Just like radar (Pulse radar vs Continuous wave radar), a laser can operate continuously or in pulses, and that choice determines the application:
Continuous wave (CW) lasers
The laser is on without interruption, at constant (relatively modest) power. Applications where duration matters more than peak:
- Target illumination and marking over a longer period (beam riding, Beam rider: the missile "rides" the continuous beam).
- Dazzlers / DIRCM: continuously blinding or deceiving sensors and seekers with modulated CW light.
- Laser communication: modulating data onto the beam.
- High-energy laser weapons: holding power (tens of kW) on one point for seconds until the target (a drone, a mortar round) fails structurally.
Pulsed lasers
The energy is stored and discharged in extremely short pulses (nanoseconds) — with enormous peak powers from a compact device (Q-switching). Applications where timing and peak count:
- Range measurement (Laser rangefinder): a sharp pulse gives a sharply measurable departure and arrival moment — exactly the pulse radar principle, but with light.
- Target designation (Laser designator): pulses in a recognisable code pattern on which the weapon homes.
- LIDAR / 3D imaging: millions of tiny pulses form a range image, pixel by pixel.
Parallel with radar
The analogy is exact: CW laser ↔ CW radar (continuous, illuminating/measuring without travel time), pulsed laser ↔ pulse radar (travel time → range, peak power ≫ average power). If you understand Radar, you get this chapter for free.