Patent ID: 8605264

Claim:
An apparatus for quantifying residual stress of a birefringent material comprising a light source generating light; a vertical polarizer being mounted in front of the light source and converting a beam of light into a beam with vertical polarization; a standard material being mounted in front of the vertical polarizer, being the same material as the birefringent material and being a birefringent flat plate without residual stress; a horizontal polarizer being mounted in front of the standard material and converting a beam of light passing through the standard material into a beam with horizontal polarization; an applied force unit applying different forces to the standard material; a spectrometer being mounted in front of the horizontal polarizer and recording intensity of light passing through the horizontal polarizer and transmittance of the standard material; and a processing module being connected to the spectrometer, deriving a stress formula from the applied forces and transmittances of the standard material and obtaining a stress distribution of the birefringent material using the stress formula and transmittance of the birefringent material.