GasFinder2-FC: Fibre Coupled TDL Analyzer


A versatile single-channel fibre-coupled analyzer that has multiple attachment head options (short or long open-path heads, extractive/in-situ probes, etc.) which is deployable in fixed installations or as a portable/battery powered unit.

What it does

  • Provides immediate and unambiguous detection of the target gas in the ambient atmosphere
  • Our technology counts every target molecule in the measurement path to give a ppm concentration

How it works

  • The analyzer is portable and can be brought to where it is needed
  • Fibre optic cable carries the laser light from the analyzer to the remotely mounted measurement head
  • The laser passes across the active measurement path
  • The laser light is then collected and the signal is carried back to the analyzer via coaxial cable
  • The ppm-m concentration is then transferred by RS-232 serial communication or 4-20mA current loop


  • No Interference with other gases and No False Alarms
  • Fast Response Times and No Memory Effects:much faster response than other gas detection technologies
  • Provides the best return on investment compared to any other system
  • Can be used in all weather conditions
  • Minimal Maintenance: checks internal reference cell every minute, robust design, and requires no consumables
  • Lowcost of ownership
  • Free and Unlimited phone and email support


Boreal Laser’s patented (US Patent 5,637,872) TDL (Tunable Diode Laser) fibre coupled monitor measures gas concentration over an open path. The monitoring system consists of an integrated transmitter/receiver, an open path transceiver head or duct probe, and a remote, passive retroreflector array. A fibre optic cable connects the transmitter to the transceiver head

or duct probe. A two-axis instrument mount and an aiming scope or red aiming laser are used to align the remote head with the retroreflector array. The returning laser signal is detected by a photo diode in the remote head or duct probe and sent back to the receiver via a coaxial cable.

The Fibre-Coupled Analyzer houses the laser diode source, the transmitter and receiver electronics and microcomputer subsystems and has connectors for 12VDC power input, and data I/O. The remote head or probe is connected with fibre optic and coaxial cables. A schematic representation of the Fibre-Coupled Analyzer system is shown below in figure 1:

The laser signal from the Fibre-Coupled Analyzer is sent through a fibre optic cable to the remote head or duct probe where it is emitted and propagates through the atmosphere to the retroreflector. It then returns to the cell where it is focused on to a photo diode detector. The detector converts it to an electrical signal which travels through a coaxial cable to the electronics in the Fibre-Coupled Analyzer. A portion of the laser beam is passed through an on board reference cell to provide a continuous calibration check. These two optical signals are converted into electrical waveforms which the computer processes to determine the actual concentration of gas along the optical path. The computed gas concentration is then displayed on the rear panel of the instrument, and can be transmitted to a computer where the data can be collected, stored, and graphically displayed. For industrial applications a 4-20mA output is also available. A software program, GasViewOP is available which runs on the computer and can be used to alter some of the parameters on the Fibre-Coupled Analyzer.

The three main parts of the equipment are:

  • Analyzer
  • Open Path Transceivers or Remote Heads and Duct Probes
  • Remote Reflectors, or Retros