MOGlabs DLC202 Bedienungsanleitung
External Cavity Diode Laser Controller
DLC102, DLC202, DLC252, DLC502
Revision 9.09
Limitation of Liability
MOG Laboratories Pty Ltd (MOGLabs) does not assume any liabil-
ity arising out of the use of the information contained within this
manual. This document may contain or reference information and
products protected by copyrights or patents and does not convey
any license under the patent rights of MOGLabs, nor the rights of
others. MOGLabs will not be liable for any defect in hardware or
software or loss or inadequacy of data of any kind, or for any direct,
indirect, incidental, or consequential damages in connections with
or arising out of the performance or use of any of its products. The
foregoing limitation of liability shall be equally applicable to any
service provided by MOGLabs.
Copyright
Copyright c
MOG Laboratories Pty Ltd (MOGLabs) 2014. No part
of this publication may be reproduced, stored in a retrieval system,
or transmitted, in any form or by any means, electronic, mechanical,
photocopying or otherwise, without the prior written permission of
MOGLabs.
Contact
For further information, please contact:
MOG Laboratories P/L
18 Boase St
Brunswick VIC 3056
AUSTRALIA
+61 3 9939 0677
www.moglabs.com
MOGLabs USA LLC
419 14th St
Huntingdon PA 16652
USA
+1 814 251 4363
www.moglabsusa.com
MOGLabs Europe
Goethepark 9
10627 Berlin
Germany
+49 30 21 960 959
Preface
Diode lasers can be wonderful things: they are efficient, compact,
low cost, high power, low noise, tunable, and cover a large range
of wavelengths. They can also be obstreperous, sensitive, and tem-
peramental, particularly external cavity diode lasers (ECDLs). The
mechanics and optics needed to turn a simple $10 120 mW AlGaAs
diode laser into a research-quality narrow-linewidth tunable laser
are fairly straightforward [1, 2, 3, 4], but the electronics is demanding
– and, until now, not available commercially from a single supplier,
let alone in a single unit.
The MOGLabs range of ECDL controllers change that. With each DLC
unit, we provide everything you need to run your ECDL, and lock it
to an atomic transition. In addition to current and temperature con-
trollers, we provide piezo drivers, sweep ramp generator, modulator
for AC locking, lock-in amplifier, feedback servo system, laser-head
electronics protection board, even a high-speed low-noise balanced
photodetector.
We would like to thank the many people that have contributed their
hard work, ideas, and inspiration.
We hope that you enjoy using the DLC as much as we do. Please let
us know if you have any suggestions for improvement in the DLC or
in this document, so that we can make life in the laser lab easier for
all, and check our website from time to time for updated information.
MOGLabs www.moglabs.com
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Safety Precautions
Safe and effective use of this product is very important. Please read
the following safety information before attempting to operate your
laser. Also please note several specific and unusual cautionary notes
before using the MOGLabs DLC, in addition to the safety precautions
that are standard for any electronic equipment or for laser-related
instrumentation.
CAUTION – USE OF CONTROLS OR ADJUSTMENTS OR
PERFORMANCE OF PROCEDURES OTHER THAN THOSE
SPECIFIED HEREIN MAY RESULT IN HAZARDOUS
RADIATION EXPOSURE
Laser output can be dangerous. Please ensure that you implement
the appropriate hazard minimisations for your environment, such as
laser safety goggles, beam blocks, and door interlocks. MOGLabs
takes no responsibility for safe configuration and use of your laser.
Please:
•Avoid direct exposure to the beam.
•Avoid looking directly into the beam.
•Note the safety labels and heed their warnings.
•When the laser is switched on, there will be a short delay of
two seconds before the emission of laser radiation, mandated
by European laser safety regulations (IEC 60825-1).
•The STANDBY/RUN keyswitch must be turned to RUN before
the laser can be switched on. The laser will not operate if
the keyswitch is in the STANDBY position. The key cannot be
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removed from the controller when it is in the clockwise (RUN)
position.
•To completely shut off power to the unit, turn the keyswitch
anti-clockwise (STANDBY position), switch the mains power
switch at rear of unit to OFF, and unplug the unit.
•When the STANDBY/RUN keyswitch is on STANDBY, there can-
not be power to the laser diode, but power is still being sup-
plied to the laser head for temperature control.
CAUTION Please ensure that the unit is configured for the correct voltage
for your AC mains supply before connecting. The supply must
include a good ground connection.
CAUTION To ensure correct cooling airflow, the unit should not be oper-
ated with cover removed.
WARNING The internal circuit boards and many of the mounted compo-
nents are at high voltage, with exposed conductors, in partic-
ular the high-voltage piezo driver circuitry. The unit should
not be operated with cover removed.
NOTE The MOGLabs DLC is designed for use in scientific research
laboratories. It should not be used for consumer or medical
applications.
Protection Features
The MOGLabs DLC includes a number of features to protect you and
your laser.
