| 摘要 |
A line narrowing unit for use within an excimer or molecular fluorine laser resonator includes a dispersive prism having antireflection coatings on entrance and exit surfaces. Entrance and exit angles and an apex angle are increased to enhance the dispersive power of the prism, while the antireflective coatings limit reflective losses. Preferably, a laser beam makes a non-symmetric pass through said prism. The apex angle is preferably greater than 65°, or even 75°, and the angle of incidence and the exit angle of the beam are each preferably greater than 65°. A beam expanding prism configured for enhanced beam expansion has an apex angle between within a range of 37.5° and 42.5°, and a beam incidence angle at the entrance surface of more than 65°, and an antireflection coating on preferably both the entrance and exit surfaces.
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