What it means
Number plates are retroreflective, so they return infrared light strongly towards the camera. That makes the plate bright while the headlights and the rest of the scene stay darker, which is ideal for plate reading. Illuminators around 850 nm reach further but show a faint red glow. Illuminators around 940 nm are invisible but need more power for the same range.
Pulsed IR fires the light in step with a very short exposure. That gives a bright, sharp image of a fast vehicle while keeping average power and heat low.
How it applies in India
Night is when many violations happen and when many cameras fail. Indian roads add unlit stretches, oncoming high beams and fog. In a specification, ask for the IR range in metres, the wavelength, whether IR is pulsed with the shutter, and sample night images at the target speed. Seatbelt and phone detection at night need enough IR to see through the windscreen. The Recon camera has built-in IR with a range of up to 40 m.