M12 class 2 laser emitter, Alignment – Banner M12 Laser Emitters User Manual

Page 5

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P/N 52989 rev. C

M12 Class 2 Laser Emitter

Banner Engineering Corp.

•

Minneapolis, MN U.S.A.

www.bannerengineering.com • Tel: 763.544.3164

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.

In sharp contrast to conventional photoelectric emitters,
M12 laser emitters have a beam divergence of only 0.03°
(0.5 milliradians) at 25° C (77°F) ambient temperature (see
Figure 3). This translates, for example, to a beam diameter of
only 0.37" at a distance of 20'. Consequently, there is very little
forgiveness for angular misalignment.

The beam size listed in Figure 3 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 3.5 mm (0.14") diameter.

The effect of angular misalignment is dramatic (see Figure 4).
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 4 shows how far the laser beam will
miss the center of the receiver lens for each degree of angular
misalignment (in any plane). 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.
This mark is used 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 5). For greater
distances, use a larger sheet of retroreflective material (see
page 7).

Sensing Distance = X

Approx.

0.5mrad = 0.029

Approx. 2 mm

W = 2 mm + 2X(tan.0029

°) = 2 mm + X(0.001)

Laser Emitter

Sensing Distance = X

Ø = Misalignment Angle

Y = X(tan Ø)

Laser Emitter

Figure 4. Beam displacement per degree of misalignment

Opposed Distance (X)

Beam Width (W)

1.5 m (5')

5.0 mm (0.20")

3 m (10')

6.5 mm (0.26")

6 m (20')

9.5 mm (0.37")

15 m (50')

19 mm (0.75")

30 m (100')

34 mm (1.34")

Beam Displacement (Y)

for 1° of Misalignment

1.5 m (5')

25 mm (1")

3 m (10')

50 mm (2")

6 m (20')

100 mm (4")

15 m (50')

250 mm (10")

30 m (100')

500 mm (20")

Opposed Distance (X)

Figure 3. M12 laser emitter beam divergence at 25°C

(beam size vs. distance)

;;

Receiver

Target

M12

Figure 5. At long distances, use retroreflective tape to locate the

beam at the receiver location. Never use a mirror as an
alignment target.

LASER LIGHT - DO NOT STARE INTO BEAM CLASS 2 LASER PRODUCT

and EN60825-1:2001 except for deviations pursuant to laser notice No. 50, dated 7-26-01

Pulse Power< 2.8 mW, 650-670 nm, 33 kHz, 7

µS Pulse. Complies with 21 CFR 1040.10

10-30 VDC

(+ON, -OFF)

LASER

M126E2LD

Alignment

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