The　phase-only　liquid　crystal　on　silicon　(LCOS)　spatial　light　modulator　has　been　used　as　a　wavefront　generator　and　reconstruction　device　for　display　applications　due　to　its　phase-only　modulating　property　of　incident　light.　In　order　to　achieve　the　best　reconstructed　phase　modulated　wavefront,　the　properties　of　LCOS　have　to　be　fully　known.　The　intensity　of　reflected　light　from　LCOS　decreases　under　normal　incidence　by　going　through　a　beam　splitter.　In　order　to　improve　the　intensity　of　the　reflected　light　beam,　the　oblique　incidence　is　preferred　during　many　applications.　The　oblique　incidence　characterization　of　a　parallel　aligned　LCOS　is　investigated　at　a　working　wavelength　of　532　nm　on　the　basis　of　double-hole　interferometric　method.　Through　experiments,　the　phase　modulation　characterization　of　LCOS　under　the　oblique　incidence　is　obtained.　In　addition,　an　image　postprocessing　method　is　proposed　to　overcome　the　effect　of　flicker　and　coherent　noise　by　simplifying　the　computation　and　increasing　the　measurement　accuracy.　The　comparison　of　experimental　results　for　different　incident　angles　indicates　that　it　plays　an　important　role　in　the　performance　of　phase　modulation　of　LCOS,　where　the　phase　modulation　decreases　with　the　increasing　angle　of　incidence.　(C)　2015　Society　of　Photo-Optical　Instrumentation　Engineers　(SPIE)