**2.2 The fabrication of optic diffuser**

Oriel® Flood Exposure Source (Model 92540-1000, Newport Co.) was used as the UV source. An optic setup was shown in Figure 3. A textured mask with random 2-15 micrometer apertures was used as mask, and polyester (PET) film was used as substrate. 75 µm thickness PET film was used as spacer. The films of photopolymerizable holographic materials were exposed vertically or 60o to collimated UV light through the mask, followed by exposing from another side to complete the polymerization process. The direct transmittance versus the tilt angle was measured with Haze meter (BYK Gardner) and the diffuser was rotated from -60o to +60o around the vertical axis.

Fig. 3. The optic set-up for fabricating optic diffuser.
