In order to realize the global calibration in line-structured-light measurement system using multiple CCDs

an approach to calibrate multiple CCDs based on an LCD target is investigated. First

a LCD target is arranged at the position of light section

and characteristic points are shown on the target one by one

which are captured by cameras at the same time. Then the relationship between the target coordinate and the image coordinate is established in a non-linear model through synchronizing pulses. Finally

the model is optimized by the shape restraints of a calibrating part to get the mapping between the light sectioning plane and the image plane. Measurements of free surface show that the data from different CCDs are well spliced in the light sectioning plane

and measurements of the calibrating part are accurate with an error less than 0.2mm in distance and 0.2°in angle. This method is easy to use

and has been successfully applied in a multi-CCD 3D measurement system.