Patent ID: 7326948
Filing Date: 2008-02-05
Classification: G03F

Abstract:
1. A beam modifying device configured to receive an input radiation beam along a first optical axis, and configured to emit an output radiation beam having a cross-section along a second optical axis, the beam modifying device comprising: a divider disposed along the first optical axis and configured to divide the incoming radiation beam into a first part and a second part, the divider being configured to direct the first part along the second optical axis and to direct the second part via a delay path; and optics forming the delay path, the optics being configured to receive the second part and to direct the second part via the delay path and then along the second optical axis, wherein the optics are arranged to mirror the second part such that the second part is mirrored with respect to the first part about an axis of symmetry within the outer boundary of the cross-section of the output radiation beam, and wherein the divider comprises a first splitter and a second splitter, the first splitter arranged at a first angle to the first optical axis and the second splitter arranged at second angle to the first optical axis that is different from the first angle, the first splitter being configured to divide a portion of the incoming radiation beam into said first part and said second part, and the second splitter being configured to divide a remaining portion of the incoming radiation beam into a third part and a fourth part, the first splitter and the second splitter being configured to direct the first and third part along the second optical axis, said optics being arranged to form a first delay path and a second delay path, the first splitter being configured to direct the second part along the first delay path to the second splitter, and the second splitter being configured to direct the fourth part along the second delay path to the first splitter.