LTB MNL Series User manual

Manual
Nitrogen Laser MNL
July 2004
LTB Lasertechnik Berlin GmbH •Rudower Chaussee 29 •D-12489 Berlin
Tel.: [phone] •Fax: [phone]
E-mail: [email protected] •http://www.ltb-berlin.de

Device manual MNL 200 1
D
De ea ar r c cu us st to om me er rs s
With the purchase of a laser from the MNL series, you
have selected a state-of-the-art Nitrogen laser.
The laser satisfies sophisticated needs and demanding
goals in various applications within the industrial area.
The following properties reveal the advantages of the
MNL.
• High pulse power
• Minimal beam divergence
• Minimal time jitter
• Pulse halfwidths in the sub-nanosecond range
• Long life
• Low costs
These properties make the laser attractive for
applications where high quality, stable output and cost-
effectiveness are required.
The MNL is used in optical spectroscopy, micro-
structuring, calibration of fast sensors and contactless
quality control of thin layers as well as in certain
applications within the environmental and
biotechnological areas.
The laser operates on the principle of transversal
excitement at atmospheric pressure (TEA laser). The
energy is stored in a decoupled capacitor/strip conductor
arrangement at about 10kV. The laser radiation is
generated by a fast high-current discharging in the laser
channels, which is triggered by a power switch
(Thyratron or spark gap). All laser functions are
controlled and monitored by an internal laser control.
Your laser has carefully been tested in an endurance test
of more than 1 million pulses. The results of the test are
included in the end test protocol accompanying the laser.
LTB wishes you much success in working with the laser
on your projects. If there are any questions in working
with the laser or suggestions how to improve the laser,
please do not hesitate to contact us.

content 2
CONTENT
1. SAFETY PRECAUTIONS 4
1.1 INVISIBLE LASER LIGHT 4
1.2 HIGH VOLTAGE UP TO 12 KV5
1.3 DANGEROUS GASES 5
1.4 PRESSURE UP TO 4.5 BARS 5
1.5 LIABILITY 5
2. SYSTEM REQUIREMENTS 6
2.1 PLACE OF INSTALLATION 6
2.2 ELECTRIC REQUIREMENTS 6
2.3 FUSES 6
2.4 NITROGEN SUPPLY / PRESSURE-REDUCING VALVE 7
2.5 CONTROL/COMPUTER 7
3. INSTALLATION 8
3.1 OPERATION PANEL 8
3.2 ACCLIMATISING THE LASER 9
3.3 INSTALLATION OF THE OPTICAL INTERFACE RS 232 9
3.4 THE INTERLOCK PLUG 10
3.4.1 THE EXTERNAL SAFETY CIRCUIT 10
3.4.2 CONNECTING EXTERNAL APPLICATIONS 11
3.4.3 CONNECTING EXTERNAL WARNING DEVICES 11
3.5 MAINS SUPPLY 11
3.6 GAS SUPPLY 12
3.6.1 INSTRUCTIONS FOR COMPLIANCE WITH THE GAS HYGIENE 12
3.6.2 CONNECTING THE LASER TO THE NITROGEN GENERATOR 13
3.6.3 CONNECTING THE LASER TO THE NITROGEN SUPPLY 13
3.7 LASER - COMPUTER - COMMUNICATION 14
3.8 INSTALLING THE USER PROGRAM WINLAC 14
3.9 USER INTERFACE OF THE WINLAC PROGRAM 15
4. OPERATING THE LASER 16
4.1 SWITCHING ON THE LASER 16
4.1.1 KEY SWITCH 16
4.1.2 ADJUSTMENT OF NITROGEN SUPPLY 19
4.1.3 OPEN THE BEAM SHUTTER 20
4.2 OPERATING THE LASER 22
4.2.1 SWITCHING ON THE OPERATIONAL READINESS 22
4.2.2. SET THE REPETITION RATE AND THE NUMBER OF PULSES 23
4.3 SWITCHING OFF THE LASER 28
4.3.1 STOPPING THE LASER OPERATION 28
4.3.2 TURNING OFF THE LASER 29
4.3.3 CLOSING THE BEAM SHUTTER 30
4.3.4 THE KEY SWITCH 30
4.3.5 THE INTERLOCK PLUG 30

