Droplet SP2 User manual

SP2
Single Particle Soot
Photometer
Laser Alignment Manual
DOC-0229 Rev. E
2400 Trade Centre Avenue
Longmont, CO 80503 USA
A L L R I G H T S R E S E R V E D

DOC-0229 Rev E
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
2
General Information
In no event will Droplet Measurement Technologies, LLC (DMT) be liable for direct, indirect, special, incidental
or consequential damages resulting from any defect or omissions in this manual.
DMT reserves the right to make changes to this manual and the products it describes at any time, without
notice or obligation. Revised editions are found on the manufacturer’s website.
All DMT product names and the Droplet Measurement Technologies Logo are trademarks of Droplet
Measurement Technologies, LLC.
All other brand and product names are trademarks, or registered trademarks, of their respective owners.
Software License
DMT licenses its software only upon the condition that you accept all of the terms contained in this license
agreement.
This software is provided by DMT “as is” and any express or implied warranties, including, but not limited to,
the implied warranties of merchantability and fitness for a particular purpose are disclaimed. Under no
circumstances and under no legal theory, whether in tort, contract, or otherwise, shall DMT or its developers
be liable for any direct, indirect, incidental, special, exemplary, or consequential damages (including damages
for work stoppage; computer failure or malfunction; loss of goodwill; loss of use, dataor profits; or for any and
all other damages and losses). Some states do not allow the limitation or exclusion of implied warranties and
you may be entitled to additional rights in thosestates.
Warranty
The seller warrants that the equipment supplied will be free from defects in material and workmanship for a
period of eighteenmonths from date of shipment or 12months from the dateof either installationor firstuse
whichever comes first. When returning the equipment to DMT for warranty or service procedures, the
equipment owner will pay for shipping to DMT, while DMT will pay the return shipping expense. Consumable
components, such as tubing, filters, pump diaphragms, and Nafion humidifiers and dehumidifiers are not
covered by this warranty.

SP2 Laser Alignment Manual
DOC-0229 Rev E 3
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
Contents
1.0 Introduction: Laser Cavity Performance.................................................................... 5
2.0 Sequence of Laser Cavity Troubleshooting................................................................ 6
3.0 Minor Alignment Process (First Option).................................................................... 8
3.1 Equipment.....................................................................................................................................9
3.1.1 Required Tools......................................................................................................................... 9
3.1.2 Recommended Tool................................................................................................................. 9
3.2 Step-by-Step Instructions for a minor alignment..........................................................................9
4.0 Major Alignment Process (Second Option).............................................................. 18
4.1 Time Requirements.....................................................................................................................18
4.2 Dangers of ESD Shock..................................................................................................................19
4.3 Tools ............................................................................................................................................19
4.3.1 Required Tools.......................................................................................................................19
4.3.2 Additional Recommended Tool .............................................................................................19
4.4 Step-by-Step Instructions for a major alignment........................................................................20
Appendix A: Tools and Replacement Items from DMT......................................................... 37
Appendix B: SP2 YAG Pump Laser Storage & Handling Instructions ...................................... 37
Storing the SP2 YAG Pump Laser.............................................................................................................37
Handling the SP2 YAG Laser ....................................................................................................................37
Appendix C: Revisions to Manual......................................................................................... 39

