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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.
Electro-optical sensors are electronic detectors that convert light, or a change in light, into an electronic signal. These sensors are able to detect electromagnetic radiation from the infrared down to the ultraviolet wavelengths. [1] They are used in many industrial and consumer applications, for example:
Opto-isolator VTL2C1 with LED input and photoresistor output. Resistive opto-isolator (RO), also called photoresistive opto-isolator, vactrol (after a genericized trademark introduced by Vactec, Inc. in the 1960s), analog opto-isolator [notes 1] or lamp-coupled photocell, [1] is an optoelectronic device consisting of a source and detector of light, which are optically coupled and electrically ...
Schematic diagram of an opto-isolator showing source of light (LED) on the left, dielectric barrier in the center, and sensor (phototransistor) on the right [note 1]. An opto-isolator (also called an optocoupler, photocoupler, or optical isolator) is an electronic component that transfers electrical signals between two isolated circuits by using light. [1]
Noise spectrum: The intrinsic noise voltage or current as a function of frequency. This can be represented in the form of a noise spectral density. Nonlinearity: The RF-output is limited by the nonlinearity of the photodetector [10] Spectral response: The response of a photodetector as a function of photon frequency.
In physics and in electronic engineering, dark current is the relatively small electric current that flows through photosensitive devices such as a photomultiplier tube, photodiode, or charge-coupled device even when no photons enter the device; it consists of the charges generated in the detector when no outside radiation is entering the detector.
Specific detectivity is given by =, where is the area of the photosensitive region of the detector, is the bandwidth, and NEP the noise equivalent power in units [W]. It is commonly expressed in Jones units ( c m ⋅ H z / W {\displaystyle cm\cdot {\sqrt {Hz}}/W} ) in honor of Robert Clark Jones who originally defined it.
Photoconductivity is an optical and electrical phenomenon in which a material becomes more electrically conductive due to the absorption of electromagnetic radiation such as visible light, ultraviolet light, infrared light, or gamma radiation.