1.
End
Pumped
DPSS
Laser
Pulse
Analysis
Team
Lambda
Gregg
Clark,
Rebecca
Dunn,
Henry
Garcia,
Chelsea
Merlo,
Randall
Mooney,
Leticia
Quiñero,
Jimmy
Wiggins
Measurements
for
pulse
width
(FWHM),
pulse
duration
(T),
average
power
(Pavg)
and
peak
power
(Ppeak))
of
a
Spectra-­‐Physics
V70
Series
Nd:YVO4
Q-­‐Switched
Laser
(
λ = 1064
nm)
were
characterized
as
a
function
of
Pulse
Repetition
Rate
(PRR)
across
a
range
a
range
of
Q-­‐Switch
operating
frequencies
.
Energy
Per
Pulse
(Epp)
and
duty
cycle
were
calculated
.
Threshold
current
and
slope
efficiency
were
determined,
as
was
top
end
rolloff.
Output
power
curves
were
generated
at
diode
pump
current
levels
of
15
A,
17
A
and
19
A.
Experimental
results
are
consistent
with
Spectra-­‐Physics
published
performance
data.
This
result
affirms
assessments
that
the
V70
series
is
an
industry
workhorse
DPSS
Q-­‐Switched
system
suitable
for
a
variety
of
applications
requiring
moderate
power
and
good
pulse
stability
with
pulse
rates
in
the
50-­‐250
kHz
range.
Laser
102
Fall
2012

2. Table of Contents
Objective........................................................................................
Theory............................................................................................
Equipment......................................................................................
Setup..............................................................................................
Procedure.......................................................................................
Data & Computations....................................................................
Results............................................................................................
Discussion...................................................................................... .
Significance....................................................................................
Appendix A: Startup Procedure......................................................
Appendix B: V-Series Specifications.............................................
Appendix C: Nd:YVO4 Specifications...........................................

3. Objective:
Observe the behavior of the Spectra-Physics V70 Series Laser to determine figures of
merit - Peak Power (Ppeak), Average Power ( Pavg), Energy per Pulse (Epp), Pulse
Width (FWHM), and Pulse Duration (T = 1/Freq) as a function of Pulse Repetition Rate
(PRR). Three sets of data were taken with diode pump current set to 15A, 17A and 19A.
Theory:
Our goal for this experiment was to characterize the behavior of the Spectra-Physics V-
Head Series Laser across a range of values for two independent variables, Pulse
Repetition Rate (PRR) and Diode Pump Current ( Ipump).
The V-Series Laser is an implementation of mature DPSS technology in a robust design.
In order to maximize conversion efficiency and pulse energy it is desirable to find
optimal values for both PRR and diode pump current.
First step is to determine values for threshold current, slope efficiency and rolloff point.
The rolloff point is determined when the power output of the vanadate crystal starts to
vary in a nonlinear way relative to linear increases in diode pump current.
Equipment:
• Spectra-Physics V-Head laser under test
• Spectra-Physics T-Remote desktop controller
• Spectra-Physics T-Series power supply
• Spectra-Physics T-Series laser operator’s manual
• Spectra-Physics T-Remote operator’s manual
• Oscilloscope
• Power meter
• Power detector head
• ND filter
• Safety glasses rated from 535nm to 1064nm

4. Setup:
Once we figured it out. The Nova II power meter is a great instrument and it is easy to
hook up and get going. The Agilent oscilloscope has so many help screens you can’t
help but get it set up right if you keep at.
We checked that we were within power density limits for the thermopile sensor, then set
up our bench as shown below.
Initial Bench Setup
This seemed like a good arrangement, we could get our scope readings and waveform
captures from the Agilent oscilloscope and then turn our attention to the Nova II.to take
our power measurements. This would let us move quickly through the experiment
without having to rearrange the test setup, always a good thing.
But it did not work. We found that the photodiode was picking up enough of a signal
from ambient light that it interfered with our waveform measurement. It also turned out
to be harder than we thought to line up the beam on the thermopile sensor. The active
area of the thermopile sensor is only about 1” wide. It turned out to be harder than we
thought to get an invisible (1064nm) Class IV beam lined up from several feet away.
We ended up with the layout below for our power measurements. The laser is running
CW at 2.31W as shown on the Nova II.

