Banner S18 Series - Manual (Page 2)

S186ELD Laser Diode Emitter
2
P/N 35749 rev. D
Banner Engineering Corp. • Minneapolis, MN U.S.A.
www.bannerengineering.com • Tel: 763.544.3164
Alignment
Conventional modulated infrared LED photoelectric emitters are designed with beam
divergence angles of several degrees. As a result, most emitters are easily aligned to their
receivers by simple line-of-sight methods.
The beam size listed in Figure 1 is also the effective beam size at the receiver. The effective
beam is equal to the minimum opaque object profile required to block the light beam. The
beam size at the emitter is 2.5 mm (0.1") diameter.
The effect of angular misalignment is dramatic (see Figure 2). The wide beam angles offered
by conventional photoelectric emitters allow several degrees of misalignment between the
optical axes of the emitter and receiver. This is not true for laser emitters which require their
beam center to directly strike the receiver lens. Figure 2 shows how far the laser beam will
miss the center of the receiver lens for each degree of angular misalignment. Note that even
at only a 5' range, one degree of misalignment will cause the laser beam to miss the lens of
most receivers.
Alignment Tip: The visible red beam of the laser emitter is easily seen in subdued lighting. At
opposed distances of up to 10', attach a sheet of white paper directly in front of the receiver
lens. Mark the location of the lens center on the paper; use the mark as an aiming target.
Sight along the beam from directly behind the laser emitter. Adjust the emitter mounting until
the red image (the dot of red light) is centered exactly on the mark. Remove the paper and
check the response of the receiver.
For longer distances (up to 25'), replace the white paper with a 4" x 4" square of high-grade
retroreflective tape (Banner model BRT-THG-4X4-5 or equivalent; see Figure 3). For greater
distances, use a larger sheet of retroreflective material (see page 4).
Description of Class 1 Lasers
Class 1
Lasers that are safe under reasonably foreseeable
conditions of operation, including the use of optical
instruments for intrabeam viewing.
Reference 60825-1 Amend. 2 © IEC:2001(E), section
8.2.
Class 1 Laser Characteristics:
Wavelength = 650 nm
Pulse Power ≤ 1 milliwatt
Pulse Width = 7 microseconds
Rep Rate = 30 microseconds
Figure 2. Beam displacement per degree of
misalignment
Figure 1. Laser emitter beam divergence at
25° C (beam size vs. distance)
Receiver
Target
Laser Emitter
Figure 3. At long distances, use
retroreflective tape to locate the
beam at the receiver location.
Sensing Distance = X
Approx.
0.5mrad = 0.029°
Approx. 2.5 mm
W = 2.5 mm + 2X(tan.0029º) = 2.5 mm + X(0.001)
W
Laser Emitter
Opposed
Distance (X)
Beam
Width (W)
1.5 m (5') 4 mm (0.2")
3 m (10') 5.5 mm (0.2")
6 m (20') 8.5 mm (0.3")
15 m (50') 18 mm (0.7")
30 m (100') 32 mm (1.3")
Sensing Distance = X
Ø = Misalignment Angle
Y = X(tan Ø)
Laser Emitter Y
Opposed
Distance (X)
Beam
Displacement (Y)
for 1° of
Misalignment
1.5 m (5') 4 mm (0.2")
3 m (10') 50 mm (2")
6 m (20') 100 mm (4")
15 m (50') 250 mm (10")
30 m (100') 500 mm (20")
NOTE: Never use a mirror as
an alignment target.
CAUTION . . .
Never stare directly into the emitter lens.
Laser light can damage your eyes. Avoid placing
any mirror-like object in the beam. Never use a
mirror as a target. (See Figure 3.)