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MOGlabs dDLC Manual

Digital diode laser controller
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Digital Diode Laser Controller
dDLC
Revision 0.1

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Summary of Contents for MOGlabs dDLC

  • Page 1 Digital Diode Laser Controller dDLC Revision 0.1...

  • Page 2: Limitation Of Liability

    MOGL Contact For further information, please contact: MOG Laboratories P/L MOGLabs USA LLC 49 University St 419 14th St Carlton VIC 3053 Huntingdon PA 16652 AUSTRALIA +61 3 9939 0677 +1 814 251 4363 info@moglabs.com...
  • Page 3 MOGL dDLC operate an , and lock it to an atomic transition, high finesse ECDL optical cavity, or beatnote offset lock to a femtosecond comb. In...

  • Page 5: Safety Precautions

    Also please note several specific and unusual cautionary notes before using the , in addition to the safety precautions MOGL dDLC that are standard for any electronic equipment or for laser-related instrumentation. CAUTION – USE OF CONTROLS OR ADJUSTMENTS OR...
  • Page 6 The unit should not be operated with cover removed. NOTE The is designed for use in scientific research MOGL dDLC laboratories. It should not be used for consumer or medical applications.

  • Page 7: Protection Features

    Protection features includes a number of features to protect you and MOGL dDLC your laser. Key-operated The laser cannot be powered unless the key-operated STANDBY switch is in the position, to enable protection against unauthorised or accidental use. The key cannot be removed from the controller when it is in the clockwise ( ) position.
  • Page 8 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.

  • Page 9: Extending Laser Lifetime

    Extending laser lifetime abs strongly recommending setting your into MOGL dDLC STANDBY mode at nights and weekends and whenever the laser is not being used for more than a few hours. Most lasers need to operate only 40 hours during a 168 hour week; thus switching to standby mode can extend the diode and piezo lifetime by a factor of four.

  • Page 10: Table Of Contents

    Contents Preface Safety precautions Protection features Extending laser lifetime 1 Quick start 1.1 Hardware connections ....1.2 Front panel ......1.3 Powering up .

  • Page 11: Contents

    Contents 3.4 External low-bandwidth (wavemeter) locking ..3.5 External high-bandwidth (PDH) locking ..3.6 Noise spectrum optimisation ....3.7 Troubleshooting error signal generation .
  • Page 12 Contents...

  • Page 13: Quick Start

    Figure 1.1: Rear-panel of the MOGLabs , including an interchange- dDLC able plate (shaded blue) which allows alternate connector arrangements for future configuration options.
  • Page 14 The type- connector below the ethernet socket is reserved for future external device connections. connector to connect the to a compatible laser head. Only dDLC LASER high quality digital dual-link cables should be used. DVI-D DL Ensure that the is powered off...

  • Page 15: Front Panel

    FREQUENCY SPAN SLOW FAST SCAN LOCK Figure 1.2: Fully-featured front-panel user-interface of the MOGLabs . The simplified “remote only” front-panel only contains the keyswitch. dDLC Safety keyswitch and multicolour indicator . Must be set to the STANDBY position to permit laser emission, see §2.1.1.
  • Page 16 FREQUENCY Laser frequency sweep amplitude: controls the height of the saw- SPAN tooth ramp driving the piezo (see §2.3). Frequency stabilisation (locking) control. The has two servo dDLC CONTROL controllers ( ) which can be operated independently SLOW FAST or in combination (see chapter Gain adjust for slow (piezo) and fast (current) feedback.

  • Page 17: Powering Up

    1.3 Powering up 1.3 Powering up 1. Ensure all hardware is connected - namely power, interlock and laser. Do not connect or disconnect the cable LASER DVI while the device is powered on. 2. Turn on the power switch on the rear of the unit (above the power input).

  • Page 18: Front Panel Control

    Chapter 1. Quick start 1.4 Front panel control can operate as a standalone device using the front panel dDLC display for intuitive control of the laser and controller functions. The left-hand side of the display shows a readout of the current device status and the right-hand side provides an interactive menu system.

