Starting　with　the　numerical　calculation　of　the　Fourier　spectrum　of　the　orthogonal　phase-coded　beam,　a　fundamental　study　on　hybrid　phase-coding　and　spatial　multiplexing　shows　that　there　will　be　a　complex　and　serious　fluctuation　in　both　intensity　and　phase　distribution　in　the　reference　beam　if　a　Fourier　transform　configuration　is　used　for　setting　up　the　reference　beam.　In　order　to　maintain　phase-only　modulation　and　orthogonality　in　the　reference　beam　pattern,　we　suggest　that　the　phase　modulator　should　be　imaged　to　the　recording　plane.