Figure 12-6.—Rotating laser level.
such as temperature and atmospheric pressure that
the built-in atmospheric correction system needs, and
by proper manipulation of the instrument controls,
the operator can obtain horizontal angles, vertical
angles, slope distances, horizontal distances, relative
elevation, and coordinates of an unknown point. The
data obtained is displayed through a liquid crystal
display and can be transmitted and stored in a
separate
data
collector.
Complete
operating
instructions are provided with the tacheometer.
LASER EQUIPMENT
Laser light is of a single color, the light waves
are in step with each other, and the light beam
spreads only slightly as the distance from the light
generator
to
the
target
increases.
These
characteristics make the laser useful for surveying
equipment used in various types of construction
layout. Although a wide variety of special-purpose
laser instruments are manufactured, most of these
have been designed for construction layout and are
classified into two general groups as follows:
1. Single-beam laser alignment instruments.
These instruments project a single beam of light that
is visible on targets under all lighting conditions.
Included in this group are laser equipped theodolites
and transits, and lasers used for alignment of pipes,
drains, and tunneling equipment.
2. Rotating laser levels. These are instruments
in which the laser beam is rotated by rapidly
spinning optics to provide a reference plane in space
over open areas.
SINGLE-BEAM LASER
ALIGNMENT INSTRUMENTS
A
typical
single-beam
laser
alignment
instrument can be mounted on a transit-like
framework with horizontal and vertical motions, a
spirit level that is parallel to the axis of the laser, and
both vertical and horizontal circles. A telescope is
attached to the laser housing to allow the operator to
sight the location of the transmitted laser spot. A
separate fanning lens, when attached, allows the
laser beam to be converted to a horizontal or vertical
line instead of a spot.
ROTATING LASER LEVEL
A self-leveling, rotating laser is shown in figure
12-6. In this instrument, the laser unit is mounted
vertically on a platform containing two orthogonally
mounted sensors that act like spirit levels and deviate
from center when the platform is not level. The
amount of deviation is detected electronically, and the
12-6
