Conventional optical smoke detector, which reliably indicates a fire condition when the smoke concentration in the protected area reaches a predefined value. The sensitivity of the detector is adjusted in the factory, according to the EN54-7 standard. The detector is controlled by a microprocessor and operates according to advanced auto-compensation algorithms for contamination of the optical chamber, signaling the need to clean the chamber. This cleaning operation is easy to perform by uncoupling and reattaching the detector body from the respective base. The construction of the optical chamber with the new technology used in the manufacturing, provides high protection against contamination of the optical chamber by dust and inert matter.