5. Setup for taking power measurements
The J20 series power supply holds all the pump diodes, power supplies and thermal
management hardware needed to run the laser head. It is located on the floor and to the
right at the base of the bench. It was out of the way there without placing strain on any of
the umbilicals that need to run between the laser head and the power supply.
Below is a picture of the Spectra Physics factory remote. It is needed to run the laser as a
standalone piece of equipment. Otherwise it is necessary to plug into the serial port on
the back of the power supply and talk to it in RS-232 at 9600-N-8-1.

6. Procedure:
The first step in the experimental procedure was to determine the threshold current and
slope efficiency of the laser under test.
Next, using the Nova II with the thermopile sensor we took power readings across a
range of pulse rates from 1 kHz to 500 kHz. A power output curve as a function of Pulse
Repetition Rate (PRR) was developed for three different pump currents at 15A, 17A and
19A.
Then we used the oscilloscope to characterize the pulse width (FWHM) and the pulse
duration (period, T). We used the scope to capture a picture of the laser pulse waveform
on one channel and the RF frequency signal that is used to drive the acousto-optic
Q-Switch on the other. This step ensured that the laser and the Q-Switch were operating
properly and that we were taking valid data.
Last, we performed a data acquisition exercise. The Agilent oscilloscope has a feature
that will let the user dump raw sampled data to a file on the floppy in .csv format. We
took this file and plotted it manually ourselves, using Excel as a software codec to
perform the digital-to-analog conversion.
From this small set of directly observed data all other figures of merit for the system can
be calculated and presented for analysis.

8. Linear
portion
of
response
curve
is
from
12
A
to
15
A Where
m
=
0.53257 when
run
against
the
linear
portion
of
the
curve
At
pump
current
of
12
A
optical
power
out
is
0.65
W b
=
-­‐5.5651
At
pump
current
of
15
A
optical
power
out
is
2.88
W
Slope
efficiency
is
∂P/∂I
in
the
linear
part
of
the
curve Where
m
=
0.17818 when
run
against
the
whole
data
set
Using
the
LINEST()
function
to
run
a
linear
regression
and
solve
y
=
mx
+
b b
=
-­‐0.8009
Slope
efficiency
= 0.532571 W/A
==>
this
value
seems
high
0.000
0.500
1.000
1.500
2.000
2.500
3.000
0
2
4
6
8
10
12
14
16
18
20
Wa-s
Amps
Threshold
Current

10. 0.500
1.000
1.500
2.000
2.500
3.000
0
50
100
150
200
250
300
350
400
450
500
Pavg
(W)
PRR
(kHz)
Pavg
v
PRR

11. 0
200
400
600
800
1000
1200
1400
0
50
100
150
200
250
300
350
400
450
500
Ppeak
(W)
PRR
(kHz)
Ppeak
v
PRR

12. Data for Ipump = 15A

13. Data for Ipump = 17A

14. V"Head'Pulse'Characterization'==>'Pavg'as'a'function'of'PRR'and'Pump'Current
Data'Taken': 12/12/12 Epp'='Pavg'*'Period
Ppeak'='Epp/FWHM'*
Pump'Current: 19'A
Diode'Temp' 30.4°C Pavg'measured'with'Nova'II'power/energy'meter
*'FWHM'values'taken'from'SP'data'sheet,'shown'below
PRR#(kHz) Pavg#(W) FWHM*#(nSec)#==>#taken#from#SP#data#sheetPeriod#(µsec)Epp#(mJ) Ppeak#(W)
1.0 0.095 100 1,000.00 95.00 950
2.5 0.112 100 400.00 44.80 448
5.0 0.124 100 200.00 24.80 248
7.5 0.139 100 133.33 18.53 185
10 0.160 100 100.00 16.00 160
15 0.191 100 66.67 12.73 127
20 0.233 100 50.00 11.65 117
25 0.265 100 40.00 10.60 106
30 0.308 100 33.33 10.27 103
40 0.381 100 25.00 9.53 95
50 0.454 100 20.00 9.08 91
60 0.520 100 16.67 8.67 87
75 0.655 100 13.33 8.73 87
100 0.895 100 10.00 8.95 90
125 1.290 100 8.00 10.32 103
150 2.072 100 6.67 13.81 138
200 2.200 100 5.00 11.00 110
250 2.196 100 4.00 8.78 88
300 2.701 100 3.33 9.00 90
400 2.866 100 2.50 7.17 72
500 2.946 100 2.00 5.89 59
750 3.139 100 1.33 4.19 42
1000 3.186 100 1.00 3.19 32
Data for Ipump = 19A

15. Waveform Capture
Laser pulse trains captured at two different PRR settings
1) The first capture takes place at PRR = 5 kHz; the period T is 200 µsec
2) The second capture takes place at PRR = 50 kHz; the period T is 20 µsec.

