Lightwave Communications LDX-3232 manual IPD Setpoint

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CA LI BRATION AND TR OUBLESHOOTING

Remote Calibration of the LDX-3232 Current Source

C H A P T E R 6

Configure the current source in the following manner for the laser current source calibration:

Function

State

GPIB COMMAND

LASER MODE

I (constant current low bandwidth)

LAS:MODE:ILBW

RANGE

Low (lowest per instrument model)

LAS:RAN x

LIMIT

90% of FS (full scale of range)

LAS:LIM:Ix

IPD SETPOINT

80% of FS

LAS:LDI

a.With the LASER output off, connect a calibrated ammeter to the PD Anode output of the Laser Current Source output connector (9 pin on rear panel), and connect the circuit of Figure 6.1 to the LASER and PD outputs with the correct load resistor for the Current Source model you are calibrating (See Table 6.2).

b.Enter the LAS:OUT ON command to turn the LASER output on. Verify proper operation, i.e. the IPD output should be close to the setpoint, and the unit should not be in current limit (read the limit status via the LAS:COND? query, bit 0).

c.Enter the LAS:CAL:MDI command to place the Current Source in its LASER Current Calibration mode. The Current Source will increase the laser current output until the current at the PD monitor (IPD) inputs equals the targeted setpoint.

d.After a few seconds, the Current Source will be ready for the actual IPD current to be entered via the LAS:MDI <nrf value> command. The measured value of the current should not be entered until the Current Source is ready to receive it. The Current Source will be ready to receive the current value when, after a LAS:CAL:MDI? query is sent, the response from the Current Source is "1".

e.Once the actual IPD value is entered via the LAS:MDI <nrf value> command, the Current Source will store the new calibration value. It will then set the output to approximately one-fourth (1/4) of the original current. (For example, if the first calibration setpoint was 4000 µA, the second setpoint will be 1000 µA.) Then, it will be ready to receive the second calibration value.

f.Input the second actual (measured) monitor diode current (as an <nrf value>) as in Step d.

g.Once the second actual IPD value is entered via the LAS:MDI command, the new calibration constants will be calculated and stored into non-volatile memory. The OPC? query may be used (after the LAS:MDI value is sent) to determine when the calibration is completed. Or, wait about two seconds before continuing with other GPIB commands.