  • Page 19: Remote Pc Operation

    Figure 1.3: Example showing the integrated oscilloscope functionality 1.5 Remote operation is designed for remote operation from a , either from dDLC the provided standalone application or by integration into ® Windows custom lab control software using a simple command interface.

  • Page 20: Locking With Internal Error

    Chapter 1. Quick start Figure 1.4: MOGLabs device discoverer which shows devices avail- dDLC able via and network interfaces. The scope automatically displays the measured photodetector volt- age and the error signal against time, for identifying and locking to features of interest. The oscilloscope supports mouse interactions and gestures (see §4.2.1) including dragging to adjust the sweep...
  • Page 21 1.6 Locking with internal error ® Figure 1.5: MOGLabs application for control and moni- dDLC Windows toring devices. dDLC 1. Adjust diode current to achieve a stable operating mode at the required optical power. 2. Ensure that the temperature of the laser has stabilised at the operating diode current (as shown in the Logging tab).
  • Page 22 Chapter 1. Quick start Figure 1.6: Typical saturated absorption spectra at wide span (A) and narrow span (B) with optimised phase. Engaging the lock stabilises to the peak (C) and increasing the gain too far leads to oscillation (D). 5. Increase the dither current in the laser settings until an error signal can be seen.
  • Page 23 1.6 Locking with internal error to the lock point, enabling comparison against the locked pho- todetector signal (magenta). If the value does not match the intended setpoint, follow the lock troubleshooting guide in §3.8. 10. Increase the slow gain K until the error signal amplitude starts to destabilise such as Figure...
  • Page 24 Chapter 1. Quick start...

  • Page 25: Laser Operation

    The external interlock input may be damaged by logic-level inputs and a relay is recommended for interfacing with logic-level systems. Confirm the details of your interlock system before connecting it to the dDLC.
  • Page 26 4. The hardware keyswitch on the front-panel must be turned dDLC to the Run (“on“) position. The keyswitch can be disabled remotely by software to guar- antee the system is disabled, but it is not possible to override the keyswitch from the Standby position.

  • Page 27: Temperature Control

    2 A into the to settle at a desired dDLC setpoint temperature, but typically the steady-state operating cur- rent is in the order of 100 mA to maintain a fixed temperature within a few degrees of ambient.

  • Page 28: Frequency Sweep

    Chapter 2. Laser operation Figure 2.1: Example of temperature overshoot and stabilisation to setpoint temperature (dashed line) to 50 mK within 3 minutes. Exact performance depends on ambient conditions, drive current, and laser chassis. 2.3 Frequency sweep The wavelength output by an external cavity diode laser depends on the diode temperature, injection current and length of the external cavity.

  • Page 29: Mode-Hops And Bias Current

    2.4 Mode-hops and bias current STACK 120V SPAN SPAN FREQUENCY TRIG time Figure 2.2: Example piezo output voltage (top) and trigger signal (bottom) when scanning. The rising trigger transition occurs when the piezo voltage is at the midpoint of the sweep. Note that the ramp slope can be inverted to sweep in the opposite direction.
  • Page 30 Chapter 2. Laser operation Diode cavity External cavities Diode gain Grating or filter COMBINED 384.0 384.1 384.2 384.3 384.4 Frequency (THz) Figure 2.3: Schematic representation for the various frequency-dependent factors of an . In this case the diode gain is so broad, variation cannot ECDL be seen on this scale.
  • Page 31 Figure 2.5: Frequency of a scanning laser measured with a MOGLabs wavemeter showing stable sweep (left) and with a mode-hop at one edge of the scan (right).
  • Page 32 Chapter 2. Laser operation Figure 2.6: Mode-hops can sometimes be identified in a photodiode sig- nal as step-changes in the optical power (arrows), or areas of high noise where the mode competition is unstable (marked sections). However, not all mode-hops are as easily identified in the photodiode signal. tions to the gain curve, shifting the gain curve envelope to match the shift in the external cavity contribution, ensuring that the position of the overall peak wavelength is smoothly varying.
  • Page 33 2.4 Mode-hops and bias current such as a wavemeter or scanning Fabry-Perot cavity. The following procedure is recommended for optimising the bias cur- rent to achieve the best MHFR 1. Initially set the to zero. OFFSET SPAN 2. Adjust the Setpoint Current to achieve a stable mode near the desired wavelength and required optical power.

