NKT Photonics PILAS User manual

Advanced Laser Diode System A.L.S. GmbH, Schwarzschildstr. 6, 124 9 Berlin, Germany -NKT Photonics A/S, Blokken 4, 3460 Birkeroed, Denmark
PILAS picosecond pulsed diode laser
Product Guide
sample manual only
-
not to be delivered
with systems

Issue: 3BP3.1
Published: April 2023
Copyright © 2021 by A.L.S. Gmb / NKT Photonics A/S. All rights reserved. Reproduction or translations of any
part of this work is prohibited.

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Contents
1 General .............................................................................................................................................................................. 5
1.1 Warranty and Assistance .................................................................................................................................... 5
1.2 Maintenance ........................................................................................................................................................... 5
1.3 General Safety Considerations ......................................................................................................................... 5
1.4 Laser Safety ............................................................................................................................................................ 6
1.4.1 General Remarks ...................................................................................................................................... 6
1.4.2 Laser Class ................................................................................................................................................. 6
1.4.3 Laser Warning Label ................................................................................................................................ 6
1.4.4 Label Location ........................................................................................................................................... 7
1.4.5 Laser Emission Warning .......................................................................................................................... 7
1.5 Delivery Volume .................................................................................................................................................... 7
2 Introduction ......................................................................................................................................................................
3 Operation .......................................................................................................................................................................... 9
3.1 Installation ............................................................................................................................................................... 9
3.1.1 Rear Elements Control Unit.................................................................................................................... 9
3.1.2 Interlock ....................................................................................................................................................... 9
3.1.3 Front Elements Control Unit ................................................................................................................ 10
3.2 Controller button/rotary knob .......................................................................................................................... 10
3.3 Remote Control ...................................................................................................................................................... 11
3.3.1 Start Operation (Examples) .................................................................................................................... 11
3.3.2 Start laser with internal triggering ........................................................................................................ 11
3.3.3 Start laser with external triggering (TTL input) ................................................................................. 11
3.3.4 Start laser with external triggering (Adjustable input) .................................................................... 11
3.3.5 Start with remote software PILAS Serial Console...........................................................................12
3.4 Controller LCD Menu .......................................................................................................................................... 13
3.4.1 Start Screen ............................................................................................................................................... 13
3.4.2 Main Menu ................................................................................................................................................. 13
3.4.3 Setup Menu ............................................................................................................................................... 13
3.4.4 Tune Setup ................................................................................................................................................ 14
3.4.5 Frequency Setup ......................................................................................................................................15
3.4.6 Trigger Setup ............................................................................................................................................15
3.4.7 CW Mode .................................................................................................................................................. 16
3.4. Save / Load Menu ................................................................................................................................... 16
4 Optical Head ................................................................................................................................................................... 17
4.1 Handling and Adjustment .................................................................................................................................. 17
4.2 Optics....................................................................................................................................................................... 17
4.2.1 Collimating Optics ................................................................................................................................... 17
4.2.2 Fiber Coupler (removable) ....................................................................................................................1
4.2.3 Fiber Coupler (fixed) ...............................................................................................................................1
4.3 Cleaning ..................................................................................................................................................................1
4.4 PILAS Optical Specifications ............................................................................................................................ 19
4.4.1 Beam Profile and Spectrum ................................................................................................................. 19
4.4.2 Polarization Free Space Version ........................................................................................................ 19
4.4.3 Peak Power Calculation ........................................................................................................................ 19
4.4.4 Timing Jitter ............................................................................................................................................. 20
4.5 Delay Times - Timings ....................................................................................................................................... 20
5 General Specifications .................................................................................................................................................21
5.1 Control Unit EGI-D2-40 .......................................................................................................................................21
6 RS232 Commands v1.1.AEe ...................................................................................................................................... 22
7 Test Reports (attached to manual) .......................................................................................................................... 22

