Banner L-GAGE LG10 Series - Manual (Page 2)

L-GAGE ™ Laser Gauging Sensor
page 2
L-GAGE Laser Gauging Sensor Overview
Banner’s Class 2 visible laser displacement sensor brings a sophisticated, yet cost-
effective solution to precision measurement applications. L-GAGE Series sensors
feature all-in-one design and require no separate controller.
Near and far sensing window limits are set quickly using simple push-button or
remote signal TEACH-mode programming. One sensor can simultaneously provide
both analog and discrete (switched) outputs. Sensing window limits for each output
may be independently programmed, if desired. The analog signal features Banner’s
unique scalable output (patent pending), which automatically distributes the 4 to 20
milliamp output signal over the width of the programmed sensing window. If an
analog voltage output is required, this can be accomplished by using an alternate
hookup. (See Hookups, page 5.)
The L-GAGE Laser Gauging Sensor boasts many additional features, including
selectable response speed, self-diagnostics with alarm output, comprehensive status
indicator system, and unique output “hold” function for momentary signal loss in
profiling applications.
Optical Triangulation
The design of the L-GAGE Laser Gauging Sensor is based on optical triangulation (see
figure 1). An emitter transmits visible laser light through a lens, toward a target. The
laser light beam from the emitter bounces off the target, scattering some of its light
through another lens to the sensor’s PSD (position-sensitive device) receiver element.
The target’s distance from the receiver determines the angle the light travels to the
receiver element; this angle in turn determines where the received light will fall along
the PSD receiver element.
The position of the light on the PSD receiver element is processed through analog
and digital electronics and analyzed by the microprocessor,
which calculates the appropriate output value. The analog
output provides a variable 4 to 20 milliamp current that is
proportional to the target’s position within the user-programmed
analog window limits (see page 8). The discrete (switched)
output energizes whenever the target is located between the
user-programmed discrete window limits. Analog and discrete
window limits may be the same, or programmed independently.
Signal
Conditioning
Circuitry
Microprocessor
Output
Circuitry
Emitter
Circuitry
Laser
Emitter
Lenses
Near
Limit
Target Movement
Programmed
Sensing Window
Far
Limit
PSD
Receiver
Element
E
R
Figure 1. Optical triangulation sensing system overview