We have developed a practical color filter liquid-crystalon-silicon
CF-LCOS microdisplay that integrated color filters
on silicon for color.1,2 The projection or viewing optics
of this breed of microdisplays is greatly simplified since
color is already available. What it needs is just a polarizing
beam splitter PBS to direct a polarized light into the display
and back to a projection lens or eyepiece. In this paper,
we present optical modeling and optimizations of the CFLCOS
microdisplays.
In our previous works, we have developed a twodimensional
2D optical modeling of small pixels in reflective
twisted nematic cells.3 In this work, we added color
filters in the simulation structures and elaborated the 2D
modeling to three dimensions. The three-dimensional 3D
optical analysis started with a numerical calculation of LC
director in rectangular mesh. Thereafter we calculated for
optical reflectance of color pixels in the visible spectrum by
extended Jones matrix. The optical reflectance spectrum was
then converted to the CIE 1931 color space for color coordinate,
which was a good measure of color purity. The optical
reflectance was also expressed spatially by the sRGB4 format
in the pixel array, so the color fringing field among small
color pixels could be visualized. With this analysis as a tool,
we proceeded to minimize the color fringing field with respect
to pixel arrangement, rubbing direction, and LC mode.
We also studied the relation of color fringing field with pixel
size and thickness of color filter, and optimized the CFLCOS
microdisplays for specific applications.
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