Abstract: A smoke detector comprising a body, having a detection chamber therein; a first transmitting tube and a second transmitting tube, arranged in the body and configured to be capable of transmitting a first ray of light and a second ray of light into the detection chamber, respectively; a receiving tube, where the first ray of light and the second ray of light can be incident after refraction and/or scattering, and which generates outputs according to the intensity of incident light; and a control device, coupled with the receiving tube to receive a first output generated by the first ray of light on the receiving tube and a second output generated by the second ray of light on the receiving tube, and configured to determine whether there is a fire based on a difference or ratio between the first output and the second output, or the combination thereof.

Abstract: The present invention provides a light source assembly applied to an alarm device, which comprises a base; a light source arranged on the base and configured to emit visible light; and a lens arranged on an emission path of the light source and configured to modulate the visible light emitted by the light source into a light distribution curve conforming to the presetting. According to the light source assembly and the alarm device including the same in the embodiment of the present invention, the light emitted by the light source is modulated through the lens, so that the angle of emission of the light source assembly and the alarm device can be fully expanded. Especially when the light source assembly and the alarm device are applied to fire-fighting devices, the alarm reception blind area can be effectively reduced, and the safety level is improved.