Abstract: An apparatus includes a first support structure configured to support an element that has an alignment marker provided with at least one height difference. The apparatus also includes an alignment sensor comprising a light source that is configured to provide a light beam that illuminates the alignment marker; and at least one detector configured to detect the at least one height difference of the alignment marker by analyzing the light beam reflected by the alignment marker. Such an apparatus may be used to align of the element with respect to the first support structure.

Abstract: A lithographic apparatus equipped with an alignment system is presented herein. In one embodiment, the lithographic apparatus includes an illumination system that provides a beam of radiation, a patterning device that imparts the beam of radiation with a desired pattern in its cross-section and is supported by a support structure, a substrate holder that holds a substrate, a projection system that projects the patterned beam onto a target portion of the substrate, and a conditioned chamber. The apparatus also includes an actuator that introduces either the patterning device or the substrate into the conditioned chamber and an alignment system, which is disposed outside the conditioned chamber, that positions the patterning device or the substrate in alignment with the projected patterned beam of radiation.