Lightwave Communications LDX-3232 manual Constant power, Cal Pd, Set equal to zero, IPD Setpoint

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CA LI BRATION AND TR OUBLESHOOTING

Local Calibration of the LDX-3232 Current Source

C H A P T E R 6

LDX-3232 Series Current Source then automatically calibrates the LASER feedback circuits.

Configure the Current Source in the following manner for the Laser Current Source calibration:

Function

State

MODE

P (constant power)

 

 

CAL PD

set equal to zero

 

 

CURRENT LIMIT

90% of FS (full scale of range)

 

 

IPD SETPOINT

80% of FS

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).

Note: If a precision ammeter is not available, use a zero-Ohm jumper in place of the ammeter. Then, place a calibrated DMM (with 0.1 mV resolution) to measure the voltage across the resistor, R1, as shown in Figure 6.1. Calculate the current in the following steps by 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. I is the actual photodiode current to be measured by the LDX-3232 Current Source. (A 4-wire [Kelvin] resistance measurement is recommended.)

b.Press the (MODE) ON switch to turn the current source output on. Verify proper operation, i.e. the IPD measurement (via DMM) and setpoint should be close, and the unit should not be in current limit.

c.Press the (GPIB) LOCAL and FINE switches at the same time to place the Current Source in its IPD Current Calibration mode.

After a few seconds the display will show the IPD setpoint value.

d.After the value on the display is stable (has not changed by more than one digit for several seconds) the LDX-3232 Current Source is ready for the actual IPD value to be entered.

Press and hold in the (PARAMETER) SET switch and turn the adjust knob until the display shows the actual monitor current, as shown on the calibrated ammeter (or the calculated IPD value from Step a).

e.Release the (PARAMETER) SET switch to store the first calibration value. The Current Source will then set the second calibration current, approximately one-fourth (1/4) of the original current. (For example, if the first calibration setpoint was 4000 µA, the second setpoint will be about 1000 µA.)

f.Press and hold in the (PARAMETER) SET switch and turn the adjust knob until the display indicates the actual current as measured by the ammeter or as calculated.

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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 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 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 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 ReferenceLASerCALMD ERRors?Calmd LAS Calpd LASerCALMD? Responsivity CAL PD parameter setting Syntax DiagramLASerCALLDI Selected. This procedure is outlined in ChapterCalibration for that bandwidth LASerCALLDV LASerCALLDI?LDI LAS CAL LAS CAL LDVLASerCALLDV? True measured value. This procedure is outlined in ChapterLASerCALMDI 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 SETLASerDISplaySET? LASerENABleCONDLASDISPLAYSET? Bit LASerENABleCOND?LAS Enab Cond 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?LASerLIMitMDP? LASerLIMitMDPMDP LAS LIM LASerLIMitV? LASerLIMitVLASerMDI? LASerMDIMDI LAS IPD MDP P PD setpoint would be usedLASerMDLN? LASerMDLNLAS Mdln LASerMDP? LASerMDPMDP LAS LAS Mode Ihbw LAS ModeLASerMODE? LASerMODEIHBWLASerMODEILBW LAS Mode MDPLASerMODEMDP LasmodeilbwLASerOUTput? LASerOUTputLAS OUT 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 clock is independent of the Timer clock LDX-3232 was last powered upTime 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 TroubleshootingRecommended Equipment Description Manufacturer/Model SpecificationDMM 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 rangeRemote Calibration of the LDX-3232 Current Source Gpib CommandLimit 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