A VCSEL array has VCSELs on a semiconductor substrate and has a prismatic or Fresnel optical structure, which is arranged to transform laser light to provide a continuous illumination pattern in a reference plane. The optical structure increases a size of the illumination pattern in comparison to an untransformed illumination pattern. The optical structure is arranged such that each VCSEL illuminates a sector of the pattern. Sub-surfaces of the optical structure with different height above the semiconductor substrate are arranged next to each other. Each VCSEL is associated with a sub-surface. A distance between each VCSEL and a size of its sub-surface is arranged such that the VCSEL illuminates only a part of the sub-surface without illuminating one of the steps. The VCSEL array has an array of microlenses, each VCSEL being associated with a microlens arranged to collimate the laser light after traversing the optical structure.