THORLABS NPL Series User manual

NPL Series
Nanosecond Pulsed Lasers
User Guide

Nanosecond Pulsed Lasers
Table of Contents
Chapter 1 Safety Information......................................................................................................1
Chapter 2 Introduction ...............................................................................................................3
Chapter 3 Quick Start Guide........................................................................................................5
Chapter 4 Operation...................................................................................................................6
Chapter 5 Specifications .............................................................................................................9
Chapter 6 Mechanical Drawings................................................................................................12
Chapter 7 Maintenance and Troubleshooting............................................................................15
Chapter 8 Declaration of Conformity.........................................................................................16
Chapter 9 Thorlabs Worldwide Contacts ...................................................................................17

Nanosecond Pulsed Lasers Chapter 1: Safety Information
Rev H, January 25, 2023 Page 1
Chapter 1 Safety Information
All statements regarding safety of operation and technical data in this instruction manual will only apply when the
unit is operated correctly. If equipment is used in a manner not specified by the manufacturer, the protection
provided by the equipment may be impaired. Only with written consent from Thorlabs may changes to single
components be carried out or components not supplied by Thorlabs be used.
Warnings and Cautions
Warning: Laser Radiation
This is a Class 3B laser system. Observe all safety precautions and wear
protective eyewear appropriate for this type of device. Align system at
lower output power if possible. Do not position device so that is
difficult to access the switch and interlock.
Caution –Use of controls or adjustments or performance of
procedures other than those specified herein may result in hazardous radiation exposure.
Caution: ESD Sensitive Component
The components inside this instrument are ESD sensitive. Take all appropriate precautions to
discharge personnel and equipment before making any connections to the unit.
Caution: Components not Water Resistant
This instrument should be kept clear of environments where liquid spills or condensing
moisture are likely. It is not water resistant. To avoid damage to the instrument, do not expose
it to spray, liquids, or solvents.
Caution: Follow Intended Usage Guidelines
Inputs and outputs must only be connected with shielded connection cables.
The safety of any system incorporating the equipment is the responsibility of the assembler of
the system. If equipment is used in a manner not specified by the manufacturer, the protection
provided by the equipment may be impaired. Only with written consent from Thorlabs may
changes to single components be carried out or components not supplied by Thorlabs be used.
There are no user serviceable components inside this device.

Nanosecond Pulsed Lasers Chapter 1: Safety Information
Page 2 TTN122959-D02
Precautions
The following statement applies to the products covered in this manual, unless otherwise specified herein. The
statement for other products will appear in the accompanying documentation.
Note: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant
to Part 15 of the FCC Rules, and meets all requirements of the Canadian Interference Causing Equipment Standard
ICES-003 for digital apparatus. These limits are designed to provide reasonable protection against harmful
interference in an industrial installation. This equipment generates, uses, and can radiate radio frequency energy
and, if not installed and used in accordance with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that interference will not occur in a particular installation.
Thorlabs is not responsible for any radio television interference caused by modifications of this equipment or the
substitution or attachment of connecting cables and equipment other than those specified by Thorlabs. The
correction of interference caused by such unauthorized modification, substitution or attachment will be the
responsibility of the user. The use of shielded I/O cables is required when connecting this equipment to all optional
peripherals or host devices. Failure to do so may violate FCC and ICES rules.
This product has been tested and found to comply with the limits according to IEC 61326-1 for using connection
cables shorter than 3 meters (9.8 feet).

