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ILX Lightwave LDX-32420, Руководство пользователя

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ILX Lightwave LDX-32420 Скачать руководство пользователя страница 39

O P E R A T I O N

Operating a Laser in Constant Power (P) Mode

22 

LDX-32420

C H A P T E R  

2

 

Operating a Laser in Constant Power (P) Mode

Suppose you want to operate a laser diode at a constant 10 W level. The LDX-
32420 allows you to operate the laser current source driver in a Constant Optical 
Power mode. In this mode, the LDX-32420 drives current to the laser to reach a 
setpoint power value (in W). The control loop feedback parameter is photodiode 
current which the LDX-32420 converts to optical power via a user-defined 
photodiode responsivity number. If laser power changes due to internal or 
environmental conditions, the LDX-32420 will increase/decrease the current to the 
laser to maintain the power setpoint. The following paragraphs detail the 
instrument configuration in Constant Power Mode.

To set the LDX-32420 in Constant Power mode, select P in the MODE section of 
the front panel by toggling the SELECT push button [LASer:MODE:MDP]. 
Repeatedly pressing the (MODE) SELECT switch cycles through the current (I) 
[LAS:MODE:ILBW], photodiode power (P) [LAS:MODE:MDP], or high bandwidth 
current (I

HBW

) [LAS:MODE:IHBW] control modes. The LED indicator shows the 

selected mode. 

Entering Photodiode Responsivity Values

The photodiode responsivity, CAL PD, is used to 
convert between photodiode current and optical 
power of the laser diode. To enter the CAL 
photodiode parameter [LAS:CALMD XX], select 
CAL PD with the (PARAMETER) SELECT push 
button by toggling down past LIM P. The indicator 
becomes lit when CAL PD is selected and the 
display indicates the responsivity parameter in  
µA/mW (not enunciated). Press the set button 
then rotate the adjust knob to enter a new value for responsivity. When the correct 
value is displayed, the number will be stored after 3 seconds. 

A method to calculate the responsivity is suggested below.

1

Measure (with a calibrated detector) the output power of the device.

2

Measure the corresponding photodiode current.

3

Calculate the responsivity by dividing the photodiode current by the optical power noting 
the units required are µA/mW.

Note:

The LDX-32420 High Power Precision Current Source can be put into a special 

mode with the CAL PD parameter set to zero. When the CAL PD value is zero, the LASER 
output will be controlled to a current setpoint value (I

PD

) in micro amps (

A). Therefore, the 

instrument is in Constant I

PD

 mode. The display will indicate 

A for photodiode measured 

current and “-.-” for power measurement.

Содержание LDX-32420

Страница 1: ...uy your excess underutilized and idle equipment along with credit for buybacks and trade ins Custom engineering so your equipment works exactly as you specify Critical and expedited services Leasing R...

Страница 2: ...Current Source LDX 32420 70041301 January 2010 ILX Lightwave Corporation 31950 Frontage Road Bozeman MT U S A 59715 U S Canada 1 800 459 9459 International Inquiries 406 556 2481 Fax 406 586 9405 ilx...

Страница 3: ......

Страница 4: ...and Specifications Product Overview 1 Initial Inspection 2 Installing Your LDX 32420 High Power Precision Current Source 2 Grounding Requirements 2 AC Line Power Requirements 2 GPIB Communication 3 T...

Страница 5: ...n 15 Digital Display 15 Adjust Knob 15 Error Indicators 16 COMM 16 PARAMETER 17 MODE 17 RANGE 17 MOD 18 Fundamentals of Operation 19 Operating a Laser in Constant Current I Mode 19 Setting Up the Prec...

Страница 6: ...rror Messages 38 Chapter 4 Command Reference LDX 32420 Device Dependent Command Reference 44 Chapter 67 Chapter 5 Functions and Features Saving and Recalling from the Front Panel 67 Saving and Recalli...

Страница 7: ...ation 76 Laser Forward Voltage Measurement Calibration 77 Remote Calibration of the LDX 32420 Current Source 78 Current Source Calibration 78 IPD Current Calibration 80 Laser Forward Voltage Measureme...

Страница 8: ...2420 Front View 5 Figure 1 2 LDX 32420 Rear View 5 Figure 2 1 Back Panel LD Connector 13 Figure 3 1 LDX 32420 Command Path Structure 30 Figure 3 2 LDX 32420 Status Reporting Schematic Diagram 34 Figur...

