Photoelectric smoke detectors operate with a continuous, focused beam of light onto a mirror from an LED light source that is aimed directly into a sensing chamber, away from the sensor. If smoke enters the chamber, the light that is reflected onto the light sensor is interrupted, scattering light in many directions and triggers the alarm. Photoelectric smoke detectors tend to respond quicker than ionization smoke alarms to smoke that is produced by a smoldering fire. Photoelectric smoke detectors can detect smoke before a fire even begins to appear.