Portable Open-Path TDL Analyzer

Introducing the GasFinder3-OP

Understanding the Fundamentals

What you need to know

At a glance, here is what you need to know about the GasFinder3-OP which makes Line-of-Sight Gas Detection Measurements.

Target Gases

Detectable Gases with TDL

The table below shows both the gases and ranges that can be used with the GasFinder3-MC.

GasFinder3-OP Assembly

Configuration Options available

The GasFinder3-OP Assembly has the following configurable options:

  • Target Gas Selection: Select both the Target Gas and Range appropriate for the application.
  • Power Supply Options: Select between 12-24 VDC or 120-220 VAC Power Supplies.
  • Retro-Reflector Assembly:
    • Retro-Array: From Path Lengths from 5 – 500 m between the GasFinder3-OP and the Retro-Reflector.
    • Retro-Enclosure: Stainless Steel or Fiberglass Reinforced Plastic Enclosures surround the Retro-Array to provide mechanical protection.
    • Retro-Heater: For outdoor applications, it is recommended to select from the 24 VDC or 110-220 VAC Heater Options.

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  • How it Works

    How It Works

    Visualization Representation

  • GasFinder3-OP Components


    The Components and their Function

    The Open Path (OPX) Head includes the following components:

    • Alignment Scope + Visible Laser: The Alignment Scope and Visible laser are the tools used to aid in performing the alignment procedure.
    • GasFinder3-OP: This includes both the Optical Components and the Analysis Electronics in one integrated package.
    • Power + Communication Outputs: The GasFinder3-OP is powered by 12-24 VDC (20 Watts) or the optional 120-240 VAC Power Supply. The GasFinde3-OP has the following outputs: Analog Loop, Modbus (RS-485), and Serial (RS-232).
    • X-Y Aiming Mount: The X-Y Aiming Mount enables the end-user to easily obtain and optical alignment. The X-Y Aiming Mount can be affixed to tripod for easy portable use.
  • Transceiver Configuration and the Retro-Reflector

    Transceiver Configuration

    GasFinder3-OP + Retro-Reflector

    Boreal Laser utilizes a Mono-Static Configuration (Transceiver and Retro-Reflector) for with its GasFinder3-OP. This differs from the Bi-Static Configuration (Transmitter and Receiver) Configuration in the following ways:

    • Ease of both Obtaining and Maintaining Optical Alignment: Without the use of tools and with one hand, the X-Y Mount enables for very fine adjustment of the GasFinder3-OP.
    • Longer Path Lengths: Higher powered Fiber-Coupled Lasers enable and the Transceiver Configuration allow for longer path lengths.
    • Tighter Beam Collimation and a Larger Target: More laser light is collected back at the GasFinder3-OP and this aids in providing a better analysis.
    • Better Tolerance to Vibration: With the Retro-Reflectors multiple Retro-Arrays focusing multiple beams of laser light back to the GasFinder3-OP, the vibration helps to average and quiet the returned signal.


    Retro-Array Selection

    Retro-Array Overview

    The Suggested Path Length is the recommended Path Length for a particular Retro-Array to ensure that there is both enough Returned Laser Light and to provide a Large Target for the Laser Beam to hit that will to allow for limited diurnal movement. The Functional Path Lengths shown state the shortest and longest Path Lengths that will provide usable Returned Laser Light under ideal conditions for each of the Retro-Arrays but are not optimize for Alignment Stability. There are the following options:

    • Short-Path Length – IMOS Retro-Array in Small Retro-Enclosure:
      • Suggested Path Length: 5 to 20 m (15 to 60 ft)
      • Functional Path Length: 5 to 30 m (15 to 90 ft)
    • Medium-Path Length – Wafer Retro-Array in Large Retro-Enclosure:
      • Suggested Path Length: 20 to 50 m (60 to 150 ft)
      • Functional Path Length: 10 to 60 m (30 to 180 ft)
    • Long-Path Length – Fourteen (14)Cornercube Retro-Array in Large Retro-Enclosure:
      • Suggested Path Length: 50 to 100 m (150 to 300 ft)
      • Functional Path Length: 20 to 350 m (60 to 1,000 ft)
    • Extra Long-Path Length –  Twenty-One (21) Cornercube Retro-Array in Large Retro Enclosure:
      • Suggested Path Length: 100 to 200 m (300 to 600 ft)
      • Functional Path Length: 20 to 500 m (60 to 1,500 ft)

    The Components and their Function

    The Retro-Reflector is comprised of the following components:

    • Retro-Enclosure + Rain/Dust Hood: The Enclosure provides mechanical protection to the Retro-Array clean and the Rain/Dust Hood keeps rain, snow, sleet, condensation, dirt, dust, and debris from accumulating on the Retro-Window.
    • Retro-Array: These are section through a cube and has three faces that form the inside of a cube and regardless of the angle of incidence of the incoming laser beam, the laser light is always reflected at 180° back to the Open Path (OPX) Head.
    • Retro-Heater:  Retro-Heaters are recommended if being installed in outdoor locations as it helps prevent water vapor from condensing on the Retro-Window.
    • Retro-Window: Like the Retro-Enclosure, this provides mechanical protection to the Retro-Array.


