Each ELDIM viewing angle instrument comes with a software that allows all standard analysis than can be made on viewing angle measurements. Many possibilities are offered to display the data in different ways. 3D representations are for example very useful to visualize the emission cone simultaneously in terms of luminance and chromaticity. All the standard units for luminance and chromaticity are available. Standard computations such as luminance contrast or color difference can be made. Even more complex computation with different data can be performed. The viewing angle measurements can be immediately analyzed with comprehensive, integrated graphs, charts and spreadsheets for:

• Luminance
• Illuminance
• CIE Chromaticity coordinate (x,y; u',v,a*,b*)
• Correlated color temperature (CCT)
• Contrast ratio
• Ellipticity and polarization orientation
• Degree of polarization
• Stokes vector

Data and graphs can be easily exported to other Windows applications. Data can also be interpolated in the Fourier plane and exported in different format for direct use in simulation softwares.

Polarization measurement on OFF state on LCD (left), cross section in polar (middle) and on Poincaré sphere (right)

Normalized lightness versus grey level and incidence angle along 0°(left) and 90°(right) azimuths

Although the Iso-Contrast curves are useful for LCDs displaying bi-level images, they are not suitable for LCDs displaying grey scale images. That’s why a specific toolbox has been developed: the grey level analysis that allows displaying grey level measurements in different ways and also calculating Reverse Images (RI), Excessively Dark Images (EDI) and Excessively Bright Images (EBI) (*). This option works in luminance and also in radiance and polarization mode.

Software interface for grey level analysis

RI (far left), EBI (middle left), EDI (middle right) and normal incidence brightness dependence (far right) for one LCD

The T-V curve of an LCD is measured at normal incidence. The transmission values are then normalized to the maximum transmission. From the normalized transmission values, normalized lightness values L* are obtained as (*) :

where Y(V) is the luminance of the transmission for an applied voltage V and Y0 is the maximum luminance for the normal incidence. The normalized lightness-voltage or lightness-grey level is then computed for all the angles and all the voltages (or grey levels). All the data can be saved and exported easily. Comparison between different types of LCD becomes much more powerful.