  • Page 34: Compliance Voltage

    Chapter 2. Laser operation 10. Adjust the diode by small amounts to try to remove CURRENT at least one of these mode hops, then attempt to increase the SPAN further. 11. If the mode hops are at both edges of the scan and cannot be removed by adjustments, attempt in- OFFSET...

  • Page 35: System Error Messages

    Insufficient compliance voltage dDLC current within the specified maximum compliance limit (see §2.5). It is recommended to set the compliance limit to ∼ 1 V above the...

  • Page 36: Troubleshooting Current And Sweep

    Cannot increase OFFSET OFFSET When hitting a limit, the value in the app is shown with a red dDLC background colour. When a large bias current is used, the laser is only Changing SPAN causes a mode-hop in quasi-thermal equilibrium because the thermal load is changing across the sweep.

  • Page 37: Troubleshooting Tec Operation

    Indicates a problem measuring the thermistor on Measured temperature is always 6 the laser head. Power-off the dDLC and reconnect the DVI cable. If the issue persists, verify the thermistor connection to the laser headboard and continuity through the DVI cable.
  • Page 38 Chapter 2. Laser operation currents inducing thermal fluctuations that perturbs the laser fre- quency. abs recommends isolating the laser head from the MOGL environment using a acrylic box or similar, in particular to block any drafts from systems. HVAC...

  • Page 39: Laser Locking

    High- bandwidth locking techniques can even reduce the time-averaged linewidth of the laser (see §3.5). has separately configurable controllers for dDLC SLOW FAST responding to perturbations on different timescales (Figure 3.1). The...

  • Page 40: Dc Locking To An Atomic Transition

    There are a wide number of techniques for generating error signals from different references, here we will outline how to configure the for the most common use-cases. dDLC locking to an atomic transition Often referred to as side-of-peak locking, the locking method adjusts the laser to maintain a specific...

  • Page 41: Ac Locking To An Atomic Transition

    locking to an atomic transition Figure 3.2: Schematic setup for satabs locking to an atomic transition. PD is a photodetector, BS beamsplitter, M mirror, λ/4 a quarter-wave waveplate. 3. Open the lock settings and set the Lock mode to External error using the PD input.
  • Page 42 Chapter 3. Laser locking laser frequency (or equivalently the reference frequency) is required. has an integrated 250 kHz oscillator which can MOGL dDLC directly dither the diode current or drive an external modulator via backpanel connector. MOD OUT Figure 3.3...

  • Page 43: External Error Signal Locking

    4. Adjust the demodulation phase to maximise the amplitude of the feature at the lock point, ensuring it has negative slope. Alternatively, use the Autoset Phase feature of the dDLC automatically optimise the phase. 5. Reduce the dither strength if required to reduce the influence of higher-order perturbations.
  • Page 44 Chapter 3. Laser locking 1. Configure the laser to sweep across the desired lock point. 2. Open the lock settings and set the Lock mode to External error using the PD input. 3. Set the master gains to 1.0. Where the gain of the external signal processing can be adjusted, it is recommended to keep the master gain near unity to reduce the amplification of input noise.

  • Page 45: External Low-Bandwidth (Wavemeter) Locking

    The following steps are recommended to configure the for lock- dDLC ing to a wavemeter, although analogous MOGL steps should apply to other wavemeter brands.
  • Page 46 SLOW 12. Adjust the gains until the laser converges at the desired rate without oscillating at the target wavelength due to mea- surement noise. Figure 3.4: Screenshot showing typical settings for a MOGLabs wavemeter to lock with a dDLC...