DOC-0229 Rev E
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
4
Figures
Figure 1: Nd: YAG Laser Resonator Cavity.............................................................................. 5
Figure 2: Troubleshooting Sequence ..................................................................................... 7
Figure 3: SP2 Spectrometer Head........................................................................................... 8
Figure 4: Mode Aperture Removal ....................................................................................... 10
Figure 5: Installing Mode Aperture in Upside-Down Position................................................ 11
Figure 6: Satisfactory Beam Profile ...................................................................................... 12
Figure 7: Undesired Higher Mode........................................................................................ 12
Figure 8: Coupler Chamber Sealing Screws .......................................................................... 13
Figure 9: Tip/tilt adjustment of output coupler mount ......................................................... 13
Figure 10: Angled entry of drivers in older systems ............................................................. 13
Figure 11: Attachment of Mode Aperture Alignment Tool ................................................... 15
Figure 12: Manual mode aperture alignment ...................................................................... 15
Figure 13: Application of extra force to assist stage springs ................................................. 16
Figure 14: Histogram Response as Chamber Plate is Translated........................................... 17
Figure 15: Ultra-Torr Fiber Passthrough Fitting.................................................................... 20
Figure 16: Unscrewing SMA Connector................................................................................ 21
Figure 17: Components of Fiber Passthrough ...................................................................... 21
Figure 18: Assembled SP2 Alignment Fixture....................................................................... 22
Figure 19: Frame-to-fixture fasteners.................................................................................. 22
Figure 20: Removing Output Coupler Mounting Screws....................................................... 23
Figure 21: Wiping the output coupler.................................................................................. 24
Figure 22: YAG Crystal and Optical Pump Assembly............................................................. 25
Figure 23: Fasteners securing YAG crystal holder to pump base........................................... 26
Figure 24: Three fasteners secure TMA to YAG crystal holder .............................................. 27
Figure 25: Screws securing halves of YAG Crystal Holder together ....................................... 27
Figure 26: YAG Crystal cushioned in holder ......................................................................... 28
Figure 27: Alignment Beam Centered on Pinholes ............................................................... 30
Figure 28: Paper between Crystal and Mode Match Optics.................................................. 31
Figure 29: Adjusters that aim the YAG Crystal Assembly...................................................... 31
Figure 30: Beam and Reflection Coincidence ....................................................................... 32
Figure 31: Paper Placed to Block Reflection from Crystal Face ............................................. 33
Figure 32: Light Concentric Around Entrance to Coupler Chamber........................................ 34
Figure 33: Locking and Adjustment Screws........................................................................... 35
Figure 34: Centered chamber (coplanar slide plate and slide rail end faces)......................... 36
Figure 35: SP2 Pump Laser in Protective Box ........................................................................ 37
Figure 36: Shorting Plug Detached (left) and Attached (right) to Power Connector ............... 38
Figure 37: Protective Cap SMA Fiber Connector; Cap Attached to Connector........................ 38

SP2 Laser Alignment Manual
DOC-0229 Rev E 5
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
Introduction: Laser Cavity Performance
Figure 1 shows a schematic depiction of the pumped Nd:YAG plano-concave laser resonator at the heart
of the SP2 spectrometer head. Particles in the aerosol jet intersect the laser beam within the resonator
cavity.
Figure 1: Nd: YAG Laser Resonator Cavity
Optimum performance of the SP2 is obtained when its laser beam is operating in the TEMoo mode, in
which the beam cross-section has a Gaussian profile. Higher-order modes will have multiple spots,
which may not affect the measurement of black carbon incandescence but will almost certainly limit the
utility of the scattering data collected. In cases where very high-order modes are present, the
incandescence data can also be compromised.
Intracavity laser power is also essential for peak measurement performance and depends heavily upon
proper alignment and the surface integrity of the optics which bound the cavity.
A minor adjustment of the Nd:YAG laser alignment can frequently restore instrument performance. If
the signal shape from a purely scattering particle is significantly non-Gaussian, such an adjustment can
usually restore the peak shape. Cleaning the delicate surfaces of the laser’s optical components can
restore lost power but is often a last resort prior to their replacement.

DOC-0229 Rev E
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
6
Sequence of Laser Cavity Troubleshooting
A significant reduction in laser power is typically caused by either misalignment of the laser cavity or
contamination of the laser optics. Total loss of laser power is usually the result of a failure in the pump
laser system, or an occlusion of the intracavity laser beam by a mechanical component such as the mode
aperture that was not secured properly.
Performance degradation is attributable to a non-Gaussian beam profile, a loss of beam power, or both.
Table 1 identifies cavity-specific causes of these symptoms and lists possible remedies.
Symptom
Causes
Remedies
Non-Gaussian beam profile
Misalignment of optical components
Adjust output coupler tip/tilt
Misalignment of mode aperture
Realign mode aperture
Loss of power
Misalignment of optical components
Adjust output coupler tip/tilt
Misalignment of mode aperture
Realign mode aperture
Contamination or degradation of
optical component surfaces
oClean surface of output coupler
oReplace output coupler
oReplace YAG crystal
Table 1: Causes and Remedies of Symptoms of Degraded Performance