content 3
5. LASER MONITORING / WARNINGS 31
5.1 INSPECTION NECESSARY 31
5.2 THE TEMPERATURE MONITORING 32
5.3 MONITORING THE NITROGEN FLOW 33
5.4 ENERGY MEASUREMENT (OPTIONAL)35
5.5 THE HIGH VOLTAGE CONTROL (OPTIONAL)36
5.6 ENERGY CONTROL (OPTIONAL)37
5.7 ADJUSTMENT OF THE SPARK GAP (OPTIONAL)38
6. ERROR MESSAGES 41
6.1 STATIC ERRORS 41
6.2 DYNAMIC ERRORS (OPERATION ERRORS)42
7. ENERGY EVALUATION TOOL 47
7.1 FUNCTIONAL DESCRIPTION 47
7.2 STARTING THE PROGRAM 50
7.3 STARTING THE ENERGY RECORDING 50
7.5 SAVING THE RECORDING IN A FILE 52
7.5 PRINTING THE RECORDING 53
7.6 QUITTING THE PROGRAM 55
8. APPENDIX 56
8.1 THE OPTIONS 56
8.2 WARRANTY 56
8.3 REGULAR INSPECTION AND MAINTENANCE 56
8.4 TECHNICAL PARAMETERS 57
8.5 SERVICE 57

Safety precautions 4
1. SAFETY PRECAUTIONS
MNL Lasers are 3B class lasers (IEC 60825-1).
Improper treatment and operation of the laser can cause
damage to your health.
Please follow carefully all the instructions in this manual.
1.1 Invisible laser light
The laser emits intensive invisible laser radiation in the
UV range.
Do not look into the laser beam!
Please always wear laser safety goggles appropriate to
the wavelength of 337 nm and ensure that all persons in
the vicinity of the laser also wear laser goggles during
laser operation.
For MNL lasers, you need class L6 laser goggles
Always close the beam shutter when the laser is not
in operation.
Please observe that there are no reflecting materials in
the beam path by which the laser beam could
unintentionally be directed towards persons or sensitive
materials.
Always use beam shutters made of inflammable
materials in your set-up.
Always follow the safety regulations.
In case of any unexpected events (fire, water or other
things), you can stop the laser operation by using
the SPACE key on your keyboard

Safety precautions 5
1.2 High voltage up to 12 kV
A high voltage of up to 12kV is generated in the laser.
Perilously high energy amounts are also accumulated in
the capacitors of the strip-conductor. Therefore, always
ground the laser sufficiently.
Do not open the laser!
Because of high voltage circuits, the laser should never
be opened nor should any objects be put into the laser
casing openings.
1.3 Dangerous gases
The high-energetic UV radiation causes ozone and
nitrogenic gases.
Please observe that the laser operating room is
sufficiently ventilated.
1.4 Pressure up to 4.5 bars
The laser works at a slight overpressure. The gas flow is
controlled by a throttle with a pre-pressure of up to 4.5
bar (abs.).
Never exceed the Nitrogen pressure of 4.5 bars.
In case of an error, the pressure will be limited by a
pressure control valve to 4.5 bar absolute. Nevertheless,
there is a risk that the output window will be damaged.
For regulating the nitrogen supply, use a pressure
reducer at any rate.
1.5 Liability
Any tampering with the laser or its adjustment must be
done by authorized service staff.
Any liability and warranty lapses with the opening of the
laser or any modifications without LTB’s explicit written
consent.

