Patent ID: 7242521

Claim:
An optical head for coupling optical radiation to and from a sample, the optical head comprising: a) a first optical fiber emitting an input beam; b) a second optical fiber receiving an output beam; c) an input collimator receiving said input beam and providing a collimated input beam; d) an output collimator providing said output beam responsive to a collimated output beam; e) a focusing element comprising a parabolic mirror receiving said collimated input beam and providing a focused input beam, and providing said collimated output beam responsive to a focused output beam; and f) a window comprising a substantially spherical surface facing away from said sample, wherein a planar interface between said sample and said head is substantially index-matched, wherein said window substantially has rotational symmetry about an axis perpendicular to said interface; wherein said window receives said focused input beam and provides a confocal input beam to said sample, wherein said window provides said focused output beam responsive to a confocal output beam emitted from said sample, wherein said confocal input beam intersects with said confocal output beam at a target region in or on said sample; wherein said parabolic mirror is substantially rotationally symmetric about said axis; wherein said axis is substantially parallel to said collimated input beam; wherein said axis is substantially parallel to said collimated output beam.