice versa, smaller divergence like 0.1–0.5 mrad results in tighter, more concentrated beams over long ranges.
Another example: for 0.1 mrad Divergence at 5mm Beam Waist the spot diameter is 105 mm at 1 kilometer distance.
Now note the following:
If multiple missiles are fired from the same launcher, they will follow roughly the same trajectory to the target.
Meaning even though the LDIRCM system is trying to blind only the first missile from said salvo, the rest of the missiles can also be involuntarily blinded by the laser beam, due to its Divergence. This is especially true for scenarios where both the launcher and the helicopter are stationary in space.
Exactly the same can happen when DIRCM is working against incoming missiles. (Even though its emitter relies on different principle of operation).
Bottom line is:
Assuming such systems are modelled realistically ingame, we would often see situations where DIRCM/LDIRCM would be overwhelmed only in rare cases when for example a missile/s is/are fired from an SPAA at a helicopter, and at the same time another IR guided missile is fired from different direction by lets say an Airplane, or for example when two independent SPAA systems (for example located at different spawns and firing from vastly different bearing) engage the helicopter simultaneously.
Sources and reading materials on the topic:
https://www.researchgate.net/publication/284156197_Requirements_for_laser_countermeasures_against_imaging_seekers