| (11) | EP 0 231 050 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Unstable laser resonator with output coupler having radially variable reflectivity |
(57) The resonator has an output coupler (2) represented by a pair of mirrors (9),(10) separated by an appropriate distance and with facing reflecting surfaces of differing curvature. The distance between the surfaces (D')(D'') and their curvatures (R'),(R'') are such as to dephase the laser rays reflected by the second mirror in a different manner at the centre and at the periphery of the coupler in relation to those reflected by the first mirror. |