A report on Photodetector

A photodetector salvaged from a CD-ROM drive. The photodetector contains three photodiodes, visible in the photo (in center).
A commercial amplified photodetector for use in optics research

Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation.

- Photodetector
A photodetector salvaged from a CD-ROM drive. The photodetector contains three photodiodes, visible in the photo (in center).

21 related topics with Alpha

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A specially developed CCD in a wire-bonded package used for ultraviolet imaging

Charge-coupled device

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Integrated circuit containing an array of linked, or coupled, capacitors.

Integrated circuit containing an array of linked, or coupled, capacitors.

A specially developed CCD in a wire-bonded package used for ultraviolet imaging
George E. Smith and Willard Boyle, 2009
The charge packets (electrons, blue) are collected in potential wells (yellow) created by applying positive voltage at the gate electrodes (G). Applying positive voltage to the gate electrode in the correct sequence transfers the charge packets.
Sony ICX493AQA 10.14-megapixel APS-C (23.4 × 15.6 mm) CCD from digital camera Sony α DSLR-A200 or DSLR-A300, sensor side
CCD from a 2.1-megapixel Argus digital camera
One-dimensional CCD image sensor from a fax machine
A frame transfer CCD sensor
Electrons are transferred serially through the gain stages making up the multiplication register of an EMCCD. The high voltages used in these serial transfers induce the creation of additional charge carriers through impact ionisation.
in an EMCCD there is a dispersion (variation) in the number of electrons output by the multiplication register for a given (fixed) number of input electrons (shown in the legend on the right). The probability distribution for the number of output electrons is plotted logarithmically on the vertical axis for a simulation of a multiplication register. Also shown are results from the empirical fit equation shown on this page.
Array of 30 CCDs used on the Sloan Digital Sky Survey telescope imaging camera, an example of "drift-scanning".
A Bayer filter on a CCD
x80 microscope view of an RGGB Bayer filter on a 240 line Sony CCD PAL Camcorder CCD sensor
Vertical smear

The basis for the CCD is the metal–oxide–semiconductor (MOS) structure, with MOS capacitors being the basic building blocks of a CCD, and a depleted MOS structure used as the photodetector in early CCD devices.

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Image sensor

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Sensor that detects and conveys information used to make an image.

Sensor that detects and conveys information used to make an image.

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A micrograph of the corner of the photosensor array of a webcam digital camera
Image sensor (upper left) on the motherboard of a Nikon Coolpix L2 6 MP
Bayer pattern on sensor
Foveon's scheme of vertical filtering for color sensing
Infrared view of the Orion Nebula taken by ESO's HAWK-I, a cryogenic wide-field imager
New iPad includes lidar sensor

When light strikes the chip it is held as a small electrical charge in each photo sensor.

One Ge (top) and three Si (bottom) photodiodes

Photodiode

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Light-sensitive semiconductor diode.

Light-sensitive semiconductor diode.

One Ge (top) and three Si (bottom) photodiodes
One Ge (top) and three Si (bottom) photodiodes
I-V characteristic of a photodiode. The linear load lines represent the response of the external circuit: I=(Applied bias voltage-Diode voltage)/Total resistance. The points of intersection with the curves represent the actual current and voltage for a given bias, resistance and illumination.
Electronic symbol for a phototransistor
Response of a silicon photo diode vs wavelength of the incident light
A one-dimensional photodiode array chip with more than 200 diodes in the line across the center
A two-dimensional photodiode array of only 4 × 4 pixels occupies the left side of the first optical mouse sensor chip, c. 1982.

P–n photodiodes are used in similar applications to other photodetectors, such as photoconductors, charge-coupled devices (CCD), and photomultiplier tubes.

CMOS image sensor.

Active-pixel sensor

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CMOS image sensor.
Blooming in a CCD image
Distortion caused by a rolling shutter
A three-transistor active pixel sensor.
A two-transistor active/passive pixel sensor

An active-pixel sensor (APS) is an image sensor where each pixel sensor unit cell has a photodetector (typically a pinned photodiode) and one or more active transistors.

Dark current (physics)

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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.

Shutter lag

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Delay between triggering the shutter and when the photograph is actually recorded.

Delay between triggering the shutter and when the photograph is actually recorded.

The "pinned photodiode" is a photodetector structure used in almost all charge-coupled device (CCD) and CMOS image sensors (CIS) due to its low noise, high quantum efficiency and low dark current.

A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.

Light

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Electromagnetic radiation within the portion of the electromagnetic spectrum that is perceived by the human eye.

Electromagnetic radiation within the portion of the electromagnetic spectrum that is perceived by the human eye.

A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.
The electromagnetic spectrum, with the visible portion highlighted
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Beam of sun light inside the cavity of Rocca ill'Abissu at Fondachelli-Fantina, Sicily
Due to refraction, the straw dipped in water appears bent and the ruler scale compressed when viewed from a shallow angle.
Hong Kong illuminated by colourful artificial lighting.
Pierre Gassendi.
Christiaan Huygens.
Thomas Young's sketch of a double-slit experiment showing diffraction. Young's experiments supported the theory that light consists of waves.
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The illumination measured by a photocell sensor does not necessarily correspond to what is perceived by the human eye and without filters which may be costly, photocells and charge-coupled devices (CCD) tend to respond to some infrared, ultraviolet or both.

Responsivity

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Responsivity measures the input–output gain of a detector system.

Responsivity measures the input–output gain of a detector system.

In the specific case of a photodetector, it measures the electrical output per optical input.

A conventional crystalline silicon solar cell (as of 2005). Electrical contacts made from busbars (the larger silver-colored strips) and fingers (the smaller ones) are printed on the silicon wafer.

Solar cell

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Electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.

Electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.

A conventional crystalline silicon solar cell (as of 2005). Electrical contacts made from busbars (the larger silver-colored strips) and fingers (the smaller ones) are printed on the silicon wafer.
Symbol of a Photovoltaic cell.
From a solar cell to a PV system. Diagram of the possible components of a photovoltaic system
NASA used solar cells on its spacecraft from the very beginning. For Example, Explorer 6, launched in 1959, had four arrays that folded out once in orbit. They provided power for months in space.
Energy volume of silicon solar cells and oil harnessed by human beings per dollar; Carbon intensity of some key electricity generation technologies.
Schematic of charge collection by solar cells. Light transmits through transparent conducting electrode creating electron hole pairs, which are collected by both the electrodes.
Working mechanism of a solar cell
The Shockley-Queisser limit for the theoretical maximum efficiency of a solar cell. Semiconductors with band gap between 1 and 1.5eV (827 nm to 1240 nm; near-infrared) have the greatest potential to form an efficient single-junction cell. (The efficiency "limit" shown here can be exceeded by multijunction solar cells.)
Reported timeline of research solar cell energy conversion efficiencies (National Renewable Energy Laboratory)
Global market-share in terms of annual production by PV technology since 1990
The roof, bonnet and large parts of the outer shell of the Sion are equipped with highly efficient monocrystalline silicon cells
Dawn's 10 kW triple-junction gallium arsenide solar array at full extension
Bifacial solar cell plant in Noto (Senegal), 1988 - Floor painted in white to enhance albedo.
Solar Impulse aircraft are Swiss-designed single-seat monoplanes powered entirely from photovoltaic cells
Early solar-powered calculator
Solar cell production by region

In addition to producing energy, they can be used as a photodetector (for example infrared detectors), detecting light or other electromagnetic radiation near the visible range, or measuring light intensity.

Noise-equivalent power

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Noise-equivalent power (NEP) is a measure of the sensitivity of a photodetector or detector system.