In an optical source or detector, the ratio of the number of output quanta to the number of input quanta.
The effectiveness of a CCD in generating electrons from the incident light falling on the CCD.
The ratio of effectiveness with which a CCD converts received photons (quanta of light) to measurable electrons. Amateur CCDs operate from about 15% up to about 75%, depending on the wavelength of light. High-end CCDs built for professional use frequently run 80% or higher.
Proportion of absorbed photons released as fluorescence.
The number of electrons generated for an incident photon in an electro-optical detection device. Used as one of the measures of detector performance.
The quantum efficiency (QE) of front-illuminated CCDs is around 40%. This means that 40 out of 100 incident photons were detected. The Imaging Technology Lab back-illuminated CCDs have a peak quantum efficiency upwards of 90%--90 out of 100 photons of a certain wavelength are detected! On the other hand, photographic film and the human eye have a peak QE of about 10%.
As photons of light hit a CCD chip they are converted into electrons which are stored and then read out at the end of the exposure. But not every photon that hits the chip is converted into an electron. How many photons are converted depends on the camera's quantum efficiency, or QE. QE is expressed as a percentage of the number of photons converted. If all the photons produced electrons, the QE would be 100%. Most amateur CCD cameras have QEs in the range of 25-50%. More advanced "back-illuminated" CCDs have QEs around 85%. Supercooled professional CCDs used at observatories have QEs closer to 98%. Compare this to film, which has a typical QE of around 2%. You can see why CCDs are so much faster
the ratio of photon-generated electrons that the pixel captures to the photons incident on the pixel area. Low fill factor reduces quantum efficiency.
The fraction of photons that strike a detector which produce electron hole pairs in the output current.
The measure of the effectiveness of an imager to produce electronic charge from incident photons. Especially important to perform low-light-level imaging.
Quantum efficiency (QE) is a figure given for a photosensitive device (charge-coupled device (CCD), for example) which is the percentage of photons hitting the photo reactive surface that will produce an electron-hole pair. It is an accurate measurement of the device's sensitivity.
The ratio of actual detectivity to theoretical detectivity for a given detector material.
In a photodiode, the ratio of primary carriers (electron-hole pairs) created to incident photons. A quantum efficiency of 70% means seven out of ten incident photons create a carrier.
Quantum efficiency (QE) is a quantity defined for a photosensitive device such as photographic film or a charge-coupled device (CCD) as the percentage of photons hitting the photoreactive surface that will produce an electron–hole pair. It is an accurate measurement of the device's sensitivity. It is often measured over a range of different wavelengths to characterize a device's efficiency at each energy.