There are two general types of cameras used for image intensification. In the most common intensified CCD camera, the ICCD, an intensifier unit is optically coupled to a CCD chip via relay lenses or fibre-optic tapered bundles. The second type is the electron-bombarded CCD camera (EBCCD) where the photoelectrons are merely accelerated (but not multiplied) before reaching the CCD chip. See EMCCD cameras under CCD Chip Types in this context.
Main disadvantages of intensified cameras are the lower quantum efficiency of the photocathode as compared to that of the CCD chip alone, increased noise and a limited intrascene dynamic range of the images because the wells fill much faster upon intensification due to the electron multiplication. ICCD cameras furthermore have a reduced spatial resolution caused by the microchannel plate.

With high-performance fibre-coupled ICCDs, single photon detection is possible. At higher light levels the gain can be adjusted to increase the dynamic range.

ICCD cameras
ICCD cameras are basically full-performance CCD cameras optically coupled in two possible ways (see below) to an intensifier. A so-called proximity-focused intensifier (or wafer tube) consists of an entrance window, a photocathode, a microchannel plate (MCP) electron multiplier and a phosphorescent output screen. The photocathode converts the photons into electrons via the photoelectric effect. The quantum efficiency of the conversion is an important parameter and depends on the coating material which differs in the different generations of intensifiers (see below). The photoelectrons are driven to the MCP which is set under a field of several hundred volts. The MCP contains millions of parallel channels with a diameter of about six micrometers in the newest generations. The channels are coated with a secondary electron emitter which generates more electrons when hit by passing electrons. The intensification gain caused by the avalanche effect of multiple collisions is adjustable over a wide range up to several 10,000. The electrons are accelerated by a voltage of several kV upon exiting the MCP before reaching the phosphor screen where they are converted back into photons with an additional multiplication factor. The screen output light is then relayed to the CCD chip either by a lens or fibre-optic coupling. The advantage of relay lens coupling is the possibility of constructing removable intensifiers that enable to easily convert the ICCD camera reversibly into a standard CCD camera or retrofit an existing camera. However, the light efficiency (a function of transmission and inversely of the square of magnification and lens f-number) is limited and causes a significant loss of signal and a reduced signal-to-noise ratio. A much more efficient method to optically couple intensifier and CCD chip is through a fibre-optic taper which, however, requires a far more sophisticated manufacturing process. Such a taper is a bundle of microscopic fibres (2 - 3 microns in diameter) that guides the light from the fluorescent screen to the CCD chip. There are up to nine fibres per pixel usually machined directly onto the diode array. Each microfibre has a cladding to maximize light transmission and a stray-light absorbing coating to contain leakage and prevent the resulting contrast reduction. The signal-to-noise ratio of ICCD cameras is usually lower than that of standard CCD cameras because thermal noise from the photocathode and multiplication noise from the MCP are additional contributions to the overall camera noise.
The low light detection abilities of intensified cameras also allow a very high time resolution. This is due to the fact that the devices can be switched on and off very fast. This so called gating is necessary to provide the time needed to move the data off the CCD chip while the influx of photoelectrons is temporarily stopped. The switchable voltage difference between photocathode and MCP enables this. If the voltage at the MCP is more positive than at the photocathode, the photoelectrons are accelerated toward the MCP; if the MCP is more negative, the electron influx is stopped and the intensifier is gated off. The relatively high resistance of the photocathode material does not allow gating faster than about 25 - 50 ns. For gating faster than 2 ns, a nickel underlayer can be deployed to reduce the resistance, which, however, lowers the transmission and consequently reduces the QE significantly.

Intensifier Generations
Intensifiers are often classified by "generations":

Gen I
These intensifiers from the 1960s did not have an MCP and offered a relatively low gain and are long outdated.

Gen II
They contain a multialkali or bialkali photocathode like the Gen I intensifiers but are equipped with MCPs. While MCPs strongly increase the gain they also cause a certain loss in efficiency because part of the photoelectrons misses the microchannels and hits the MCP surface instead and is lost for detection.

Super Gen II
Improvements of the photocathodes with increased QE and extended spectral range in recent years have led to sensitivities that may equal those of Gen III intensifiers.

Gen III
Here the photocathode coating is made of gallium arsenide (GaAs) and has a much improved quantum efficiency as compared to the older Gen II photocathodes, especially in the near infra-red. A drawback, however, is that the MCPs have to be coated with a thin metal oxide barrier film to prevent destructive ion feedback to the fragile photocathodes. This coating reduces electron transmission and cancels out some of the efficiency gain.

Gen III Plus
These intensifiers have improved QE in the blue-green region of the spectrum which is of importance in scientific applications.

Gen IV
These intensifiers are only available for the US military and are highly sensitive in the green to near infra-red region. They deploy improved GaAs or GaAsP (gallium arsenide phosphide) photocathodes that do not require ion-barrier films.

EBCCD Cameras
This type of intensified cameras is kind of an intermediate between CCD and ICCD cameras. Like ICCDs they contain a photocathode to generate photoelectrons but do not feature an MCP. The photoelectrons are accelerated by a high voltage gradient (1.5 - 2 kV) before "bombarding" a back-thinned CCD chip. Unlike photons, which, depending on the QE, are converted into one electron at the most when collected by a photodiode of a CCD chip, the impact of an accelerated electron generates up to several hundred new charges. This is only a modest gain if compared with ICCDs but in general EBCCDs have a higher spatial resolution and a better signal-to-noise ratio.