Time Delay and Integration
Encyclopedia
A time delay and integration (TDI) charge-coupled device
(CCD) is widely used for observation of high speed moving objects undetectable by classic CCD. Useful in a wide range of imaging applications that require both high speed and high sensitivity: earth observation satellites, inline monitoring and inspection, guidance, sorting, etc.
A TDI clock is used to synchronize the movement of charged packets in a CCD with that of another movement. For example, in some digital X-ray
mammography
systems, the X-ray tube
and CCD detector move across the breast at a speed V+. At the same time, the CCD detector reads out the information in the opposite direction at speed V−. This compensatory motion essentially freezes the motion of the detected X-ray information. The TDI clock ensures that speed V+ equals V−.
Charge-coupled device
A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...
(CCD) is widely used for observation of high speed moving objects undetectable by classic CCD. Useful in a wide range of imaging applications that require both high speed and high sensitivity: earth observation satellites, inline monitoring and inspection, guidance, sorting, etc.
A TDI clock is used to synchronize the movement of charged packets in a CCD with that of another movement. For example, in some digital X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
mammography
Mammography
Mammography is the process of using low-energy-X-rays to examine the human breast and is used as a diagnostic and a screening tool....
systems, the X-ray tube
X-ray tube
An X-ray tube is a vacuum tube that produces X-rays. They are used in X-ray machines. X-rays are part of the electromagnetic spectrum, an ionizing radiation with wavelengths shorter than ultraviolet light...
and CCD detector move across the breast at a speed V+. At the same time, the CCD detector reads out the information in the opposite direction at speed V−. This compensatory motion essentially freezes the motion of the detected X-ray information. The TDI clock ensures that speed V+ equals V−.