Страница 9: ...L I S T O F FIG U R E S vi LDX 32420...

Страница 10: ...9 Table 3 2 LDX 32420 Often Used Commands 32 Table 3 3 LDX 32420 Series Default Settings for Output Off Registers 35 Table 3 4 Error Code Classifications 38 Table 3 5 LDX 32420 Series Error Codes 38 T...

Страница 11: ...L I S T O F TA B L E S viii LDX 32420...

Страница 12: ...ngerous situation which can result in serious injury or death WARNING Visible and or invisible laser radiation Avoid direct exposure to the beam General Safety Considerations If any of the following c...

Страница 13: ...ative Humidity 80 RH non condensing Operating temperature range of 0 C to 40 C Storage and transportation temperature of 40 C to 70 C Maximum altitude 3000 m 9843 ft This equipment is suitable for con...

Страница 14: ...n Authorization number RA from ILX Customer Service 2 Attach a tag to the instrument identifying the owner and indicating the required service or repair Include the instrument serial number from the r...

Страница 15: ...ou get the most out of your ILX Lightwave product we ask that you direct any product operation or service related questions or comments to ILX Lightwave Customer Support You may contact us in whatever...

Страница 16: ...the shipping box You or your shipping service are responsible for any shipping damage when returning the instrument to ILX Lightwave ILX recommends you insure the shipment If the original shipping con...

Страница 17: ...WA R R A N T Y xiv LDX 32420...

Страница 18: ...LDX 32420 to ILX Lightwave for service and repair to ensure that safety features are maintained Product Overview The LDX 32420 Precision High Power Laser Diode Current Source provides up to 20A of DC...

Страница 19: ...al Power Cord Shipping Kit Verify the line voltage indicated on the rear panel is correct for your facility Check for damage from shipping Installing Your LDX 32420 High Power Precision Current Source...

Страница 20: ...e male female connectors on each end so that several cables can be stacked This allows more than one cable to be attached to any one device However the maximum length of the GPIB cables must not excee...

Страница 21: ...ed on the rear panel of the instrument one is a terminal block labeled Interlock 1 the other is a BNC labeled Interlock 2 Interlock 1 is a normally open switch which defeats the output of the instrume...

Страница 22: ...1 Figure 1 1 LDX 32420 Front View Figure 1 2 LDX 32420 Rear View Laser Mode Selection Current Range Selection Parameter Selection GPIB Section Power Switch Display Adjust Section Modulation Input Conn...

Страница 23: ...nt during shipment use the original shipping containers and accessories if possible Re install the ESD protective caps on the rear and front panels over the connectors 9 pin D or hybrid BNC and GPIB S...

Страница 24: ...ndwidth Mode Low Bandwidth Mode 5 mA 5 mA 5 mA 5 mA Transient Operational4 1 kV EFT Surge5 25 mA 80 mA 25 mA 80 mA Compliance Voltage Adjust Range 0 4 V 0 4V Resolution 100 mV 100 mV Accuracy of FS 2...

Страница 25: ...PD Responsivity Range10 0 00 to 100 00 A mW 0 00 to 100 00 A mW PD Responsivity Resolution 0 01 A mW 0 01 A mW Optical Power Range 0 00 to 100 00 W 0 00 to 100 00 W Optical Power Resolution 0 01 W 0 0...

Страница 26: ...t change to trigger pulse 9 Measured current through GPIB or USB command instrument front panel displays setpoint current 10 The responsivity value is user defined and is used to calculate the optical...

Страница 27: ...invite you to contact us at any time with your suggestions DESCRIPTION MODEL NUMBER 20A Interconnect Cable 9W4 to 7W2 CC 320 20A Interconnect Cable 9W4 to Ring Lug CC 325 Single Rack Mount Kit RM 139...

Страница 28: ...not respond verify that it is connected to line power If line power is not the problem remove the power cord and contact ILX Lightwave or your local distributor for troubleshooting The Power On Seque...

Страница 29: ...ons from the LDX 32420 current source output to the anode and cathode of the laser diode be made using stranded or solid core wire For best performance in any of the LDX 32420 s operating modes we rec...

Страница 30: ...ed CURRENT SOURCE on the back panel is used to connect your laser diode to the LDX 32420 There are connections provided for laser cathode and anode photodiode cathode and anode laser forward voltage a...

