Lightwave Communications LDX-3232 manual Laser Forward Voltage Measurement Calibration

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C H A P T E R 6

CALIBRATION AND TR OU BLESHOOTING

Remote Calibration of the LDX-3232 Current Source

Laser Forward Voltage Measurement Calibration

The following procedure is for calibrating the LASER voltage measurement.

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

Function	State	GPIB Command
LASER MODE	I (constant current low bandwidth)	LAS:MODE:ILBW
RANGE	2000 mA	LAS:RANGE1
CURRENT LIMIT	Set to FS (full scale of range)	LAS:LIM:Ix
I SETPOINT	400 mA	LAS:LDI 400

a.With the LASER output off, connect a calibrated voltmeter, in parallel with a resistor (15 Ω, 5 W), to the LASER output (Laser Anode and Laser Cathode) on the rear panel of the Current Source.

b.The current source output must be on in order to enter the LDV calibration mode. Enter the LAS:OUT ON command to turn the current source output on.

c.Enter the LAS:CAL:LDV command to place the Current Source in its LASER Voltage Calibration mode.

d.Enter the measured voltage (in volts) via the LAS:LDV <nrf value> command. The measured value of the voltage should not be entered until the LDX-3232 Current Source is ready to receive it. The current source will be ready to receive the voltage value when, after a LAS:CAL:LDV? query is sent, the response from the Current Source is "1".

e.Once the actual voltage value is entered via the LAS:LDV <nrf value> command, the Current Source will set the current to approximately one-fourth (1/4) of the original value. It will then expect the second calibration voltage point.

f.Input the second actual (measured) LASER forward voltage (as an <nrf value>) as in Step d.

g.Once the second actual voltage value is entered via the LAS:LDV command, the Current Source will store the new calibration constants. The OPC? query may be used (after the LAS:LDV value is sent) to determine when the calibration is completed. Or, wait about two seconds before continuing with other GPIB commands.

