ADP　(NH4H2PO4)　crystals　were　grown　through　the　traditional　method　and　rapid　growth　technology.　The　optical　homogeneity　of　rapid　grown　ADP　crystals　was　analyzed　by　laser　interferometry　and　X-ray　topography.　Laser　interferometry　revealed　sector　boundaries　at　which　optical　homogeneity　decreased　dramatically.　The　main　defects　that　seriously　reduced　the　optical　homogeneity　of　the　rapid　grown　ADP　crystal　were　sector　boundaries,　growth　bands　and　inclusions.　The　concentration　of　Fe　and　Cr　impurities　was　tested　by　a　plasma　emission　spectrometer.　It　was　found　that　the　preferential　incorporation　of　metallic　impurities　into　the　prismatic　faces　resulted　in　high　density　of　growth　bands　and　inclusions,　thus　reducing　optical　homogeneity　of　the　prismatic　sector.　©　Science　China　Press　and　Springer-Verlag　Berlin　Heidelberg　2010.