THORLABS LD2000R Operating Manual Download

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LD2000(R)

0187-D01 Rev F, 3/22/2011

Page 2

www.thorlabs.com

Table of Contents

Part 1.

Description ........................................................................................... 3

Compatible Laser Diode Styles ............................................................................................ 3

Part 2.

LD2000 Overview ................................................................................ 4

2.1.

Slow Start Circuit ............................................................................................ 4

2.2.

Limit Current Circuit ...................................................................................... 4

2.3.

Constant Power Feedback Loop ..................................................................... 4

2.4.

Theory of Operation ........................................................................................ 5

Part 3.

Operating the LD2000 ......................................................................... 7

3.1.

Setup ................................................................................................................. 7

Setting the Feedback Resistor .............................................................................................. 9

3.2.

Operating Modes ........................................................................................... 10

CW Operation .................................................................................................................... 10

Analog Modulation ............................................................................................................ 10

External Modulation Operation ......................................................................................... 11

Part 4.

Specifications ...................................................................................... 13

Part 5.

Regulatory .......................................................................................... 14

Part 6.

Thorlabs Worldwide Contacts .......................................................... 15

Summary of Contents for LD2000R

Page 1: ...LD2000 LD2000R OEM Laser Diode Driver with Analog Modulation Operating Manual ...

Page 2: ...Slow Start Circuit 4 2 2 Limit Current Circuit 4 2 3 Constant Power Feedback Loop 4 2 4 Theory of Operation 5 Part 3 Operating the LD2000 7 3 1 Setup 7 Setting the Feedback Resistor 9 3 2 Operating Modes 10 CW Operation 10 Analog Modulation 10 External Modulation Operation 11 Part 4 Specifications 13 Part 5 Regulatory 14 Part 6 Thorlabs Worldwide Contacts 15 ...

Page 3: ...also be controlled via an external voltage source The LD2000 supports a wide range of laser diodes with drive currents up to 100 mA and photodiode currents from 20 µA to 2 mA The LD2000 also has an external modulation input to support applications that require modulating the laser output The LD2000R is a RoHS compliant version of the LD2000 and features the same operation and specifications as the...

Page 4: ... 2 Limit Current Circuit The limit current circuit is a constant current source which can be set by the on board trim pot or an external control voltage This determines the maximum drive current that can be supplied to the laser The transfer function for this control is 40 mA V The current limit also determines the laser current when operating in the constant current mode 2 3 Constant Power Feedba...

Page 5: ...or The loop time constant can be extended by adding an external capacitor across CX1 and CX2 Note all control signals are based on the photodiode current The user must refer to the manufactures spec sheets of the particular diode that will be used to correlate this to the laser output power 2 4 Theory of Operation The LD2000 uses the internal monitor photodiode provided on most low power diode las...

Page 6: ...nternal reference we will use this to derive the feedback gain setting resistor value The LD2000 has an internal transimpedance gain of 20 kΩ Without a user installed feedback resistor the transimpedance gain is RF 20 kΩ and VError is equal to where IMon is the feedback monitor photocurrent The total transimpedance gain should be set so that the photocurrent at the maximum laser power equals 2 5 V...

Page 7: ...re provided in Figure 1 and described below The LD2000 can be used with A D or F style diodes The D and F style diodes will need to be configured like an A style diode see page 3 for diagrams Please note that the EK2000 is not compatible with the F Pin Style LD2000 Pin Out 1 CX1 2 CX2 3 Analog Modulation 4 Slow Start 5 PD Current Trimpot 6 PD Current Setpoint 7 REF Out 2 5 V 8 PD AMP Out 9 V 10 GN...

Page 8: ...board trimpot 6 PD Current Setpoint This pin controls the PD Current according to a transfer function of 50 µA V with 0 V being the laser is completely off 0 PD current The laser output increases as this voltage increases 7 REF Out This is a buffered 2 5V voltage reference 8 PD AMP Out This is an analog voltage proportional to the photodiode current and referenced to one half the supply voltage as...

Page 9: ...one by following the procedure below 1 Determine the appropriate feedback gain using the following calculation 20 000 8 000 1 where RF EXT is the external gain setting resistor to be added in ohms and IMON is the monitor current for a particular laser in Amps 2 Pick the nearest standard value resistor 0 25 W 5 or better 3 Connect RF EXT across pins 8 and 12 of the LD2000 WARNING The LD2000 uses CM...

Page 10: ...o FULL ON 6 Short pin 16 to ground 7 Turn both the PD Current Trimpot and the Current Limit Trimpot counterclockwise 20 turns each to set these at their minimum operating points 8 Turn the DC power supply on and use a voltmeter to monitor the LIMIT OUT on pin 18 9 Adjust the Current Limit Trimpot clockwise slowly while observing the LIMIT OUT to set the maximum operating current for your laser ref...

Page 11: ... 20 000 2 5 External Modulation Operation The laser output power can be controlled via an external modulation voltage while operating in the Constant Power Mode The laser output is inversely proportional to the modulating voltage with 0 V being the laser fully on and 2 5 V turning the laser fully off 1 To use the external modulation perform the following steps 2 Set up the LD2000 for Constant Powe...

Page 12: ...t feedback gain is usually too high for most lasers 3 If the feedback gain is too low for a laser i e the maximum laser power can be reached at a point somewhere below the maximum setting of PWR Limit than use care to set the PWR Limit control to the maximum desired operating power before applying the modulating voltage Modula on Voltage Output Power Pmax 2 5 V Clipping due to Current Limit being ...

Page 13: ...dth 3db Bandwidth Nominal 10 kHz Actual Bandwidth is Laser Dependent Power Supply Supply Voltage V 8 to 12 VDC Supply Current 30mA Plus Laser Current General Dimensions 2 x 1 3 x 0 5 Operating Temperature 20 to 60 C Storage Temperature 65 to 150 C Packaging PCB DIP Plastic Encapsulated Note 1 Higher Photodiodes currents are easily supported by adding a single external resistor Mechanical Drawing 1...

Page 14: ...oducts such as Pure OEM products that means assemblies to be built into a unit by the user e g OEM laser driver cards Components Mechanics and optics Left over parts of units disassembled by the user PCB s housings etc If you wish to return a Thorlabs unit for waste recovery please contact Thorlabs or your nearest dealer for further information 5 1 Waste Treatment is Your Own Responsibility If you...

Page 15: ... Fax 44 0 1353 654444 www thorlabs de email sales uk thorlabs com France Thorlabs SAS 109 rue des Côtes 78600 Maisons Laffitte France Tel 33 0 970 444 844 Fax 33 0 811 381 748 www thorlabs de email slaes fr thorlabs com Scandinavia Thorlabs Sweden AB Box 141 94 400 20 Göteborg Sweden Tel 46 31 733 30 00 Fax 46 31 703 40 45 www thorlabs de email scandinavia thorlabs com Japan Thorlabs Japan Inc 5 1...

Page 16: ...Thorlabs Inc 435 Route 206N Newton NJ 07860 USA Phone 973 579 7227 Fax 973 300 3600 www thorlabs com ...

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