31 October 1996 Using TDI camera with nonzero viewing angles for surface inspection
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A variety of time delay and integration (TDI) arrays have been developed. The TDI image sensor offers significant improvement in performance over a linear CCD-sensor with respect to sensitivity. This is particularly significant in low level operations since the exposure time is increased by a factor which is equal to the number of the TDI stages in the sensor. Typically, the use of a TDI camera is restricted to cases where the surface is viewed from the direction of the surface normal. This is because the TDI-camera sensor has to be parallel to the viewed surface plane, in order to avoid a decrease of image quality due to varying magnification. However, in certain visual inspection applications it would be advantageous to use non-zero viewing angles. Three different solutions were tested and analyzes: a commercial shifting lens, standard lenses with an extension structure to support the lens in the shifting position and a commercial shifting and tilting lens. The results indicate that the TDI-camera can be used with viewing angles up to 30 degrees from the surface normal,which has been found to be the optimal viewing angle in some visual inspection applications.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jari Miettinen, Jari Miettinen, Xu Zelin, Xu Zelin, Heikki J. Ailisto, Heikki J. Ailisto, } "Using TDI camera with nonzero viewing angles for surface inspection", Proc. SPIE 2908, Machine Vision Applications, Architectures, and Systems Integration V, (31 October 1996); doi: 10.1117/12.257249; https://doi.org/10.1117/12.257249

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