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Figures
Figure 1 Explanatory label laser class ....................................................................................................................6
Figure 2 Aperture label ..............................................................................................................................................6
Figure 3 Explanatory data label ...............................................................................................................................6
Figure 4 Warning label ...............................................................................................................................................6
Figure 5 Laser warning and model/part number ................................................................................................ 7
Figure 6 Laser head front side, laser emission ................................................................................................... 7
Figure 7 Gain switch, numerical simulation of carrier and photon density development .......................
Figure EGI-D2-40 rear panel with identification label (shown label is n example) ................................9
Figure 9 Interlock connector polarity .....................................................................................................................9
Figure 10 EGI-D2-40 front panel ............................................................................................................................ 10
Figure 11 NKTP support website ............................................................................................................................ 12
Figure 12 PILAS serial console screenshot......................................................................................................... 12
Figure 13 Start screen and two possible start error messages ..................................................................... 13
Figure 14 Main menu (left with internal trigger, right with eternal TTL trigger) ......................................... 13
Figure 15 Setup menu ............................................................................................................................................... 13
Figure 16 Tune menu ................................................................................................................................................ 14
Figure 17 Frequency menu ...................................................................................................................................... 15
Figure 1 Trigger menu ............................................................................................................................................ 15
Figure 19 CW menu ................................................................................................................................................... 16
Figure 20 Save Load menu .................................................................................................................................... 16
Figure 21 Laser head dimension and mounting scheme (“FS” free space version shown) .................. 17
Figure 22 Polarization maintaining fiber, orientation ...................................................................................... 1
Figure 23 Spectrum, center an FWHM ................................................................................................................ 19
Figure 24 Standard elliptical beam Profile (“FS” versions) ............................................................................ 19
Figure 25 Beam profile out of SMF ("FC" version) ............................................................................................ 19
Figure 26 Polarization .............................................................................................................................................. 19
Figure 27Jitter measurement ................................................................................................................................ 20
Figure 2 Timings, delays ...................................................................................................................................... 20

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1 General
The information given in this document is subject to change without notice.
Copyright Advanced Laser Diode Systems A.L.S. GmbH 2021.
A.L.S. GmbH is wholly owned subsidiary of NKT Photonics A/S, Blokken 4, 3460 Birkeroed, Denmark
All rights reserved. Reproduction, adaptation, or translation without prior written permission is prohibited,
except as allowed under the copyright laws.
1.1 Warranty and Assistance
This instrument manufactured by Advanced Laser Diode Systems is warranted against defects in material
and workmanship for a period of 12 months from date of shipment to the customer. During the warranty
period, Advanced Laser Diode Systems will, at its option, either repair or replace products which prove
to be defective.
The warranty does not apply to defects resulting from improper use or maintenance by the buyer, from
unauthorized modifications or operation outside the environmental specifications and from electrostatic
discharge (ESD).
For warranty service or repair, please contact NKT Photonics A/S service and support. The instrument
should be sent in appropriate packing, only after confirmation from service and support department.
Please enclose a detailed fault report including instrument type and serial number.
1.2 Maintenance
The instrument does not require special maintenance if it is used correctly.
1.3 General Safety Considerations
Before switching on the instrument, make sure it has been properly grounded through the supplied AC
power cable to a socket outlet with a protective earth contact. Any interruption of the grounding can
result in personal injury.
This instrument must be used under normal conditions and as specified, otherwise the protection
provided by the instrument could be impaired.
Always replace blown fuses with the same rating and acting speed.
ESD: Electrostatic discharge (ESD) on or near the connectors can damage electronic devices inside the
instrument. Personnel should touch the metal frame of the instrument for a second before touching any
connector.
Caution – use of controls or adjustments or performance of procedures other than those specified herein
may result in hazardous radiation exposure.
There is no scheduled maintenance necessary to keep the product in compliance although we
recommend a calibration on a regular interval of five years.
There is no service allowed by the customer.
The driver or laser head must never be opened by the customer. Opening of laser head will damage the
warranty label and internal sealing and can be detected by A.L.S. GmbH. If one these protections are
damaged the warranty is lost.

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1.4 aser Safety
1.4.1 General Remarks
The radiation of the laser diode used in this instrument may be visible or invisible. The laser diode emits
radiation in the 365 nm to 2000 nm spectral region.
Use caution to avoid hazardous exposure to the beam. Take precautions to eliminate exposure to a
direct or reflected beam. Do not view the laser beam directly or indirectly with optical instruments or
human eye. We point out, that collimated laser beams are especially dangerous, not losing their
damage potential for eyes and skin with distance.
1.4.2 aser Class
This PILAS laser system is classified as class 3B laser product according to IEC 60 25-1:2014 during all
procedures of operation.
lass 3B laser systems require wearing certified laser safety glasses.
The laser radiation is emitted through the optics at the front side of the optical head or by an attached
optical fiber guiding the laser light.
1.4.3 aser Warning abel
According to laser safety regulations the following class 3B laser product explanatory labels are used.
For the detailed laser parameter please see the test report. For laser heads with wavelengths outside
400 to 700 nm the label with “WARNING INVISIBLE RADIATION” is used.
According to laser safety regulations the following class 3B laser product explanatory (data) label and
aperture label are used:
 Average radiant power at max. rep. rate: P
0
 Peak radiant power: P
p
 Pulse duration: t
 Max. pulse repetition rate: f
 Emitted Wavelength: 
According to laser safety regulations the following warning label is used:
Figure 1 Explanatory label laser class
Figure 3 Explanatory data label
Figure 2 Aperture label
Figure 4 Warning label
5000
3000
100
40
1550