Nanosecond Pulsed Lasers Chapter 2: Introduction
Rev H, January 25, 2023 Page 3
Chapter 2 Introduction
The NPL series of pulsed diode lasers are designed to provide a convenient, turn-key source of nanosecond pulse
trains. Model options are summarized in the table below and include different typical emission wavelengths,
output powers, repetition frequency range, and fixed or adjustable pulse widths.
Series Overview
Models with Item # suffix A provide fixed-duration 10 ns pulses in response to a user-supplied trigger input.
Models with Item # suffix B offer variable pulse width control and internal oscillators that trigger the laser pulses
at 1 MHz, 5 MHz, or 10 MHz in addition to user-triggered operation. Models with Item # suffix C offer higher pulse
energies, variable pulse width control, and user trigger input at repetition frequencies up to 50 kHz. The optical
output is a free-space beam with an integrated factory set collimated lens. Note that the shutter is permanently
attached.
Item #
Typical Center
Wavelength
Pulse Width
Peak Output
Power
Internal
Trigger
Max Rep.
Rate
NPL64A
640 nm ± 10 nm
10 ns
13 mW
No
10 MHz
NPL41B
405 nm ± 10 nm
6 ns to 38 ns
38 mW
Yes
10 MHz
NPL45B
450 nm ± 10 nm
5 ns to 39 ns
75 mW
NPL49B
488 nm ± 10 nm
6 ns to 39 ns
50 mW
NPL52B
520 nm ± 10 nm
5 ns to 39 ns
30 mW
NPL64B
640 nm ± 10 nm
5 ns to 39 ns
50 mW
NPL79B
785 nm ± 10 nm
6 ns to 39 ns
88 mW
NPL82B
820 nm ± 10 nm
6 ns to 39 ns
88 mW
NPL91B
905 nm ± 10 nm
6 ns to 39 ns
88 mW
NPL98B
980 nm ± 10 nm
6 ns to 39 ns
38 mW
NPL41C
405 nm ± 10 nm
6 ns to 129 ns
1000 mW
No
50 kHz
NPL45C
450 nm ± 10 nm
1600 mW
NPL52C
520 nm ± 10 nm
1500 mW
NPL64C
640 nm ± 10 nm
1000 mW
NPL81C
808 nm ± 10 nm
1500 mW

Nanosecond Pulsed Lasers Chapter 2: Introduction
Page 4 TTN122959-D02
Inputs and Controls
The only differences in theback panels of the A, B, and C versions, shown below, are the pulse width and repetition
rate controls. Models with Item # suffix A have neither, suffix B models have both pulse width and repetition rate
control, and suffix C models have only pulse width control. In these images, the shorting device (interlock pin) that
ships installed in the Interlock jack has been removed.
Figure 1 Back Panel of NPLxA Lasers
Figure 2 Back Panel of NPLxB Lasers
Figure 3 Back Panel of NPLxC Lasers
Interlock
Jack
Pulse Width
Control
Pulse Width
Control
Key
Switch
Power
Jack
Key
Switch
Power
Jack
Key
Switch
Power
Jack
Laser
Status
Trigger
Port
Repetition
Rate
Control
Interlock
Jack
Laser
Status
Trigger
Port
Interlock
Jack
Laser
Status
Trigger
Port

Nanosecond Pulsed Lasers Chapter 3: Quick Start Guide
Rev H, January 25, 2023 Page 5
Chapter 3 Quick Start Guide
1. Mount the laser head as needed using the supplied ECM225 clamps and either imperial or metric screws.
After screwing the ECM225 clamps to any convenient base or post, such as one of Thorlabs’ TR series
optical posts, snap the clamps on to the bottom side of the NPL housing. Firmly tighten the clamps using
the locking screws. Figure 4 shows an example of an NPL laser head mounted on an optical table.
2. Orient the laser to ensure the output beam will be safely contained.
3. Connect the power supply cable to the head, and then plug the power supply into mains power.
4. Make sure the shutter has been rotated to the closed position and interlock pin is in place at this time. An
external interlock circuit can be added later for more convenient integration of the interlock safety
feature.
5. Put on laser safety goggles if your situation requires them.
6. Turn the power switch on using the key switch.
7. The dual color LED indicator (red/blue) will blink until the laser temperature has stabilized. Initial warm
up can take 30 - 60 seconds. The indicator will then glow continuously when the laser output is enabled.
Note there is a four second delay between the time the indicator glows solid and laser output is enabled.
Note also that there will be no optical output unless the laser is triggered. The B versions are triggered
either externally or via internal oscillator, and the A and C versions require an external trigger.
8. Ensure the laser is pointing in a safe direction, and then rotate the shutter to the open position. For the B
and C versions of the laser, note that adjusting the variable pulse width and/or repetition rate controls
will change the average output power.
Note the beam shape is asymmetric as is typical of solid-state diode lasers that do not use anamorphic optical
components to circularize the beam. Anamorphic elements, such as anamorphic prism pairs, are available from
Thorlabs.
Figure 4 Laser Head Mounted Using the Included ECM225 Clamps

