Cleaning system for a smoke detector

1. An optical smoke detector comprising:

a sensor chamber, wherein internal walls of the sensor chamber are black;

a housing having walls that define the sensor chamber and a labyrinth;

a light source configured to illuminate a gas within the sensor chamber;

a light detector configured to detect light from the light source that has been scattered by smoke within the sensor chamber; and

an ultrasonic transducer configured to cause oscillations to dislodge accumulated particulate matter from at least one or more of the walls of the smoke detector that at least partially define the labyrinth;

wherein the smoke detector is configured to automatically activate the ultrasonic transducer in response to an estimated degree of fouling on the one or more walls of the labyrinth exceeding a threshold value; and

wherein the degree of fouling on the one or more walls of the labyrinth is estimated based on a level of light detected by the light detector that is configured to detect light from the light source that has been scattered by smoke within the sensor chamber, the degree of fouling being estimated based on a level of light detected when the sensor chamber does not contain smoke.

2. An optical smoke detector according to claim 1 , wherein the smoke detector is configured to periodically activate the ultrasonic transducer.

3. An optical smoke detector according to claim 1 , wherein the light source is a light-emitting diode.

4. An optical smoke detector according to claim 1 , wherein the at least one component includes one or both of the light source and the light detector.