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The paper describes the method of HOE fabrication using direct exposure-controlled e-beam writing of binary and multilevel phase reliefs in a resist layer. Beamsplitters with diffraction efficiency of over 70 % have been made using this technique. INTRODUCTIONThe computer simulation gives the relationship between beamsplitter performance parameters and the necessary fabrication accuracy [1]. According to the computations, the most critical requirement in achieving the smallest variation of output beam intensities is the exactness of the phase relief depth [2,3]. The depth value should be accurate to im over the whole beamsplitter aperture to provide the intensity variations of no greater than Actually, the average departure of the relief depth from the computed value should not exceed tim. FABRICATION OF BINARY ELEMENTS.The substrates we use are 25x25 mm thermostable glass plates 1.5 mm thick. The plate surface roughness Rz is 0.05, and the flatness is no greater than half an interference ring. An anti-reflection MgF2 layer is evaporated on one of the plate surfaces. An electron-sensitive resist layer is centrifugally deposited on the other. The resist is dried in a infrared dryer. We apply a short-term increase of temperature at the end of the dry to make the resist surface smoother. Fig. 1 gives the transmission spectra of an uncoated glass substrate (1), one-sidedly coated substrate (2), and the substrate with a resist layer (3). At 0.532 tm the transmittance ofthe resist-coated sample is 93.5 %, which is quite acceptable for most applications. T%-----% 92 91 90 89 87 86 -ii --

Different rules for weighting input vectors in high-order associative memory models are considered. Numerical simulation results are given showing the advantage of the pattern weighting in recognizing high-correlated patterns. An optoelectronic implementation of the inner-product associative memory with weighting method is presented.

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