The Vaisala SPECTRACAP® Oxygen Transmitter OMT355 offers Tunable Diode Laser (TDL) technology in a compact probe suitable for field use. The SPECTRACAP® sensor measures oxygen concentration optically by measuring the absorption of light from a tunable diode laser. For oxygen sensing the laser is tuned to a wavelength which is characteristic for the oxygen molecule. The OMT355 can be flange-mounted directly into a process without sampling or sample conditioning equipment. This provides the user real-time measurement data without sampling or sample switching delays. In addition, the stainless steel probe tolerates aggressive chemicals and excessive amounts of moisture. For processes with high temperatures, elevated pressures or excessive solids content, an optional sampling cell is available for the transmitter. As the sensor is very robust and has low sensitivity to gas flow and pressure variations, the associated sampling system is simple and can be installed near the sampling point.