Relative stereo image processing and its application to visual inspection of assembled PCBs

3-D measurement of electronic components has been required to inspect the assembled PCB, visually. In many cases, the methods such as structure light methods were introduced into the practical inspection lines. The visual inspection systems with structure method are usually expensive and functionally limited. To solve the problem, a relative stereo method has been developed to the PCB visual inspection system. The relative stereo system has the unique feature of calibration free precise 3-D measurement. In the paper, the optical structure of the system and its processing method has been introduced.