PHASE DIFFERENCE CONTROLLER AND OPTICAL DEVICE

摘要

PROBLEM TO BE SOLVED: To obtain the phase difference controller which stably operates without being affected by external environment by detecting a phase difference and performing feedback control over an electric signal so that the phase difference becomes equal to a target phase difference. SOLUTION: A phase difference varying element 1 varies the phase difference with the electric signal. A phase difference detecting means 2 comprises a phase difference detecting optical system 21 and a phase difference detecting circuit system 22 and detects the phase difference. A phase difference control means 3 comprises an error signal detection part 31 and a drive circuit system 32, and performs the feedback control over the electric signal so that the detected phase difference matches the target phase difference. Namely, the phase difference detecting circuit system 22 generates a signal Sout representing the phase difference from the signal detected by the phase difference detecting optical system 21. The error signal detection part 31 generates an error signal Er of the signal Sout based upon the target value. The drive circuit system 32 controls the voltage applied to a liquid crystal panel 1-1 so that the error signal Er becomes 0.