Schematic of a QHQ stack. [(a) and (e)] Polarizer, [(b) and (d)] quarter-wave plate, and (c) half-wave plate
The spatially varying orientation of the slow axis of the half-wave plate in the plane of the plate
V-COPA alignment setup view from the side of the LC cell with no voltage applied, showing the effect of the surface alignment. The 16 horizontal rectangles are an end view of eight pairs of electrodes on the surfaces of the cell substrates. The vertical rectangles represent the vertically aligned LC directors. Near electrode 3, the tops of the directors are slightly tipped into the paper, while near electrode 6 they are slightly tipping out of the paper.
The V-COPA cell structure. Shown are the top and bottom glass substrates with their patterned electrodes. Also shown is the desired director configuration (when a voltage is applied) that lies in the plane with an angle about the axis that varies linearly as a function of .
V-COPA spiral grating with a period resulting from calculations and initial conditions described in the text. The top graph shows the plane in the middle of the cell. The bottom graph is the side view of the director configuration. The curves show the equipotential field with 0.33 V between each level.
Same view as Fig. 5, showing the effect of changing the locations of and from those shown in Fig. 5
Same view as Fig. 6, showing effect of changing the locations of and from those shown in Fig. 6. Relative to Fig. 5, it can be seen that the pitch of the spiral has been reduced to .
Periodic grating formed from the initial condition shown in Fig. 5, by changing the locations of the dc offsets. The resulting period is reduced from that in Fig. 5 to .
Scalar theory calculation results: (a) incident Gaussian beam, (b) far field intensity vs angular position for case in Fig. 5, with a period, and (c) far field intensity vs angular position for a case with period. Graphs (b) and (c) are normalized to the peak height in graph (a), and therefore show the diffraction efficiency for the diffracted light beam.
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