Nanosecond Pulsed Lasers Chapter 4: Operation
Page 6 TTN122959-D02
Chapter 4 Operation
Block Diagram
The block diagram in Figure 5 depicts the internal architecture of the laser head, which contains all of the pulser
drive electronics, safety interlocks, and trigger circuits, as well as the temperature stabilization system. The dual
color LED indicator (red/blue) is designed to be visible through most laser safety glasses. It blinks during the 30 -
60 s warm up and glows continuously while the laser is enabled.
Power is supplied by the included +15 V power supply. For the B versions of the laser, nothing else is required to
produce stable trains of nanosecond laser pulses. The A and C versions require only the application of an external
trigger. The elements unique to the B versions are noted in Figure 3 by the yellow blocks. The Repetition Rate
Control and Oscillators provide internally-generated trigger signals, which make it possible for the B versions to
produce stable trains of nanosecond pulses without an external trigger.
Figure 5 Block Diagram of the NPL Series Laser Head
Power
Power is supplied by the external, +15 V, wall-mounted DS15 Power Supply included with the unit and shown in
the left image of Figure 6. The power supply includes a location-specific plug. The mini-XLR type connector, which
uses a latching mechanism to prevent accidental pull-out, plugs into the laser head as shown in the right image of
Figure 6.
Figure 6 The DS15 Power Supply (left) connects to the back panel of the laser head (right).

Nanosecond Pulsed Lasers Chapter 4: Operation
Rev H, January 25, 2023 Page 7
The key switch controls power to all internal components. When the key switch is turned on, the temperature
stabilization system is activated. There is a 30 - 60 second warm up, during which time the LED indicator light
blinks. When the LED stops blinking, there is an additional four second delay and then laser is enabled. Note there
will not be any optical output until the interlock is satisfied, a trigger signal is supplied, and the shutter is opened.
Interlock Circuit
The laser is equipped with a phono-type interlock jack located on the back panel. To enable the laser source, a
short circuit must be applied across the terminals of the interlock connector. The shorting device (interlock pin)
installed in all units shipped from Thorlabs performs this function. Leave the shorting device installed unless using
an external safety circuit or other type of remotely controlled switch to enable laser output.
Making use of the Interlock feature requires the appropriate 2.5 mm phono-type plug, which is shown in the left
diagram of Figure 7 and is readily available through most electronics retailers. The plug should be wired to the
external safety circuit or switch and then plugged into the back panel’s interlock jack in place of the shorting
device. The electrical specifications of the interlock jack are listed in the following table, and the circuit schematic
describing how the interlock jack is connected inside the laser head is shown in the right diagram of Figure 7.
Parameter
Specification
Interlock Switch Requirements
Must be Normally Open Dry Contacts,
Apply no External Voltages to the Interlock Input
Type of Mating Connector
2.5 mm Mono Phono Jack
Open Circuit Voltage
5 VDC
(Center Pin is at 5 VDC, Ring is Ground)
The user’s safety circuit must be attached to the phono plug and wired such that the ring and center pin are
shorted when it is safe to enable the laser. The laser will be enabled when connection is closed. If it changes to an
open state, the laser source will turn off.
Figure 7 The interlock circuitry internal to the laser head (right) applies a 5 VDC bias across the ring and
center pin of the phono-type plug (left). An external circuit that shorts the ring and center pin enables
the laser.

