The fundamentals of particle counters are relatively simple. You need to know how and why they work. If you have a basic grasp of these fundamentals, you’ll be on your way to better understanding particle counters. An aerosol particle counter works on the principal of either light scattering or light blocking. An aerosol stream is drawn through a chamber with a light source (either Laser Based Light or White Light). When a particle is illuminated by this light beam, it is redirected or absorbed. Light scattered by a single particle in a specific direction in relation to the original direction has a unique signature which relates to the size of the particle. This allows for sizing and counting of individual particles. A particle counter is made up of 4 components: Light Source (Gas Based Laser, Solid State Laser Diode, High Intensity Light) Photo Detection Electronics Sample Flow System Counting Electronics