principle of operationthe lasir is based on the absorption of light in the near infrared region of the spectrum. what is unique to the lasir is its very special light source, called a tunable diode laser. these tiny devices are similar to the solid state lasers used in ecommunication and in consumer products such as laser printers and compact disc players. laser diodes can be se-lected which are unique to a particular gas ensuring that the measurement is free from interferences from any other gas or particle.
gases that can be measured with the lasir include: hf, hcl, hbr, hi, hcn, co, co2, ch4, c2h2, c2h4, c2h6, c3h8, ch2chcl, no, no2, nh3, h2s, h2o, o2 ,d2o, hod
industries that are using these systems include:
| aluminium | semiconductor | power generation | specialty gases | natural gas |
| ?b>petrochemical | landfills | oil refineries | combustion | geothermal |
| incinerators | sewage and waste treatment | pulp and paper | auto-exhaust | cement |
| glass | fertilizer | | steel | |
main advantages - no interferences from other gases: tdlas technology provides the most interference free method of any analytical technique.
- no interference from particles: measurements of gas concentrations are unaffected by the presence of particles, including rain and snow.
- fast time response: measurements can be made in less than 1 second if desired.
- high sensitivity: sensitivities down to and below 1 ppbv depending on the path length
- fiber optic link for remote control: permits the instrument to be located long distances from the measurement point
- cost effective: multiplexing of fiber optic cables permit simultaneous measurement at a number of locations with the same instrument
- long paths lengths: up to 1 kilometer
- easy to install and rugged, maintenance-free operation
- can cover a broad range of concentrations