Nanosecond Pulsed Lasers Chapter 4: Operation
Page 8 TTN122959-D02
Pulse Widths and Repetition Rates
NPL series lasers with Item # suffix A and C require a user trigger input to the SMA connector on the back panel.
The NPL64A laser supports rates up to 10 MHz. The C version supports rates up to 50 kHz. The slowest supported
edge transition time for the trigger signal is 1 ms. See the specifications in Chapter 5 for correct voltage levels.
Lasers with Item # suffix B offer additional controls for varying repetition rate using internal oscillators as well as
selecting a user trigger. Use the included 2.5 mm flathead screwdriver to operate these controls. The photograph
in Figure 8 shows three oscillator settings: A, B, and C. These positions provide repetition frequencies of 1 MHz, 5
MHz, and 10 MHz, respectively. Position D allows the user to apply an external signal to trigger the laser pulses.
This control can be seen immediately to the right of the pulse width control in the photo and can be adjusted with
the same small screwdriver.
Lasers with Item # suffix B and C offer controls for varying the pulse width. Use the included 2.5 mm flathead
screwdriver to operate this control as shown in Figure 8. The range of pulse widths for each model are listed in
the specifications table in Section 5.1. The pulse width control directly programs the pulse generator and has 16
positions, which allows the pulse width to be adjusted in approximately 15 equal increments. Plots of typical
pulses and of typical pulse width as a function of control setting are available in the web presentation.
Figure 8 Use the included 2.5 mm flathead screwdriver to adjust the pulse width and repetition rate
controls.
Trigger Port
The Trigger In/Out port has dual function. If the internal oscillators are used (on B models), then the Trigger port
provides an output signal that is synchronized with the pulse generation. In the user-triggered mode, the SMA
port allows external trigger signals to drive the pulse generator. See the Specifications table in Chapter 5 for the
correct signal levels and port impedances.
Optical Output
The optical output is finally enabled by opening the safety shutter. This is done by rotating the flap through
180°. Magnets will hold the flap either in the open or closed position. Note that the shutter is permanently
attached.

Nanosecond Pulsed Lasers Chapter 5: Specifications
Rev H, January 25, 2023 Page 9
Chapter 5 Specifications
Optical Specifications
Item #
NPL64A
NPL41B
NPL45B
NPL49B
NPL52B
Center Wavelength (Typ.)
640 ± 10 nm
405 ± 10 nm
450 ± 10 nm
488 ± 10 nm
520 ± 10 nm
Pulse Width
(FWHM)
Min a
10 ± 1 ns b
6 ± 1 ns
5 ± 1 ns
6 ± 1 ns
5 ± 1 ns
Max a
38 ± 3 ns
39 ± 3 ns
39 ± 3 ns
39 ± 3 ns
Internal Trigger
No
Yes (1, 5, or 10 MHz)
Max Trigger Frequency c
10 MHz
Pulse Energy (Typ. Max) d
0.12 nJ
1.5 nJ
3.0 nJ
2.0 nJ
1.2 nJ
Average Power (Max) d
1.2 mW
15 mW
30 mW
20 mW
12 mW
Peak Power (Typ. Max) e
13 mW
38 mW
75 mW
50 mW
30 mW
Beam Pointing Accuracy f
≤3°
Beam Divergence
(1/e2), Typ. g
Major
1.5 mrad
0.5 mrad
0.5 mrad
0.5 mrad
1.5 mrad
Minor
0.5 mrad
0.3 mrad
0.25 mrad
0.3 mrad
0.5 mrad
Beam Full Width
(1/e2) at 5.0 m
Major
5.3 mm
2.5 mm
3.3 mm
3.0 mm
3.2 mm
Minor
2.1 mm
1.7 mm
1.6 mm
1.8 mm
2.0 mm
Collimating Lens
C340TMD-B
C610TMD-A
a
The pulse widths of lasers with item # suffix B or C are adjustable over 16 discrete settings, from the minimum to the
maximum specified widths. Refer to the web presentation for plots of typical pulses as well as plots of typical pulse widths
vs. the pulse width control setting.
b
Pulse widths are of fixed duration. Refer to the web presentation for plots of typical pulses.
c
The maximum supported edge transition time is 1 ms.
d
This specification is given for operation at the max repetition rate and with the greatest pulse width achievable by the
laser.
e
These specifications are typical maxima and are given for pulses that reach maximum output power. Some short duration
pulses do not reach maximum output power and therefore have reduced average output powers.
f
Relative to a beam axis normal to the plane of the front panel.
g
The major axis of the ellipse is vertically oriented when the bottom surface of the laser head is in the horizontal plane.
Item #
NPL64B
NPL79B
NPL82B
NPL91B
NPL98B
Center Wavelength (Typ.)
640 ± 10 nm
785 ± 10 nm
820 ± 10 nm
905 ± 10 nm
980 ± 10 nm
Pulse Width
(FWHM)
Min a
5 ± 1 ns
6 ± 1 ns
6 ± 1 ns
6 ± 1 ns
6 ± 1 ns
Max a
39 ± 3 ns
39 ± 3 ns
39 ± 3 ns
39 ± 3 ns
39 ± 3 ns
Internal Trigger
Yes (1, 5, or 10 MHz)
Max Trigger Frequency c
10 MHz
Pulse Energy (Typ. Max) d
2.0 nJ
3.5 nJ
3.5 nJ
3.5 nJ
1.5 nJ
Average Power (Max) d
20 mW
35 mW
35 mW
35 mW
15 mW
Peak Power (Typ. Max) e
50 mW
88 mW
88 mW
88 mW
38 mW
Beam Pointing Accuracy f
≤3°
Beam Divergence
(1/e2), Typ.
Major
1.5 mrad
0.3 mrad
0.5 mrad
1.0 mrad
0.5 mrad
Minor
0.5 mrad
0.15 mrad
0.6 mrad
0.5 mrad
0.5 mrad
Beam Full Width
(1/e2) at 5.0 m
Major
4.8 mm
3.8 mm
2.9 mm
5.0 mm
2.6 mm
Minor
2.7 mm
3.3 mm
1.4 mm
2.8 mm
1.3 mm
Collimating Lens
C340TMD-B
A375TM-B
C340TMD-B
A375TM-B