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1.4.4 abel ocation
The shown laser head and labels are samples:
 Warning label for laser radiation is
attached on top of the laser head near
the laser emission aperture as shown in
the diagram.
 Laser aperture label is attached on top
of the laser head with the arrow
pointing towards the laser emission
aperture as shown in the diagram.
 Explanatory laser data label is
attached on top of the laser head as
shown in the diagram.
 Explanatory laser class label is
attached on top of the laser head as
shown in the diagram.
 Laser head identification (model/part
number) label is attached on top of the
laser head as shown in the diagram.
1.4.5 aser Emission Warning
The Laser emission LED is a bright white light
LED which should be visible also with most
Laser safety goggles. Do not look into the
laser beam while observing or checking the
LED status. The controller “ON” button can
be used as laser emission LED too. The
controller “ON” button will light up red when
laser is switched on.
1.5 Delivery Volume
 Control unit: EGI-D2-40
 Optical head: PiLxxx-FS (FS free space version, FC for fiber coupled version. “xxx“
wavelength code)
 Connection cable: PIL1-MH-03 (for connection head with controller. For CE conformity
please plug the two ferrites onto the DVI cable. One on every end
near the DVI connector)
 Tools in blue box: key switch, hexagon socket screwdriver 1.5mm, 1.2mm slot screwdriver
1.2mm slot screw (only for fiber coupler, fiber collimator or microfocus
option), eccentric key (only for fiber coupler or fiber collimator option)
 AC Power Cable: EU, US, China, Japan
 Manual including Test Report at the end or separately
Figure
6
Laser head front side, laser e ission
LED position (“FS” free space version shown)
Figure
5
Laser warning and odel/part nu ber
label location (labels are exa ples)

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2 Introduction
The PILAS is a compact system generating ultra-short optical pulses using diode lasers. The system
consists of a control unit and an optical head with the electrical driver and the laser diode. The optical
head is configured to emit short light pulses within one wavelength in the spectral region between 365
nm and 2000 nm. Each head is individually adjusted to the laser diode to achieve optimal pulses emission
performance down to pulse widths of 20 to 70 ps and optical peak powers between 20 and 1500mW.
Several optical output options are available, including free space collimating optics, fiber coupled
versions for multi- or single mode fibers and different micro foci.
Repetition rates of up to 40 MHz, very low jitter and different triggering possibilities make the PILAS a
flexible and reliable system suitable for a wide range of applications.
The PILAS system uses the technique of gain-switching of laser diodes.
The laser diode represents a low impedance load, which is driven by special electronic circuit that
generates an electrical pulse of high amplitude, variable pulse widths and a jitter of less than 3-4ps.
The following diagram illustrates the behavior and the relationship of electrical pumping current i, carrier
density n and photon density N.
0 10 20 30 40 50 60 70 80 90 100
0.00
0.25
0.50
0.75
1.00
TIME (arb.u.)
nth
Current i
Photon den . N
Carrier
den . n
Figure 7 Gain switch, nu erical si ulation of carrier and photon density develop ent
The diagram shows that an increasing pumping current increases the carrier density n. At the carrier
density threshold n
th
a population inversion results in lasing emission from the laser diode. If the pumping
current i is switched off shortly after this event, the carrier density n drops below the threshold again. This
results in the emission of a single optical pulse. Applying the pumping current i for a longer period would
lead to the emission of multiple pulses. These so-called relaxation oscillations continue for a short time
(0.5 to 2ns depending on the diode laser technology and electronic circuit settings).
The pumping current i is connected to our TUNE value, which can be changed at the controller LCD menu
(see chapter “Operation” and following). The controller, the laser head and the cables introduce a
nonlinear frequency response, leading to different TUNE values for the repetition rates.
The required TUNE value for the black filled nominal or standard pulse at figure 7 can be found in our
Test Report attached to this manual.
Although we specify the TUNE value for nominal pulse only, it is possible to use lower and higher TUNE
values. This will lead to non-calibrated pulses deviating from the standard gain-switched pulses (see
chapter “Tune Setup” how to adjust TUNE). For one selected frequency (typically the maximum of 40MHz)
we show such sample measurement of three pulses: below nominal pulse amplitude, nominal pulse,
above nominal pulse amplitude. This “Tune scan” can be found in the Test Report attached to this manual.

