Abstract:
A lithographic apparatus includes an alignment sensor configured to determine the position of an alignment target comprising a periodic structure. The alignment sensor includes a demultiplexer (700) to demultiplex a number of intensity channels (one of them shown to be output at fiber 702). The demultiplexer includes a number of stages arranged in series and a number of demultiplexing components (706, 708a,b, 710a-d,712a-h), each demultiplexing component being operable to divide an input radiation beam into two radiation beam portions. The first stage has a first demultiplexing component (706) that is arranged to receive as an input radiation beam an incident radiation beam. Each successive stage is arranged such that it has twice the number of demultiplexing components as a preceding stage, each demultiplexing component of each stage after the first stage receiving as an input one of the radiation beam portions output from a demultiplexing component of the preceding stage.
Abstract:
A measurement apparatus, including: a tapered optical fiber, the tapered optical fiber having an input to receive radiation and having an output to provide spectrally broadened output radiation toward a measurement target, the tapered optical fiber configured to spectrally broaden the radiation received at the input; and a detector system configured to receive a redirected portion of the output radiation from the measurement target.