Self-leveling construction alignment laser

A system for projecting and utilizing a light beam as a reference line for laying conduit comprising:

• a light beam projecting device mounted in a housing having an opening in the front thereof to allow the projection of a beam of light therefrom;
• light compensator means within said housing for intercepting said beam of light and automatically correcting slight deviations of the light beam from true horizontal, said compensator having a liquid-air interface remaining parallel to true horizontal to provide compensation,
• means for supporting said light beam projecting device within a conduit,
• means for adjusting said light beam projecting device relative to said support means in a vertical and horizontal plane whereby said light beam emitted from said light beam projecting device may be adjusted to track a predetermined path within said conduit,
• electrically operated means connected between said support means and said light beam projecting device for rotating said projecting device in a horizontal plane thereby providing for azimuthal adjustment of said light beam projected therefrom, and
• a manually operated mechanical override operable from the rear of said housing to provide for manual horizontal rotation of said projecting device relative to said support means.

A system for projecting and utilizing a light beam as a reference line for laying conduit comprising:

• a light beam projecting device for projecting the reference beam of light,
• structure associated with said light projecting device for positioning said light beam projecting device within said conduit in the vertical plane passing through the center line of said conduit and parallel to the center line of the conduit,
• means controllable from the rear of said housing for deflecting said light beam in a vertical plane to vary the grade of said beam projected by said device,
• an indicator readable from the rear of said housing for indicating the grade at which said light beam is projected,
• electrically operated means connected between said centering structure and said projecting device for rotating said device in a horizontal plane thereby providing for azimuth adjustment of said light beam projected therefrom, and
• a manually operated mechanical override operable from the rear of said device to provide for manual horizontal rotation of said device relative to said centering structure.

A method for projecting a light beam as a reference line for laying conduit, comprising the steps of:

• inserting into an existing conduit a light projecting device having a front vertically adjustable leg and horizontally pivotable and vertically adjustable side legs,
• adjusting the font leg to position the front of the device on the longitudinal axis of said conduit,
• pivoting the side legs through equal angles to center the rear of the light projecting device in said conduit,
• vertically adjusting the rear legs to level the light projecting device, and
• deflecting said light beam emitted from the light projecting device through a vertical angle to establish a reference line beam in the vertical plane through said existing conduit and at the chosen vertical angle.