Страница 31: ...f the 9W4 connector of the back panel When connecting to the instrument a twisted pair shielded cable is recommended for best signal quality The shield should be connected to earth ground at the LDX 3...

Страница 32: ...and laser optical power W in both setpoint and measurement modes It will also display error codes that relate to LASER operation Error indicators underneath the display indicate control errors and ar...

Страница 33: ...2 2 LDX 32420 Error Indicators COMM REMOTE indicates the unit is under remote operation TALK LISTEN indicates remote communications to and from the instrument through GPIB or USB computer interfaces...

Страница 34: ...or approximately 3 seconds the value will be stored MODE I unit is configured for constant current bandwidth limited mode P unit is configured for constant power mode IHBW unit is configured for const...

Страница 35: ...utput The input for this signal is a BNC located in the MOD section labeled External This port is configured as a differential input allowing the shell to be grounded through the connecting instrument...

Страница 36: ...W 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 LASer MODE ILBW photodiode power P LASer MODE...

Страница 37: ...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 t...

Страница 38: ...s output is enabled The instrument will drive the current source to the value set by the corresponding MODE setpoint The OUTPUT switch has a toggling action Pressing the switch again will disable the...

Страница 39: ...trol modes The LED indicator shows the selected mode Entering Photodiode Responsivity Values The photodiode responsivity CAL PD is used to convert between photodiode current and optical power of the l...

Страница 40: ...P When the LIM P is indicated by the accompanying LED the display will indicate the limit setpoint in W Press the PARAMETER SET push button and then rotate the adjust knob to set the limit to 15 W Th...

Страница 41: ...O P E R A T I O N Operating a Laser in Constant Power P Mode 24 LDX 32420 C H A P T E R 2...

Страница 42: ...and over the GPIB or USB bus will automatically put the instrument in remote mode The REMOTE indicator will identify when the current source is in remote operation mode When the instrument is in remot...

Страница 43: ...LED display in the format Adr XX The default address from the factory is Address 1 The GPIB address can be changed via the front panel as described in the next section Changing the GPIB Address If it...

Страница 44: ...ncluded in the shipping kit Once connected the ILX Virtual COM Port driver provides a simple programmable interface to the USB port COM PORT Settings Required BAUD 19200 DATA BITS 8 PARITY NONE STOP B...

Страница 45: ...ters shown with the Device Dependent commands in Chapter 4 are optional letters and may be used for clarity For example the following commands are equal LAS DIS 1 LAS Dis 1 LAS DISPLAY 1 In this examp...

Страница 46: ...S LDI When sending commands through the GPIB bus the LDX 32420 uses a terminator of NL END new line with EOI For users whose GPIB driver defaults expect a carriage return in the terminator CR NL END t...

Страница 47: ...the legal paths is listed below followed by its list of path options each of that is followed by the commands themselves It is recommended that the first time user begin learning the commands by using...

Страница 48: ...A list of all of the GPIB IEEE488 Common Commands supported by the LDX 32420 follows For more information on these commands refer to an ANSI IEEE 488 1987 standards reference Note Care should be taken...

Страница 49: ...rrent source measured value LAS LDV NONE Used to return the measured laser voltage value LAS LIM ILOW 1 Used to set the low range current limit LAS LIM IHIGH 1 Used to set the high range current limit...

Страница 50: ...ot reset until the Event Register is queried the status cleared by the CLS command or the instrument is powered off Conditions reflect the current state of the instrument and therefore may change many...

Страница 51: ...ion Complete 1 Request Control 2 Query Error 3 Device Dependendent Error 4 Execution Error 5 Command Error 6 User Request 7 Power On 0 N A 1 N A 2 LASER Event 3 LASER Cond 4 Message Available 5 Event...

Страница 52: ...the register output is not reported in the Status Byte Register Rather it sets the hardware that controls the output switching The events and conditions that may be set to cause the current source ou...

Страница 53: ...utput Changed to be Out of Tolerance 2 N A 10 N A 3 LASER Power Limit output on 11 High Temperature Limit Condition 4 N A 12 N A 5 N A 13 N A 6 N A 14 N A 7 N A 15 N A 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0...

Страница 54: ...s set after the conditions outlined in the Operation Complete Definition have been satisfied The WAI common command is an example of a sequential command that forces the next command to wait until the...

Страница 55: ...done all of the error messages that are resident in the error queue are returned up to 10 may be stored Reading the error queue via GPIB or USB clears the error queue Table 3 4 Error Code Classificat...

