Homodyne interferometric receiver and calibration method having improved accuracy and functionality

摘要

A method and system for measuring the phase difference between two orthogonally polarized components of a test beam as well as the intensities of these two components. A partially-polarizing beamsplitter (101) divides a polarized test beam (103) into first and second spatially- separated beams (154,104). The first beam (154) passes through a wave plate (160) oriented so as to retard the phase of the s polarization component with respect to the p polarization component. The first beam (154) then passes through a first polarizing beamsplitter (155), to produce a first pair of spatially separated output beams (156,157) with mutually-orthogonal linear polarizations. The second beam (104) is likewise passed through a second polarizing beamsplitter (105) to produce a second pair of linearly-polarized output beams (106,107). Photodetectors (108,109,158,159) send an electrical signals proportional to the intensities of the beams (106,107,156,157) to a computer (99). The computer (99) calculates the phase difference between the s and p polarization components of the test beam, as well as the relative intensities of the s and p polarization components of the test beam. The invention also provides methods and means for calibrating the inventive apparatus using polarizing elements (52,53,54) and a beam block (51). The calibration procedure determines the phase retardance of the wave plate (155), the polarizing characteristics of the partially-polarizing beamsplitter (101), and the electrical characteristics of each of the photodetectors (108.109,158,159).