The superconducting camera, SCAM, is an ultra-fast photon-counting camera developed by the

European Space Agency , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (120 ...

. It is cooled to just 0.3 K (three-tenths of a degree Celsius above

absolute zero Absolute zero is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as zero kelvin. The fundamental particles of nature have minimum vibra ...

). This enables its sensitive electronic detectors, known as

superconducting tunnel junction The superconducting tunnel junction (STJ) — also known as a superconductor–insulator–superconductor tunnel junction (SIS) — is an electronic device consisting of two superconductors separated by a very thin layer of insulating material. Cu ...

detectors, to register almost every photon of light that falls into it. Its advantage over a CCD (

charge-coupled device A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a ...

) is that it can measure both the brightness (rate) of the incoming photon stream and the colour (

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...

energy In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of ...

) of each individual

photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, so they alwa ...

. The number of free primary

electrons The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have n ...

generated per photon event is proportional to the photon energy and amounts to ~18,000 per

electronvolt In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacu ...

, and therefore if the device is operated in single-photon count mode the energy of each captured photon can be calculated in the visible-light range, where photons have energies of a few electronvolts, each generating >20,000 electrons. In a normal CCD, only one primary electron is generated per photon, except for very energetic photons, like

X-rays An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nbs ...

, where a normal CCD can operate in a similar way to a SCAM.

References

European Space Agency: ESA's new camera will revolutionise the way astronomers observe the Universe

S-Cam 3, the detector
Infrared imaging Infrared telescopes Astronomy image sensors {{astronomy-stub