Abstract: A lithographic apparatus is provided that has a sensor at substrate level, the sensor including a radiation receiver, a transmissive plate supporting the radiation receiver, and a radiation detector, wherein the sensor is arranged to avoid loss of radiation between the radiation receiver and a final element of the radiation detector.

Abstract: A lithographic apparatus includes an illumination system configured to condition a radiation beam; a support constructed to support a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam; a substrate table constructed to hold a substrate; a projection system configured to project the patterned radiation beam onto a target portion of the substrate; and a detector for measuring the intensity of the radiation after it has passed through the projection system. The apparatus further includes a polarization changing element, such as a quarter-wave plate, that is adjustable; and a polarization analyzer, such as a linear polarizer, wherein the polarization changing element and the polarization analyzer are arranged in order in the radiation beam path at the level at which a patterning device would be held by the support.