Thermomagnetic writing characteristics of holograms on amorphous magnetic films and application to optical matched filtering

Abstract

AbstractWriting 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 holograms 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.