An optical apparatus (110) includes a base member (121) with a plurality of grooves (181-187, 191-197), and includes a respective lens (11-17) fixedly mounted in each groove. Optical filters (31-35) are mounted on the support member in predetermined locations. One such lens is fixedly secured to an input optical fiber (21), and the input fiber is used to introduce radiation into the apparatus. Several output optical fibers (22-27) are successively positioned in relation to respective lenses by a fiber positioner (302), which monitors the amount of radiation passing through the fiber being positioned, and then causes a laser (303) to fuse the fiber end to the associated lens in a selected position.