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 Moving Vessel Profiler (MVP) was used aboard the NOAA vessel Thomas Jefferson as part of the Deepwater Horizon Response in the Gulf of Mexico. CLICK HERE to see the NOAA report and video on the NOAA web site.  |
LOPC Brochure
( 591k PDF File )
( Web Version )
ASLO 2004 Poster
(2MB JPG)
LOPC System Integration Guide (1.4MB)
Related Topics:
LOPC Add-ons
LOPC Add-on Chart
Moving Vessel Profiler
ODIM Brooke Ocean Winches
alexherman.com
Site Map
Laser Optical Particle Counter (LOPC™)
- Next-Generation Particle Measurement Instrumentation
- Next-Generation Particle Measurement Instrumentation
The Laser Optical Particle Counter (LOPC) is the next generation in particle profiling. The LOPC’s high speed processing and improved detection plane provides detection counts at higher resolutions and higher concentrations with lower coincidence. This also allows the LOPC to be integrated into tow bodies such as the Moving Vessel Profiler (MVP™), traveling at up to 12 knots and still providing reliable data. However, the LOPC is designed to be adaptable to any tow body and operate stand-alone as well. Click here to see an animation showing the internal layout of the LOPC. The Flash 4 plug-in (or higher) is required to view the LOPC animation.
Features
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More compact
The LOPC is small enough to be installed in a variety of existing towbodies. It's lightweight construction from aluminium allows a variety of mounting arrangements. The instrumentation is contained within a single housing allowing for a compact design. The sample tunnel is interchangeable with a large volume (2.5X) sampling tunnel.
Adaptable to most platforms
The LOPC can be adapted for various applications.
Improved coincidence limit
Beam resolution has improved the plankton coincidence counting (ie. 2 or more particles in the beam.) The LOPC can operate in higher particle concentrations of approximately less than or equal to 10 6/m 3.
>100 microns resolution
The resolution achievable with the LOPC is a significant improvement over existing technologies, allowing an improved lower detection limit.
Measures shape outlines >1.5mm
The LOPC is capable of providing cross-sectional shape profiles of plankton >1.5mm and <= 35mm. The larger the animal size, the better the resolution of the shape, eg. euphausiids can be clearly resolved using a larger volume tunnel.
Tow speed estimation
A statistical estimation of the flow speed is made using the transit time of particles in the beam, thereby providing the user with estimates of flow volume.
Serial interface to CTD
In the standard configuration the instrument supports a serial interface to a CTD.
Analog interface available
In the standard configuration the instrument supports an analog interface for other instruments such as fluorometers or other sensors.
Modular expandability
The LOPC system is designed to be expandable using add-on components and optional equipment. This allows the system to be used in the field or in the lab, with new or previously collected samples. Visit the LOPC Add-ons and Options page for more information, or use the handy Add-ons and Options table for an at-a-glance listing and to download technical drawings.
Newly updated!
LOPC System Integration Guide - Details and how-to information on integrating LOPC with your equipment! Click here to download! (PDF Format - 1.4MB)
ALSO, view the LOPC Poster that was presented at the ASLO 2004 Conference. Click here to download! (JPG Format - 2MB)
Improved Interface Software
The LOPC Interface Software offers real-time data collection and graphical display.
- Instrument control - the GUI provides the user with a simple interface to control the instrument (LOPC) without knowledge of the underlying instrument or control commands.
- Data acquisition - The LOPC software acquires data from the instrument via a serial port and parses the data using a framed, binary byte-stuffing protocol.
- Real-time data processing and display - collected data is processed in real-time and graphically displayed for immediate interpretation by the user.
- Data Playback - raw data files can be replayed for post-deployment observation and analysis purposes.
The image to the right is a LOPC Software screen capture showing data collection during a calibration check. This data is produced by dropping various sized micro-beads (extremely small, precision-machined glass beads, often resembling powder) through the tunnel of the LOPC. The histogram in the main window displays the counts vs. size distribution (number of beads detected) for the smaller beads, while larger beads (>1.5mm) are displayed in the scrolling window to the right of the histogram. Sufficient data can be collected from larger particles to reproduce a shape outline or profile and these are displayed in real-time as they pass through the tunnel.
When external sensors are attached, such as an Applied Microsystems Limited (AML) CTD, the data is integrated into the LOPC data stream and displayed in various text boxes (the control bar across the bottom of the screen), as well as, in time-based strip-charts as those in the screen shot to the left. This particular data set was collected with an LOPC and an AML CTD integrated in a Moving Vessel Profiler (MVP). The time-based plots in this screen shot show Depth, Salinity and Counts Per Second (CPS). Other available plots are Temperature, Counts Per Second (Windowed), Counts Per Volume and Flow Speed. Any combination of these plots can be selected while underway.
To view the animations and video below, click on the icon to the left and click 'Open' when prompted. If you would like to download the animations for later viewing, click on 'Save' when prompted.
These animations and video have an integrated media player so they will run independently on any computer.
Select from the following animations:
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LOPC using micro-beads (1064 KB) |
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LOPC using micro-beads and 6 mm beads (1011 KB) |
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LOPC on MVP (3006 KB) |
The animations will begin playing upon opening and will loop (play over and over) until the user hits 'ESC' and closes the software or right-click with the mouse and select 'Exit'.
LOPC Deployment Methods
The LOPC can be deployed for data collection using various methods, however, it has been specifically designed and evolved to easily integrate with the Moving Vessel Profiler (MVP), Multi Sensor Free Fall Fish (MSFFF).
The LOPC integrated with the MVP allows large amounts of data collection over vast areas. It can be towed up to 12 knots, with automatic undulation and minimal user intervention thanks to the MVP's computer controlled winch system.
Using the LOPC's external instrument inputs, the LOPC can be deployed with the MVP and also provide CTD data (requires a CTD) and other data streams on the same sea cable used to tow the MVP Fish, potentially with a single pair of conductors.Below are some examples of other LOPC deployment methods.
Video:
These video files are MOV files and require Apple QuickTime to play. A free copy of QuickTime can be downloaded here.
Since these files are rather large, we recommend that they be downloaded (by right-clicking and selecting "Save Target as...") and stored on your computer for future viewing.
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LOPC on a Ring-Net (4035 KB) |
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LOPC on Bioness (11649 KB) (The LOPC in this video is used with the optional wide-tunnel system.) |
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Visit the GLOBEC site for the latest on ocean profiling |
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• COML Home • Gulf of Maine Area Program (Biodiversity study) |
The Laser Optical Particle Counter was developed by Dr. Alex Herman at the Department of Fisheries and Oceans, Ocean Sciences Division, Bedford Institute of Oceanography. |
Dr. Alex Herman now has a site devoted to the latest developments in LOPC technology. Visit www.alexherman.com for all the details. (Recently updated with new post-processing software) |
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URL: http://www.brooke-ocean.com/lopc.html (Last Updated: March 22, 2011)