How Laser Sensor Spot Size Affects Sensitivity

Laser sensors are widely used in industrial measurement, environmental monitoring and medical instruments. Their operating principle relies on emitting and receiving laser light; spot size is an important controllable factor that affects sensor sensitivity.

Effect mechanisms

Smaller spots concentrate energy and can increase local irradiance, improving sensitivity on smooth, highly reflective surfaces. But too small a spot may miss surface irregularities and reduce overall received energy. Larger spots distribute energy over a wider area, which can lower per-area irradiance but improve stability and coverage on rough or low-reflectivity surfaces.

Optical system quality and detector type also influence the relationship. Experiments show that optimal spot size depends on target material and measurement goals; for metal surfaces smaller spots often yield higher sensitivity, while for rough materials larger spots may perform better.

In practice choose spot size according to the target's reflectivity, surface texture, motion state and the sensor's optical/detector design to achieve the best sensitivity and measurement performance.