Polarization-insensitive dichroic filter for automatic optical inspection of printed circuit boards

Abstract

A polarization-insensitive dichroic filter was designed and fabricated at an angle of 45 deg with a slope of 13.0 and an average transmittance of 96.41% for a wavelength range about 300 nm for use in the automatic optical inspection (AOI) of a printed circuit board. The filter supports the inspection of PCBs with a high signal-to-noise ratio. The AOI had a resolution of 25.39 line pairs/mm in the tangential and sagittal directions.