Abstract: A fixture for use in adjusting a laser type leveling instrument has a cradle mounted on a base and operative to support the instrument with its normally vertical axis disposed horizontally. A pentaprism is mounted on a rotable platform on the base to reflect a laser beam, emitted by an instrument in the cradle and impinging on the pentaprism, in a horizontal path. The rotatable platform for the pentaprism permits movement of the pentaprism from a first position in which the beam is directed forwardly and a second position in which the beam is reversed and reflected rearwardly.

Abstract: The laser beam level instrument includes a laser diode mounted on a pendulous platform suspended from a frame by gold plated Mylar strips which also serve as conductors for supplying power to the diode. The strips are mounted with a 180 degree twist to overcome resistance to flexing/bending so that the platform moves freely under the influence of gravity to provide automatic self-leveling. The diode operates on low d.c. voltage but if d.c. is applied to the strips the magnetic field around the Mylar strips will have sufficient force relative to the geomagnetic field to interfere with free pendulation. So 4.5 volts d.c. is stepped up and inverted to about 20 volts a.c. to avoid interference with the geomagnetic field and to reduce power loss across the gold plated strips. The a.c. voltage is then stepped down and converted back to d.c. voltage (2-3 volts) on the platform to power the diode.