  • Page 47: External High-Bandwidth (Pdh) Locking

    In this arrangement, we still recommend using the servo of the SLOW to correct for long-term drift, rather than controlling the dDLC SLOW actuator from an external servo. Using the provides the most dDLC flexibility for remote control and monitoring, and avoids potential issues related to saturation of the controller.
  • Page 48 3. Connect the output from the to the on the MON A PD IN and set the to output dDLC FAST ERROR 4. Connect from the to the on the TRIG OUT dDLC SWEEP IN and configure the...
  • Page 49 FAST+P to “stretch” the error signal as described in the Application Note. The error signal should now be clearly visible on the integrated oscilloscope mode. dDLC 11. Adjust the to put the resonance in the centre of OFFSET the sweep and reduce the as far as possible.

  • Page 50: Noise Spectrum Optimisation

    §3.2. The Laser unlocked noise spectrum was obtained in Scan Mode with zero span manually centred on the atomic resonance. The Off MOGLabs DLC-202 + ECD-003 monoblock laser noise spectra 1000.00 Unlocked 10.00 Piezo 1.00...
  • Page 51 3.6 Noise spectrum optimisation resonance curve was similarly obtained with the laser unlocked but tuned far away from any resonances. This represents the overall noise floor of the frequency discriminator: it is meaningless to try to reduce the laser frequency noise below this level. When feedback is enabled, the noise for low Fourier frequen- SLOW...

  • Page 52: Troubleshooting Error Signal Generation

    Chapter 3. Laser locking 3.7 Troubleshooting error signal generation Check the Lock Mode and Lock Source in the Lock Settings. Confirm Error signal is zero that dither is enabled when using -locking, and when using exter- nal dither (such as a coil) connect to an oscilloscope set MOD OUT to 50 Ω...

  • Page 53: Troubleshooting Lock Stability

    3.8 Troubleshooting lock stability When encountering difficulties related to engaging the frequency lock, we recommend using the “Lock diagnostics” tab in the dDLC PC app (see §4.4) to identify what behaviour is occurring upon activating the locks. Try inverting the polarity of the servo controller to Servo does not lock to zero-crossing confirm the action is correct.

  • Page 54: Saturated-Absorption Recommendations

    Chapter 3. Laser locking A sudden perturbation was detected in the controller out- Display shows LOCK WARNING put (at least 20% output change in 10ms). Usually this represents a significant perturbation that likely destabilised the lock. For exam- ple, after a mode-hop the laser may lock to a different resonance. controller has reached saturation of its out- controller gives FAST...
  • Page 55 It is vital that the coil be located far from the and from the laser dDLC head, or that it be shielded. A layer of high-permeability material (soft iron or mu-metal) is probably adequate. To test this, simply reverse the polarity of the coil connection.
  • Page 56 Chapter 3. Laser locking...

  • Page 57: Software Control

    Starting the application will display dDLC the discoverer (Figure 4.1) which scans your and local network devices. Select the desired device and click Connect to dDLC start the application. Figure 4.1: MOGLabs device discoverer which shows devices avail- dDLC able via and network interfaces.
  • Page 58 In environments that contain more than one device, MOGL dDLC recommends assigning a name to each to more easily identify the desired connection. Clicking the Rename button in the discoverer allows a user-specified string to be assigned to each unit.
  • Page 59 4.1 Overview ® Figure 4.3: MOGLabs application for control and moni- dDLC Windows toring devices. dDLC with a green background, warning states are shown in orange, and error states in red. 3. Primary function on/off controls, permitting enabling or dis- abling of core functionality.
  • Page 60 Chapter 4. Software control toset option which measures the scope capture and automat- ically sets the parameter. 6. Tabs for accessing different application functionality, such as spectrum analysis or logging. 7. Drop-down boxes for selecting the channels and graph scaling of the oscilloscope feature.
  • Page 61 This generally makes Ether- net more desirable for remote operation and logging, but raises the possibility of simultaneous access from multiple locations At this stage the dDLC does not provide “local lockout” or similar functionality.

