Cut Sheet

Sensing Distance = X
Ø = Misalignment Angle
Y = X(tan Ø)
Y
Figure 3. Beam Displacement per degree of misalignment
Sensor-to-Target
Distance (X)
Beam Displacement (Y)
for 1º of Misalignment
1.5 m (5 ft) 25 mm (1 in)
3 m (10 ft) 50 mm (2 in)
6 m (20 ft) 100 mm (4 in)
15 m (50 ft) 250 mm (10 in)
30 m (100 ft) 500 mm (20 in)
For example, with one BRT-51X51BM mounted at a distance of 6 m (20 ft) 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 in).
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 (for example, BRT-TVHG-2X2) 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 scan 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 SMB30SC (see Brackets on page 11). This 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
7 indicates the diameter of the smallest opaque rod which will reliably break the laser beam at several sensor-to-object
distances using sensor model QS30LLP(Q). These minimum object sizes were measured with the sensor aligned to a
BRT-51X51BM reflector and the gain set to maximum using the Max Excess Gain SET. This sensor is typically
recommended for long-range applications of relatively small targets that will completely break the beam.
Sensor-to-Object
Distance (X)
Minimum Object
Detection Size
0.3 m (1 ft) 2.5 mm (0.10 in)
1.5 m (5 ft) 5.0 mm (0.20 in)
3 m (10 ft) 7.0 mm (0.28 in)
18 m (59 ft) 13 mm (0.52 in)
Figure 4. Minimum object detection size vs.
distance from sensor, model QS30LLP(Q)
Smaller objects can be detected by using model QS30LLPC(Q),
adjusting the sensor gain down using the Manual Adjust, or performing
a Low-Contrast SET of the reflector. Objects as small as 2.0 mm can be
reliably detected after performing the Low-Contrast SET at ranges up
to 6 m (18 ft). This sensor is typically recommended for shorter-range
applications detecting very small targets that may break only a portion
of the beam.
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 18 m range.
• BRT-TVHG-2X2 recommended for applications up to 2 m range. (This retroreflector is an adhesive-backed sealed
tape with micro-prism geometry.)
WORLD-BEAM QS30 LLP and LLPC
P/N 112355 Rev. E www.bannerengineering.com - Tel: [phone]