SP2 Laser Alignment Manual
DOC-0229 Rev E 7
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
Figure 2 presents the recommended troubleshooting sequence for restoration of lost power. Difficulty
and cost increase as the sequence progresses.
Figure 2: Troubleshooting Sequence
Minor Alignment
Major
Alignment

DOC-0229 Rev E
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
8
Noteworthy components of the SP2 spectrometer head are identified in Figure 3.
Figure 3: SP2 Spectrometer Head
Minor Alignment Process (First Option)
These are adjustments that can be made without removal of core optical components. A minor
alignment adjustment of the Output Coupler or Mode Aperture, without removal of the spectrometer

SP2 Laser Alignment Manual
DOC-0229 Rev E 9
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
head, can frequently restore instrument power. If the signal shape from a purely scattering particle is
significantly non-Gaussian, a small adjustment of the Output Coupler can usually restore the peak shape.
When checking the beam profile with the beam scan camera, it is recommended that the Mode
Aperture be removed from the optical path to ensure that the entire beam profile is shown in the beam
scan image. A good way to do this is to remove the mode aperture and reinstall it upside-down, while
maintaining the seal for the flow system to operate.
1.1 Equipment
1.1.1 Required Tools
•Beam scan camera
•Two 5/64 ball-end hex drivers, screwdriver handle preferred
•One 3/32 ball-end hex drivers, screwdriver handle preferred
•One 5/32 long stem ball-end hex driver, screwdriver handle preferred
•Multi-bit tool set such as a Chapman set having changeable screwdriver and hex bits
•Aerosol generator and 0.24-0.28 micron PSL particles.
Note: The terms “hex” and “allen” are used interchangeably throughout this document to describe a screw driver
of hexagonal cross section.
1.1.2 Recommended Tool
•SP2 mode aperture alignment tool
1.2 Step-by-Step Instructions for a minor alignment
1) Run the SP2 for 15-30 minutes with a filter on the inlet to remove as many particles as possible
from the instrument. (Leave the filter in place until step 28) is reached.)
2) With the laser operational, record the YAG power voltage reported in the SP2 software.
3) Shut off the laser and then the sample pump.
4) Remove the top cover from the SP2 analyzer chassis and wait 1-2 minutes for all flow to stop.

DOC-0229 Rev E
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
10
5) Remove the mode aperture by removing the two 4-40 Allen head screws with a 3/32” driver and
lifting the mode aperture straight up. It is useful to remove the screws and then use needle-
nose pliers to grasp the aperture and remove it. Take care not to lose the O-ring. See Figure 4.
Figure 4: Mode Aperture Removal
6) Turn on the laser current and DO NOT TURN ON THE SAMPLE PUMP. Make note of the YAG
power reading and turn the laser off. If the YAG power has increased by more than 10% over
the measurement made in step 2), realignment of the mode aperture can increase the laser
power.
7) If the laser power does not increase by more than 10%, it is recommended that the beam mode
be evaluated also to insure the laser is in optimum operating condition. This will be checked in
the following steps.

SP2 Laser Alignment Manual
DOC-0229 Rev E 11
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
8) Reinsert the mode aperture in an upside-down orientation, while leaving the small O-ring
underneath it, and screw it in place. (This creates the necessary seal for the SP2 flow system,
while at the same time ensuring that the mode aperture is not blocking the laser.) See Figure 5.
Figure 5: Installing Mode Aperture in Upside-Down Position
9) Remove the laser power monitor from the coupler end of the laser frame. The laser power
monitor should be set aside. It may be necessary to remove the right-side panel from the SP2 to
access the screws on the laser power monitor. The reference to the right side of the SP2 is as
viewed from the front of the instrument.
10) Install the beam scan camera. Consult DOC-0175 for details of beam scan camera installation or
operation.
11) With the Mode Aperture installed in the upside-down position, turn on the flow system. Wait
for the sample flow to stabilize at its set-point. Turn the laser current down to approximately
1800 mA and turn on the laser.
12) Observe the laser mode. A beam profile depicting the desired TEMoo mode is shown in Figure 6,
while an undesired higher mode (note the non-Gaussian pattern) is shown in Figure 7. If the
Mode Aperture