    Retro-Enclosure Options

    The Retro-Enclosure has the following configurable options:

    • Small Retro-Enclosure: This enclosure is only used for Short-Path Length (5-20m) Applications.
    • Large Retro-Enclosure: This enclosure is used with Medium-Path (20-50m), Long-Path (50-100m), Extra Long-Path (100-200m) Applications.
    • 304 Stainless Steel (SST) Enclosure Material: This is the most popular and typical section for heavy industrial applications.
    • Fiberglass Reinforced Plastic (FRP) Enclosure Material: Most often used in light industrial applications.


    Retro-Heater Options

    The Retro-Heater has the following configurable options:

    • Recommended for Outdoor Installations: The Retro-Heater helps to keep condensation from building on the Retro-Window and causing a Beam Block Scenario.
    • Hazardous Area Heater & Thermostat: Both of these components are supplied with flying leads and are to be installed as per local electrical code.
    • 24 VDC Powered Retro-Heater (25W): Includes a 40°C (104°F) Thermostat.
    • 110-240 VAC Powered Retro-Heater (50W): Includes a 40°C (104°F) Thermostat.



    The Cornercube is comprised of the following components:

    • Cornercube Returns the Laser Light: Back towards the Open Path (OPX) Head for analysis. The way the Cornercube is configured, the Laser Beam will be focused on the Collecting Optics of the Open Path (OPX) Head with a size around 6″.
    • Laser Light is Always Reflected 180°: Due to the orientation of the three faceted mirrors. The Cornercubes have a tolerance of 30 arc-seconds.
    • Cornercubes for the Retro-Array:  To provide a larger target for the Laser Beam to hit. Each Cornercube will return its own individual Laser Beam and focus it on the Collecting Optics of the Open Path (OPX) Head.
    • It is Common to Oversize the Retro-Array: To provide even better alignment stability. The larger the Retro-Array, the more movement from the support structure can be tolerated.


    Calculating Laser Dot Size:

    Follow the following instruction to Calculate the Laser Dot Size:

    • Laser Light Emitted is Collimated: The Laser Dot will grow the further it travels from the Open Path (OPX) Head.
    • Collimated to 0.05 Degrees (0.9 Milliradian): Using milliradian allows for much easier calculations.
    • Formula for Calculating Laser Dot Size: 0.9 Milliradians (Beam Divergence) x Path Length (m) = Dot Size (mm)
    • Important for Procurement and Design: To ensure that alignment stability is maintained throughout Diurnal (Day/Night) and Seasonal Temperature swings are metal structures will expand and contract.
  • Accessories

    Tilt-Pan Scanner

    Used with the GasFinder3-OP

    The Tilt-Pan Scanner is comprised of the following components:

    • Scan Multiple Retro-Reflectors: With the Tilt-Pan Scanner, one (1) GasFinder3-OP can be used to aim at eight (8) successive Retro-Reflectors to create eight (8) different Active Measurement Paths.
    • Auto Light Level (Rx) Optimization: Upon moving to the Retro-Reflector, it will optimize the amount of Laser Light (Rx) and on stationary paths, it can be programmed to do this routine on a user defined time period.
    • Controlled by GasViewMP Software:  The Tilt-Pan Scanner is controlled by the GasViewMP Software which is ran with the Remote Monitoring + Control Center.
    • Mounting Options: The Tilt-Pan Scanner can be mounted on either a Heavy Duty Tripod or it can permanently affixed to a mounting structure.

    Remote Monitoring + Control Center

    Manage Remote Monitoring Campaigns

    The Remote Monitoring + Control Center enables the following:

    • Control the Tilt-Pan Scanner: The Tilt-Pan Scanner is controlled by the GasViewMP Software which is ran with the Remote Monitoring + Control Center.
    • Interface with the GasFinder3-OP: Also with the GasViewMP Software, the GasFinder3-OP can be remotely interfaced with.
    • Enable Remote Communication:  Within the Remote Monitoring + Control Center, the End-User has a choice to interface with either a Cell Modem or Radio Modem.
    • Power Distribution: The End-User has the option of powering the all of the equipment with either 12-24VDC or 120-240 VAC. The Remote Monitoring + Control Center handles the power distribution to all of the other equipment.


