TDI Line Scan Cameras

Time delay integration (TDI) offers a unique imaging solution that can improve both speed and signal-to-noise ratio.
During TDI mode, the charge-coupled device (CCD) captures an image of a moving object while transferring integrated signal charges synchronously with the object’s movement.This method increases the collected signal by a factor equivalent to the number of TDI stages or transfers, thereby improving the signal-to-noise ratio by the square root of the number of TDI elements.

Correct implementation of a TDI camera allows continuous movement of the sample past the detector in one axis, yields a significant increase in throughput (i.e. sample area scanned/unit time) over traditional stop-and-start stage and camera acquisition methods.TDI requires the coordination of the movement of the sample with the direction of TDI on the sensor.

This combination results in continuous scanning of the sample with high sensitivity and high speed.

TDI drastically reduces the amount of scan time needed compared to a 2D camera as the mechanical stop-start time is virtually eliminated and the settle time of each 2D camera position is eliminated.

X-ray TDI cameras are useful for in-line applications requiring high-speed operation with high sensitivity. Applications which operate under low brightness, whilst requiring high-resolution, can be a problem for conventional line sensor cameras. The interal gain offered by an X-ray TDI camera greatly improves the image quality obtained in these types of applications.

TDI is a special image acquisition method which has been used extensively in machine vision applications for industrial inspection. It is also suitable for applications where it is desired to record a linear movement, or where the aspect ratio of the subject being imaged is significantly asymmetric. Hamamatsu has extensive experience in the design and implementation of TDI sensors, cameras and systems.

Principle

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