98 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 Safety Information and the Manual General Safety ConsiderationsSafety Symbols Safety Marking SymbolsWarranty Claims for Shipping Damage Comments, Suggestions, and Problems Description of the problemModel Number Serial Number End-User Name Company Phone Fax Xiv LDX-3232 Introduction and Specifications Product OverviewInitial Inspection Installing Your LDX-3232 High Compliance Current SourceAC Line Power Requirements Grounding RequirementsGpib Address Gpib ConnectorTilt-Foot Adjustment Operating the LDX-3232 Precision Current SourceLDX-3232 Front View Maintenance Specifications Type Pulse Width Delay TTL13 µs 12 ms Available Options and Accessories Description Model NumberApplying Power to Your LDX-3232 Power On SequenceConnecting to the Laser Power On StateCommon Laser Cathode Photodiode Anode Back Panel LD Connector Interlock ConnectionsSetting the PD Bias Photodiode ConnectionsGrounding Considerations Operating a Laser in Constant Current I Mode Front Panel OperationDisplay Setting Up the Precision Current Source E R a T I O N Operating a Laser in Constant Power P Mode Entering Photodiode Responsivity ValuesMethod to calculate the responsivity is suggested below Error Indicators LDX-3232 Error IndicatorsError Indicators LDX-3232 Reading the Gpib Address Changing the Gpib AddressLDX-3232 Current Source Command Set Command SyntaxChanging Operation from Local to Remote OFF OLD NEW True False SET Reset LASLDI? Command Paths LDX-3232 Command Path StructureIEEE488.2 Command Commands LDX-3232 Frequently Used Commands NoneLIM Status Reporting Event and Condition RegistersOperation Complete Definition LDX-3232 Status Reporting Schematic Diagram Disabled 10 N/A Enabled 11 N/A 12 N/A 13 N/A 14 N/A 15 N/A Output Off RegisterLASerENABleOUTOFF nrf LASerENABleOUTOFF? Command Timing and Completion Error MessagesError Code Classifications Response MessageMode Used to enter the laser current calibration mode Used to create a delay in the execution of furtherCommands Used to enter the laser voltage calibration modeSets the enable register for Laser conditions Returns status of photodiode monitor power displayEnables Laser display to show parameter values Returns the value of the LAS conditions enable registerUsed to enable/disable the front panel modulation input Used to return the optical power from monitorUsed to set the constant optical power setpoint, if Or P optical powerReturns the elapsed time since the timer was last reset Returns the status of the Term commandPowered up Used to return the Laser setpoint tolerance valueLDX-3232 Device-Dependent Commands Command Description FormatLDX-3232 Device-Dependent Command Reference DelayERRors? LASerCALMDCalmd LAS Calpd Responsivity CAL PD parameter setting Syntax Diagram LASerCALMD?Selected. This procedure is outlined in Chapter LASerCALLDICalibration for that bandwidth LDI LAS CAL LASerCALLDI?LASerCALLDV LAS CAL LDVTrue measured value. This procedure is outlined in Chapter LASerCALLDV?LASerCALMDI MDI LASerCALMDI?LASerCOND? LAS CAL IPDLASerDEC LAS DIS LASerDISplayLASerDISplay? LASDIS?Lasdisldi LASerDISplayLDILASerDISplayLDI? LDILASerDISplayLDV? Voltage measurement Syntax DiagramLASerDISplayLDV LASDISLDV?LAS DIS MDI LASerDISplayMDILASerDISplayMDI? LAS DIS IPDPPD LASerDISplayMDPLASerDISplayMDP? LAS DIS MDPLAS DIS Param LASerDISplayPARAMLASerDISplaySET LAS DIS SETLASerENABleCOND LASerDISplaySET?LASDISPLAYSET? LASerENABleCOND? BitLAS Enab Cond Action enables the Laser status event register so that LASerENABleEVEntAn nrf value whose sum represents the bits that are enabled LasenabeventLASerENABleEVEnt? LAS Enab EVELASerENABleOUTOFF LASerENABleOUTOFF? LAS Enab OutoffLASerEVEnt? LASerENABleEVEnt commandCommand while the condition status is constantly changing LAS EVELASerINC Function for the Laser outputLASerLDI? This measurement is updated approximately once every 600 msLASerLDI LAS LDIFor LDV calibration LASerLDVLASerLDV? LAS LDVLimit in use depends on the Laser output range selection LASerLIMitI2LASerLIMitI2? LAS LIMLASerLIMitI4? Displayed, and then releasing the SET switchLASerLIMitI4 LASLIMI4?LASerLIMitMDP LASerLIMitMDP?MDP LAS LIM LASerLIMitV LASerLIMitV?MDI LAS IPD LASerMDILASerMDI? MDP P PD setpoint would be usedLASerMDLN LASerMDLN?LAS Mdln LASerMDP LASerMDP?MDP LAS LASerMODE? LAS ModeLAS Mode Ihbw LASerMODEIHBWLASerMODEMDP LAS Mode MDPLASerMODEILBW LasmodeilbwLASerOUTput LASerOUTput?LAS OUT LAS RAN LASerRANgeLASerRANge? LASRAN?LASerSETLDI? Where the response is the constant I setpoint value, in mA30 µA, for use in constant P mode with Calpd = LASerSETMDI?LASerSTEP Where the response is the constand PPD setpoint, in mWLASerSETMDP? 100 µALASerTOLerance LASerTOLerance commandLASerSTEP? LAS TOLSecond is the time window, in seconds LASerTOLerance?MESsage MESMESsage? RADixRAD Term 0 command is sent or the LDX-3232 is powered offRADix? Means hexadecimal, and OCT means octalLDX-3232 was last powered up Time clock is independent of the Timer clockTime Last TIMER? query is returned Since the last TIMER? query was issuedTimer Seconds since the last TIMER? query was issuedFunctions and Features Saving and Recalling from the Front PanelUsing the Laser Compliance Voltage Adjustment Saving and Recalling Under Remote OperationUsing the LDX-3232 Current Source’s Trigger Function LDX-3232 Rear PanelModulating the Laser Current Source BNC Interlock Usage ExampleModulating the Laser Current Source Functions and Features Calibration and Troubleshooting Calibration OverviewDescription Manufacturer/Model Specification Recommended EquipmentDMM Range Local Calibration of the LDX-3232 Current SourceCurrent Source Calibration Current LimitIPD Current Calibration Set equal to zero Constant powerCAL PD IPD Setpoint2000 mA Laser ModeLaser Forward Voltage Measurement Calibration Set to FS full scale of range Gpib Command Remote Calibration of the LDX-3232 Current Source Limit Lasldi nrf value command IPD Setpoint Function State Gpib Command EEPROM, Lllll will be displayed on the display the laser Troubleshooting GuideGeneral Current source must be recalibratedFeature can be defeated via the Lasenableoutoff Command101 Response Message