16. The following two captures show the tight timing relationship between Q-Switch
operation and laser pulse generation
Note how the laser pules fires in the middle of the 1.6µsec pulse suppression interval.
Here the time scale has been changed so that a series of pulse train events can be seen on
the screen at once.

17. The waveform below is a closer look at the RF signal that energizes the acousto-optic
transducer in the Q-Switch.
Using the tools built into the oscilloscope it is easy to see that the signal is in the RF
range, with a frequency of 40 mHz and a period of 25 nsec.
Analysis & Results:
This was a good exercise in pulsed system characterization. By making some fairly
straightforward measurements it is possible to fully characterize the behavior of
Q-Switched laser systems.
With one exception, discussed below, our results agreed reasonably well with Spectra-
Physics published performance data for this system.
Examination of the Pavg and Ppeak curves for the three pump currents at 15A, 17A and
19A reveals interesting behavior. The curves generated at 15A and 17A were as
expected; however the 19A curve did not follow expected behavior. At 15A and 17A
output power (Pavg) was starting to level out and remain fairly constant over the rest of
the PRR operating range out to 500 kHz.
At a pump current of 19A the output power curve did not develop smoothly. It wandered
around as PRR increased, finally approaching (but not reaching) the level of stability that
the system showed at the lower pump currents until it was way out on the curve with a
PRR of about 300 kHz

18. We realized that the laser was no longer operating in the linear portion of the P/I
response curve. Between 17A and 19A the laser had moved past the roll off point. At
19A the laser was over-driven, being pushed by too much current and not responding to
an increase in pump current with a proportional increase in output power.
The gain medium had become saturated and would no longer do what we asked of it.
Discussion:
We learned that it is not possible to directly determine an accurate value for FWHM
using the oscilloscopes we currently have in the laboratory. Although the scopes sample
every 5 nsec, only every 100th
sampled data point is written into the frame buffer that is
displayed on the screen or saved to the .csv file on the disk. For our purposes the
oscilloscope has a sampling rate of once every 500 nsec, not once every 5 nsec. It is not
possible to accurately measure an event with a duration that is less than the sampling
period. Since FWHM for this system is on the order of 100 nsec, we cannot determine
the pulse width accurately with a device that has a sample period of 500 nsec.
The best place on the P/I curve to operate this system is as far out on the linear portion of
the P/I curve as one can go without going past the roll off point. Operating the laser in
this region with pump current set as high as possible (but not beyond) the roll off point
and with a PRR of between 50-500 kHz will optimize laser power output, beam mode
quality and pump diode operating lifetime.
Significance:
The best place to operate a laser is at the far end of the linear region of the P/I curve.
Since the P/I curve is unique to each system, for the highest level of performance each
system must be tested and characterized to determine its individual value for maximum
pump current.
This is why lasers are never delivered from the factory with a capability for the end-user
to vary pump current. It is too easy for the customer to fiddle around trying to squeeze a
little more power out of the laser (which has already been set for maximum safe power
output by the OEM) and end up overdriving the system, with attendant damage and
shortened operating lifetimes for pump diodes, optics, coatings and the system as a
whole.