DOC-0229 Rev E
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
12
laser mode is satisfactory, and the problem is low laser power, the optics may be contaminated.
It is recommended that the user proceed to later sections of this document to pursue optics
cleaning or replacement, per the recommended troubleshooting sequence given in Figure 2. If
the laser mode is unsatisfactory, proceed to step 13).
Figure 6: Satisfactory Beam Profile
Figure 7: Undesired Higher Mode
13) Turn off the laser current, and then the flow system. Wait 1-2 minutes for all flow to stop
before continuing.

SP2 Laser Alignment Manual
DOC-0229 Rev E 13
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
14) Remove the two Phillips head (cross-recess) sealing screws in the top of the coupler chamber.
See Figure 8.
Figure 8: Coupler Chamber Sealing Screws
15) Insert a 5/64” hex driver into both of the holes on the top of the coupler to engage the coupler
adjustment screws. As the drivers are inserted, make sure that the adjustment screws are not
turned. Figure 9 illustrates the drivers properly engaged. (Two walls have been removed in this
figure to improve the view). For SP2 instruments with serial numbers less than 020, the drivers
must be inserted at a slight angle to contact the adjustment screws (Figure 10).
Figure 9: Tip/tilt adjustment of output coupler mount
Figure 10: Angled entry of drivers in older systems

DOC-0229 Rev E
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
14
16) Turn on the laser without the flow system running. While turning the Allen drivers slightly, less
than 1/16th of a turn, observe the laser modes on the beam scan display. Adjust both drivers
until the SP2 YAG laser mode shows TEM00, as depicted in Figure 6. One driver will move the
modes (the pattern of maxima and minima) in the vertical direction, and the other in the
horizontal direction. Once the laser mode is adjusted, carefully remove the drivers while
observing the mode on the display to ensure that removing the drivers does not change the
coupler alignment.
17) Turn off the laser current and install the two sealing screws removed in step 0.
18) Remove the beam scan camera and reinstall the laser power monitor.
19) Turn on the flow system and wait for the sample flow rate to stabilize. Turn on the laser at the
current used in 6). Compare the YAG power to that measured previously. If the power does not
return to a satisfactory level, proceed to Section 0 to pursue optical cleaning or replacement
(per the troubleshooting sequence), or simply return the SP2 to DMT for service. If the laser
power is satisfactory, record the laser power value and continue.
20) Turn off the laser current, and then the sample pump, and reinstall the mode aperture in its
proper orientation. Make sure to put the O-ring on the mode aperture first, and then reinsert
aperture and O-ring into the Mode Aperture block. Placing the O-ring on the block and then
reinserting the aperture can damage the O-ring, as the mode aperture has sharp edges. It is
possible for pieces of the O-ring, if cut, to hang into the beam path.
21) Again, start the sample flow and let it stabilize. Turn on the laser current and record the YAG
power. If the power is within a few percent of that measured in Step 19), there will be no need
for a mode aperture adjustment. You may proceed to Step26) to adjust the position of the
detector chamber, which ensures the sample jet is aligned with the new beam position.
Otherwise, continue with the following steps to adjust the mode aperture position.
22) If the right-side panel has not been removed from the SP2 chassis, remove it at this time.
Loosen the four holding screws in the mode aperture block very slightly. The block should move
when moderate side force is applied but be not so loose that the O-ring behind the block is not
in good contact with the YAG crystal chamber. See Figure 3.
23) If the mode aperture adjustment fixture is available, install it with two clamps and two fasteners
as shown in Figure 11. The adjustment of the mode aperture should be done in the chassis. It
may be necessary to cut or move some of the wire ties on the top of the laser frame to mount
the aperture adjustment fixture. If the adjustment fixture is not available, the mode aperture
can be moved manually as shown in Figure 12.

