The silicon positive-intrinsic-negative (PIN) photodiode is a ubiquitous component that detects light in photometric devices from fluorescence instruments in the laboratory to laser speed guns on the highway. Each application has different requirements for price, frequency, response time and sensitivity, and designers must often trade off one or more of those requirements to obtain optimum performance for a given application. Meet the authors Nick Bertone is a product manager at PerkinElmer Optoelectronics Canada in Vaudreuil, Quebec, Canada. He holds a bachelor's degree in physics from McGill University.