Droplet SP2 User manual

Manual for SP2
Beam-Scan Camera
and Software
2400 Trade Centre Avenue
Longmont, CO 80503 USA
DOC-0175 Revision D
A L L R I G H T S R E S E R V E D

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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 thismanual.
DMT reserves the right tomake 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, data or 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 eighteen months from date of shipment or 12 months from the date of
either installation or first use 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.

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C O N T E N T S
1.0 Introduction ..................................................................................................4
2.0 Installation....................................................................................................4
3.0 Operation......................................................................................................6
4.0 Troubleshooting ..........................................................................................12
Appendix A: Changes to manual................................................................................13
Appendix B: Assembly Drawing.................................................................................13
Figures
Figure 1: SP2 Laser Mode in the TEMoo Mode, as Viewed in the vBeam Control Panel..7
Figure 2: The SP2 Laser Beam in the TEMoo Mode, as Viewed in the Surface Plot .........8
Figure 3: SP2 Laser Beam in the TEMoo Mode, as viewed in the Graphical Plot .............8
Figure 4: The SP2 Laser Beam in a Higher-Order Mode, as viewed in the vBeam
Control Window .........................................................................................................9
Figure 5: The SP2 Laser Beam Plot in a Higher-Order Mode........................................10
Figure 6: The SP2 Laser Beam Viewed Graphically in a Higher-Order Mode................10

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Introduction
Optimum performance of the SP2 is obtained when the YAG laser beam is operating in the
TEMoo mode. This is defined by a single laser beam spot which 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.
The SP2 beam scan camera and software is designed to facilitate observing and setting the
mode of the YAG laser in the SP2. The system consists of a Mightex CCD camera which has been
fitted with a high Optical Density (OD) filter. A mounting bracket allows the camera to be
mounted in the position normally occupied by the YAG power monitor on the SP2. The light-
intensity data from the camera is recorded and processed by a software package made by
Visulux, called vBeam. In the Windows 7 32-bit version, the vBeam software has code in it to
read only a camera with a specific serial number. If multiple units of the camera and software
are purchased, the installed software must be correlated with a given camera. With Windows 7
64-bit version and newer, the drivers should enable the software to find the correct serial
number of your camera automatically. In both versions of Windows 7, it is necessary to load the
software thru both USB ports so that the camera will be found by the system. If the software is
loaded into one port and the camera is plugged into the other USB port, the camera will not be
found.
Installation
For installation of the software, follow the instructions given in the Visulux manual. This manual
will discuss the installation of both the driver for the camera and the Visulux executable
software. In the setup of the Visulux software, one minor change from the default values is
recommended. The software will be installed in the folder Program Files/Visulux. Navigate to
the Visulux folder and open the file mightex.prop using Notepad. The following shows the
contents of this file. The default for the exposure time is 10000. This will result in saturation of
the camera response, and it is recommended that this be set at 5000 for a starting value. This
can be adjusted later as needed.

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The following is the listing of the mightex.prop file:
; gain is normally 1.0, but can be as high as 16
gain=1.0
; gamma is from 0.0 to 2.0
gamma=1.0
; contrast is from 0 to 100 in percent
contrast=50
; brightness is from 0 to 100 in percent
brightness=50
; exposure time is in microseconds, so 30000 us = 30 ms
; can be up to 750 ms (750000)
exposure time=10000
;
; the frame rate slows greatly at the higher exposure times. 750000
; is the maximum exposure time on the Mightex cameras. That should
; be enough to integrate multiple laser pulses if needed.
It is recommended that exposure time be lengthened until saturation happens. Then back off
the exposure time by 500 or 1000 units. Saturation will not cause damage to the camera, and it
can be useful to operate in this mode, as the base of the beam will be easier to visualize. No
studies have been done on modifying the other parameters in the mightex.prop file.
CAUTION: The Mightex camera is fitted with a 5 OD filter for standard operation. This reduces
the laser power to a range where the camera can provide a good beam profile. The laser power
that is available at the YAG power monitor can be up to 200mW. The Mightex camera is rated to
withstand laser power of up to a MAXIMUM of 70mW only under certain conditions, which are
unspecified. Operation of the camera on the SP2 with any neutral density filter having an OD of
less than 2 will void the warranty of the product. The Measured leakage should be between 80
–100 mw

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Operation
The Visulux software is computationally intensive and testing of the simultaneous operation of
the Visulux software and the SP2 acquisition software has not been conducted. No conflicts are
expected, but the performance of both software operations simultaneously is not known. It is
possible that these programs can operate simultaneously, but it is the responsibility of the user
to determine the suitability of the SP2 computer for simultaneous operation.
Remove the YAG power monitor and insert the pin (See Appendix B) of the Mightex camera into
the bracket mounted on the SP2. The bracket provides the proper alignment for the camera and
no alignment adjustments are needed. If a simple check of the laser mode is being conducted,
start the Visulux software, and in addition to the basic control window, it is suggested that the
surface and plot windows be opened. These are initialized by clicking on the appropriate boxes
in the View menu of the tool bar. Turn on the SP2 instrument, and if the Visulux software is
being used on a separate computer, the standard SP2 startup and operation is recommended. If
the user is operating the Visulux software on the SP2 computer and is testing performance with
both software packages, it is recommended the standard SP2 operation be set up and then the
Visulux software started.

