Time Delay And Integration Image Research Articles

Image restoration of hybrid time delay and integration camera system with residual motion

In this paper, we present a hybrid system for time delay and integration (TDI) image restoration. Images are degraded by residual motion, which distorts and blurs the TDI images during exposures and excludes the along-track scanning motion. The motion trajectory is estimated from the image sequence captured by an auxiliary high-speed camera. In order to make the estimated results less sensitive to the imaging conditions and noise, a new method based on cross-correlation is introduced for motion estimation. Then geometric distortion of the TDI image is removed by choosing the correct blurred block according to the central of the corresponding motion trajectory and the final image is restored row by row with the Richardson-Lucy algorithm. Simulated and experimental results are given to prove the effectiveness of our system.

Restoration of TDI camera images with motion distortion and blur

Platform movement during exposure of imaging system severely degrades image quality. In the case of Time delay and integration (TDI) camera, abnormal movements cause not only image blur but also distortion, for image Point Spread Function (PSF) is space-variant. In this paper, we present a motion degradation model of TDI image, and provide a method to restore such degraded image. While a TDI camera is imaging, it outputs images row by row (or line by line) along the scanning axis, and our method processes in the same track. We firstly calculate the space-invariant PSF of each row using the movement information of the TDI camera. Then, we substitute pixels of the row and the ones of their neighbor rows together with the PSF into standard Richardson–Lucy algorithm. By deconvoluting we get the restored pixels of the row. The same operations are executed for all rows of the degraded TDI image. Finally, a restored image can be reconstructed from those restored rows. Both simulated and experimental results prove the effectiveness of our method.

Electron beam inspection system based on the projection imaging electron microscope

An electron beam inspection system based on the projection imaging electron microscope was developed and the proof-of-concept system has been constructed and evaluated. The secondary electrons are projected through the projection imaging optics and imaged onto the image detection system. The projected secondary electron image is amplified by the microchannel plate and converted to an optical image by the fluorescent screen and detected by the 2048 element, eight-tap time delay and integration (TDI) image sensor. The stage is linearly moved in synchronism with the TDI signal output data rate, and then, the secondary electron image is continuously captured. The spatial resolution of around 0.1 μm has been obtained in this experiment. Several images obtained by the TDI imaging mode are also demonstrated.

TDI imaging and scanning moiré for online defect detection

This paper explains the application of scanning moiré in association with TDI (Time Delay and Integration) imaging for complete peripheral inspection of cylindrical objects. Based on the structured light technique, a grating pattern modulated by deformations, such as dents on the surface of a rotating cylindrical object, is recorded using a TDI camera. The illumination system consists of an intensity modulated, line generating laser diode aligned at an angle to the camera axis. By using the TDI option for recording every nth line, an online scanning moiré pattern is generated. After providing a simple explanation of the scanning moiré, the effects of object rotation speed and TDI scan speed on the fringe pattern are discussed and demonstrated. The techniques presented here offer low cost solutions to industrial machine vision tasks related to peripheral imaging and inspection of cylindrical objects.

A Large Area TDI Image Sensor for Low Light Level Imaging

A 1030 X 128 element time delay and integration (TDI) CCD image sensor has been developed for low-light-level (L/sup 3/) imaging applications. For L/sup 3/ imaging, output is derived from a high-gain low-noise floating-gate amplifier (FGA). For larger input signal levels, a second, resettable floating-gate amplifier (RFGA) with lower gain and wider dynamic range provides output in parallel to the FGA. The device features four-phase buried-channel construction and a polysilicon gate design tailored to produce optimum broad-band responsivity. Input signal levels of 500 electrons have been successfully imaged and amplifier noise levels of approximately 20 electrons have been observed.

A large area TDI image sensor for low light level imaging

A 1030 × 128 element time delay and integration (TDI) CCD image sensor has been developed for low-light-level (L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) imaging applications. For L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> imaging, output is derived from a high-gain low-noise floating-gate amplifier (FGA). For larger input signal levels, a second, resettable floating-gate amplifier (RFGA) with lower gain and wider dynamic range provides output in parallel to the FGA. The device features four-phase buried-channel construction and a polysilicon gate design tailored to produce optimum broad-band responsivity. Input signal levels of 500 electrons have been successfully imaged and amplifier noise levels of approximately 20 electrons have been observed.