Optical apparatus for combining light beam arrays having different wavelengths.

摘要

Optical apparatus for performing wavelength-dependent beam combination. The apparatus relies on a polarization beam splitter (11) in combination with other optical elements to develop combined beams with the same polarization type and that are therefore suitable for polarization-dependent combination with other beam arrays. A dichroic mirror (243), which is used as the wavelength-dependent element of the apparatus, is oriented such that the incident beams are substantially perpendicular to the mirror. With this orientation, the dichroic mirror achieves near-ideal performance even with beam arrays having a substantial angular field. The apparatus also uses two plates (244, 242) which, although designed for operation as quarter-wave plates at one of the two wavelengths being combined, are oriented with their respective fast axes substantially perpendicular to each other such that polarization conversions, effected by the plates on beams having the other of the two wavelengths, substantially cancel each other.