want to know about optical smoke detector?

Answer 1

An optical detector is a light sensor. When used as a smoke detector it includes a light source (infra-red LED), a lens to collimate the light into a beam like a laser, and a photodiode or other photoelectric sensor at right-angles to the beam as a light detector. In the absence of smoke, the light passes in front of the detector in a straight line. When smoke enters the optical chamber into the path of the light beam, some light is scattered by the smoke particles, and some of the scattered light is detected by the sensor. An increased input of light into the sensor sets off the alarm.

Another type of optical detector works by using a straight line infra-red beam from the sender to the receiver. When smoke enters the beam, some light is scattered which results in less light detected by the receiver. A decreased input of light into the receiver sets off the alarm.
Optical smoke detectors are quick in detecting slow burning, smoky fires.
http://en.wikipedia.org/wiki/Smoke_detector

An optical smoke detector having a smoke sensing chamber comprising a point source of light mounted on the middle of a photodetector, the source of light transmitting in a forward direction and away from the photodetector and further having the point source of light located at the center of curvature of a spherical reflector. During normal standby periods when there are no smoke particles in the chamber to scatter the light, the light is transmitted to the spherical reflector and reflected back to the source without falling on the photodetector. In the presence of smoke the light is scattered and falls on the photodetector to indicate the presence of the smoke.
http://www.delphion.com/details?pn10=US04221485

Answer 2

the light scatter type
One end has a photocell and the other a light source. a barrier is in between. barrier prevents light reaching the photo cell.when smoke enters the detector it scatters the light, thus helping it to reach the photocell. this produces a signal and triggers an alarm.
This type of detector does not allow light inside. Only smoke can enter.

Answer 3

it detects smoke thus indicating fire or possibility of a fire. works on the principle that light scatters when the medium in which it travels has particles. the detector is first calibrated to work in normal air which is present everywhere. when the particulate count increases above the set value the sensor is activated.
regards

Answer 4

Take a look at

http://home.howstuffworks.com/smoke.htm