20. APPENDIX A
SJCC
LASER 102
NO:
DATE:
REV:
3
11/20/12
A
APPROVALS:
Total number of pages is V. P. Eng Eng Mgr Mfg Mgr Q. A. Mgr Doc Control Laser Tech
Startup Procedure
Spectra-Physics
Nd:YVO4 Q-Switched V-Head Laser
REV UPDATED BY DATE APPVD
BY
DATE
A Initial Release
Startup Procedure
Spectra-Physics
Vanadate Q-switched
V-Head Laser
Information contained in this
document is considered to be
confidential and is not to be used in
any manner without the express
permission of SJCC Laser Tech
Department.
_______________________
Print below and
sign your name below line

21. Table of Contents
A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
Purpose ……………………………………………………………..
Procedure Scope: …………………………………………...…,,,,,,,,
Equipment Needed …………………………………………………
Reference Documentation …………………………………………..
Responsibilities ……………………………………………………..
Definitions ………………………………………………………….
Laser Overview ……………………………………………………..
Laser System Set-up ………………….…………………………….
System Start-up and Shut-down …………………………………….
List of Illustrations…………………………………………………..

22. A. Purpose
The purpose of this procedure is to make sure the turn-ON and turn-OFF steps for a Spectra-Physics V-
Head laser are correctly.
B. Procedure Scope
This procedure applies to any T-Series V-Head Vanadate Q-Switched laser manufactured by Spectra-
Physics.
C. Equipment Needed
Spectra-Physics V-Head laser under test
Spectra-Physics T-Remote desktop controller
Spectra-Physics T-series power supply
Spectra-Physics T-Series laser operator’s manual
Spectra-Physics T-Remote operator’s manual
Oscilloscope
Power meter
Power detector head
ND filter
Safety glasses rated from 535nm to 1064nm
D. References: Spectra-Physics T-Series Q-Switch V-Head Laser User’s Manual
Laser Institute of America Laser Safety Guide
Inspection and Evaluation of Optics - Laser Lab and Mfr Best Practices
Encyclopedia of Laser Physics and Technology - © Dr. Rüdiger Paschotta
Sam’s Laser FAQ -> http://www.repairfaq.org/sam/lasersam.htm
E. Responsibilities: It is the responsibly of Quality Assurance Department to verify that the provisions
of this document are followed.
F. Definitions:
acousto-optic modulators: optical modulators based on the acousto-optic effect
bandwidth: frequency (or wavelength) range between ±3 dB rolloff points
beam divergence: an angular measure (radians) for how fast a laser beam expands in the far field
beam pointing fluctuations: variation in the propagation vector of a laser beam
beam profilers: device for measuring the energy intensity profile of a laser beam across a transverse
section
beam quality: a measure for how well a laser beam can be focused
beam radius: radius of the transverse section of a light beam orthogonal to direction of propagation
beam shapers: optical devices for modifying the shapes of laser beams
beam splitters: devices for splitting a laser beam into two or more beams
beam waist: location with minimum beam radius

23. brightness: a term mostly used in a qualitative way, related to the output power and beam quality of a
laser; quantitatively: synonymous with luminance
cavities: resonant chambers (resonators) for light or for microwaves
coherence: E field and B field vectors maintain a fixed phase angle between the electric field values at
different locations or at different times
collimated beams: laser beams with weak divergence
continuous-wave operation: operation mode of a laser with continuous light emission
dichroic mirrors: mirrors with significantly different reflection or transmission properties at two
different wavelengths
dielectric coatings: thin-film coatings made of transparent dielectric material with different indices of
refraction, e.g. for laser mirrors or anti-reflection coatings
dielectric mirrors: mirrors consisting of multiple thin layers of dielctric coatings. Very high refectivities
( >99 ) can be obtained using this technique
diffraction-limited beams: beams with a minimum possible beam divergence for a given waist radius
diode bars: a type of semiconductor laser containing a one-dimensional array of broad-area emitters
diode-pumped lasers: solid-state lasers which are pumped with laser diodes
diode stacks: arrangements of multiple diode bars, delivering very high output power
electro-optic modulators: optical modulators based on the electro-optic effect
end pumping: a technique of optically pumping a laser medium in the axis parallel to the laser beam
eye-safe lasers: lasers emitting in a wavelength region and with limited optical power such that the risk
of serious injury to the eye is relatively low.
gain: a measure of the strength of optical amplification
gain bandwidth: the width of the optical frequency range in which significant gain is available from an
amplifier
gain switching: a technique for generating short optical pulses in a laser by modulating the laser gain
gas lasers: lasers with a gas (or plasma) as gain medium
Gaussian beams: light beams where the electric field profile in a plane perpendicular to the beam axis
can be described with a Gaussian function, possibly with an added parabolic phase profile
Gaussian pulses: pulses with a temporal intensity profile which has a Gaussian shape
infrared light: invisible light with wavelengths roughly between 750 nm and 1300nm

