A novel architecture of the optical multiple-image encryption based on the modified Gerchberg-Saxton algorithm (MGSA) by using cascading phase only functions (POFs) in the Fresnel transform (FrT) domain is presented. This proposed method can greatly increase the capacity of the system by avoiding the crosstalk, completely, between the encrypted target images. Each present stage encrypted target image is encoded as to a complex function by using the MGSA with constraining the encrypted target image of the previous stage. Not only the wavelength and position parameters in the FrT domain can be keys to increase system security, the created POFs are also served mutually as the encryption keys to decrypt target image from present stage into next stage in the cascaded scheme. Compared with a prior method [Appl. Opt.48, 2686-2692 (2009)], the main advantages of this proposed encryption system is that it does not need any transformative lenses and this makes it very efficient and easy to implement optically. Simulation results show that this proposed encryption system can successfully achieve the multiple-image encryption via fewer POFs, which is more advantageous in simpler implementation and efficiency than a prior method where each decryption stage requires two POFs to accomplish this task.
The triple-metal-layer periodic structures in the anode for top-emission organic light-emitting diodes (TEOLEDs) are reported in this paper. The anode consists of aluminum (Al) and nickel/gold (Ni/Au) periodic structures. The Al is used for high reflectivity and Ni/Au for high work function by enhancing the hole injection from the anode into the organic hole injection layer. The Ni and Au work functions were measured at 5.3 and 5.1 eV, respectively, which were higher than that of a single Al layer at 4.2 eV. This two pair Ni/Au anode device exhibits high reflectivity and reveals the microcavity effect to increase luminescence efficiency. The optimum current efficiency with the two pair Ni/Au anode is increased to 7.99 cd/A compared with the one pair Ni/Au anode (6.85 cd/A) and three pair Ni/Au anode (5.07 cd/A).
A reverse-tilt-domain boundary wall in a polymer-encapsulated nematic liquid crystal was examined. A boundary wall in which the liquid crystal director was nearly planar midway through the wall was formed during UV polymerization; it remained stable even though the liquid crystal molecules in neighboring domains are nearly vertically aligned. The formation of the boundary wall was found to be suppressed by the oblique irradiation with linearly polarized UV light. #
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