Страница 56: ...PIB controller failed to read all of the RESPONSE MESSAGE E 501 LASER interlock disabled output E 503 LASER open circuit disabled output E 504 LASER current limit disabled output E 505 LASER voltage l...

Страница 57: ...RE M O T E O PE R A T I ON Error Messages 40 LDX 32420 C H A P T E R 3...

Страница 58: ...ant LAS CALMD NONE Returns the CAL PD monitor responsivity constant LAS CAL LDI NONE Used to enter the laser current calibration mode LAS CAL LDI NONE Returns the ready state for entering the laser cu...

Страница 59: ...ister LAS ENAB EVE 1 Sets the enable register for LAS events LAS ENAB EVE NONE Returns the value of the LAS event enable register LAS ENAB OUTOFF 1 Sets the enable register for LAS conditions that tur...

Страница 60: ...t source output status LAS RAN 1 Sets the laser current output range LAS RAN NONE Returns the laser current output range LAS SET LDI NONE Returns the laser constant I current setpoint LAS SET MDI NONE...

Страница 61: ...el operation are denoted by Front Panel in bold text at the upper right hand corner of the command description The following pages contain a reference for the device dependent commands This reference...

Страница 62: ...out 0 5 seconds have elapsed from the time this command is executed Note Care should be taken to set the GPIB time out appropriately for use with the Delay command Note When using the USB interface qu...

Страница 63: ...to enter the LASER current setpoint measurement and limit calibration mode The LASer CAL LDI query is used to determine that the LDX 32420 is ready for a value to be entered during the calibration cy...

Страница 64: ...command The LASer CAL MDI command is used to enter the LASER photodiode current calibration mode The LASer CAL MDI query is used to determine that the LDX 32420 is ready for a value to be entered duri...

Страница 65: ...Therefore the user should test for the Open Circuit Event via the LAS EVEnt query The LASER condition status is constantly changing while the event status is only cleared when the event status is rea...

Страница 66: ...do nothing The minimum time to complete one decrement is about 20 ms Therefore values for the second optional parameter time between decrements have a practical minimum of 20 Examples LAS MODE I LAS S...

Страница 67: ...splay for laser current values LAS DIS LDI response 0 means that the LDI measurement is not displayed The LASer DISplay LDV command sets the laser display to show the laser forward voltage measurement...

Страница 68: ...alues LAS DIS MDI response 0 means that the laser photodiode monitor current measurement is not displayed The LASer DISplay MDP command sets the display to show the monitor photodiode power measuremen...

Страница 69: ...r Display Param action selects a parameter and displays its value The LASer DISplay SET command sets the display to show the setpoint of the selected display mode The LASer DISplay SET query returns t...

Страница 70: ...er down unless the power on status clear flag is set true for more information see the PSC definition in the GPIB IEEE488 specification Examples LAS ENAB COND 129 action enables the LASER status condi...

Страница 71: ...formation see the PSC definition in the GPIB IEEE488 specification Examples LAS ENAB EVENT 136 action enables the LASER status event register so that the Open circuit and Power limit events will be re...

Страница 72: ...atus clear flag is set true for more information see the PSC definition in the GPIB IEEE488 specification The factory default value for this register is B0000100000001000 H808 or 2056 decimal Examples...

Страница 73: ...e condition status is constantly changing Examples LAS EVE response 513 means that the LASER output tolerance changed and current limit events have occurred since the last LASer EVEnt query Radix Hex...

Страница 74: ...al parameter time between increments have a practical minimum of 20 This command should not be overlapped with LAS DEC or other LAS INC commands Examples LAS MODE I LAS STEP 3 LAS INC action The laser...

Страница 75: ...nt limit for the 10 A range on the LDX 32420 Parameters Amps represents the LASER limit current in A Notes The current limit is in effect in all modes of operation ILBW IHBW or P The current limit in...

Страница 76: ...o a value that corresponds to producing 10 00 W of photodiode feedback optical power LAS LIM MDP response 3 0 means the monitor photodiode power limit is set to 3 0 W The LASer LIMit V command sets th...

Страница 77: ...value of the optical power setpoint in W if the CALMD CAL PD responsivity is greater than 0 The LASer MDP query returns the value of the laser photodetector power measurement in W Parameters Watts re...

Страница 78: ...e low bandwidth enables the output low bandpass filter Examples LAS MODE ILBW action sets the laser output for constant I mode low bandwidth The LASer MODE MDP command selects laser constant power mod...

