http://files.engineering.com/getfile.aspx?folder=6466415e-a83f-407a-a32c-e6180c8a83c9&file=Specifying_position_and_orientation_of_a_thin_part_on_a_PCB.pdf
I had a PCBA with two Fiducials and an image sensor (Fiducials are exposed copper pads on the PCB typically about 1mm in diameter. They are...