24. laser beams: light beams propagating coherently in one direction
laser crystals: transparent crystals with laser-active dopants, used as laser gain media
laser diode modules: modules containing diode lasers, and possibly also some optics, cooling devices,
electrical elements, etc.
laser diodes: semiconductor lasers with a current-carrying p–n junction as the gain medium
laser heads: assemblies containing a mounted gain medium and means for pumping and cooling, or the
complete optical parts of a laser, or assemblies for directing a laser beam to a workpiece
laser light: light generated with a laser device
laser mirrors: high-quality mirrors used in laser resonators and other optical setups
laser resonators: optical devices which serve as basic building blocks of lasers
laser safety: safety of the use of laser devices
laser threshold: an operation condition of a laser where laser emission just starts to occur
laser transitions: quantum transitions where stimulated emission of photons is used to obtain optical
amplification
lasers: device generating visible or invisible light, based on stimulated emission of light
luminescence: light emission which is not caused by heating
M2
factor: a parameter for quantifying the beam quality of laser beams
metastable states: excited states (particularly electronic states in laser gain media) which have a
relatively long lifetime due to slow radiative and non-radiative decay
neodymium-doped gain media: laser gain media containing laser-active neodymium ions
optical filters: devices with a wavelength-dependent transmission or reflectivity
optical intensity: optical power per unit area
optoelectronics: the technology of electronic devices that interact with light
output couplers: partially transparent laser mirrors, used for extracting output beams from laser
resonators
photonics: the science and technology of light
photons: quanta of light energy
Pockels cells: electro-optic devices, used for building Q-Switch modulators

25. polarization of laser emission: E field oscillation of a laser beam is constrained to a two dimensional
plan
population inversion: a state of a medium where a higher electronic energy level has a higher
population than a lower energy level
power spectral density: optical power or noise power per unit frequency interval
power meters: devices for optical power measurements, based on heating of an absorber structure
pulse repetition rate: the number of pulses emitted per second e.g. by a mode-locked or Q-switched
laser
pulsed lasers: lasers emitting light in the form of pulses
pulses: flashes of light
Q factor: a measure of the damping of resonator oscillations, quantifies losses for each round trip
through the resonator.
Q-switched lasers: lasers which emit laser light in short optical pulses, relying on the method of Q
switching
Q switches: optical switches typically used for generating nanosecond pulses in lasers
Q switching: a method for obtaining energetic pulses from lasers by modulating the intracavity losses
rare-earth-doped gain media: laser gain media which are doped with rare earth ions
Rayleigh length: the distance from a beam waist where the mode radius increased by a factor square
root of 2
refractive index: a measure of the reduction in the velocity of light in a medium
resonant frequency doubling: frequency doubling with a nonlinear crystal placed in a resonant
enhancement cavity
resonator modes: modes of an optical or microwave resonator, both longitudinal and transverse
side pumping: a technique of pumping a solid-state laser in directions which are approximately
transverse to its beam direction
slope efficiency: differential power efficiency of a laser once it has crossed threshold and begun lasing
solid-state lasers: lasers based on solid-state gain media (usually ion-doped crystals or glasses)
thermal lensing: a lensing effect induced in birefringent media by temperature gradients
threshold pump power: the pump power at which the laser threshold is reached and the laser begins to
emit radiation
ultraviolet lasers: lasers which generate ultraviolet ( λ < 400 nm ) light

26. ultraviolet light: invisible light with wavelengths shorter than λ 400nm
vanadate lasers: lasers based on rare-earth-doped yttrium, gadolinium or lutetium vanadate crystals,
usually Nd:YVO4

