Patent ID: 7180051

Claim:
A polarization state detecting system comprising: first dividing means for dividing incident light into two light beams having the same polarization state as the incident light, wherein said first dividing means includes a first element, a second element and a third element, said second element is disposed so that a p-polarization component reflected by said first element is reflected by said second element as an s-polarization component, said third element is disposed so that a p-polarization component transmitted through said first element is transmitted by said third element as an s-polarization component, and one of the two light beams is light reflected by said first element and reflected by said second element, while the other of the two light beams is light transmitted through said first element and transmitted through said third element; a detector for detecting one of the two light beams from said first dividing means, through a polarizer, said polarizer is adapted to divide the one light beam into two orthogonal polarized light beams, and wherein said detector includes two detecting elements for detecting the two polarized light beams, respectively; acquisition means for acquiring information regarding the polarization state of the incident light on the basis of an output of said detector; and second dividing means for dividing the other light beam from said first dividing means, into two light beams having the same polarization state as the other light beam, a second detector for detecting one of the two light beams from said second dividing means, through a polarizer, and a third detector for detecting the other of the two light beams from said second dividing means, through a phase plate and a polarizer.