Lightwave Communications LDX-3232 manual IPD Current Calibration

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C H A P T E R 6

CALIBRATION AND TR OU BLESHOOTING

Local Calibration of the LDX-3232 Current Source

a.Measure and record the resistance of a 1Ω, 20 W resistor (A 4-wire [Kelvin] resistance measurement is recommended.) Connect the load resistor across the LASER output terminals (Laser Anode and Laser Cathode) on the 9 pin connector of the rear panel.

b.Connect the calibrated DMM across the load resistor. Configure the multimeter to measure voltage in volts. You will be calculating the actual Laser current in the following manner using Ohm's Law.

I = V/ R

--where V is the accurately measured voltage across the resistor, and R is the accurately measured load resistance in Ohms. I is the actual Laser current in Amps.

Note: Check the current measuring range of your multimeter. You may be able to measure

Laser Output current in mA by connecting the meter directly to the outputs of the Laser

Current Source.

c.Press the (MODE) ON switch to turn the current source output on. The output must be on in order to enter the LASER I calibration mode.

d.Enter the LASER I calibration mode by pushing the (GPIB) LOCAL and (DISPLAY) SELECT switches at the same time. The display will blank and the Current Source will drive the current output to the setpoint and the Display will indicate output current in mA.

e.Calculate the actual current through the load as described in step b. Press and hold in the (PARAMETER) SET switch and turn the adjust knob until the display indicates the calculated actual current.

f.Release the (PARAMETER) SET switch. After the (PARAMETER) SET switch is released, the Current Source will drive the current output to about 25% of the first calibration setpoint.

g.Calculate the measured current again through the load resistor.

h.Press and hold in the (PARAMETER) SET switch and turn the adjust knob until the display indicates the actual current as calculated in step g.

i.Release the (PARAMETER) SET switch to accept the second calibration point. After the (PARAMETER) SET switch is released, the Current Source will calculate the calibration constants and store them to nonvolatile memory. In low bandwidth calibration mode, the LDX-3232 Series Current Source will also perform current limit calibration, indicated by the CURRENT LIMIT LED flashing.

j.Turn the current source output off. Change the Mode to IHBW (high bandwidth constant current mode). Repeat the calibration procedure as described above.

k.Change the output range to high range and repeat the calibration procedure as described above.

IPD Current Calibration

The following procedure is for calibrating the LASER IPD (PD monitor) setpoint and measurement. This procedure calibrates the feedback circuits for constant IPD and constant PPD modes. When these values are reached and are stable, the user enters the actual value of the monitor current, measured with a DMM. The

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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 OverviewInstalling Your LDX-3232 High Compliance Current Source AC Line Power RequirementsInitial Inspection Grounding RequirementsGpib Connector Tilt-Foot AdjustmentGpib Address 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 create a delay in the execution of further CommandsUsed to enter the laser current calibration mode Used to enter the laser voltage calibration modeReturns status of photodiode monitor power display Enables Laser display to show parameter valuesSets the enable register for Laser conditions Returns the value of the LAS conditions enable registerUsed to return the optical power from monitor Used to set the constant optical power setpoint, ifUsed to enable/disable the front panel modulation input Or P optical powerReturns the status of the Term command Powered upReturns the elapsed time since the timer was last reset 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 LASerCALLDI? LASerCALLDVLDI LAS CAL LAS CAL LDVTrue measured value. This procedure is outlined in Chapter LASerCALLDV?LASerCALMDI LASerCALMDI? LASerCOND?MDI LAS CAL IPDLASerDEC LASerDISplay LASerDISplay?LAS DIS LASDIS?LASerDISplayLDI LASerDISplayLDI?Lasdisldi LDIVoltage measurement Syntax Diagram LASerDISplayLDVLASerDISplayLDV? LASDISLDV?LASerDISplayMDI LASerDISplayMDI?LAS DIS MDI LAS DIS IPDLASerDISplayMDP LASerDISplayMDP?PPD LAS DIS MDPLASerDISplayPARAM LASerDISplaySETLAS DIS Param LAS DIS SETLASerENABleCOND LASerDISplaySET?LASDISPLAYSET? LASerENABleCOND? BitLAS Enab Cond LASerENABleEVEnt An nrf value whose sum represents the bits that are enabledAction enables the Laser status event register so that LasenabeventLASerENABleEVEnt? LAS Enab EVELASerENABleOUTOFF LASerENABleOUTOFF? LAS Enab OutoffLASerENABleEVEnt command Command while the condition status is constantly changingLASerEVEnt? LAS EVELASerINC Function for the Laser outputThis measurement is updated approximately once every 600 ms LASerLDILASerLDI? LAS LDILASerLDV LASerLDV?For LDV calibration LAS LDVLASerLIMitI2 LASerLIMitI2?Limit in use depends on the Laser output range selection LAS LIMDisplayed, and then releasing the SET switch LASerLIMitI4LASerLIMitI4? LASLIMI4?LASerLIMitMDP LASerLIMitMDP?MDP LAS LIM LASerLIMitV LASerLIMitV?LASerMDI LASerMDI?MDI LAS IPD MDP P PD setpoint would be usedLASerMDLN LASerMDLN?LAS Mdln LASerMDP LASerMDP?MDP LAS LAS Mode LAS Mode IhbwLASerMODE? LASerMODEIHBWLAS Mode MDP LASerMODEILBWLASerMODEMDP LasmodeilbwLASerOUTput LASerOUTput?LAS OUT LASerRANge LASerRANge?LAS RAN LASRAN?Where the response is the constant I setpoint value, in mA 30 µA, for use in constant P mode with Calpd =LASerSETLDI? LASerSETMDI?Where the response is the constand PPD setpoint, in mW LASerSETMDP?LASerSTEP 100 µALASerTOLerance command LASerSTEP?LASerTOLerance LAS TOLLASerTOLerance? MESsageSecond is the time window, in seconds MESMESsage? RADixTerm 0 command is sent or the LDX-3232 is powered off RADix?RAD Means hexadecimal, and OCT means octalLDX-3232 was last powered up Time clock is independent of the Timer clockTime Since the last TIMER? query was issued TimerLast TIMER? query is returned 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 Local Calibration of the LDX-3232 Current Source Current Source CalibrationRange Current LimitIPD Current Calibration Constant power CAL PDSet equal to zero IPD SetpointLaser Mode Laser Forward Voltage Measurement Calibration2000 mA Set to FS full scale of rangeGpib Command Remote Calibration of the LDX-3232 Current SourceLimit Lasldi nrf value command IPD Setpoint Function State Gpib Command Troubleshooting Guide GeneralEEPROM, Lllll will be displayed on the display the laser Current source must be recalibratedFeature can be defeated via the Lasenableoutoff Command101 Response Message
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