StellarNet Inc. offers a low-cost, rugged, high-throughput filtered retro-reflection probe that is ideal for use in an industrial process environment. Like the retro-reflection probe, it is capable of operating at temperatures from -50°C to 300°C and at pressures up to 3000 psi. This outstanding performance is achieved by using Kalrez® O-ring seals. The filter probe is available in fixed path lengths of 2, 5, 10, 20 and 50 mm. The optical fiber is 400-micron core fused silica and is clad in stainless steel armor. If needed, the armor can be sealed with Teflon® to provide a barrier to the environment. A four-inch extension tube is added to the rear of the probe to allow direct insertion into a process stream. The extension tube can be adapted to the customer's process connection requirements. The filter probe is available in both UV and NIR versions, as dictated by the customer's application needs.  

TECHNOLOGICAL INNOVATIONS  The filter probe actually contains a complete retro-reflection probe that is fitted into a metal sleeve with a sintered metal tip. This tip is available in pore sizes of 2, 5 and 10 microns. A side arm of the housing allows application of a vacuum to draw a sample into the probe, and positive pressure to expel the sample and clean the sintered metal tip. The filter probe incorporates a back reflecting aluminum mirror for high light return in the UV region. With this design, the sensitive aluminum layer is back-coated on a silica disk with a  protective MgF2 overcoat. The mirror is then sealed into the bottom of the probe. Both the mirror and the collimating lens are held in the stainless steel housing with Kalrez® O-rings. All wetted surfaces are silica, stainless steel or Kalrez®. For more demanding applications, the optical surfaces may be over coated with diamond-like carbon film*. This film improves corrosion resistance and reduces fouling.  

* Visible and NIR use only.