Laser Monitoring System
EMAX-3100
User ManualLaser Monitoring System – EMAX-3100

Contents
1General Description

2

Safety Note

3Getting Started

4

Operation of Laser Monitoring System

54.1

EMAX-3100 TX Laser Transmitter set-up

4.2

EMAX-3100 RX Laser Receiver set-up

4.3

Optimize Audio Quality

4.3.1

Change Laser Power

4.3.2

Reduce Ambient Noises

4.3.3

Audio Filter

4.3.4

Choose Suitable Target Points

Using a Laptop as Monitor and Recorder
5.1 Video Monitor
5.2 Audio Playback and Recording
5.2.1

Audio Recording

5.2.2

Settings of the SR5 Software

5.3 Software Information6Cleaning

7Technical Data

8Appendix
8.1 Laser Transmitter EMAX-3100 -TX
8.2

Laser Receiver EMAX-3100 RX

8.3

Switch-On-Box

Laser Monitoring System – EMAX-3100

1 General Description
The Laser Monitoring System EMAX-3100 is specially designed for acoustic room monitoring.
This system is operated by transmitting an invisible laser beam to the window of the target room. Thewindow pane is slightly vibrating in accordance to the sound waves emanating from speech.
The angle of reflection will be slightly changed. The receiver picks up the reflected beam that ismodulated by the window pane vibrations. The positional change of the reflected beam will, of course,
also be detected. The picked up speech can now be monitored and recorded. The targeted distances
Range from 5 meters to 2000 meters.
The Laser Monitoring System consists of a laser transmitter EMAX-3100 TX and a laser receiver
EMAX-3100 RX. Both transmitter and receiver can be mounted on a gear head of a tripod.
The transmitter is supplied with a telescopic sight to aid adjustment of the laser beam. An IR-sensitive
B/W CCD camera is used for detection and adjustment of the reflected laser beam.
The audio signal, which is gained from the reflected laser beam, will be amplified and fed to an
adjustable headphone input and a line output respectively. High-pass and low-pass filters may be
used to improve audio quality.
Laser transmitter EMAX-3100 TX
Laser type
Wave length
Output power
Focal distanceEye piece
Search tone
Power supply
Power consumption
Dimensions
WeightSemiconductor laser
790 nm30 – 50 mW, internally regulated
f = 75 mm
Telescopic sight 4x15
Switchable
12 V DCca. 100 mA
280 x 100 x 54 mm
800 g

Laser receiver EMAX-3100-TX RX
Receiving unit
Lens
Connections
Audio filter
Sighting mechanism
Power supply
Power consumption
Dimensions
WeightPSD (optical band-pass filter)f = 75 mm
Headphones, line output
Low-pass and high-pass, adjustable
B/W camera (75 mm lens)
12 V DCca. 170 mA (with camera), 70 mA (cameraoff)
170 x 100 x 45 mm
900 g1

Laser Monitoring System – EMAX-3100

2 Safety note
According to the international standard IEC 6086325-1 / Edition 1.2 27001-08 .Safety oflaser products, the laser transmitter EMAX-3100-3100 TX is classified as Laser Device
Class 3B.

A safety zone of at least 20 m is compulsory! Do not direct the laser beam at persons or animals withinsafety zone! Special Safety Glasses are needed for operation.

3 Getting started
Mount both laser transmitter and laser receiver onto the gear heads of each tripod. Extend the center
column of the tripod by at least 10 cm. Bring transmitter and receiver into position.
•Make sure there is a line-of-sight between transmitter/receiver and window of the target room.

•The angle of incidence is equal to the angle of reflection. This applies to horizontal as well as
vertical level.

•A higher angle of incidence produces a higher angle of reflection. Detection of the reflectedbeam can thus be made more difficult.