27. G. Laser Overview
Laser Crystal Operation:
A neodymium-doped (1-3%) crystal of yttrium vanadium oxide (Nd:YVO4) is used as a
gain medium. Vanadate has a broad absorption maximum centered around 808nm. When
pumped at 808nm the crystal will lase at multiple wavelengths. 1319nm, 1338nm,
946nm and 1064nm have all been demonstrated. The1064nm wavelength exhibits the
highest gain and is typically selected as the design wavelength. Choosing the highest
gain wavelength achieves the best conversion efficiency. The V-Head laser we use
operates at 1064nm.
Resonator Cavity Operation:
The V-Head laser cavity is built in two sections shaped like a folded “V” with a single
laser diode pump input. The oscillator runs at pulse repetition rates of 50 kHz to 500
kHz. Operating the laser at pulse repetition rates greater than 350 kHz is considered
continuous operation.
Laser Pump Operation:
A stacked-laser diode pumping system with a fiber optic delivery system excites the
Nd(3+) ions in the vanadate crystal lattice up to the pump band energy level. From there
the level drops to the metastable state which has a An output beam mode of TEM00 is
desired so the crystal is end pumped. Careful design and assembly enable mode-
matching (alignment of the beam waists of the 808 nm pump beam and the 1064nm
output beam) to generate TEM00 emission and optimizing output power.

28. An illustration outlining the structure of the V-Head resonator cavity is shown below.
Picture 1: V-Head Resonator Cavity
Q-switch Operation:
A Q-switch, in this case an acousto-optic (AO) device powered by a radio-frequency
source, is used to increase optical amplification. The V-Head Q-Switch is energized by
applying a 40 mHz RF signal to the base of the acousto-optic transducer. The gain
medium will continue to store energy when the the Q-switch is energized so that
resonator cavity Q is high and corresponding cavity energy losses are low. Then the 40
mHz signal is suppressed for 1.6 µsec, switching the cavity Q to a low level. When the
Q-Switch is no longer energized, it becomes transparent to the incident 1064nm beam
and a pulse is released. The Q-Switch becomes transparent and the laser fires after the
pulse holdoff period elapses. The energy stored in the crystal is released in a pulse less
than 120ns wide. For our laser the pulse holdoff period is set to 0.8 µsec, so the laser
fires in the middle of the RF suppression gap.

29. The oscilloscope screen capture below shows the laser pulse
Picture 2: Pulse capture during RF suppression
The lower trace is the 40mHz RF signal for the Q-Switch. The upper trace is the laser
output, inverted for scale considerations so we could get everything on the oscilloscope
screen and capture it to disk.
Picture 3: Pulse train and Q-Switch RF
Picture 3 demonstrates the timing relationship between RF for the transducer and the
laser pulse. The laser pulse is right in the middle of the Q-Switch RF suppression
interval.

30. Picture 3 compresses the time scale so it is possible to see several pulse train events in
sequence.
In both pictures the upper trace is the laser pulse waveform while the lower trace is the
40mHz RF signal for the Q-Switch.
Picture 4: 40mHz RF for Q-Switch modulation
Picture 4 is a closer look at the 40 mHz RF signal applied to the Q-Switch transducer to
energize it and suppress pulse emission. Using the built in measurement capabilities of
our oscilloscope it is easy to see that the transduce is a classic RF signal, a pure sine
wave oscillating at 40 mHz.
Non-linear Crystal Operation:
There is no non-linear crystal used inside this laser for harmonic generation. The V-Head
output consist solely of the fundamental wavelength at 1064nm.

31. H. Laser System Set-up
The V-Head laser connections are comprised of an FCBar laser fiber module connection
for the laser pump and an RF connection for powering the Q-switch. Both of these
connections are powered through the associated V-head laser power supply, which is
power through a standard computer power cord to, plugged into a standard 110VAC wall
outlet.
I. System Start-up and Shut-down
There two main startup sequences namely Cold Start and Warm Start. Cold start is when
the power supply was turned off, while warm start is when system is in a standby mode
i.e. the laser is off but the power supply was left on.
Turning on the laser
1. Turn the system power on.
2. Wait until the boot sequence is finished. The following message will show on the
Power Supply
3. LCD: BOOT COMPLETE
LASER DIODE OFF
CURRENT MODE READY (or POWER MODE READY)
A “READY” message will be displayed on the remote.
4. Press #3 button (CFG) menu) on the left and get into CONFIGURATION
SCREEN.
5. Use #4 button to scroll the cursor on the far right of the screen to the menu item-
“DMOD.”
6. The diode control mode can now be toggled between power mode and current
mode using the two arrow keys on the lower right side of the remote.
Turning off the laser
It is recommended that you leave the laser in a standby mode when not in use. This
means that you turn off the laser but leave the power supply power switch on at all times.
This will keep the SHG crystal at the optimal operating temperature, thus reduce warm-
up time.
1. Turn off the laser diode emissions, using theRS-232 command (DEL). Verify that
the laser output power or diode current has dropped to zero.
2. Turn off the main power to the power supply.

