The diffraction characteristics of random binary-amplitude diffracting
screens are investigated. It is shown that, for such a random diffrac
ting screen with complex amplitude transmittance t equal to either 0 o
r 1, the diffraction efficiency of the screen is maximized when 50% of
the screen has transmittance t = 1, independent of other characterist
ics of the screen. The maximum diffraction efficiency equals 1/4. For
this result to hold the screen must be adequately modeled by a station
ary binary random process.