Страница 79: ...h the status of the switch is on the output may not have reached the setpoint value Examples LAS I 2 LAS OUT ON action sets the laser output current to 2 A and then enables the output Las OUT response...

Страница 80: ...hen CALMD CAL PD is not zero in mW where the response is the constant PPD setpoint in mW Examples LAS Set MDP response 10 0 means the laser monitor photodiode feedback setpoint is 10 0 W CALPD 0 The L...

Страница 81: ...ering or exiting LASER current tolerance may be used to generate service requests Note If the tolerance is set too tight it may never be achieved This is due to the calibration of the setpoint and mea...

Страница 82: ...the words decimal hexadecimal binary or octal are required When the RADIX is selected all status condition and event queries will return values in the new radix All of the above radixes may be used to...

Страница 83: ...temporarily sets CR NL END as the output terminator Term response 1 means that the CR NL END terminator is temporarily being used The TIME query allows the programmer to determine how much time has p...

Страница 84: ...ameters saved by using the SAVE function would be Constant Current Mode 10A range a limit setpoint of 8A a laser current setpoint of 7 5A and Display Mode I Once this setup is saved the LDX 32420 Curr...

Страница 85: ...n critical load set the LASER voltage limit as described in Chapter 2 Then with the LASER output on slowly increase the LASER current and watch the LASER voltage measurement Press the DISPLAY SELECT p...

Страница 86: ...ource See Figure 5 1 The TTL pulse is approximately 13 s wide and has a delay time of about 10 12 ms after the current setpoint is changed via remote command This delay does not include transmission t...

Страница 87: ...ith the ability to signal when its temperature control has gone outside of some tolerance window will allow the LDX 32420 to safely disable the current source output before thermal damage occurs to th...

Страница 88: ...s than one second to switch between modes and the current source output must be off MODE ON indicator unlit in order to change ranges The limit clamp function for DC output current applies to the modu...

Страница 89: ...on source to inject the modulation signal To disable the output press the OUTPUT push button again When the LDX 32420 current output is off an internal short is placed across the output This short wil...

Страница 90: ...the current source in both ranges and both modes low and high bandwidth calibrating the photodiode monitor current measurement and finally the forward voltage measurement The current limits are calib...

Страница 91: ...2420 Calibration of the LDX 32420 Current Source There are three calibration adjustments required for the current source They are calibration of the constant current source for both bandwidths and ran...

Страница 92: ...the Display will indicate output current in mA e Calculate the actual current through the transducer as described in step b Press and hold in the PARAMETER SET switch and turn the adjust knob until t...

Страница 93: ...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...

Страница 94: ...ource output on The current source output must be on in order to enter the LDV calibration mode c Enter the LASER V calibration mode by pushing the GPIB LOCAL and RANGE switches at the same time The d...

Страница 95: ...ill wait indefinitely for an input yet not allow any input until the calibration is finished Current Source Calibration There are three calibration adjustments required for the LDX 32420 Current Sourc...

Страница 96: ...or example the measured value of the current should not be entered until the LDX 32420 Current Source is ready to receive it The Current Source will be ready to receive the new measured value when aft...

Страница 97: ...IPD 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 So...

Страница 98: ...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 32420 Current Source is ready to receive it The curre...

Страница 99: ...librated Instrument resets at power up or any LASER mode change Hold COM LOCAL button RANGE button and FINE button as you are powering up the instrument This clears the laser board EEPROM LLLLL will b...

Страница 100: ...ed the limit setpoint Normally this limit will cause the output to shut off This feature can be defeated via the LAS ENABLE OUTOFF command Open circuit error occurs during calibration Check load conne...

Страница 101: ...ing the ERR query When this is done all of the error messages that are resident in the error queue are returned up to 10 may be stored Reading the error queue clears the error queue Table 6 2 Error Co...

Страница 102: ...r device was addressed to talk but GPIB controller failed to read all of the RESPONSE MESSAGE E 501 LASER interlock disabled output E 503 LASER open circuit disabled output E 504 LASER current limit d...

Страница 103: ...C A L IB R A TI O N A N D TR OU BL E S HO O T IN G Error Messages 86 LDX 32420 C H A P T E R 6...

Страница 104: ...uipment Have surplus equipment taking up shelf space We ll give it a new home Learn more Visit us at artisantg com for more info on price quotes drivers technical specifications manuals and documentat...

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