Proven Long Life Lasers™ In Optical Particle CountersSource: Hach Company - Particle Counting Division
Optical particle counters (OPC) utilize light illumination and extinction to determine the presence, size, number and/or concentration of particles. Particles are typically suspended in a fluid or air, which flow through the volume that is illuminated and viewed by the detection system. The basic components of such a system are a laser illumination source; a view volume in which the particles to be detected reside and into which the illumination is directed; and one or more sensors, which are typically photodetectors, that can detect optical disturbances of the illumination caused by the particles in the view volume. The illumination source in an optical particle detection system is typically a semiconductor diode laser. The laser source must be stable, quiet, and have long life.
While many OPC suppliers claim long life lasers, Hach Ultra has verified laser life testing, patented technology for improving both laser life and instrument performance, and has validated product field data to prove the performance. Long Life Lasers™ by Hach Ultra are now employed in all MET ONE 3400 Series portable air particle counters, MET ONE R4000, 6000 and 7000 Series remote air particle counters for continuous monitoring, and HIAC 9703 and HIAC 9705 liquid particle counters.
The road to long lasting lasers and reliable particle counters starts with choosing the right laser. Certain Gallium arsenide (GaAs) lasers offer the most mature laser technology and have the longest operating lifetime. GaAs lasers are now widely used in the fiber optic telecommunications industry where high performance and reliability are of paramount importance. This same technology is used in Hach Ultra MET ONE optical particle counters with lasers operating at the material peak wavelength near 830 nanometers. Typical GaAs lasers are rated to have a mean-time-to-failure (MTTF) greater than 100,000 hours. At 8,760 hours per year, this equates to over 11 years of continuous operation.