CHU, H JHON, YM CHOI, SS PARK, DY 2024-01-21T20:36:25Z 2024-01-21T20:36:25Z 2021-09-02 1995-09 0021-4922 https://pubs.kist.re.kr/handle/201004/145011 A simple modification of the output coupler to a standard positive-branch confocal unstable resonator (PBUR) was proposed and the output characteristics were investigated and compared with those of the standard PBUR. We utilized a small convex mirror of 1.8 mm diameter as an output coupler in order to reduce the beam divergence and to eliminate the subsidiary spot caused by the Fresnel reflection effect in the standard PBUR. We obtained a single spot in the focal plane with a nearly diffraction-limited beam divergence of 0.09 mrad. English JAPAN J APPLIED PHYSICS SIMPLE MODIFICATION OF POSITIVE-BRANCH UNSTABLE RESONATOR FOR DIFFRACTION-LIMITED XECL LASER-BEAM Article 10.1143/JJAP.34.4799 1 JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS, v.34, no.9A, pp.4799 - 4802 JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 34 9A 4799 4802 scie scopus A1995RX26800037 2-s2.0-0029371415 Physics, Applied Physics Article STANDARD PBUR MODIFIED PBUR FRESNEL REFLECTION EFFECT DIFFRACTION-LIMITED BEAM DIVERGENCE SPOT SIZE