BRT-51X51BM BANNER ENGINEERING, BRT-51X51BM Datasheet - Page 2

• Manufacturer Part Number: BRT-51X51BM
• Description: Reflector
• Manufacturer: BANNER ENGINEERING

Specifications of BRT-51X51BM

• Reflector Type: Square Acrylic Target
• Accessory Type: Reflector
• For Use With: Retroreflective Laser Sensor

WORLD BEAM
Conventional retroreflective photoelectric sensors are extremely easy to align. Beam angles
are wide, and retro targets are forgiving to the light beam’s angle of incidence. The beam of
this laser sensor is very narrow, compared with the beam of most retro sensors. As Figure 2
indicates, the effect of angular misalignment can be dramatic. Alignment is critical because the
beam may miss the retroreflective target unless the target is large.
For example, with one BRT-51X51BM mounted at a distance of 6 m (20') from the sensor, one
degree of angular misalignment will cause the center of the laser beam to miss the center of
the target by 100 mm (4").
Alignment Tip
When using a small retroreflective target at medium or long range, it is often useful to
temporarily attach (or suspend) a strip of retroreflective tape (e.g., BRT-THG-2) along a line
that intersects the actual target. The visible red laser beam is easily seen in normal room
lighting on such tape. Sight along the beam toward the target (from behind the sensor). Move
the sensor to sweep the laser beam back and forth across the retro tape strip. Use the tape
strip to guide the beam onto the target.
Consider using sensor mounting bracket model SMB18SF or SMB3018SC (see page 5). A swivel
bracket can simplify multiple-axis alignment. Alignment is complete when the visible image is
centered on the retro target. The perpendicularity of the laser beam to the face of the retro
target is forgiving, just as it is with a conventional retroreflective sensor.
Effective Beam Size
Unlike conventional retroreflective sensors, the retroreflective laser has the ability to sense
relatively small profiles. Figure 3 indicates the diameter of the smallest opaque rod which will
reliably break the laser beam at several sensor-to-object distances. These minimum object
sizes were measured with the sensor aligned to a BRT-51X51BM reflector and with the sensor
set for an excess gain of about 10X. Flooding effects are possible when the gain is much
higher. This means that sensor gain may have to be reduced in some situations in order to
reliably detect these minimum object sizes.
Note that the shape of the beam is elliptical. The minimum object sizes listed assume passage
of the rod across the major diameter of the ellipse (worst case). It may be possible to detect
objects smaller than the sizes listed if the direction in which the objects pass through the
beam can be controlled.
Retroreflector Recommendations
• BRT-51X51BM recommended for beam-block applications up to 10 m range.
• B RT-TVHG-2X2 recommended for applications up to 1.5 m range. (This retroreflector is an
Both reflectors are included with the sensor. See page 6 for information about ordering
replacements or other reflector options.
NOTE: W hen sensing objects with specular reflections, use the sensor’s side-mounting option
2
adhesive-backed sealed tape with micro-prism geometry.)
mirror-like object in the beam. Never use a mirror as a retroreflective target.
P/N 118900 rev. C
to optimize sensing performance.
CAUTION . . .
Never stare directly into the sensor lens. Laser light can damage your eyes. Avoid placing any
®
QS18LLP Series -
Installation Notes
Polarized Retroreflective Laser Sensors
Banner Engineering Corp. • Minneapolis, MN U.S.A
www.bannerengineering.com • Tel: [phone]
Figure 1. Sensor features
Figure 2. Beam displacement per degree of
Figure 3. Minimum object detection size vs.
Sensor to Object
Distance from
Distance (X)
Sensor-to-
10 m (33')
10 m (33')
1.5 m (5')
0.3 m (1')
1.5 m (5')
3 m (10')
6 m (20')
3 m (10')
6 m (20')
Single-turn
Sensitivity
Adjustment
Target
misalignment
distance from sensor
Y = X(tan Ø)
Green
LED
Ø = Misalignment Angle
Beam Displacement (Y)
for 1° of Misalignment
Minimum Object
Detection Size
2.5 mm (0.10")
5.0 mm (0.20")
6.5 mm (0.26")
100 mm (4")
150 mm (6")
10 mm (0.40")
13 mm (0.52")
25 mm (1")
50 mm (2")
Sensing Distance = X
Yellow
LED
Y