Non-perpendicular incidence in transmissive LCSLM: influence in the modulation prediction

H. Figueroa and I Moreno


In general, to determinate applications of liquid crystal spatial light modulators (LCSLM), it is necessary to find the display operational modulation curves, considering the optical setup in which it will be used. This requires the use of a
SLM physical model to characterize the Jones matrix of the device. From these, the modulator operation curve is obtained under any polarization configuration, and it is possible to predict the SLM behavior, to modulate in amplitude or phase modulation. The characterization procedure is usually performed with normal incidence. Nevertheless, if the illumination is off-axis, it could deteriorate the prediction of their behavior and consequently the expected modulation of polarized light. In this work we analyze experimentally the behavior of the transmissive LCDSLM when the incident beam impinging on it is off-axis. It is observed that the amplitude modulation is scarcely noticeable, when the incident light beam is non-perpendicular to LCD, different to configuration 0°, as it was characterized. The situation is different
when we study the phase only modulation configuration. In this case, a variation in operation curve versus inclination of incident light beam is observed. This result can be important to optimize some experiments or to take advantage, in only
one optical setup, to implement polarized beams with controlled slight phase differences between them. Likewise, the Jones matrix of the LCSLM dispositive is obtained, and it is possible to observe variations in any matrix components
whereas the angle of the incident light beam is varying. Also, experimental curves for amplitude and phase modulations are presented.