Search results
Results from the WOW.Com Content Network
Conceptual through-beam system to detect unauthorized access to a secure door. If the beam is interrupted, the detector triggers an alarm. A photoelectric sensor is a device used to determine the distance, absence, or presence of an object by using a light transmitter, often infrared, and a photoelectric receiver. They are largely used in ...
This is often connected to an electrical trigger. The trigger reacts to a change in the signal within the light sensor. An optical sensor can measure the changes from one or several light beams. When a change occurs, the light sensor operates as a photoelectric trigger and therefore either increases or decreases the electrical output.
One category of presence sensing devices is Photoelectric Sensors. Light Curtains also fall into this category. Light curtains use many infrared light beams to form a perimeter around machinery. When two or more consecutively adjacent beams are interrupted, a kill-switch stops the machine until the boundary is reset.
Photoemission or photoelectric effect: Photons cause electrons to transition from the conduction band of a material to free electrons in a vacuum or gas. Thermal: Photons cause electrons to transition to mid-gap states then decay back to lower bands, inducing phonon generation and thus heat.
The photoelectric effect is the emission of electrons from a material caused by electromagnetic radiation such as ultraviolet light. Electrons emitted in this manner are called photoelectrons. Electrons emitted in this manner are called photoelectrons.
A phototube or photoelectric cell is a type of gas-filled or vacuum tube that is sensitive to light. Such a tube is more correctly called a 'photoemissive cell' to distinguish it from photovoltaic or photoconductive cells. Phototubes were previously more widely used but are now replaced in many applications by solid state photodetectors.
Incident IR photons can cause electronic excitations. In photoconductive detectors, the resistivity of the detector element is monitored. Photovoltaic detectors contain a p-n junction on which photoelectric current appears upon illumination. An infrared detector is hybridized by connecting it to a readout integrated circuit with indium bumps ...
A view through the window of an ultrahigh vacuum chamber for angle-resolved photoemission spectroscopy. The crystal holder with integrated e-beam heating is attached to a xyz+theta manipulator on top, and by a silver braid to a cryocooler on the bottom. The lens of the electron analyzer and UV source capillary are visible on the right.