US 7 012 241
Lenses are the standard solution to focus the light from LEDs for use with line scan cameras. A major disadvantage for use with color line scan cameras is chromatic aberration. Due to the different diffraction, the color composition changes at the scanning position. This is avoided by using an elliptical reflector. Another advantage is the significantly higher efficiency compared to the use of rod lenses.
DE10 2006 017 912
High-power LEDs and the necessary driver electronics were initially correspondingly expensive. By means of lateral spherical segments, the laterally emitted light is reflected back and redirected in the desired direction by another specular reflector between the LEDs. By "recycling" the lateral radiation, the number of LEDs can be halved and the costs are significantly reduced.
DE 10 2019 118 557
Wide-angle lenses have a sharp drop in brightness towards the edges. This can be compensated for by shading correction when using a line scan camera. The prerequisite for this is that the lighting can also illuminate all areas in the image accordingly. In special applications such as the automatic inspection of roads, the aim is on the one hand to capture as wide an area of the road as possible (even beyond the measurement vehicle). On the other hand, the superstructures are limited in width. The present invention directs the light laterally beyond the width of the vehicle, resulting in higher brightness levels there. This is advantageous when controlling the line scan camera with the wide-angle lenses.