Computer generated diffractive optical elements, known as 'focusators'
, provide very complicated focal intensity distributions. The manufact
ure of such elements is very expensive and must be preceded by compute
r simulation of their performance. A computational experiment, with la
ser beam focusators focusing into a segment, is described in this pape
r. Estimations of power efficiency and focal line quality for various
focusator phase functions are obtained. Different methods of focusator
synthesis are analysed.