ABSTRACT
Discrete Infrared Light Emitting Diodes and photosensors can be utilized to form a safety shield to protect dangerous areas from accidental intrusion. A vertical cavity surface-emitting laser or additional lensing is used, more than one photosensor is illuminated with the highest intensity on the photosensor directly in line with the light beam of the emitter. The emitter groups can be pulsed at very short intervals, thus reducing the radiation pattern on the photosensors from adjacent emitters. Hazardous fluids such as gasoline require special handling and precise acknowledgement of the fluid level limits. An emitter and photosensor can be utilized to project a light beam down a quartz or plastic rod with a cone feature at the far end. The level of fluid can be acknowledged by using a sight tube and two sensors. One sensor will identify the low fluid level and the other will identify the high fluid level. Photosensors have been used to speed up production in factories.