SP2 Laser Alignment Manual
DOC-0229 Rev E 15
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
Figure 11: Attachment of Mode Aperture Alignment Tool
Figure 12: Manual mode aperture alignment

DOC-0229 Rev E
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
16
24) With the sample pump and laser both running, make adjustments to the position of the mode
aperture block. While making these adjustments, monitor the YAG laser power to maximize the
YAG power reading. The springs in the mode aperture tool usually do not apply sufficient
restoring force to move the holder when the screw is backed out. Finger pressure opposite the
direction of the screw is recommended, as depicted in Figure 13.
Figure 13: Application of extra force to assist stage springs
25) When the optimum laser power has been obtained, tighten the mode aperture block holding
screws by small amounts at a time, alternating between the screws on opposite sides, until the
mode aperture block is firmly secured in place. Do this while monitoring the YAG power to
ensure that the power is not reduced in the tightening process. The optimum laser power
should be at least 90% of that measured in Step 19). The adjustment fixture can now be
removed, if it was used.
26) After adjusting the position of the coupler, or other optical components, the beam position is
likely to have been moved slightly. The sample jet must be aligned to the new beam position to
ensure that detection peaks from scattering particles have a Gaussian shape. Loosen the two
10-32 slide screws (Figure 3) that hold the chamber slide plate to the base of the YAG laser
frame, by approximately one-half turn. Record the position of the micrometer head that moves
the chamber slide plate, and back the micrometer out by 0.012 inches (twelve tick marks on the
micrometer). Make sure the chamber has moved also by pushing it towards the micrometer.
Tighten the two screws that lock the chamber in position.
27) Prepare an aerosol generator or other source of particles that can provide approximately 0.24-
0.27-micron PSL particles at a nominal concentration of 300/cc.
28) Remove the filter from the SP2 sample inlet and connect the particle stream to the inlet. After
the concentration has stabilized, record data for 20,000 particles. Record the position of the
chamber as given by the micrometer along with the data file numbers.
29) Loosen the two screws holding the chamber slide plate and advance the micrometer inwards by
0.002 inches (two tick marks on the micrometer). Retighten the screws. Start a new data file
and repeat the recording process for another 20,000 particles at the new chamber position.
30) Continue this process, moving the chamber in 0.002-inch increments, and recording new 20,000
particle files, until the chamber is 0.012 inches (twelve tick marks) past the original position
recorded in Step 26).

SP2 Laser Alignment Manual
DOC-0229 Rev E 17
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
31) Following the completion of the chamber slide scan, remove the particle stream and put the
filter back on the sample inlet. Using PSI/DMT toolkit, or some other data analysis software,
process the chamber slide data. Generate a histogram of each of the files collected at the
different chamber positions. Figure 14 shows an example of the histogram response as the jet
crosses the laser beam. When the position of the jet is optimized in relation to the laser beam,
the distribution from that position will be the most symmetric and have the highest center-peak
height (as read on the horizontal axis in this example). See position 212 in Figure 14. As the jet
moves to either side of this position, the histogram will be spread out asymmetrically on the left
side, indicating a larger number of particles not passing through the center of the beam, and
reflecting less of the laser’s light. When the optimum position of the chamber is determined,
move the chamber to that position as measured by the micrometer. It is recommended that
the chamber be moved out beyond the optimum position and then moved inward with the
micrometer to the optimum position. Tighten the chamber locking screws, and, if system
performance has been restored, reinstall the side and top panels on the SP2 chassis.
Figure 14: Histogram Response as Chamber Plate is Translated

DOC-0229 Rev E
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
18
Major Alignment Process (Second Option)
If the minor alignment process does not restore the necessary laser power, the next step is to clean (or
replace) and realign the “core optical components.”These include the following items:
•Output coupler
•YAG Crystal
•Mode Match optics
•Pump Laser Fiber-Optic face
Because a large section of the coupler’s surface is exposed to the interior of the cavity (not partially
occluded by the mode aperture, like the YAG crystal face), the output coupler is the most susceptible to
a contamination event. However, since it is necessary to take apart the spectrometer head to remove,
or clean, any of the core optical components, it is recommended that ALL of these components be
inspected, and cleaned while the spectrometer is disassembled, to save time. If proper optical cleaning
techniques are used, the optical surfaces should not be adversely affected by the cleaning process. For
video instruction on the correct cleaning techniques, please visit the DMT FTP site
(dmtftp.dropletmeasurement.com) to download the SP2 optical cleaning training videos. Users will need
a username and password to access this site; contact DMT to obtain this information.
1.3 Time Requirements
Unfortunately, there is no way to evaluate the quality of the optics without checking their performance,
all together, in an operational SP2 laser system. Following any removal and re-installation of the core
optical components, a full alignment is usually required.
The following Steps in the “Major Alignment Process” are listed in the order that they should be
undertaken for the most efficient use of time, and for the highest probability that normal function of the
SP2 will be restored by following this section only once. With practice, this process can be completed in
about three hours, but will typically take much longer for newer users.
You may choose not to undertake all of the major alignment process at once. However, if you are going
through the process in an effort to troubleshoot low laser power, for example, and you clean or replace
the coupler only, and this does not fix the problem, you will need to repeat the bulk of the process to
check the other optics.