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3 Operation
The following chapters describe controller settings. Nothing needs to be adjusted on the laser head to
start operation.
3.1 Installation
Set up controller and laser head in stable position. Connect the power supply cable to the controller (100V
- 240V, 50Hz - 60Hz). Connect the laser cable PIL1-MH-03 between controller and laser head. The key
switch can be found in the laser head transport box. If the primary fuses are blown, they can easily be
replaced by the user. Before switching on the controller, the rear panel power switch must be set to “1”.
3.1.1 Rear Elements Control Unit
Figure 8 EGI-D2-40 rear panel with identification label (shown label is n exa ple)
3.1.2 Interlock
Laser emission is possible with activated interlock only (otherwise LCD error message appears). Activated
means that a +5V control voltage is pulled down to ground (GND). For operation the interlock
cable/connector must be connected to the rear panel 2.5mm plug. A two-pole 2.5mm interlock connector
with short circuited cables is shipped with the system. The base contact is GND and the tip is +5V. You
can cut off the cables and connect them with your interlock switch or use your own 2.5mm plug.
Figure 9 Interlock connector polarity

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3.1.3 Front Elements Control Unit
Figure 10 EGI-D2-40 front panel
1. Laser connection (to optical head)
2. illuminated Liquid crystal display (LCD)
3. UP, DOWN navigation buttons
4. MODE key, selection, confirmation and return
5. Rotary knob, value setting
6. ON laser button with red laser emission LED (there is also a 2
nd
laser emission LED on front side
of laser head)
7. Trigger input, TTL, BNC plug
. Trigger input, variable, BNC plug
9. Trigger output, BNC plug
10. Power key switch
11. Power LED, green
3.2 Controller button/rotary knob
The digital control unit of the PILAS is operated by four keys UP, DOWN, MODE, ON and rotary knob (see
image).
You can select the different menus by pressing MODE keys. The UP and DOWN keys are for selections
within the menus. The rotary knob will change the selected value. With the MODE button you confirm and
leave the selected menu level automatically.
The ON button with red light emitting diode (LED) is for switching the laser emission on/off. A red glowing
indicates laser emission. A white light LED on the laser head front side will also indicate laser emission.

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3.3 Remote Control
Only one of the USB or the RS232 interfaces should be connected and used. Connecting via computer
RS232 COM Port will not require any drivers. Connecting via USB will require the installation of a virtual
com port chip set driver (VCP) from FTDI. The controller will appear as virtual COM port afterwards.
3.3.1 Start Operation (Examples)
A complete list of remote commands can be found in the in chapter “RS232 Commands…”.
Before starting you must ensure that all laser safety measures are set.
Start your computer terminal program for transmitting remote commands between computer and laser
controller. Check for correct settings and for termination char.
Connect RS232 or USB cable and power up the system with a 12V DC external power supply. System
will boot up and require some seconds before accepting remote commands. At the connected COM
port, it will send a multiline status message.
In the following examples the termination CR is shown with “\r”.
Controller will reply with “done” message when command was accepted and executed. Invalid
commands sent to controller will return the following error messages:
“invalid command!”
“data format error!”
3.3.2 Start laser with internal triggering
Above commands will enable laser emission at 1.25MHz until ld=0 shuts down emission finally.
3.3.3 Start laser with external triggering (TT input)
Above commands will enable laser emission at external repetition rate until ld=0 shuts down emission
finally. The external clock must be supplied via the TTL plug.
3.3.4 Start laser with external triggering (Adjustable input)
Above commands will enable laser emission at external repetition rate until ld=0 shuts down emission
finally. The external clock must be supplied via the Adj. plug.
Properties
Connection
UART
interface support data bits
, 1 stop
-
bit
null modem cable /cross over cable (2 on 3, 3 on 2)
data transfer rate 19200 baud
carriage return (
\
r,
CR
-
0xd) string for termination
Sent
Description
Return Message
ts=0
\
r
Enable internal triggering
done
\
r
\
n
f=1250000
\
r
Set repetition rate to 1.25MHz
done
\
r
\
n
ld=1
\
r
Switch on laser emission
done
\
r
\
n
ld=0
\
r
Switch off laser
emission
done
\
r
\
n
Sent
Description
Return Message
ts=2
\
r
Enable external triggering (TTL plug)
done
\
r
\
n
ld=1
\
r
Switch on laser emission
done
\
r
\
n
ld=0
\
r
Switch off laser emission
done
\
r
\
n
Sent
Description
Return
Message
ts=1
\
r
Enable external triggering (
Adj.
plug)
done
\
r
\
n
te=1
\
r
Set rising trigger edge
done
\
r
\
n
tl=
-
500
\
r
Set trigger level to
-
500mV
done
\
r
\
n
ld=1
\
r
Switch on laser emission
done
\
r
\
n
ld=0
\
r
Switch off laser emission
done
\
r
\
n