After transmitter and receiver are brought into position, take the following steps•

Connect a video monitor and headphones to receiver•

Secure power supply for transmitter and receiver•Turn on camera switch on receiver

4 Operation of Laser Monitoring System
4.1

EMAX-3100 TX laser transmitter set-up
1. Direct laser transmitter at target (window) by means of the telescopic sight.
Large window panes may cause interferences through their natural vibration. You should
therefore choose the target point closer to the window frame.
2. Open aperture of transmitter lens (F1.8).
3. Adjust focus of transmitter lens. The value should be approximately the distance to target.

2Laser Monitoring System – EMAX-3100

4.2

EMAX-3100 RX laser receiver set-up
1. Adjust receiver by means of CCD camera so that the target point of the laser beam can beseen on the video monitor.
Adjust aperture and focus of camera lens to get an optimum image on the video monitor.
Successful adjustment is indicated by two light spots which can be seen on the monitor:
a. Target point of transmitted laser beamb. Target point of reflected laser beamReflectedlaser beamTransmitted
laser beam

Fig. 1: Target point of the laser beam

2. Fine-tune focus of transmitter lens until target point of transmitted laser beam can be seenclearly on video monitor.
3. Adjust the gear head of the laser transmitter so that the reflected laser beam meets the laser
receiver. Target points of both transmitted and reflected laser beam must be brought intosame position.
Use the video monitor as adjusting aid. Should you encounter an over modulated display on
your monitor which is caused by the reflected laser beam, the adjustment has beensuccessful.

3

Laser Monitoring System – EMAX-3100

Fig. 2: Successful adjustment

4. Mount the supplied video filter on lens of CCD camera.
5. Stop down lens of CCD camera and focus reflected laser beam through correction oftransmitter lens. Adjust focus until you can see an image of the reflected laser beam on yourvideo monitor which is very small. A clear light/dark boundary should be seen in the margin ofthe image.

Fig. 3: Focused laser beam

6. Turn on search tone generator of laser transmitter.
7. Open aperture of receiver lens (F1.8) and put focus into (∞) position.

4

Laser Monitoring System – EMAX-3100

8. Extend centre column of the receiver tripod until the receiver lens is within range of thereflected laser beam. Right height is reached as soon you can hear the search tone of thelaser transmitter via your headphones.
9. Turn off search tone generator of laser transmitter.
10. Aim for optimum audio quality by adjusting height, direction and slope of laser receiver.
11. Turn off CCD camera.

4.3

Optimize audio quality

Audio quality is dependent on several factors, e.g. small deformations of window panes or differencesin temperature within the line-of-sight of the laser beam may change the angle of reflection. The
following steps may be taken to optimize audio quality:

4.3.1 Change laser power
You can change laser power by adjusting the aperture of the transmitter lens. The smaller theaperture, the lower is the laser power.
In general, you should reduce the laser power as much as possible. A major criterion is still therequired volume of the audio signal.

4.3.2 Reduce ambient noises
Reflections and overmodulation of the optical sensor may interfere with the audio signal. Theseinterferences may be reduced by adjusting the aperture of the receiver lens.

4.3.3 Audio filter
Assessment of audio quality is very subjective and may vary from user to user. The audio amplifier ofthe laser receiver gives you the option to use and adjust high-pass and low-pass filters individually.

4.3.4 Choose suitable target points
Rain, may interfere with audio signals. You may reduce those interferences when choosing suitabletarget points. The adjustment of laser receivers, however, requires some experience and should
therefore be regularly trained.

5Laser Monitoring System – EMAX-3100

5 Using a laptop as monitor and recorderShould you wish for better ease of use, you may very well use a laptop as monitor and audio recorder.
Should you decide to use a laptop, it has to be connected to the laser receiver via the supplied switchon box. The switch-on box is equipped with a video grabber. The video grabber hast to be connectedto the laptop via USB.