SP2 Laser Alignment Manual
DOC-0229 Rev E 19
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
1.4 Dangers of ESD Shock
Warning: There are components inside the SP2 that are sensitive to Electro-Static Discharge (ESD) and
can be rendered non-functional if subjected to ESD shock. It is a good practice to wear a ground strap,
and/or other means of ESD protection, while working inside the SP2. The detector boards are especially
sensitive, and care must be taken when handling and removing the detector chamber, particularly when
the detectors are unplugged. Please contact DMT if you need recommendations for safe handling
procedures.
1.5 Tools
1.5.1 Required Tools
•Beam scan camera
•SP2 Laser Alignment Fixture, alignment pin holes
•2 5/64 ball end Allen drivers, screwdriver handle preferred
•3/32 ball end Allen driver, screwdriver handle preferred
•9/64 ball end Allen driver, screwdriver handle preferred
•5/32 ball end Allen driver, screwdriver handle preferred
•3/16 ball end Allen driver, screwdriver handle preferred
•1/16 ball end Allen driver, screwdriver handle preferred
•1.5 mm L style Allen wrench
•#1 Phillips head screwdriver (modified)
•9/16 open-end wrench
•7/16 open-end wrench
•Multi-bit tool set, such as a Chapman set, having changeable screwdriver and Allen bits
•Optical cleaning supplies, Absorbond TX404 cleaning wipers and 100 % HPLC grade ethanol.
•Finger cots or powder-free gloves (gloves are recommended)
1.5.2 Additional Recommended Tool
•SP2 mode aperture adjustment tool

DOC-0229 Rev E
© 2018 DROPLET MEASUREMENT TECHNOLOGIES LLC
20
1.6 Step-by-Step Instructions for a major alignment
Note: All references to “front”, “back”, “right”, and “left” are with respect to the instrument as viewed
from the front.
1) The laser frame (spectrometer head) must be removed from the chassis to proceed. Turn off
the laser and sample pump and shut down the SP2.
2) Remove the top and right-hand side panels from the SP2 chassis, if they are in place.
3) Disconnect all electrical connections to the spectrometer head and detector chamber: the
Bendix connector (for crystal temperature control) at rear, laser power monitor from front,
detector signal and power connections, and chamber temperature sensor. It will be necessary
to cut some wire ties to remove some of the cables from the spectrometer head.
4) Disconnect the exhaust flow connection at the base of the detector chamber on the left side. If
you have an older SP2, disconnect the line to the pressure transducer from the left side of the
chamber. Remove the Sheath flow connection from the side of the sample jet assembly.
Remove the laminar flow element (LFE) from the inlet by removing the nut at the bulkhead
fitting on the front panel and the nut where the LFE mounts to the jet assembly. Lift the tube
carefully off the jet assembly and slide it back to come out of the front panel bulkhead.
5) Remove the 8 socket head cap screws that hold the side cover at the right rear of the laser
frame (covering the YAG chamber).
6) CAREFULLY loosen the Swagelok UltraTorr Knurled nut on the rear of the laser frame where the
pump optical fiber passes through (Figure 15). Unscrew the knurled nut all the way off, Let the
knurled nut and the O-ring compression fitting gently rest on the fiber.
Figure 15: Ultra-Torr Fiber Passthrough Fitting
Caution!
Do Not remove or loosen!
Swagelok
UltraTorr
Knurled nut