System requirements 6
2. SYSTEM REQUIREMENTS
2.1 Place of Installation
The laser has to be operated and stored in a dry, dust-
poor and well-ventilated area.
temperature humidity
Storage and
operation +5 … +35 °C 65 %
Please observe that the laser is not placed close to any
heat sources.
Moreover, ensure that there is no blockage of ventilation
fans or other air vents on the laser casing. These include
side panels, the back panel and the bottom of the casing.
2.2 Electric requirements
You need a grounded contact socket with a protective
conductor connection (protection class 1) protected with
at least 6A. The appropriate values for the power input
are:
230 V, 50/60Hz
115 V, 50/60Hz
Please only connect the laser to mains that matches
the given values on the specification label on the
operating panel of the laser.
2.3 Fuses
The fuses are located above the main plug on the
operating panel of the laser. The fuses' nominal values
are:
230 V – 2 x 3.15 AT
115 V – 2 x 6.30 AT
4
Operating panel
Front panel
Back panel
Beam output

System requirements 7
2.4 Nitrogen supply / Pressure-reducing valve
For the Nitrogen supply, you will need:
• Nitrogen with a purity of 99.996%
(Quality 4.6) or better
• A pressure-reducing valve when using a nitrogen
bottle
low-pressure side -- 0 … max. 10 bar
high-pressure side -- bottle pressure
• A Polyurethane-hose (∅4mm), delivered with the
laser and directly connectable to the laser and the
pressure-reducing valve.
The following details may help in calculating your
Nitrogen requirements:
• the approximate nitrogen consumption is 5l/h – 7l/h
• usually, the pressure of a nitrogen gas bottle is 150
bars minimum.
• The usable amount of gas is calculated by:
bottle volume x bottle filling pressure
Therefore, a 10 l bottle, filled with 150 bar nitrogen,
contains 1500 l nitrogen and will last for about 300 hours
of laser operation. The nitrogen supply is automatically
stopped by turning off the laser.
Gas generators are a safe alternative to gas
bottles or central gas supplies.
2.5 Control/Computer
To operate the laser a PC is required.
You will find an opto-electronic interface adapter that is
used to complete the connection between the laser and
the PC in the utility bag. If you would rather work with a
notebook, a special adapter is available from LTB.
PC requirements:
• IBM-compatibility 386 or higher
• 4 MB RAM, 1 MB free hard-disk storage
• WINDOWS 9x, WINDOWS NT, WINDOWS XP
• A mouse
• A serial COM interface, 9-pin
• CD-ROM drive
• free slot in the PC-casing (for internal current supply)

Installation 8
3. INSTALLATION
3.1 Operation Panel
1 Main fuses
2 Mains plug
3 Key switch
4 INTERLOCK socket
5 POWER ON ("Laser ON" lamp)
6 LASER EMISSION INDICATOR (warning lamp
signals operational readiness and operation)
7 Optical external trigger input
8 Optical PRE-trigger output
9 Electrical output of the optical trigger module with
SMB connector (optional)
10 Optical RS 232 interface
11 Nitrogen inlet
12 Mirror
6
5
3
1
2
4
10
12 11 9 7 8

Installation 9
3.2 Acclimatising the laser
We recommend that the laser is acclimatised in the
operating room for at least an hour after transport or after
moving or changing the operating location.
3.3 Installation of the optical interface RS 232
The laser can only be operated and monitored via its serial
interface. The user program WINLAC allows the
comfortable operation via PC or Laptop.
A Duplex-OWG and two optical interfaces, one in the laser
and the other one in the PC or Laptop, effect the connection
between the laser and the computer.
The interface in the laser is already mounted, but the
interface in the computer needs to be installed.
Screw the interface adapter (LWL/232-IF) onto a free serial
port (e.g. COM 2, 9-pin) on the backside of your computer.
Turn on your computer.
You have correctly installed the interface if the transmitter
line of the interface adapter emits a red light.
interface adapter
COM port
Duplex-OWG

Installation 10
3.4 The Interlock plug
The interlock plug is an important safety feature during laser
operation
It is provided for:
• closing the external safety circuit
• integrating external applications in the safety circuit of
the laser
• connecting external warning devices
The safety circuit is supplied from a safety extra-low voltage
of 12 V / 20 mA.
Without the interlock plug, you cannot operate the
laser!
3.4.1 The external safety circuit
For operating the laser, the external safety circuit always
has to be closed.
Put the interlock plug into the interlock socket on the
operating panel of the laser and fix it in place with the
screws.
The external safety circuit is now closed and laser operation
is possible.

