A lithographic projection apparatus is disclosed. The apparatus includes an illuminator for conditioning a beam of radiation, and an article holder. The article holder includes a plurality of protrusions arranged to provide a substantially flat plane of support for supporting an article to be placed in a beam path of the beam of radiation. The protrusions are generally spaced apart equidistantly at a first distance. The article holder also includes a pair of electrodes for clamping the article to the holder. The electrodes are disposed in substantially the same plane above or below the protrusions, and are spaced apart from one another by a gap. Neighboring protrusions within the plurality of protrusions that are located on opposite sides of the gap are spaced apart by a second distance that is greater than the first distance.