Nanosecond Pulsed Lasers Chapter 5: Specifications
Page 10 TTN122959-D02
Item #
NPL41C
NPL45C
NPL52C
NPL64C
NPL81C
Center Wavelength (Typ.)
405 ± 10 nm
450 ± 10 nm
520 ± 10 nm
640 ± 10 nm
808 ± 10 nm
Pulse Width
(FWHM)
Min
6 ± 1 ns
Max
129 ± 5 ns a
Internal Trigger
No
Max User Trigger Frequency c
50 kHz
Pulse Energy (Typ. Max) d
128 nJ
204 nJ
186 nJ
126 nJ
186 nJ
Average Power (Max) d
6.4 mW
10.2 mW
9.3 mW
6.3 mW
9.3 mW
Peak Power (Typ. Max) e
1000 mW
1600 mW
1500 mW
1000 mW
1500 mW
Beam Pointing Accuracy f
≤3°
Beam Divergence
(1/e2), Typ.
Major
4.9 mrad
2.4 mrad
3.7 mrad
10.2 mrad
9.5 mrad
Minor
0.2 mrad
0.14 mrad
0.6 mrad
0.5 mrad
0.85 mrad
Beam Full Width
(1/e2) at 5.0 m
Major
21 mm
19.2 mm
16.5 mm
43 mm
49 mm
Minor
1.0 mm
1.3 mm
1.9 mm
1.2 mm
1.3 mm
Collimating Lens
C610TMD-A
C610TMD-B
A397TM-B
Trigger Specifications
Parameter
Specification
Coupling
AC Coupled
Max Input Frequency h
Item # Suffix A or B
10 MHz
Item # Suffix C
50 kHz
Input Voltage
200 mVpp to 2 Vpp
Input Impedance
5 kΩ
Output Voltage i
900 mV (Hi-Z Load)
600 mV (50 Ω Load)
Max Jitter j
20 ps RMS
100 ps Peak-to-Peak
Delay from External Trigger Input to Optical Output k
35 ns ± 5 ns
Delay from Internal Trigger to Optical Output i
28 ns ± 5 ns
h
The maximum supported edge transition time is 1 ms.
i
Available only on NPL series lasers with Item # suffix B.
j
Applies to external triggering (all item numbers) and internal triggering (only models with Item # suffix B).
k
External trigger delay is measured between the Trigger SMA connector and the optical output at the lens.

