Patent DE-102012111090-A1 (DE)
Title: Device, useful for changing length of optical path of beam bundle, comprises entrance and exit planes, optical path, rotatable mirrors, and control device, where length of path is adjusted by changing angle of rotation of mirror
Inventor: PETSCHIK NORBERT
IPC: B23K26/06
Filed: 2012-11-19
Abstract: The device comprises an entrance plane (30) occurring on an incident or an incident beam in the device, an exit plane through which the radiation beam of the device fails or turns, an optical path defined between the entrance plane and the exit plane, first (10) and second rotatable mirrors rotated about their pivot axes to a first and second angles and disposed in the optical path, and a control device. A length of the optical path is adjusted by changing an angle of rotation of at the mirror. The beam as a whole is reflected twice in the optical path to the rotating mirror or mirrors. The device comprises an entrance plane (30) occurring on an incident or an incident beam in the device, an exit plane through which the radiation beam of the device fails or turns, an optical path defined between the entrance plane and the exit plane, first (10) and second rotatable mirrors rotated about their pivot axes to a first and second angles and disposed in the optical path, and a control device. A length of the optical path is adjusted by changing an angle of rotation of the mirror. The beam as a whole is reflected twice in the optical path to the rotating mirror or turning mirrors. A propagation of the beam is described by a main beam. The main beam in a distance transversely to the axis of rotation impinges on the rotating mirror, and a position of the beam the exit plane is independent of the length of the optical path. The control device is configured so that the angle of rotation of the rotating mirror is set in a targeted manner and is selectable according to control information. The device further comprises a deflection device adapted and arranged to deflect or distract the beam, a reflector unit, which is arranged in the optical path so that the beam incident on the reflector unit comes in a direction, which is parallel to the direction of the incident beam, which fails or turns from the reflector unit, a beam splitter, a third rotatable mirror (60), a fourth rotatable mirror, and a first (45) and/or a second optical system (50) arranged in the beam path. The optical path is arranged such that a beam from the entry plane is applied onto the rotary mirror, the deflection device, and the reflector unit before the beam reaches to the exit plane. The rotating mirror is adapted and arranged to receive the beams of the deflection device as a function of the first angle performed at different positions. The length of the optical path depends on the first angle. The direction and the position of the beam at the exit plane are constant and independent of the length of the beam path. The beam splitter is arranged in the beam path such that impinging beam spaced from the reflector unit and the exit plane is separated from the entry plane and the reflector unit. The reflector unit is formed as a retro-reflector device adapted and arranged such that the beams are incident to the retro-reflector device. A first axis of rotation is present at a distance from the first rotating mirror, and a second axis of rotation is present at a distance from the second turning mirror. The third rotating mirror is rotated about a third axis of rotation by a third angle, and the fourth rotatable mirror is rotated to a fourth axis of rotation by a fourth angle. The control device is further adapted to adjust the third angle of rotation and the fourth rotational angle so that the beam coming from the second rotating mirror fails, is incident on the third rotating mirror and is diverted to the fourth mirror, so that the direction of the beam and constant position of the fourth mirror are constant. The first axis of rotation and the second axis of rotation coincide to each other, and form a common first double-rotational axis. The first and second mirrors are synchronized with each other so that an amount of the first angle corresponds to an amount of the second angle. The third axis of rotation and the fourth axis of rotation coincide to each other, and form a common second double axis of rotation. The third and fourth mirrors are synchronized with each other for rotation so that an amount of the third angle corresponds to an amount of the fourth angle. The first double-rotational axis is spaced apart from the second double-rotational axis of rotation. The beam bundle from the direction of the entrance plane is incident in a first direction of the beam splitter and in the second direction to the first rotating mirror. The beam incident on the first reflecting mirror is reflected back from the first reflecting mirror. Surface normal of the first, second, third and fourth rotating mirrors is perpendicular to the direction of the first, second, third and fourth axes of rotation respectively. The axes of rotation are parallel to each other. The first and/or second optical system is adapted to change divergence of the beam. A cross-sectional diameter of the beam has a minimum value assumed in a region located along the beam path in which the main beam has maximum distance across the axis of rotation of the mirrors and/or the beam path lies in a midway between the first turning mirror on the entrance plane and the last rotary mirror to the exit plane. Independent claims are included for: (1) a focusing device; (2) a beam position and beam divergence-changing device; and (3) a method for controlling a device for changing a length of an optical path.