EMCCD Tutorial
Q1 What are Electron Multiplying CCDs (EMCCDs)?
Current trends in photonics are placing unprecedented demands on detector technology
to perform at significantly greater levels of sensitivity. Electron Multiplying
Charge Coupled Device (EMCCD) technology has been designed to respond to this growing
need and in turn is opening up new avenues of novel experimental design. In early
2000, Andor Technology coined the term ‘Electron Multiplying CCD (EMCCD)’ to amply
describe the underlying process that defines this novel new technology platform.
Essentially, the EMCCD is an image sensor that is capable of detecting single photon
events without an image intensifier, achievable by way of a unique electron multiplying
structure built into the chip. The fact that an EMCCD does not require an image
intensifier, means that we are able to utilize the full QE of the silicon sensor,
which can be as high as 95%. It is the combination of minimal noise floor and high
QE that renders EMCCD the most sensitive detector technology available. Physically,
EMCCDs resemble a conventional frame transfer CCD structure, with the image or data
captured in the image area before being shifted behind a masked storage area and
read out.
In EMCCD sensors, the shift register is extended to include an additional section
– the gain register. Gain can be increased to a degree, readily tunable in real
time through the software, where extremely weak signals may be detected above the
read noise of the camera at any readout speed. This is important because the traditional
problem of combining sensitivity with speed in standard CCDs is that the two are
mutually exclusive, i.e. greater read noise detection limits
Gain can be increased to a degree, readily tunable in real time through the software,
where extremely weak signals may be detected above the read noise of the camera
at any readout speed. This is important because the traditional problem of combining
sensitivity with speed in standard CCDs is that the two are mutually exclusive,
i.e. greater read noise detection limits result from faster pixel readout.