Lithographic apparatus and device manufacturing method utilizing a multiple dictionary compression method for FPD

A lithographic apparatus, comprising:

• an array of individually controllable elements that modulate a beam of radiation;
• a compressed pattern memory that stores a compressed representation of a requested dose pattern to be formed on a substrate by the modulated beam;
• and
• a dictionary decompressor that at least partially decompresses the compressed representation, wherein the dictionary decompressor comprises
• a first dictionary memory that is an external dictionary memory,
• a first dictionary decoder that at least partially decompresses at least a part of the compressed representation by extracting, from the first dictionary memory, portions of pattern data corresponding to references to the first dictionary memory contained in the compressed representation, and
• a second dictionary decoder, having an internal dictionary memory, that at least partially decompresses at least a part of the compressed representation by extracting, from the internal dictionary memory, portions of pattern data corresponding to references to the internal dictionary memory contained in the compressed representation,
• wherein the requested dose pattern comprises two groups of repeating pattern features;
• and
• the dictionary decompressor is configured so that:
• the external dictionary memory stores pattern data corresponding to a first of the groups, and
• the internal dictionary memory stores pattern data corresponding to a second of the groups, wherein the repeating pattern features in the first group are larger than the repeating pattern features in the second group.