  • Page 62: Oscilloscope Mode

    Chapter 4. Software control 4.2 Oscilloscope mode The oscilloscope feature displays two channels simultaneously which can be selected from the drop-down menus. By default the capture is set to timebase which captures one duration of the laser AUTO sweep, but other options are available. The capture is triggered such that the middle of the sweep is always in the middle of the capture.

  • Page 63: Device Settings

    4.3 Device settings Similarly, scrolling the mouse wheel adjusts both simultaneously to zoom in or zoom out from the position of the mouse cursor. Combining the mouse wheel with the keys allows directly adjusting CTRL the setpoint current or scan bias while looking at the sweep, which is convenient for finding a stable operating mode and optimising the scan-range there (see §2.4.1).
  • Page 64 Chapter 4. Software control Desired operating temperature of the laser diode. Setpoint temperature Temperature measured by the thermistor in the laser head. Measured temperature ◦ Displayed in red when the temperature is more than 1 C from the ◦ setpoint, and green when within 0.1 C of the setpoint.
  • Page 65 4.3 Device settings Critical resistance below which the short-circuit alarm will be Short-circuit resistance triggered when running at least 100 mA. Critical resistance above which the open-circuit alarm will be Open-circuit resistance triggered when running at least 100 mA. 4.3.2 Laser settings Figure 4.9: Screenshot of typical laser settings dialog box.
  • Page 66 Chapter 4. Software control current should be set at least 10 mA above the highest intended operating current. Safe current As part of the laser build process, a safe operating current will be specified for checking the health of the diode laser. It is strongly recommended to check the output power of the laser at the safe current to check for damage after shipping or relocating the laser.
  • Page 67 Sweep piezo amplitude from bias currents beyond what can normally be generated by the . This parameter controls the amplitude of the sweep fed to the dDLC piezoelectric transducer, which effectively increases the relative bias current at the expense of ramp voltage.
  • Page 68 Chapter 4. Software control 4.3.3 Current presets Often there are a number of useful laser currents relevant to different diagnostic or operating conditions (such as low power/high power operating modes). Current presets provide a mechanism for storing named settings for later reference. Figure 4.10: Screenshot of current presets popup menu (left) and associ- ated settings dialog (right).
  • Page 69 4.3 Device settings Figure 4.11: Screenshot of typical lock settings dialog box for a locked laser. The Slow Lock and Fast Lock buttons both represent the servo lock status, and can be clicked to toggle the lock state. FSC Mode An external fast servo controller (such as the ) is MOGL used instead of the internal...
  • Page 70 Chapter 4. Software control ORANGE Servo is running but a warning condition was identified (check the logging tab). Does not necessarily mean the laser is un- locked, but should be checked. RED An error was detected and the lock needs to be reset. BLACK Servo is not available for the specified Lock type.

  • Page 71: Lock Diagnostics

    4.4 Lock diagnostics 4.3.5 Monitor outputs units with a rear-panel supporting monitor output dDLC connectors, the signals output on the connectors MON-A MON-B can be specified from the Settings menu bar. Figure 4.12: Screenshot showing monitor signals available for the rear- panel monitor outputs.
  • Page 72 Chapter 4. Software control Figure 4.13: Screenshot showing application running in dark mode. Figure 4.14: Screenshot showing expected behaviour of the servo SLOW upon being engaged. Once the controller activates (dashed line), the con- troller action integrates the error signal to reach the lock point at the zero crossing corresponding to the absorption peak within the first 10ms and then stabilises.

  • Page 73: Spectrum Analyser Mode

    4.5 Spectrum analyser mode Figure 4.15: Screenshot showing lock diagnostic when the FAST controllers compete. Upon engaging the controller (dashed SLOW FAST line) both controllers are seen to continuously integrate indicating they are opposing each other’s action. In this case the -block needed to be enabled on the servo.
  • Page 74 Chapter 4. Software control windows, which can result in clearer spectra that reach down to lower frequencies, but have fewer available channels and a much slower acquisition time. Figure 4.16: Screenshot showing spectrum analyser mode comparing sev- eral traces. The dashed line is moved by double-clicking in the graph area, with associated frequency displayed in the bottom left.
  • Page 75 4.5 Spectrum analyser mode Figure 4.17: Screenshot of trace options in spectrum analyser mode. Se- lect the Store live option to record the most recent spectrum to the stored trace. Sometimes it can be difficult to intuit when the total noise is min- imised because the control action can act to shift noise power at low frequency to high frequency, changing the shape of the noise pro- file without decreasing the total noise.