32. APPENDIX B
V-Xtreme Specifications
Spectra-Physics V-Head Q-Switched DPSS Laser *
*From V-Series product data sheet published on Spectra-Physics web site.
Spectra-Physics V-Head Q-Switched DPSS Laser

33. APPENDIX C
Nd:YVO4 Specification *
* Data sheet published by Coherent, Inc.
Printed in the U.S.A. MC-070-03-5C0103
Copyright ©2002 Coherent, Inc.
Coherent follows a policy of continuous product improvement.
Specifications are subject to change without notice.
Coherent offers a limited warranty for all crystals. For full details
on warranty coverage, please refer to the Service and Support
section at www.CoherentInc.com, or contact your local Sales or
Service Representative.
C O H E R E N T, I N C .
5100 Patrick Henry Drive
Santa Clara, CA 95054
Phone: 1-800-527-3786
1-408-764-4983
Fax: 1-800-362-1170
1-408-988-6838
Email: tech.sales@CoherentInc.com
Web: www.CoherentInc.com
LOCAL OFFICES
Japan +81 (3) 5635 8700
Europe +49 (6071) 9680
Neodymium Doped Yttrium Orthovanadate
Nd:YVO4
Chemical Formula Ndx Y1-x VO4 [x] = 0 to 0.03
Crystal Structure Tetragonal, 4/mmm
Lattice Parameters (Å) a = b = 7.12; c = 6.29
Density (g/cm3) 4.22
Melting Point (°C) 1810 ± 20
Hardness (Mohs) 4.5 - 5
Thermal Expansion Coefficients (x 10-6/°K) αa = 5.5 ± 1.5
αc = 11 ± 1.5
Thermal Conductivity (W/m/°K ) κa = 5.23 (Parallel to C)
κc = 5.10 (Perpendicular to C)
Typical Lasing Wavelength 1.0643 µm
Peak Absorption Wavelength 810 nm
Absorption Bandwidth (FWHM) 8 nm
Refractive Indices no = 1.9721; ne = 2.1858 @ 808 nm
no = 1.9573; ne = 2.1652 @ 1064 nm
Optical Transmission Range (nm) 400 to 3800
Intrinsic Loss @ 1064 nm <0.01 cm-1
Sellmeier Equations (λ in µm) no
2 = 3.7783 + 0.0697/(λ2 - 0.0472) - 0.0108λ2
ne
2 = 4.5991 + 0.1105/(λ2 - 0.0481) - 0.0123λ2
Thermo-Optic Coefficients (10-6/°K) dno/dT = 8.5
dne/dT = 3.0
Fluorescence Lifetime (µs) [Nd]= 0.4% 1.0% 2.0%
110 97 63
Polarized Laser Emission Parallel to Optic Axis (C-Axis)
Stimulated Emission Cross Section (22 ±3) x 10-19 cm2 @ 1064 nm
Absorption Coefficient [Nd]=1.0% σ = 31 ± 3 cm-1; π = 9 ± 2 cm-1 @ 808 nm
Wavefront Distortion λ/8
Perpendicularity <30 arcminutes
Parallelism <1 arcminute
Surface Quality (scratch dig) 10/5
Coating Reflectivity (standard DBAR) R < 0.10% @ 1064 nm, R < 0.50% @ 808 nm
Damage Threshold (standard DBAR) 500MW/cm2 @ 1064 nm (10 sec pulses)
Dimensional Tolerances ± 0.10 mm (cross sections)
± 0.10 mm (lengths)
Available Sizes Rods - diameters 3 to 6 mm up to 20 mm lengths
Rectangular parts from 2 x 2 mm to 10 x 10 mm
Cross Sections up to 20 mm lengths
Crystal Axis Orientation ±0.5 degree
YVO4 Linear
Optical Properties
Nd:YVO4 - Neodymium Doped Yttrium Orthovanadate
Typical Crystal
Element
Specifications
YVO4 Physical
Properties