04_06

LDX-3232

97

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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 Model Number Serial Number End-User Name Company Phone Fax Comments, Suggestions, and ProblemsDescription of the problem Xiv LDX-3232 Product Overview Introduction and SpecificationsAC Line Power Requirements Installing Your LDX-3232 High Compliance Current SourceInitial Inspection Grounding RequirementsTilt-Foot Adjustment Gpib ConnectorGpib Address Operating the LDX-3232 Precision Current SourceLDX-3232 Front View Maintenance Specifications 13 µs 12 ms Type Pulse Width DelayTTL 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 ConnectorGrounding Considerations Setting the PD BiasPhotodiode Connections Display Operating a Laser in Constant Current I ModeFront Panel Operation 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 AddressChanging Operation from Local to Remote LDX-3232 Current Source Command SetCommand Syntax OFF OLD NEW True False SET Reset LASLDI? LDX-3232 Command Path Structure Command PathsIEEE488.2 Command Commands LIM LDX-3232 Frequently Used CommandsNone Operation Complete Definition Status ReportingEvent and Condition Registers 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 Commands Used to create a delay in the execution of furtherUsed to enter the laser current calibration mode Used to enter the laser voltage calibration modeEnables Laser display to show parameter values Returns status of photodiode monitor power displaySets the enable register for Laser conditions Returns the value of the LAS conditions enable registerUsed to set the constant optical power setpoint, if Used to return the optical power from monitorUsed to enable/disable the front panel modulation input Or P optical powerPowered up Returns the status of the Term commandReturns the elapsed time since the timer was last reset Used to return the Laser setpoint tolerance valueCommand Description Format LDX-3232 Device-Dependent CommandsDelay LDX-3232 Device-Dependent Command ReferenceCalmd LAS Calpd ERRors?LASerCALMD LASerCALMD? Responsivity CAL PD parameter setting Syntax DiagramCalibration for that bandwidth Selected. This procedure is outlined in ChapterLASerCALLDI LASerCALLDV LASerCALLDI?LDI LAS CAL LAS CAL LDVLASerCALMDI True measured value. This procedure is outlined in ChapterLASerCALLDV? LASerCOND? LASerCALMDI?MDI LAS CAL IPDLASerDEC LASerDISplay? LASerDISplayLAS DIS LASDIS?LASerDISplayLDI? LASerDISplayLDILasdisldi LDILASerDISplayLDV Voltage measurement Syntax DiagramLASerDISplayLDV? LASDISLDV?LASerDISplayMDI? LASerDISplayMDILAS DIS MDI LAS DIS IPDLASerDISplayMDP? LASerDISplayMDPPPD LAS DIS MDPLASerDISplaySET LASerDISplayPARAMLAS DIS Param LAS DIS SETLASDISPLAYSET? LASerENABleCONDLASerDISplaySET? LAS Enab Cond LASerENABleCOND?Bit An nrf value whose sum represents the bits that are enabled LASerENABleEVEntAction enables the Laser status event register so that LasenabeventLAS Enab EVE LASerENABleEVEnt?LASerENABleOUTOFF LAS Enab Outoff LASerENABleOUTOFF?Command while the condition status is constantly changing LASerENABleEVEnt commandLASerEVEnt? LAS EVEFunction for the Laser output LASerINCLASerLDI This measurement is updated approximately once every 600 msLASerLDI? LAS LDILASerLDV? LASerLDVFor LDV calibration LAS LDVLASerLIMitI2? LASerLIMitI2Limit in use depends on the Laser output range selection LAS LIMLASerLIMitI4 Displayed, and then releasing the SET switchLASerLIMitI4? LASLIMI4?MDP LAS LIM LASerLIMitMDPLASerLIMitMDP? LASerLIMitV? LASerLIMitVLASerMDI? LASerMDIMDI LAS IPD MDP P PD setpoint would be usedLAS Mdln LASerMDLNLASerMDLN? MDP LAS LASerMDPLASerMDP? LAS Mode Ihbw LAS ModeLASerMODE? LASerMODEIHBWLASerMODEILBW LAS Mode MDPLASerMODEMDP LasmodeilbwLAS OUT LASerOUTputLASerOUTput? LASerRANge? LASerRANgeLAS RAN LASRAN?30 µA, for use in constant P mode with Calpd = Where the response is the constant I setpoint value, in mALASerSETLDI? LASerSETMDI?LASerSETMDP? Where the response is the constand PPD setpoint, in mWLASerSTEP 100 µALASerSTEP? LASerTOLerance commandLASerTOLerance LAS TOLMESsage LASerTOLerance?Second is the time window, in seconds MESRADix MESsage?RADix? Term 0 command is sent or the LDX-3232 is powered offRAD Means hexadecimal, and OCT means octalTime LDX-3232 was last powered upTime clock is independent of the Timer clock Timer Since the last TIMER? query was issuedLast TIMER? query is returned Seconds since the last TIMER? query was issuedSaving 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 TroubleshootingDMM Description Manufacturer/Model SpecificationRecommended Equipment Current Source Calibration Local Calibration of the LDX-3232 Current SourceRange Current LimitIPD Current Calibration CAL PD Constant powerSet equal to zero IPD SetpointLaser Forward Voltage Measurement Calibration Laser Mode2000 mA Set to FS full scale of rangeLimit Gpib CommandRemote Calibration of the LDX-3232 Current Source Lasldi nrf value command IPD Setpoint Function State Gpib Command General Troubleshooting GuideEEPROM, Lllll will be displayed on the display the laser Current source must be recalibratedCommand Feature can be defeated via the Lasenableoutoff101 Response Message
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