Multiple-Axis Crosshairs
Three skewed lines provide alignment when viewed along each of three mutually orthogonal axes. Device viewed in either direction along given axis, provides for viewing from any of six directions perpendicular to faces of cube. Location of common or target point can be "empty"; no part of any crosshair has to pass through target point. Simpler and more compact than previous sets of crosshairs, device also more accurate and reliable because same wire defines same plane from two different directions.
Barns, Chris↗