Temperature-independent quarter wave plate compensated liquid crystal shutter with a self-diagnostic shutter monitor

A temperature-independent quarter wave plate compensated liquid crystal shutter (QWP-LCS) with a self-diagnostic shutter monitor is proposed. During the QWP-LCS operation, the QWP is mechanically switched to become a positive (P-) QWP. When the bottom LC layer is switched to become a negative (N-) [P-] QWP by applying a suitable electric field, the QWP-LCS becomes a null [λ/2] plate and is closed [opened]. When the QWP-LCS is in close state and the embedded optical sensor detects light leakage caused by the temperature variation, the LCs in bottom layer are automatic tuned electrically by the self-diagnostic shutter monitor to compensate for the change in phase retardation resulting from the temperature variation and keep the QWP-LCS closed. Moreover, when the QWP-LCS is in open state, the exposure of the QWP-LCS is corrected by the self-diagnostic monitor by using its built-in database. Hence, the exposure of the proposed QWP-LCS is temperature-independent. The complete operation flow of the self-diagnostic shutter monitor is discussed in detail. The monitor can be extended to all nematic LCSs with specific limitations. The temperature-independent shutter can be applied to various fields, such as laser and imaging systems.