Abstract: An optical system or apparatus whereby 3 identical optical trains or paths of light providing steropsis are obtained for surgery and other uses, and by which four (4) viewing stations with balanced light are achieved. Documentation devices and observers see the target or object area as viewed at these stations. The apparatus comprises a housing having a chamber divided into two communicable cavities at an obtuse angle to one another, with four viewing stations mounted on the housing having access to the chamber and cavities in which a network of prisms is located to provide redirection of light in a balanced manner to all four viewing stations. Light is introduced through an opening or a set of three ports on the base of the housing, and is channelled to the port stations by the network of prisms.

Abstract: A surgical instrument comprising a pair of co-axially assembled tubes having their distal walls in bearing relationship and with registrable openings extending through such distal end and annular walls correspondingly joined to their respective distal walls. The inner tube reversibly rotates within its matched outer tube in operation of the invention, as action by cutting edges formed about such openings severs tissue drawn into the inner tube by suction. Each distal end wall includes a pair of circular cutting edges, those in the inner tube having a straight cut across its thickness while those in the outer tube have a full radiused cut across its thickness. Full radiused cuts across the thicknesses of the annular walls of the inner and outer tubes are provided for arcuately-formed and parallel cutting edges forming the respective openings in these tubes in their annular walls. A method to form these openings by means of these cutting edges is disclosed.