Array illuminators based on diffractive optical elements

This paper is a presentation of array illuminators based on diffractive optical elements. Theses devices are among the most commonly used nowadays. Particular attention is paid to three of them: Dammann gratings and similar elements, Talbot illuminators and lenslet arrays. Although they are very close in terms of design and fabrication, they differ, by the diffraction regimes in which they operate. Therefore, we emphasize this peculiarity which results from the properties of the respective diffraction regimes and we show how the choice of an array illuminator is mainly dependent on the application requirements.