Colorimetry of Guest-Host Displays

The quality criteria of guest-host devices in display systems are based on the following principal characteristics  

The Dichroic Ratio N = D /D which strongly correlates with the dye order parameter and can be improved by a special choice of molecular fragments of the dye (see Chapter 2). 

The Perceived Contrast Ratio between on and off states is defined by averaging the transmission with the function of the sensititivity of the human eye y ) and the spectral distribution of the illumination source H ) (4.59). The transmission of the guest-host display is written as 

FIGURE 4.27. Transmission characteristics of a twist-cell in parallel polarizers at oblique incidence [159], ie = 30°. (a) Nematic mixture without dye and (b) dye-doped nematic mixture. Curves 1, 2, 3 correspond to different voltages Ui U2 Us. 

TABLE 4.10. Different realizations of the guest-host displays. 

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