Softstart A time delay (3 s) followed by linearly ramping the diode cur-
rent (3 s max).
Circuit shutdown Many areas of the circuitry are powered down when not in use.
The high voltage supply and piezo drivers, the diode current
supplies, the coil driver, and others are without power when
the unit is in standby mode, if an interlock is open, or a fault
condition is detected.
Current limit Sets a maximum possible diode injection current, for all op-
erating modes. Note that current supplied through the RF
connector on the laser headboard is not limited.
Cable continuity If the laser is disconnected, the system will switch to standby
and disable all laser and piezo power supplies. If the laser
diode, TEC or temperature sensor fail and become open-circuit,
they will be disabled accordingly.
Short circuit If the laser diode, TEC or temperature sensor fail and become
short-circuit, or if the TEC polarity is reversed, they will be
disabled accordingly.
Temperature If the detected temperature is below −5◦C or above 35◦C, the
temperature controller is disabled.
Internal supplies If any of the internal DC power supplies (+5, ±10, ±12 V) is
1 V or more below its nominal value, the respective components
(temperature controller, diode current supply) are disabled.
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Protection relay When the power is off, or if the laser is off, the laser diode
is shorted via a normally-closed solid-state relay at the laser
head board.
Emission indicator The MOGLabs controller will illuminate the emission warn-
ing indicator LED immediately when the laser is switched on.
There will then be a delay of at least 2 seconds before actual
laser emission.
Mains filter Protection against mains transients.
Key-operated The laser cannot be powered unless the key-operated STANDBY
switch is in the RUN position, to enable protection against
unauthorised or accidental use. The key cannot be removed
from the controller when it is in the clockwise (RUN) position.
Interlocks Both the main unit and the laser head board have interlocks,
to allow disabling of the laser via a remote switch, or a switch
on the laser cover.
Contents
Preface i
Safety Precautions iii
Protection Features v
1 Introduction 1
1.1 Basicoperation...................... 1
1.2 Passive frequency control . . . . . . . . . . . . . . . . 2
1.3 DC locking to an atomic transition . . . . . . . . . . . 4
1.4 AC locking to an atomic transition . . . . . . . . . . . 5
2 Connections and controls 7
2.1 Front panel controls . . . . . . . . . . . . . . . . . . . 7
2.2 Front panel display/monitor . . . . . . . . . . . . . . . 10
2.3 Rear panel controls and connections . . . . . . . . . . 12
2.4 Internal switches and adjustments . . . . . . . . . . . 15
2.5 Feedback configurations . . . . . . . . . . . . . . . . . 20
2.6 Digitalcontrol....................... 23
2.7 Internal trimpots . . . . . . . . . . . . . . . . . . . . . 24
3 Operation 25
3.1 Simplest configuration . . . . . . . . . . . . . . . . . . 25
3.2 Laser frequency control . . . . . . . . . . . . . . . . . 26
3.3 External scan control . . . . . . . . . . . . . . . . . . . 27
3.4 Locking to an atomic transition: DC .......... 28
3.5 Locking to an atomic transition: AC .......... 31
3.6 Externalsweep ...................... 34
3.7 Locking using an external signal . . . . . . . . . . . . 34
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3.8 External control of lock frequency setpoint . . . . . . 36
4 Optimisation 37
4.1 Frequency reference . . . . . . . . . . . . . . . . . . . 37
4.2 Noisespectra....................... 39
A Specifications 41
A.1 RF response ........................ 45
A.2 Sweep saturation and trigger . . . . . . . . . . . . . . 45
B Troubleshooting 47
B.1 STANDBY/RUN indicator ................. 47
B.2 Diode OFF/ON indicator................. 48
B.3 250 kHz modulation . . . . . . . . . . . . . . . . . . . 49
B.4 Locking........................... 51
C Using DBR/DFB diodes 53
C.1 Fine current control . . . . . . . . . . . . . . . . . . . 53
C.2 DC current feedback . . . . . . . . . . . . . . . . . . . 53
C.3 Slow current feedback . . . . . . . . . . . . . . . . . . 54
C.4 Locksaturation ...................... 54
C.5 Specialoptions...................... 54
D Modulation coils 55
D.1 Field requirements . . . . . . . . . . . . . . . . . . . . 55
D.2 Coilimpedance ...................... 56
D.3 Impedance matching . . . . . . . . . . . . . . . . . . . 57
D.4 Tuning ........................... 58
D.5 Shielding ......................... 59
E External modulators and injection current modulation 61
E.1 Coupling circuit . . . . . . . . . . . . . . . . . . . . . . 61
E.2 Injection current modulation . . . . . . . . . . . . . . . 62
F Photodetector 65
F.1 Photodiodes........................ 66
G Laser head board 67
G.1 Headboard connectors . . . . . . . . . . . . . . . . . . 67
G.2 Dual piezo operation . . . . . . . . . . . . . . . . . . . 68
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