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In the present paper, a new method of selective image amplification using two photorefractive BaTiO3 crystals is proposed and the amplification characteristics of this method are investigated. The gain of beam amplification obtained using the proposed method is almost equal to the product of the gain obtained from each crystal. The rise time of the amplification output also changes when the signal beam power changes with time. The blurring of images caused by the amplification reveals a very small region. The images obtained using this method are more distinct than those obtained using single BaTiO3 crystals, and amplified images obtained by the selective image amplification are of high quality. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(7): 14–21, 2000 [ABSTRACT FROM AUTHOR]

Writing and reconstruction of holograms on the amorphous magnetic films have been studied and results of matched filtering of imagery by using the hologram filter have been reported. The resolving power of imagery on thin films of GdTbFe and TbFe is 1800 line pairs/mm. The minimum energy Ew for recording hologram on thin films of GdTbFe and TbFe is 100 mJ/cm² and 50 mJ/cm², respectively. Ew of TbFeCo and DyFe films is 3000 mJ/cm² and 20 mJ/cm², respectively. First order diffraction efficiency of all holograms is of the order of 10-5 ∼ 10-4 percent. Unknown patterns are recorded on the amorphous film as input imagery. Detection of a desired pattern has been made using the spatial matched filtering method that includes a Fourier transform hologram filter. When GdTbFe and TbFe films are used as the filters, correlation output can be detected through the matched filter with 20 dB signal-to-noise ratio. [ABSTRACT FROM AUTHOR]