Installation 11
3.4.2 Connecting external applications
For protection against laser radiation, the position switches
of any lasers or other devices or the main safety switch of
your laboratory can be connected together to one external
safety circuit. The laser and its accompanying apparatus
can then be turned off from this interlock plug.
In the interlock plug, the PINs 3 and 5 are connected.
You can integrate your equipment in the interlock circuit as
follows:
1. Open up the interlock plug with a screwdriver and loosen
the connection between PIN 3 and PIN 5.
2. Solder the endings of your circuit on PIN 3 and PIN 5 and
close the interlock plug.
3.4.3 Connecting external warning devices
Additionally, you can integrate an external warning device
(electronic relay or warning lamp) connecting it to PIN 1 and
PIN 2.
An interlock relay can be obtained from LTB.
3.5 Mains supply
Please find your power cord in the utility bag.
The power plug is on the operating panel of the laser.
3
5
20 mA
Include your circuit
here
view of the solder side
1
9

Installation 12
3.6 Gas supply
3.6.1 Instructions for compliance with the gas hygiene
Operate your laser only with nitrogen of the quality 4.6 or
better. We recommend the mini gas generator MNG 100 or
compressed gas cylinders filled with the specified gas.
Central supply lines for technical nitrogen are not suited,
even not with additional filter equipment.
The gas discharge in the laser is particularly perturbed by
an augmented O2or H2O portion in the ppm range.
They cause irreversible damages in the laser head.
1. Before connecting the gas supply line and taking into
operation the laser make sure that the complete
nitrogen gas supply system, from the generator or
pressure reducer up to the gas input connector at the
laser is flushed carefully, so that no air is in the lines.
2. Only after having pressed all air out of the lines (flush
with nitrogen for a few seconds), you may remove
the blind plug from the gas inlet of the laser and
replace it with the gas hose, which is still flown
through with nitrogen.
Lasers equipped with a gas generator carry these
flushing routines out automatically when taken into
operation.
3. Before the first operation of the laser we recommend
by all means to have the switched-on laser flushed at
least 30 minutes without operating it. The set gas
pressure should be approx. 2500 mbar. (The
pressure is displayed in the WINLAC software.)
4. Please see to it that the whole gas equipment is
leak-proof.
When the laser is switched off, its inlet valve is
closed; a pressure drop in the gas supply line is a
certain indication of a leak. Via leaky lines, impurities
get into the laser head and lead to a long-lasting
energy loss and increased electrode wear. Heavy
impurities cause high-voltage spark-overs in the
laser head.
Lasers that have been operated with non-specified laser
gas by accident should at any rate be sent to LTB for laser
head cleaning.

Installation 13
3.6.2 Connecting the laser to the nitrogen generator
This procedure is comprehensively described in the Manual
of the N2generator.
3.6.3 Connecting the laser to the nitrogen supply
1. Remove the gas outlet nipple from the pressure-
reducing valve on your gas bottle.
2. Screw the gas connection adapter from the utility bag
onto the pressure reducer. (Pressure reducers normally
have a ¼" thread on the gas outlet)
3. Now, plug one end of the gas hose into the gas
connection adapter on the pressure reducer.
If you want to remove the hose again, press the blue
plastic ring of the adapter and pull out the
simultaneously.
Before you connect the gas hose with the nitrogen inlet
of your laser, please make sure that the rules for the
gas hygiene acc. to point 3.7 are observed!
If there are any problems in preparing the nitrogen supply,
please call our customer service.
Do not improvise any connections!
Gas outlet
adapter
Gas hose
Nitrogen inlet
7
3