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Figures 1 -3 show the data obtained for a YAG laser beam when set properly. These plots show
the view of the beam effectively end-on in the control panel, and the beam profile in the plot
and surface views. The measurement will appear to have considerable jitter in the plot view.
This is caused by the short exposure time. If the beam profile appears basically Gaussian,
(normal or even distribution) but the top of the view is flat in the plot or profile views, this is
caused by measurement saturation. The exposure time should be reduced to change this.
Figure 1: SP2 Laser Mode in the TEMoo Mode, as Viewed in the vBeam Control Panel

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Figure 2: The SP2 Laser Beam in the TEMoo Mode, as Viewed in the Surface Plot
Figure 3: SP2 Laser Beam in the TEMoo Mode, as viewed in the Graphical Plot. The upper plot shows the
beam slightly out of adjustment and not following the Gaussian curve.

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The Visulux software will allow for power measurement of the YAG laser. If a power meter is
available, the laser power can be measured with the YAG power monitor and the camera
removed from the output of the YAG laser. The camera is then installed on the laser, and the
Settings toolbar opened. Then open the Calibrate Power/Energy window. Either the laser
power as measured above can be entered, or the voltage as measured from the YAG power
monitor can be entered. Click on OK, and this power reading will appear in the data table. It is
important to note that this power reading will be valid only for the same value of exposure time
as when the calibration parameters were entered. It is highly unlikely that the relationship
between power readout and exposure time setting is linear, so if the exposure time is changed
the power should be recalibrated. Any changes in the neutral-density filter will also change this
value. The exposure time is being run at or below the minimum recommended value, and this
will result in considerable variation in the power readout with the camera.
If the above tests show that the SP2 YAG laser beam is in a satisfactory mode, no further
adjustments are needed. Upgrades to the Visulux software are planned in the future to allow for
continuous logging of the data, and this may be useful while collecting data with the SP2.
Figures 4-6 show measurements of a YAG laser that is in a higher-order mode. These can appear
as either a distortion of a single spot, or even multiple distinct spots. If both the X and Y axis are
in higher-order modes, multiple spots in both directions can appear.
Figure 4: The SP2 Laser Beam in a Higher-Order Mode, as viewed in the vBeam Control Window

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Figure 5: The SP2 Laser Beam Plot in a Higher-Order Mode
Figure 6: The SP2 Laser Beam Viewed Graphically in a Higher-Order Mode

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If the YAG laser is out of adjustment, or the user wishes to observe the mode structure, the
following procedure should be followed:
1. Install the camera as directed previously.
2. Remove the SP2 mode aperture from the holder.
3. Remove the two screws on the top of the coupler mount that allow access to the
adjustment screws.
4. Start the Visulux software.
5. Start the YAG laser and observe the laser beam profile.
6. For SP2 instruments SN 007 and above, insert a 5/64”ball driver into the access hole.
SP2 instruments below this serial number require a 1/8”ball driver. It can be useful to
use a flashlight to look into the access hole and locate the position of the adjustment
screw. For some of the SP2 instruments, the adjustment screws will be either forward
or backward of the access hole. It will always be in line along the long axis of the laser
frame. Insert the ball drivers carefully, trying not to turn the adjustment screws.
7. Turn the adjustment screws a minimal amount until a feeling is obtained for the
amount of adjustment to bring the laser in and out of TEMoo mode. If the laser is
operating in a very high-order mode and an adjustment is made, the laser can be
extinguished. Very carefully turn the screw in the reverse the direction and the laser
should restart.
8. After the laser is adjusted satisfactorily, remove the adjustment tools, while the laser is
still operational. This will insure that no unintended adjustment takes place while the
tools are removed.
9. Shut off the YAG laser, reinstall the screws on the top of the coupler mount, and install
the mode aperture.
10. For optimal instrument performance, it is recommended that the mode aperture
adjustment be checked as well as the alignment of the chamber. Please see the most
current Revision of the SP2 Operator Manual DOC-0171 for instructions on these
adjustments.

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Troubleshooting
Problem
Possible Cause
Solutions
No response when > is clicked
in Visulux software.
Camera is not responding.
Check the serial number of camera and
open the Visulux software folder to check
for the presence of the proper key. There
may be more than one key present in the
software folder, and the key ID may be a
bit hard to decipher but check the camera
serial number and it should be close to
one of the keys present. The master CD of
the Visulux software will contain the
proper key file.
Beam plot and surface picture
appear truncated at the top of
the profile.
Camera is saturated and cannot
respond properly.
Reduce laser power or reduce exposure
time.
No response when > is
clicked in Visulux software.
Camera is not selected as input
device.
On the toolbar, go to View (if Input
Control is not checked, check the box to
bring up this window, which will be titled
Camera).Under Select a video board, the
camera should appear here and be
highlighted. If it is not, highlight this.
Appendix A: Changes to Manual
Revision Date
Revision #
Summary
Section
4-8-10
C
Updated assembly drawing
Appendix B
1/10/17
D
General updates
All Sections

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Appendix B: Assembly Drawing