  • Page 76: Logging

    Chapter 4. Software control 4.6 Logging The logging tab shows the temperature stability and locking servo outputs over long timescales, as well as an event log of timestamped debug information about device operation. In the event of unexpected device behaviour or error condition, check the event log for additional diagnostic information.

  • Page 77: Firmware Update

    4.7 Firmware update abs will release new versions of the firmware running on the MOGL to provide new functionality and address issues identified in dDLC previous versions. abs strongly recommends updating to the MOGL latest firmware whenever possible to achieve the best performance.
  • Page 78 Click Update All to begin the update process. Do not interact with while the firmware update is in progress as the results dDLC may be unpredictable. The PC application is disabled while the firmware update dialog is shown, or if a firmware update is detected to have been initiated.

  • Page 79: A Specifications

    A. Specifications Values for parameters marked with an asterisk ∗ are calculated from detailed simulations. Experimental verifications are in progress. Parameter Specification Current regulator (B5110 single-channel driver) Output current 0 to 1200 mA ±5 µA, control ±8 nA √ ∗ Noise 240 pA/ Hz @ 1 kHz...
  • Page 80 Appendix A. Specifications Parameter Specification Piezo (B1190 dual-channel driver) Piezo output Two independent channels 0 to 140 V, 30 mA (charge and discharge) Sweep/control Individual sweep and control DACs 16-bit unipolar Resolution Sweep: 2.5 mV at maximum range Control: variable gain 200 µV to 4 µV per LSB √...
  • Page 81 8 BNC connectors 4 analogue in (PD IN, AUX A, AUX B, FAST) 2 analogue out (CHAN A, CHAN B) MOD OUT, TRIG out 1 MOGLabs LASER (DVI-D DL socket) Analogue in (4) Signal range ±4.096 V protected to ±15 V Photodetector AC: 12.5 MHz >...
  • Page 82 Display 127mm, 800x480 pixels, full colour Connectivity Communications TP 10/100 ethernet; USB 2.0 Type B Laser Standard: MOGLabs DVI-D DL socket Option: Toptica DLPro Power out ±15 V photodetector supply (M8-3 Thorlabs compatible) Power & dimensions IEC input 90 to 264 Vac 47 –...

  • Page 83: B Command Language

    B. Command language acts as a simple device and socket MOGL dDLC USB-CDC server, so no specific device drivers or s are required to commu- nicate with it. Therefore the is cross-platform and language- dDLC agnostic, since most languages have built-in support serial port and socket-based protocols.

  • Page 84: Python Library

    Appendix B. Command language Figure B.1: Demonstration of interacting with the using the Device dDLC Commander. Outbound transmissions are timestamped and shown in blue, errors are shown in red. Commands that perform an action always respond with a string prefixed by OK or ERR.
  • Page 85 B.2 Python library B.2.1 MOGDevice class The MOGDevice represents a single connection over provides two main mechanisms for interaction: ask and cmd. Both functions are blocking and wait for a CRLF-terminated response. If the response string has the prefix ERR, an instance of DeviceError is raised with details of the failed query.
  • Page 86 Appendix B. Command language connection and stores the results as keys which can be accessed directly by indexing the device instance via __getitem__(). "type" Product name string (e.g. DDLC). "code" PCB identification string. "rev" Mainboard PCB revision to identify firmware compatibility.
  • Page 87 USBError and attempts to clarify the error description. B.2.4 Example code The following example demonstrates simple interaction with the dDLC including separation of device errors from communications errors. Demonstration of the MOGDevice class import logging , time...

