Lightwave Communications LDX-3232 manual Setting Up the Precision Current Source

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O P E R A T I O N

Operating a Laser in Constant Current (I) Mode

Setting Up the Precision Current Source

C H A P T E R 2

Set the LDX-3232 in Constant Current, low bandwidth mode by selecting I in the MODE section of the front panel. Do this by toggling the SELECT push button until the I indicator is illuminated. Repeatedly pressing the (MODE) SELECT switch cycles through the current (I), light power (P), or high-bandwidth current (IHBW) control modes.

Next, in the RANGE section set the current source range by selecting the 2000 mA range indicated by the accompanying LED. You will need to press the SELECT push button twice to change the range. It must be pressed twice quickly (within less than 1 second) to switch between ranges, and the LASER output must be off (LASER MODE ON indicator unlit) in order to change ranges.

Configure the display so that it reads laser current in mA. Press and release the SELECT switch in the DISPLAY section of the front panel until the mA annunciator is lit. The (DISPLAY) SELECT switch is also used to select the IPD (PD current, µA), PPD (laser power, mW), or V (forward voltage, V) measurement or setpoint display modes. When the setpoint mode is active, the corresponding annunciator will flash to indicate setpoint rather than measurement display.

To only view the setpoint, press and hold down the display SELECT switch for two or more seconds. When the SELECT switch is released the previous measurement mode will be restored.

At this point the LDX-3232 is in Constant Current Mode, (I), in the 2000 mA range, and the display is reading in mA. Next, we need to adjust the setpoint of the laser current source.

To adjust the setpoint of the current source to 1500 mA, turn the adjust knob to vary the setpoint. When the adjust knob is turned, the LDX-3232 automatically changes to setpoint mode indicated by the flashing annunciator. Adjust the setpoint to 1500 mA. After an adjustment has been made, and the adjust knob is released, the setpoint mode will time out in three seconds. The display will revert to the original measurement display mode (I, IPD, V, or PPD).

The instrument is still not ready to turn on the laser. One of the laser protection features our precision current sources offer is a fully independent hardware current limit. The current limit protects your laser by never allowing the laser drive current to exceed the limit independent of the setpoint and the output control mode (Constant Current or Constant Power).