Nanosecond Pulsed Lasers Chapter 5: Specifications
Rev H, January 25, 2023 Page 11
Power, Environmental, and Physical Specifications
Parameter
Specification
DC Input Voltage Range to Laser Head
14 V to 16 V
DC Input Current to Laser Head
800 mA Max
AC Input Frequency Range to DS15 Power Supply
50 Hz - 60 Hz
AC Input Voltage to DS15 Power Supply
100 V to 240 V
Operating Temp Range
10 °C to 40 °C
Storage Temp Range
0 °C to 50 °C
Humidity Range (RH)
5% to 85%
Dimensions
(L x W x H)
Without ECM225 Clamps
139.6 mm x 61.5 mm x 48.7 mm
(5.49" x 2.42" x 1.92")
With ECM225 Clamps
139.6 mm x 61.5 mm x 54.7 mm
(5.49" x 2.42" x 2.15")

Nanosecond Pulsed Lasers Chapter 6: Mechanical Drawings
Page 12 TTN122959-D02
Chapter 6 Mechanical Drawings
NPL64A
Figure 9 Mechanical Drawing of the NPL64A

Nanosecond Pulsed Lasers Chapter 6: Mechanical Drawings
Rev H, January 25, 2023 Page 13
NPL Series Lasers with Item # Suffix B
Figure 10 Mechanical Drawing for NPL Series Lasers with Item # Suffix B

Nanosecond Pulsed Lasers Chapter 6: Mechanical Drawings
Page 14 TTN122959-D02
NPL Series Lasers with Item # Suffix C
Figure 11 Mechanical Drawing for NPL Series Lasers with Item # Suffix C

Nanosecond Pulsed Lasers Chapter 7: Maintenance and Troubleshooting
Rev H, January 25, 2023 Page 15
Chapter 7 Maintenance and Troubleshooting
Maintenance
The NPL laser should not require regular maintenance. If necessary, the housing can be cleaned using a soft cloth
moistened with a mild glass cleaner. Do not use acetone, chemical solvents, or harsh cleaning solutions, and do
not spray cleaning solutions directly onto the unit. See Section 7.2 for advice on cleaning the lens.
The NPL does not contain any user-serviceable components. If malfunctions occur, please contact Thorlabs’
technical support ([email protected]). Do not disassemble the unit.
See the troubleshooting guide below for basic help.
Troubleshooting
Problem
Suggested Checks
No Output
Check that power is supplied and connected properly.
Check that key switch is turned on.
Confirm that laser is warmed up (30 - 60 s).
Confirm the interlock circuit is complete.
Check that the indicator LED is glowing continuously.
Check that a trigger signal is being provided.
Check that the shutter is open.
Beam is Distorted
Check to see if the lens dirty. If so, see the cleaning instructions in “Lens is Dirty.”
Lens is Dirty
Blow any loose dust off with dry air.
If lens requires further cleaning, gently wipe with lens tissue that is moistened with
either isopropyl or methyl alcohol. Do not apply drops of solvent directly to the lens. Do
not use acetone or other aggressive solvents.
Power is Low
NPL64A: Check the trigger frequency.
Item # Suffix B: Check the trigger frequency and settings of pulse width and repetition
rate controls.
Item # Suffix C: Check the trigger frequency and pulse width control setting.
Figure 12 Table captions should use the Figure style.

Nanosecond Pulsed Lasers Chapter 8: Declaration of Conformity
Page 16 TTN122959-D02
Chapter 8 Declaration of Conformity

Nanosecond Pulsed Lasers Chapter 9: Thorlabs Worldwide Contacts
Rev H, January 25, 2023 Page 17
Chapter 9 Thorlabs Worldwide Contacts
For technical support or sales inquiries, please visit us at www.thorlabs.com/contact for our most up-to-date
contact information.
USA, Canada, and South America
Thorlabs, Inc.
[email protected]m
[email protected]om
UK and Ireland
Thorlabs Ltd.
[email protected]m
[e-mail]
Europe
Thorlabs GmbH
[email protected]om
Scandinavia
Thorlabs Sweden AB
[e-mail]
France
Thorlabs SAS
[email protected]m
Brazil
Thorlabs Vendas de Fotônicos Ltda.
[email protected]om
Japan
Thorlabs Japan, Inc.
[email protected]
China
Thorlabs China
[e-mail]

www.thorlabs.com