disclosed are a light polarization state detection apparatus , a detection method and a light polarization state modulation method . the light polarization state detection apparatus comprises a lens with a variable birefringence feature as an optical phase modulator , a polarizer as a sop analyzer , a plurality of common lenses and a ccd as imaging devices , and a data processing and displaying unit . the sop detection apparatus uses wide special birefringence distribution of birefringence optical elements such as a grin lens to obtain the stokes parameters of light to be measured by ccd single frame imaging , and can rapidly accurately measure the sop . the sop detection apparatus is simple in structure , lower in cost without containing any motion parts and electrical modulation devices , and is a fully static full stokes parameters sop detection apparatus .