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LDX-3232

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Contents User’s Guide Page Table of Contents Remote Operation Command Reference Iv LDX-3232 List of Figures Vi LDX-3232 List of Tables Viii LDX-3232 General Safety Considerations Safety Information and the ManualSafety Marking Symbols Safety SymbolsWarranty Claims for Shipping Damage Description of the problem Comments, Suggestions, and ProblemsModel Number Serial Number End-User Name Company Phone Fax Xiv LDX-3232 Product Overview Introduction and SpecificationsGrounding Requirements Installing Your LDX-3232 High Compliance Current SourceAC Line Power Requirements Initial InspectionOperating the LDX-3232 Precision Current Source Gpib ConnectorTilt-Foot Adjustment Gpib AddressLDX-3232 Front View Maintenance Specifications TTL Type Pulse Width Delay13 µs 12 ms Description Model Number Available Options and AccessoriesPower On Sequence Applying Power to Your LDX-3232Power On State Connecting to the LaserCommon Laser Cathode Photodiode Anode Interlock Connections Back Panel LD ConnectorPhotodiode Connections Setting the PD BiasGrounding Considerations Front Panel Operation Operating a Laser in Constant Current I ModeDisplay Setting Up the Precision Current Source E R a T I O N Entering Photodiode Responsivity Values Operating a Laser in Constant Power P ModeMethod to calculate the responsivity is suggested below LDX-3232 Error Indicators Error IndicatorsError Indicators LDX-3232 Changing the Gpib Address Reading the Gpib AddressCommand Syntax LDX-3232 Current Source Command SetChanging Operation from Local to Remote OFF OLD NEW True False SET Reset LASLDI? LDX-3232 Command Path Structure Command PathsIEEE488.2 Command Commands None LDX-3232 Frequently Used CommandsLIM Event and Condition Registers Status ReportingOperation Complete Definition LDX-3232 Status Reporting Schematic Diagram Output Off Register Disabled 10 N/A Enabled 11 N/A 12 N/A 13 N/A 14 N/A 15 N/ALASerENABleOUTOFF nrf LASerENABleOUTOFF? Error Messages Command Timing and CompletionResponse Message Error Code ClassificationsMode Used to enter the laser voltage calibration mode Used to create a delay in the execution of furtherCommands Used to enter the laser current calibration modeReturns the value of the LAS conditions enable register Returns status of photodiode monitor power displayEnables Laser display to show parameter values Sets the enable register for Laser conditionsOr P optical power Used to return the optical power from monitorUsed to set the constant optical power setpoint, if Used to enable/disable the front panel modulation inputUsed to return the Laser setpoint tolerance value Returns the status of the Term commandPowered up Returns the elapsed time since the timer was last resetCommand Description Format LDX-3232 Device-Dependent CommandsDelay LDX-3232 Device-Dependent Command ReferenceLASerCALMD ERRors?Calmd LAS Calpd LASerCALMD? Responsivity CAL PD parameter setting Syntax DiagramLASerCALLDI Selected. This procedure is outlined in ChapterCalibration for that bandwidth LAS CAL LDV LASerCALLDI?LASerCALLDV LDI LAS CALLASerCALLDV? True measured value. This procedure is outlined in ChapterLASerCALMDI LAS CAL IPD LASerCALMDI?LASerCOND? MDILASerDEC LASDIS? LASerDISplayLASerDISplay? LAS DISLDI LASerDISplayLDILASerDISplayLDI? LasdisldiLASDISLDV? Voltage measurement Syntax DiagramLASerDISplayLDV LASerDISplayLDV?LAS DIS IPD LASerDISplayMDILASerDISplayMDI? LAS DIS MDILAS DIS MDP LASerDISplayMDPLASerDISplayMDP? PPDLAS DIS SET LASerDISplayPARAMLASerDISplaySET LAS DIS ParamLASerDISplaySET? LASerENABleCONDLASDISPLAYSET? Bit LASerENABleCOND?LAS Enab Cond Lasenabevent LASerENABleEVEntAn nrf value whose sum represents the bits that are enabled Action enables the Laser status event register so thatLAS Enab EVE LASerENABleEVEnt?LASerENABleOUTOFF LAS Enab Outoff LASerENABleOUTOFF?LAS EVE LASerENABleEVEnt commandCommand while the condition status is constantly changing LASerEVEnt?Function for the Laser output LASerINCLAS LDI This measurement is updated approximately once every 600 msLASerLDI LASerLDI?LAS LDV LASerLDVLASerLDV? For LDV calibrationLAS LIM LASerLIMitI2LASerLIMitI2? Limit in use depends on the Laser output range selectionLASLIMI4? Displayed, and then releasing the SET switchLASerLIMitI4 LASerLIMitI4?LASerLIMitMDP? LASerLIMitMDPMDP LAS LIM LASerLIMitV? LASerLIMitVMDP P PD setpoint would be used LASerMDILASerMDI? MDI LAS IPDLASerMDLN? LASerMDLNLAS Mdln LASerMDP? LASerMDPMDP LAS LASerMODEIHBW LAS ModeLAS Mode Ihbw LASerMODE?Lasmodeilbw LAS Mode MDPLASerMODEILBW LASerMODEMDPLASerOUTput? LASerOUTputLAS OUT LASRAN? LASerRANgeLASerRANge? LAS RANLASerSETMDI? Where the response is the constant I setpoint value, in mA30 µA, for use in constant P mode with Calpd = LASerSETLDI?100 µA Where the response is the constand PPD setpoint, in mWLASerSETMDP? LASerSTEPLAS TOL LASerTOLerance commandLASerSTEP? LASerTOLeranceMES LASerTOLerance?MESsage Second is the time window, in secondsRADix MESsage?Means hexadecimal, and OCT means octal Term 0 command is sent or the LDX-3232 is powered offRADix? RADTime clock is independent of the Timer clock LDX-3232 was last powered upTime Seconds since the last TIMER? query was issued Since the last TIMER? query was issuedTimer Last TIMER? query is returnedSaving and Recalling from the Front Panel Functions and FeaturesSaving and Recalling Under Remote Operation Using the Laser Compliance Voltage AdjustmentLDX-3232 Rear Panel Using the LDX-3232 Current Source’s Trigger FunctionBNC Interlock Usage Example Modulating the Laser Current SourceModulating the Laser Current Source Functions and Features Calibration Overview Calibration and TroubleshootingRecommended Equipment Description Manufacturer/Model SpecificationDMM Current Limit Local Calibration of the LDX-3232 Current SourceCurrent Source Calibration RangeIPD Current Calibration IPD Setpoint Constant powerCAL PD Set equal to zeroSet to FS full scale of range Laser ModeLaser Forward Voltage Measurement Calibration 2000 mARemote Calibration of the LDX-3232 Current Source Gpib CommandLimit Lasldi nrf value command IPD Setpoint Function State Gpib Command Current source must be recalibrated Troubleshooting GuideGeneral EEPROM, Lllll will be displayed on the display the laserCommand Feature can be defeated via the Lasenableoutoff101 Response Message
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