| 摘要 |
<p>In order to cool an optical assembly made up of a lens and of at least one optically inactive transparent plate, a cooling gas is circulated, on the one hand, between the lens and the plate and, on the other hand, over the outer face of the plate. A gas (air, N2, He, Ar) at a temperature below room temperature, preferably between +20 DEG C and -80 DEG C, is employed for this purpose. The optical assembly is cooled in order to bring it to an equilibrium temperature before the energy beam, for example the laser beam, is sent through it; the instability due to the swelling of the lens is thus avoided.</p> |