5.1

Video monitor

Launch VLC media player by double-click the button. Select a recording device as follows:

1. Open Media/Open Capture Device…

Fig. 4: Open Capture Device
2. Select video device USB 2.0 Grabber
3. Select audio device None
4. Click the checkbox Show more options
5. Set Caching to 0 ms
6. Click [Play]6

Laser Monitoring System – EMAX-3100

Fig. 5: Select Capture Devices

7. After some seconds a video will be displayed.

7

Laser Monitoring System – EMAX-3100

5.2

Audio playback and recording

Use the SR5 Real Time Audio Filter & Spectrum Analyzer program for playback, editing andrecording of audio signals.
For setting the software please see 5.2.2 Settings of the SR5 software.

1. Launch SR5 by double-click the button
2. Start playback by clicking.

button3. Activate FFT filter by clicking

button (or F2)

4. Open filter window by clicking

button (or F7)

Fig. 6: Program window SR5

5. By dragging the mouse over the filter window, you may create random audio filters to optimise
the audio quality. You can reset all audio filters by right-clicking in the filter window andselecting the All Max function.

5.2.1 Audio recording
1. Select a file path and file name for your audio recording. Clickbutton.
The program will add date and time to the file name automatically.
2. Start recording by clicking

button.

3. Stop recording by clicking

button.

8

Laser Monitoring System – EMAX-3100

5.2.2 Settings of the SR5 software
To set the input and output audio devices open Tools/Setup Audio Devices.

Fig. 7: Setup Audio Devices SR5Select input devices as shown in the figure below. To set the output devices please select Auto.

Fig. 8: Select audio devices SR55.3

Software information

We have used open-source software which can be downloaded from the internet for free:• VLC media player
Download via
www.videolan.org/vlc• SR5 Real Time Audio Filter & Spectrum Analyzer
Download via
www.ar5.com

6 Cleaning
The system should be cleaned only with a damp cloth. Please do not use solvents!

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Laser Monitoring System – EMAX-3100

7 Technical Data
Laser transmitter EMAX-3100 TX
Laser typeWave length
Output power
Focal distanceEye piece
Search tone
Power supply
Power consumption
Dimensions
WeightSemiconductor laser
790 nm30 – 50 mW, internally regulated
f = 75 mm
Telescopic sight 4x15
Switchable
12 V DCca. 100 mA
280 x 100 x 54 mm
800 g

Laser receiver EMAX-3100 RX
Receiving unit
Lens
Connections
Audio filter
Sighting mechanism
Power supply
Power consumption
Dimensions
WeightScope of Delivery:

PSD (optical band-pass filter)f = 75 mm
Headphones, line output
Low-pass and high-pass, adjustable
B/W camera (75 mm lens)
12 V DCca. 170 mA (with camera), 70 mA (cameraoff)
170 x 100 x 45 mm
900 g

Laser transmitter EMAX-3100 TX
Laser receiver EMAXI-3100 RX
LaptopSwitch-on box
2 tripods incl. gearheads
2 Power supply units
User manual, transport box

10Laser Monitoring System – EMAX-3100

8 Appendix
8.1

Laser transmitter EMAX-3100 TX

13

2

1

2
3

LED Power supply
continuous:
operating voltage onflashing:operating voltage < 9 V
Connection – power supply
Switch – search tone generator

11

Laser Monitoring System – EMAX-3100

8.2

Laser receiver EMAX-3100 RX4568745678

Video output (monitor)
Switch - CCD camera
Line output (recorder)
Connection – power supply (or switch-on box)
Connection - headphones

12Laser Monitoring System – EMAX-3100

910910111213
1411 12

13

14

Low-pass control
High-pass control
LED power supply
continuous:
operating voltage on
flashing:
operating voltage < 9 V
Volume control
Overmodulation display (CLIP)
Amplifier control (GAIN)

13

Laser Monitoring System – EMAX-3100

8.3

Switch-on box

15161516
17181718Connection – laser receiverLine output (for PC microphone input)
Connection – power supplyUSB14