Abstract: A drill bit (20, 420, 520, 620, 720, 820, 920, 1020) is provided that includes a connector (32, 232, 532, 632, 732, 832, 932, 1032), which includes a shank (34), configured to receive torque; a proximal electrically-conductive coupler (36, 436, 536, 636, 736, 836, 936, 1036), which is disposed at a distal end (28) of the shank (34), rotationally fixed with respect to the shank (34); and a distal electrically-conductive coupler (38, 238, 438, 538, 838, 738, 838, 938, 1038). The distal electrically-conductive coupler is rotationally fixed with respect to the proximal electrically-conductive coupler, electrically isolated from the proximal electrically-conductive coupler, and shaped so as to define a distal-electrically-conductive external contact surface (62, 862, 962, 1062). The drill bit further includes a drill shaft (30, 130, 230, 330, 430, 830) including an electrically-conductive outer electrode (44) and an electrically-conductive inner electrode (46, 146, 246, 346, 846).

Abstract: A boresight module comprising a housing defining an optical axis and having a day optical window and a night optical window; a source of sensible radiation located along the optical axis; a collimator mounted in association with the housing operative to receive beams of radiation emitted by the radiation source and to reflect the beams parallel to the optical axis; and an optical assembly made from a single piece of material mounted within the housing and comprising first and second optical surfaces in respective optical association with the day and night optical windows and positioned so as to receive the reflected beams such that a first plurality of the beams is deflected by the first optical surface through the day optical window and a second plurality of the beams is deflected by the second optical surface through the night optical window.