Installation 14
3.7 Laser - Computer - Communication
The laser now needs to be connected to your computer.
In the utility bag, you will find an electric/optical interface
adapter with an OWG-Duplex cord. Please observe that the
plug is coded.
1. Screw the interface adapter (LWL/232-IF) onto a free
serial port (e.g. COM 2, 9-pin) on the backside of your
computer.
2. Gently plug the other plug with the coding down into
the optical interface RS 232 [10] at the operating panel
of your laser.
The optical connection between the laser and the PC is now
complete.
3.8 Installing the user program WINLAC
1. Put the CD with the name WINLAC in the CD-ROM
drive of your computer.
2. Carry out the install.exe. The program will be
automatically copied on the hard disk drive of your
computer.
Start the program WINLAC and familiarise with the user
interface.
MNL 200
1
2
MNL 200

User control panel of the WINLAC program 15
3.9 User interface of the WINLAC program
Warm up control
Selection of the required
repletion rate in integers
Stops the laser
operation
Selection of the required pulse
number in integers between
0 – 65.535
Selection of the operation
mode,
Starts the laser operation
Port monitoring
Pressure
monitoring
High voltage on;
Laser is ready for
operation
Shut down of the
high voltage.
Resets the laser to
the stand-by mode
Program exit
Shows the current
gas mode
High voltage
adjustment
(optional)
Signals the laser
readiness for operation
Selection of
port
Laser configuration Temperature monitorin
g
Laser type
Energy display
(optional)
Pulse counter shows
number of total pulses
Switches the energy
control on or off
(optional)
Indicates a faulty
energy measuring
Starting of the
flushing routine

Laser operation 16
4. OPERATING THE LASER
4.1 Switching on the laser
4.1.1 Key switch
Turn the key switch on the operating panel of the laser to
position I. The green diode above the key-switch should
now light up.
The laser switches automatically into the ONLINE mode.
The laser-computer-communication is electronically
monitored. It is operating correctly if the blue and the green
triangles in the left corner of the user interface flash
alternately
If the connection is not correct, a NO CONNECTION
message will flash. Then you should change the COM port
in the user interface.
Click System in the drop down menu and then go to
Options or click directly on COM.

Laser operation 17
Select the appropriate port (COM 1 … 9)

Laser operation 18
After turning the key switch, the 10-minute flush-warm-up
and conditioning phase of the laser begins that lasts
approx. 25 minutes. This phase is displayed in per cent.
The steps are displayed separately.
During this time you cannot operate or internally flush the
laser.
The laser is ready for operation, when the box
READY
lights up in green.

Laser operation 19
4.1.2 Adjustment of nitrogen supply
When using the N2generator MNG 100, the pressure and
the gas quantity is adjusted automatically.
When using a gas cylinder, you can adjust the nitrogen
pressure with the pressure-reducer on the cylinder, and
thus choose between semi-sealed or flow mode.
The monitoring of the adjustment is depicted on the monitor
graphically and numerically.
The number of visible segments of this bar display (totalling
5) gives clues for the adjustment of the gas pressure.
1 segment Low or no pressure: semi-sealed-mode
2 segments Switch-over range (hysteresis) semi-sealed / flow-mode
3 segments Economical gas consumption, flow-mode ≤5 l/h
4 segments Increased gas consumption, flow-mode 10 - 20 l/h
5 segments Overpressure: hazard to the laser; error message
The Semi-Sealed mode
At a pressure below 1400 mbar, the laser switches
automatically into the semi-sealed mode.
Please observe, that the laser has to be flushed after
200,000 pulses after working in the semi-sealed mode.
Otherwise, the laser will stop operating after a warning
period.
Please see section 5.3 for more specific description.