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Section 1  Preparing to Build
6.6 Laser Systems
The laser has been integrated into the
building industry. Manufacturers have been
able to produce low-power, visible lasers in
small, inexpensive units. Using various names—
laser plane, construction laser, laser transit, or
simply laser level—the operating principle of
the various units is essentially the same. They
perform most of the functions of a conventional
transit. However, they need only one person
to carry out any layout operation. Some are
designed to rotate 360°, allowing the operator
to establish level lines throughout the structure
without moving the instrument.
Safety Note
For safety, power output of the laser is
controlled. Federal regulations limit Class II
construction lasers to 1 milliwatt and Class IIIa
units to less than 5 milliwatts. These levels are
safe for the eyes so long as the user does not
stare into the beam. Manufacturer’s cautions
should be carefully observed.
A laser level can be set to emit a laser beam for
a full 360°withoutbeingtendedbyaninstrument
person. Figure 6-24 shows the laser transmitter
and its receiver. During use, the transmitter is
untended. The receiver can be tended by a rod
Figure 6-24. Laser level and receiver. The transmitter
is at the right and the receiver is at the left. (Spectra-
Physics Laserplane, Inc.)
Laser level:  Leveling instrument that emits a level
laser beam over 360°without being attended. A receiver
attached to a rod and attended by a rod holder makes a
sound when the laser beam strikes it.
C
B
A
Figure 6-22. A transit can be used to lay out or check
points in a vertical plane.
90°
Figure 6-23. Using the transit to plumb an object. First,
align the vertical crosshair with the base. Then, swing
the telescope to or near the top. Adjust the object for
plumb as needed. Reposition the instrument at a 90°
angle to the first line and repeat the process.