PURPOSE: To reduce the energy density and increase the life of a band narrowing element by specifying the laser beam entering the band narrowing element into either P waves or S waves by a deflecting prism, and further enlarging the laser beam by the deflecting prism prior to entering it into the band narrowing element.
CONSTITUTION: For a narrow band excimer laser, two sheets of etalons 3 functioning as a band narrowing element, a polarizing prism 4 functioning as a beam expander and a polarizer, a laser chamber 5, and a λ-quarter plate (λ) 6 as a compensating plate are arranged between a full reflecting mirror 1 and a full reflecting mirror 2. According to this constitution, energy density is lowered by putting the light, which passes the band narrowing element, into either polarizing component by the separation of the P waves and S waves by the polarizing prism 4. Moreover, by reciprocating it with a polarizer 6, the λ-quarter plate 4 functions the same as a λ-half plate, i.e., a polarization plane rotating equipment, whereby P waves are converted into S waves or S waves into P waves and are taken out of the resonator.
WAKABAYASHI OSAMU
KOBAYASHI YUKIO
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