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A photoresistor can be used in light-sensitive detector circuits and light-activated and dark-activated switching circuits acting as a semiconductor resistance. In the dark, a photoresistor can have a resistance as high as several megaohms (MΩ), while in the light, it can have a resistance as low as a few hundred ohms.
A densitometer is a device that measures the degree of darkness (the optical density) of a photographic or semitransparent material or of a reflecting surface. [1] The densitometer is basically a light source aimed at a photoelectric cell . [ 2 ]
Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. [1] There are a wide variety of photodetectors which may be classified by mechanism of detection, such as photoelectric or photochemical effects, or by various performance metrics, such as spectral response.
An optical sensor converts light rays into electronic signals. It measures the physical quantity of light and then translates it into a form readable by an instrument. An optical sensor is generally part of a larger system that integrates a source of light, a measuring device, and the optical sensor. This is often connected to an electrical ...
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 ...
The use of the human eye as a detector led to photometric units, weighted by the eye's response characteristic. Study of the chemical effects of ultraviolet radiation led to characterization by the total dose or actinometric units expressed in photons per second. [1] Many different units of measure are used for photometric measurements.
An 80-year-old woman died one month after her Sleep Number bed suddenly moved without warning and trapped her against a wall for two days last year, a new lawsuit alleges.
DEAP-3600 - Dark Matter Experiment using Argon Pulse-shape Discrimination - is a second generation dark matter detector, using 3600 kg of liquid argon. This experiment aims to detect WIMP -like dark matter particles through argon scintillation, producing small amounts of light that is detected by extremely sensitive photomultiplier tubes .