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3.3.5 Start with remote software PI AS Serial Console
You can download a simple serial console for sending
commands and receiving the output on the NKTP support
website (description or look can change):
This software is available for Windows in a 64 and 32 bit version.
It uses preset serial settings of 19200 baud, bytes , stopbit one
and time out 1s. It can send single remote commands to the
controller and display the received message.
Figure 12 PILAS serial console screenshot
1. For the USB connection to work, install the VCP driver before launching the software.
2. Select COM port from Combobox. Wrong port will raise error messages. You can power on/off
controller and check with “Update Ports” which port appears/disappears to find correct port.
3. Commands from the accepted firmware (V11AEe) can be entered in the entry widget. For
command list see “Commands” menu.
4. Confirm command to be sent with “Send” button or RETURN on keyboard.
 “Help” menu show help text.
 Controller and program messages (errors for instance) will be displayed in the “Received:”
window.
 “Debug” checkbox enables timeout (seconds) change (required for certain time-consuming
commands) and wait (seconds) increase. Increasing wait between send and received can help
to avoid serial errors.
 With “Debug” checkbox enabled, any input can be send to controller. Please note, that certain
commands can lead to a non-functioning system!
 “Clear Received” will clear “Received:” window.
 “Clear Transmitted” will clear window for sent commands (history list).
 “Save Received” will save text in “Received:” window to a file.
 Last sent command can be recalled with ￪ on keyboard. Arrows Up, Down cycle through sent
command list.
 Longer text will generate scrollbar in “Received:” window and you can you resize window
bottom right.
Figure 11 NKTP support website

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3.4 Controller CD Menu
The following adjustable laser parameters will be set by software menu:
 pulse repetition rate / frequency
 TUNE (pulse amplitude and width)
 Temperatures (only in debug mode)
 CW mode (only if ordered)
 Trigger methods a) internal 25Hz to 40 MHz b) external single shot to 40 MHz
 Input trigger TTL or variable
 trigger threshold and edge if trigger supplied by BNC plug ( ) (variable)
3.4.1 Start Screen
After switching on the control unit, you get the text message:
For operation the interlock cable/connector must be connected to the rear panel 2.5mm plug. If the laser
head is not connected an error message will be displayed too.
3.4.2 Main Menu
With interlock and laser head connected the controller shows the main menu after start up:
Figure 14 Main enu (left with internal trigger, right with eternal TTL trigger)
By pressing ON button, the laser would start operating with displayed parameter.
The TUNE value can be changed in the main menu by turning the rotary knob (but only if “manual” mode
is selected in menu “TUNE Setup”).
Pressing the MODE button switches to Setup menu.
Note: For internal triggering the current set frequency is displayed. For external triggering with
f>150Hz, the measured frequency of the trigger source is shown. For lower frequencies, the value will
be less exactly. This value should be seen as an indicator of the trigger clock and not an (exact)
measurement.
3.4.3 Setup Menu
Figure 15 Setup enu
Figure 13 Start screen and two possible start error essages

