Influence of the incident angle in the performance of Liquid Crystal on Silicon displays

Abstract

Abstract:In this paper we experimentally analyze the performance of a twisted nematic liquid crystal on silicon (LCoS) display as a function of the angle of incidence of the incoming beam. These are reflective displays that can be configured to produce amplitude or phase modulation by properly aligning external polarization elements. But we demonstrate that the incident angle plays an important role in the selection of the polarization configuration. We performed a Mueller matrix polarimetric analysis of the display that demonstrates that the recently reported depolarization effect observed in this type of displays is also dependant on the incident angle.

Study of Liquid Crystal on Silicon Displays for Their Application in Digital Holography

“…By performing a summation of intensities corresponding to N different equally spaced values of θ 2 , completing a rotation of 360 degrees, some terms of Eq. (2) vanish due to the orthogonal properties of the sinusoidal sampled functions (Lizana et al, 2009). Besides, by performing another summation of different intensities, but now, multiplying the intensities by the sine or by the cosine of the corresponding angle θ 2 , different terms in Eq.…”

“…(2) vanish. In this way, the following mathematical expression for the Stokes parameters is obtained (Lizana et al, 2009):…”

“…In such situations, the LCoS display response can be notably different. However, the characterizing method described in this section can be extended to different experimental conditions, such as the incident angle (Lizana et al, 2009) or the wavelength (Lizana et al, 2008c). …”

“…In the case of LCoS displays, diverse polarimetric studies have proved that they are non-diattenuating devices (Lizana et. al, 2008c;Lizana et al, 2009;Márquez et al, 2008) and the corresponding M D matrices can be approximated to the identity matrix. Therefore, when applying the Lu-Chipman polar decomposition to the LCoS display case, the following relation holds :…”

“…However, some authors have discovered that LCoS displays may introduce non-negligible values of effective depolarization at the reflected beam (Lizana et al, 2008a;Márquez et al, 2008;Wolfe & Chipman, 2006), which are originated by the electrical addressing schemes applied in these devices (Hermerschmidt et al, 2007). This effective depolarization depends on the incident angle (Lizana et al, 2009;Verma et al, 2010), the wavelength (Lizana et al, 2008c) and the state of the polarization of the incident beam . In this situation, the application of an optimizing method that includes the unpolarized light contribution observed when working with LCoS display becomes mandatory.…”