Synrad p250, Руководство пользователя, Страница: 35 / 106

LASER DESIGN PAGE | 35
Converting the laser polarization from linear to circularly polarized light gives uniform cut quality in both
axes. Circularly polarized light can be generated without significant power loss by using a circular
polarizer (also known as a cut quality enhancer or CQE) or a simple phase retarding mirror. For the
simplest and most cost-effective solution, a reflective phase retarder, laser polarization must be rotated
by 45°.
The p250 is horizontally polarized at the faceplate. Rotating the polarization is usually done by mounting
the laser at 45° to the horizontal or by using two or more mirrors. A CQE typically incorporates the
turning mirrors and phase retarder into one housing.
Beam conditioning
The p250 laser incorporates a novel beam conditioning system that first converts the beam to a circular
profile, cleans up the beam to remove side lobes and improve beam quality. To do this, the laser beam
exits the resonator and is turned back on itself through a front folding block that directs the beam into a
cylindrical lens. The lens converts the beam into a round beam which is then focused by a spherical
focusing mirror through a water-cooled aperture (to remove any side lobes) and then onto another
spherical mirror that collimates the beam.
Figure 4-3 Converting 45° linear polarization to circular polarization.
*
*(Original p250 Operation Manual Version 1 illustration courtesy of II-VI inc.). p250 Output Beam is
Linearly Polarized parallel in respect to the Baseplate. The polarization must be rotated by 45° before
hitting the phase retarder.