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With the UP and DOWN keys, you can navigate within the setup menu. The selected menu is marked by
“<” sign on right side. This is valid also for the next menus.
For switching to desired menu press MODE button.
The following menus are accessible from here:
 Main Menu < screen switches back to main menu
 Tune Setup < Tune value menu
 Frequency Setup < Selection of frequency parameter
 Trigger Setup < Selection for external trigger parameter
 CW Mode < CW options (out of function when CW option is not ordered)
 Save Settings < save set up (saving TUNE, Frequency and Tune MODE)
 oad Settings < load stored setup (saving TUNE, Frequency and Tune MODE)
3.4.4 Tune Setup
Figure 16 Tune enu
Mode: By turning the rotary knob you can select between “manual” and “automatic” TUNE mode. In
“automatic” mode the default TUNE values from the manufacturer are used and locked. In “manual” mode
the TUNE values can be changed by the user. To alter them press the UP or DOWN key until the “<” mark
is in the row for “Value”. Now the TUNE value can be adjusted by rotary knob.
Value: The TUNE value can be adjusted between 100 and 0% (in manual mode only).
TUNE 100% low laser pulse amplitude
TUNE 0% high laser pulse amplitude
The recommended TUNE value for the optimum pulse shape can be found in the delivered test report.
In some cases, we recommend adjusting the TUNE value by +/- 5% to find optimum pulse parameter.
Please note that the TUNE value can be adjusted in the main menu by turning the rotary knob too (but
only if “manual” mode is selected).
For external and internal (fine mode) frequencies values not given in the test report, the TUNE values will
be interpolated in “automatic” TUNE mode linearly. They can be changed manually if mode is set to
“manual” in TUNE menu.
Please note: Confirming with the MODE key will jump back to the setup menu also.
Note: The controller can store one TUNE set only in EPROM. In case you have ordered multiple heads,
you have the following options:
First: Switch Tune Mode to “manual” and apply the correct TUNE for the laser head at the specific
frequency manually with the rotary knob.
Second: the programmed tune values can be re-programmed by a remote command (via RS232 serial
interface). Please contact us for documentation.
Third: We can provide a GUI program for remote controller reprogramming (via RS232 serial interface).
Prior to operating the system, you can select a laser head and program the corresponding TUNE value
into the controller EPROM. Please contact us.

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3.4.5 Frequency Setup
Figure 17 Frequency enu
The maximum adjustable frequency can be found in the test report or purchase information (40MHz
standard).
In the second row you can select between “coarse” and “fine” frequency resolution for internal triggering.
Selection is done with the rotary knob.
Mode coarse: With this option the frequency is adjusted in the third row in predefined steps. For the
40MHz version: 1kHz, 100kHz, 1MHz, 10MHz, 20MHz, 22MHz, 23MHz…41MHz.
Mode: fine: With this option the frequency is adjusted in the fourth row in fine steps. For most applications
“coarse” is the better option. Lowest internal frequency is 25Hz.
By pressing the UP and DOWN key you can navigate to the frequency rows.
F: If “coarse” is selected the frequency is adjusted in this third row by rotary knob.
F: If “fine” is selected the frequency is adjusted in this fourth row. Continue pressing UP and DOWN for
switching between the digits of the frequency value in fourth row. The digit value is adjusted by rotary
knob.
Confirm selected frequency value with MODE key.
Please note: Confirming with the MODE key will jump back to the setup menu also.
3.4.6 Trigger Setup
Figure 18 Trigger enu
Source: With the rotary knob you can switch between: “internal”, “ext. TTL” (external TTL) and “ext. Adj”
(external adjustable or variable) mode.
At “internal” setting the oscillator of the controller is used for generating the frequency. The “Edge” and
“Level” is only used for external triggering.
For “ext. TTL” a trigger signal to the TTL BNC plug must be provided. An external oscillator will give the
clock. Minimum required trigger voltage is 1.5V.
For “ext. Adj” a trigger signal up to +5/-5V BNC plug must be provided. An external oscillator will give
the clock.
Lowest jitter is provided by “internal” clock.
“ext. TTL” provides the lowest jitter for external clock.
For variable and low clock signal amplitudes use “ext. Adj” input resulting in slightly increased jitter.
Please note that external oscillators may have worse frequency stability than controller internal clock.
This can lead to increased jitter of subsequent pulses. Low external clock signal amplitude can also lead
to increased jitter or bad laser pulse signal quality.

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We recommend checking the controller trigger output signal because the trigger output is linear to
the signal the laser diode is seeded with. Optimize the trigger threshold and (if possible) amplitude
until the trigger output is clean and stable (no double or multiple pulses within a period).
The impedance for all BNC plugs is 50. The external trigger sources must provide an impedance of
50. Other values can lead to impedance mismatch and failure in external triggering.
The applied external clock frequency must not be higher than the device maximum allowed frequency
(see purchase information).
Edge: Select leading or trailing edge for external and internal triggering.
The following settings are only used for “ext. Adj” triggering.
evel: Select trigger threshold level in Volt for “ext. Adj” triggering.
The applied external clock is measured, and the frequency is displayed in the main menu. If external
triggering does not work the laser cannot be switched on and frequency shows 0Hz.
For external and internal (fine mode) frequencies values not given in the test report, the TUNE values will
be interpolated linearly when TUNE mode “auto” is selected. TUNE values can be adjusted manually if
TUNE mode is set to “manual” in the TUNE menu.
Please note: Confirming with the MODE key will jump back to the setup menu also.
3.4.7 CW Mode
Figure 19 CW enu
Operation: The CW option can be switched on or off if available.
Power: The optical CW power in % can be adjusted if available.
A laser head can operate in one of the following two CW modes:
First for some laser heads the CW power can be adjusted by rotary knob between 0% and 100%. 0%
means low power (but not 0 mW!), 100% maximum CW power. Please reduce the power by rotary knob
to 0%, before switching on CW by changing OPERATION to ON This ensures that CW operation starts
with low power. CW power depends nonlinear with % value.
Secondly some laser heads emit their maximum CW power right away if OPERATION is switched ON
independent on % value. Turning the rotary knob will change the displayed % value but has no influence
on CW power.
Whether the laser head belongs to first or second type you can see in the test report.
Please note: Confirming with the MODE key will jump back to the setup menu also.
3.4.8 Save / oad Menu
Figure 20 Save Load enu
Within this menu you have the option storing some working parameters like TUNE and frequency.
There are three memory slots.
Please note: Confirming with the MODE key will jump back to the setup menu also.