    For GasFinder3-OP, Small/Large Retro-Reflectors

    Tilt-Pan Scanner Tripod

  • HMI Touchscreen

    HMI Touchscreen

    Use and Function

    The HMI Touchscreen provides you with the following advantages:

    • Provides Valuable Local Indication: It can be invaluable for field operations to have local indication to gain a better understanding of their process. If this equipment is being used as a Leak Detection device, then this could provide early warning of a small leak or provide rapid indication of a large discrete leak. As well, if this is being used for In-Situ or Extractive Analytical Measurements, then this can ensure the process is within the control envelope. Their are broad types of display options: Graphical and Numerical.
    • Enables Intuitive Local Interface: It is not practical to bring a laptop into a process area and it is not always easy to install software on a corporate computer without permission or a work order from your IT Department. Technicians no longer need to pack a laptop or find away to balance it in the field as the every command or configuration option is available via the HMI Touchscreen.
    • Use in Hot and Cold Applications: The Display and Touchscreen functions work throughout the ambient temperature range of -55 to 65°C (-67 to 149°F).
    • Intuitive Interface: Easily navigate the menu to access programmable features and functions.


    Local Indication Display Options

    The Field Mounted GasFinder3-OP (Portable Open Path) provides you with the following advantages:

    • Graphical Display: This display option is typically used if trending the concentration variables is of use to operations.
    • Numerical Display (Single Channel): This high contrast display is often the display of choice for leak detection applications as it shows the status of the Hi and Hi-Hi Alarm Relays.

  • Power + Communication

    Power + Communication

    Overview of Inputs and Outputs

    Here is a more detailed overview of the Power + Communication Options available with the GasFinder3-OP (Portable Open Path) :

    • Serial via RS-232: Each and every reading produces its own serial string and these are stored as daily Logfiles.
    • MODBUS via RS-485: Every variable generated by the analyzer are Addressable Registers.
    • Power Requirements: The GasFinder3-OP (Portable Open Path) is powered with 12-24 VDC and under normal operation draws 20 watts for 100ms, there is an In-Rush Current of 2.5mA (Non-Hydrogen Fluoride) and 3.1mA (Hydrogen Fluoride).
    • Analog (Optional): There are a number of sub 4 mA variables to note: 2.7 mA = Low Light (Beam Block) and 3.6 mA = General Fault.

    Serial (RS-232)

    Data String

    Below is the configuration of information found on the Data String.

    Debug String

    Below is the configuration of information found on the Data String.


  • Enhanced Data Storage & Access

    Enhanced Diagnostics

    Easily Access your Collected Data

    The Field Mounted GasFinder3-OP (Portable Open Path) provides you with the following advantages:

    • Store and Access 20 Years’ of Data: The End-User has full access to all generated data from the GasFinder3-OP (Portable Open Path).
    • Visualize Data with the Excel Marco: Easy visualize both sample and diagnostic data. Contact your representative for more information.
    • USB Accessible Data Storage: The GasFinder3-OP (Portable Open Path) has the ability to store all of its generated data over its entire lifespan. This is easily accessible via a FAT32 USB Thumb Drive or Memory Stick. The GasFinder3-OP (Portable Open Path) automatically bins the Logfiles into timestamped 24 hour periods. The Logfiles are in CSV Format and can easily be visualized with our Excel Macro.
    • Micro-USB Connection: Serial connection to use GasView Software is included
  • Internal Reference Cell

    Set, Forget, & Detect

    Overview of the Internal Reference Cell(s)

    The Internal Reference Cell(s) within the GasFinder3-OP (Portable Open Path) provides you with the following advantages:

    • Fail Safe Design: Boreal Laser has focused exclusively on Laser Based Gas Analysis since 1990 and has built an analyzer with +30 years of expertise to provide a Fail Safe instrument that employs detailed diagnostics to help increase the confidence of both technicians and operations. If the GasFinder3-OP (Portable Open Path) is running without fault or status inhibition codes, then the system can be trusted to work as there are no undisclosed failure modes.
    • Essentially Zero Measurement Drift: The Internal Reference Cell ensures that the GasFinder3-OP (Portable Open Path) is still emitting Laser Light at the appropriate wavelength/frequency required to detect that particular target gas. By remaining “Line Locked” or “Line Centered”, we can essentially eliminate Measurement Drift and the requirement for routine intervention and calibration.
    • No Field Calibration: In addition to the GasFinder3-OP (Portable Open Path) interrogating its Internal Reference Cell every minute, the system also compares itself against the permanently stored calibration waveform each and every sample to ensure that the most accurate measurement possible is being made.
    • No Field Intervention: There is no end-user intervention required as all the checks and adjustments from the Internal Reference Cell are done autonomously and automatically. Beyond Optical Alignment of the Measurement Heads, there are no field adjustments to be made with the GasFinder3-OP (Portable Open Path).



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