  • Page 88: System Overview

    B.3 System overview Returns the model, serial number, firmware versions, and any user- INFO assigned name associated with the . Similar to the query dDLC *IDN? standardised across devices. SCPI Returns the version numbers of the component firmwares on the de- vice as a comma-separated list.

  • Page 89: Laser Control

    B.4 Laser control B.4 Laser control Returns string containing most standard setpoints and readings, REPORT providing a simple mechanism to snapshot device state with re- duced communications overhead compared to making multiple sep- arate queries. The key-value pairs are delimited with a colon ( code 0x3a) ASCII and separated with a line-feed (...
  • Page 90 This voltage is PDOFFSET removed from the input signal at the input to the . Also dDLC accepts the optional argument which automatically measures AUTO offset from the current input. Get/set the demodulation phase of the modulator, in degrees. Also...

  • Page 91: Sweep

    B.5 Sweep ◦ phase by 90 , and to run the optimisation algorithm using the error signal amplitude. B.5 Sweep Get/set the sweep span (amplitude), in percentage full-scale. SPAN Get/set the offset of the sweep in percentage full-scale. OFFSET Automatically limited by the chosen to prevent truncation of SPAN the sweep.

  • Page 92: Locking

    Appendix B. Command language Report the measured voltage across the , in volts. TEC,V Get/set the polarity inversion state. TEC,INV Get/set the acceptable temperature range. Used as safeguard to TEC,TMIN/TMAX prevent operation with the wrong polarity. Get/set the permitted range of resistance, in ohms.
  • Page 93 B.7 Locking EXT External error mode where the error signal is sup- plied directly to the specified input, also used for locking (§3.1). SLOW External servo mode, used for wavemeter lock- SLOW ing (§3.4). The input signal is fed directly to the controller output, and the controller is SLOW...
  • Page 94 Appendix B. Command language Activate the lock for the associated servo. The lock will then be < type > ,LOCK engaged at the midpoint of the sweep to prevent inducing a mode- hop. < > Disable lock for the associated feedback channel; that is, switch to type ,UNLOCK scanning mode.

  • Page 95: C Error Indicators

    C. Error indicators detects a wide range of fault conditions and MOGL dDLC deactivates related circuitry accordingly. The front-panel LEDs display provide indication of the state of these functions. C.1 Keyswitch STANDBY Colour Status GREEN Keyswitch is set to RUN and no error detected...

  • Page 96: System States And Error Messages

    Capture debug ZIP item from the Help menu. Figure C.1: Menu item to capture diagnostic information about the dDLC C.4.1 Normal operation STANDBY System is disabled by user input, generally because the keyswitch is in the STANDBY state.
  • Page 97 C.4 System states and error messages C.4.2 Error states INTERLOCK One of the interlock preconditions is not being met, see §2.1. TOGGLE KEYSW Hardware or software toggle of the keyswitch is required to resume normal operation, see §2.1.1. KEYSW OVERRIDE System is disabled because the keyswitch was overridden by software.
  • Page 98 Appendix C. Error indicators...

  • Page 99: D Connectors And Cables

    LASER Socket: DVI-D DL (Dual Link) Plug: DVI-D SL (Single Link) Do not use SL cables Figure D.1: LASER connector on rear panel of , and plug of common dDLC display cable, unsuitable for use with due to missing connections. dDLC...

  • Page 100: Photodetector

    figurations. Please contact abs if you intend to use the MOGL dDLC to operate a laser that uses multiple piezoelectric transducers. D.2 Photodetector The photodetector signal is connected via a standard connector.

  • Page 101: Remote Interlock

    D.3 Remote interlock D.3 Remote interlock The remote interlock input permits integration with laboratory inter- lock systems, see §2.1. The associated rear-panel interlock socket is a standard 3.5 mm cylindrical stereo headphone jack. The two signal pins (for two lasers) are connected to ground via 10 k resis- tor.
  • Page 104 MOG Laboratories Pty Ltd © 2007 – 2025 49 University St, Carlton VIC 3053, Australia Product specifications and descriptions in this doc- Tel: +61 3 9939 0677 info@moglabs.com ument are subject to change without notice.

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