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4 Optical Head
The optical head is connected to the Laser connector of the control unit with the cable PIL1-MH-03
electrically. Please attach the screws of the cable to the control unit and the optical head gently. To fix
the head mechanically, please use the five M4 threads (please check thread length) in the base plane of
the optical head or the four corner through holes.
For detailed parameters please see the test report as a reference. Three main versions are offered:
 “FS” version - collimating optics, free space laser beam
 “FC” version – fiber coupling with fiber output FC/APC (removable)
 “FC” version - internal fiber coupling with fiber output FC/APC (fixed coupling)
Figure 21 Laser head di ension and ounting sche e (“FS” free space version shown)
4.1 Handling and Adjustment
The following chapters describe the main optics shown in the picture above that can be used in
conjunction with PILAS-systems. You will find the optics used for your system in the PILAS-test report
attached to the manual.
4.2 Optics
A.L.S. GmbH uses high quality laser optics from Copyright Schäfter + Kirchhoff GmbH Germany. For
details please see shipped test report.
4.2.1 Collimating Optics
The collimating optics delivers an elliptical collimated beam. For details please see shipped test report.
Our AR coated Bi-asphere lenses used for collimating the laser diode show the same correction and
imaging quality compared to microscope lenses with three or four elements. The high NA lenses capture
most of the emitted light. But caused by their specific manufacturing process, these lenses have
microstructures on their surfaces, which also appear in the collimated beam, but not in the focused spot
(see figure 24). For superior collimated beam profiles, we always recommend the fiber coupling option
and a fiber collimator.
The inner tube, which holds the lens, is fixed to the main optics housing with two hexagon socket set
screws on top. For re-focusing, first loosen these screws, and then use the delivered hexagon socket
screwdriver to turn the optics. By slowly rotating the tool, the inner tube is slightly moved longitudinal in
the main housing. After re-focusing, tighten the two screws again. Due to the mechanic tolerances
changing the collimation may also change the beam axis.

P a g e | 18
4.2.2 Fiber Coupler (removable)
The “FC” option is delivered with a fiber coupling unit and a single or multimode mode fiber attached to
it as standard. The single mode fiber can be PM fiber (polarization maintaining) or standard single mode
fiber. The fiber coupling unit is plugged into to the main optics housing following the collimating tube.
The laser beam coupler is fixed to the main housing with three hexagon socket set screws at the end of
the main housing.
In case of removing the fiber coupler, using another fiber or misalignment, the coupler needs be
optimized by customer. For a detailed fiber coupling description please contact us.
For most cases where the coupling is misaligned only slightly, it is sufficient to optimize the tilt
adjustment only with the three counter hexagon socket set screws parallel to optical axis and no to
touch the lens position.
The inner tube of the fiber coupler, which holds the focusing lens, is fixed to the housing with two small
slotted set screws in the middle. For re-focusing to the fiber connector end surface, first loosen these
screws and insert the delivered adjusting tool with an eccentric aligning plug in the right position into the
hole of the housing of the laser beam coupler. By slowly rotating the tool, the inner tube is slightly moved
longitudinal in the main housing. After re-focusing, tighten the two screws again.
The optical axis of the laser beam coupler is aligned to the optical axis of the collimated laser beam
(paraxial fiber coupling). This is done by slightly adjusting the three hexagon head cap screws clockwise.
Near optimum power coupling the three counter hexagon socket set screws are for locking and fine
adjustment. All six screws are located parallel to the optical axis.
Please note, that the fiber connector of single mode fibers attached to the coupler is tightened with a
small slotted set screw. Before screwing off the fiber connector this small screw must be loosen and after
connecting again it must be tightened again with less pressure.
In case of polarization maintaining fiber, the laser diode polarization is aligned to the slow axis. The slow
axis is aligned to the connector key as shown in the picture. Most common PM fiber type is PANDA.
Figure 22 Polarization aintaining fiber, orientation
4.2.3 Fiber Coupler (fixed)
Optional the laser head is shipped with an internal fixed fiber coupler.
4.3 Cleaning
The need for cleaning of any precision optics should be reduced to a minimum by covering the optics
and by use of a protective enclosure or similar to avoid contamination. We recommend that dust is blown
off only. The laser must be switched off while checking and cleaning!
For the fiber coupled version “FC” keep the fiber connector end face clean. Connecting our output fiber
to other fibers may exchange dust particles among them. We recommend a fiber inspection and clearing
on regular base. The laser must be switched off while checking the fiber connector!

