Abstract: In an apparatus for manipulating laser beams with mirrors, the beam is caused to emerge substantially in alignment with the initial direction of the incoming beam by deflecting the incoming beam with a first mirror whose position is selectively adjustable to a second mirror which preferably has a parabolic surface, and then from the second mirror the beam is directed to a third, flat mirror whose position is also adjustable so that the beam is focussed on the region to be treated in a position substantially in alignment with the initial direction of propagation. An improved system for supplying screening gas to the region under treatment is also disclosed.

Abstract: The optical device is preferably used for a telescope, and has a pair of reflectors attached to a front end of a cylindrical section, so that objects can be searched or traced. The optical device has a first reflector provided in front of an object lens, which is provided at a front end of a rotatable cylindrical section. The first reflector reflects the light in a direction perpendicular to the optical axis of the object lens. A second reflector provided is close to the first reflector and the second reflector reflects the reflected light from the first reflector in parallel to the optical axis of the object lens. The first reflector can be rotated in a plane which is positioned between the first reflector and the second reflector and which is perpendicular to the optical axis of the object lens, and the second reflector can be independently rotated on the optical axis thereof.