How do Smoke Detectors Work At their core, smoke alarms are very simple devices that need only two functions: a way of detecting smoke and a way of alerting people to the problem. From new technology involving lasers to old world technology that relies on a lonely individual sitting in a tower on the side of a mountain just waiting to see smoke, all do the same thing in different ways. The two most commonly used smoke alarms (mainly because they are inexpensive) are photoelectric and ionization detector alarms. The difference between the two lies in how they detect smoke particles. Depending on the conditions of the fire, one type is usually better than the other. Many other kinds of detectors exist that are more expensive and often situation specific (such as needing to protect classified documents or computer servers). These tend to be much more sensitive and allow for many different levels of detection and alarm. The most common of these is aspiration detectors. Photoelectric ...