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4.4 PI AS Optical Specifications
The optical specifications are given in the test report attached to this manual. A short description of these
specifications is given here:
4.4.1 Beam Profile and Spectrum
The collimation with a one lens system results in an elliptical beam profile with modulations from the lens
manufacturer process (see chapter “Collimating Optics”). The best beam profile is emitted out of single
mode fiber (SMF). The better quality comes at expense of lower output power (typical SMF coupling
efficiency is 40 to 60%).
The optical spectrum of a picosecond pulsed gain switched diode laser is broadened (chirp) and has a
different center wavelength compared to the CW spectrum (for Fabry-Perot type lasers). It also shifts with
higher frequency to longer wavelengths. This depends on laser diode type, wavelength and pulse
settings. Typically, the shift from 1kHz to 40MHz is about 0.2nm only.
4.4.2 Polarization Free Space Version
The laser beam is linear polarized with a ratio of 100:1 or 20dB. The
direction of polarization is parallel to the bottom/table plane and
perpendicular to propagation axis (red arrow).
The figure shows the collimated elliptical output beam of PILAS (blue
ray) and the direction of polarization (red arrow).
4.4.3 Peak Power Calculation
A useful relation between optical average power 

, pulse energy  and frequency  is:



With equation above peak power 

can be calculated approximately when the pulse width  is
measured (0. 5 is a pulse shape factor):



  

 
Specification
Unit
Description
Beam diameter
mm
Beam diameter for intensity drop to 1/e
2
* m
aximum (100% to 13.5%)
Beam
divergence
mm
Half beam divergence for intensity drop to 1/e
2
*
maximum (100% to 13.5%)
Wavelength
nm
Center wavelength pulsed operation
Spectral width
nm
Width of optical spectrum at 50% amplitude points
Frequency
Hz
rate at which the pulses are
emitted
(pulse repetition rate)
TUNE value
%
correspond to laser diode current inversely
for pulsed operation
, low TUNE = high diode current
FWHM
ps
pulse width, time between 50% amplitude of rising
and
falling flank
RMS
-
Jitter
ps
Timing jitter for an
edge
-
reference measurement also phase jitter or time interval Error (TIE)
Av.power
µW
Optical average power
Energy
pJ
Optical pulse energy
Peak power
mW
Optical peak power
Figure 25 Bea profile
out of SMF ("FC" version)
Figure 24 Standard elliptical
bea Profile (“FS” versions)
Figure 23 Spectru , center an FWHM
Figure 26 Polarization

P a g e | 20
4.4.4 Timing Jitter
The measured timing jitter reflects fluctuations of the optical pulse
arrival time 

(at 50% amplitude) in reference to the controller electrical
trigger out signal (from which also the optical signal is generated inside
the laser head).
Let 

be the measured time deviation from the ideal optical pulse
rising flank position 

for measurement  (sampling oscilloscopes
measure many edges): 





The oscilloscope calculates the standard deviation of 

which is
same as RMS value here because 

average value is zero for
random jitter distribution (Gaussian):




 
!
"


#
$%&



Reported timing jitter  is also called time interval error or phase
jitter and is an upper limit because it includes oscilloscope jitter.
4.5 Delay Times - Timings
The signal timings are shown in the sketch below. Please note: they vary depending on laser head model
and factory settings. You need to add/subtract delays corresponding to your installed
cables/fibers/optical path lengths for signal arrival time. A standard delay of 11.4ns between laser seed
and BNC trigger out is activated by internal jumper.
Figure 28 Ti ings, delays
For certain custom systems the internal standard delay is set to 0ns. This would modify +19ns to ns,
+32ns to 21ns and +37ns to 26ns (see sketch).
Figure 27Jitter easure ent