Filter Holder for Glass Fiber Filters Simple measurements for particulate absorption WPI’s filter holder for particulate absorption measurements is specially designed for field use. It is rugged and portable. It performs as well as a laboratory based spectrophotometer. It can be directly connected to WPI’s line of fiber optic spectrometers and light sources. Instead of collecting your samples, transporting them to a laboratory, and accepting the loss of spectral information associated with it (Sosik, 1999), particulate absorption can now be measured on site. QFT1 other CCD, PDA or scanning type spectrometer with fiber optic capabilities. Performance A significant advantage of the filter holder is its large beam diameter of 5 mm, resulting in “averaging out” of larger non-organic particles frequently found on the filter pad when using natural samples. The removable filter fixture allows simple filter alternation and cleaning. Specifications GF/F Filter Diameter 25 mm Wavelength Range 280-730 nm * Fiber Optic Connection ∅ 600 μm / SMA Material in contact with filter pad Delrin Weight .....................................0.5 kg (1 lb) How does it work ? Particulate absorption of fresh and seawater can be determined by filtering a known amount of sample through a Glass Fiber Filter (GF/F) and measuring the particulate absorption coefficient ap(λ) concentrated on the filter. This technique is called quantitative filter technique (QFT) and corrects for the pathlength amplification, an effect of scattering. The correction of the pathlength amplification and the correction of the non-linear relationship between the optical density of samples on a Whatman GF/F filter and in suspension are discussed in Mitchell (1990). * Using a TIDAS E spectrometer and D4H UV/VIS light source. References Mitchell, B. G., “Algorithms for Determining the Absorption Coefficient of Aquatic Particles Using the Quantitative Filter Technique (QFT)”, SPIE Vol. 1302 Ocean Optics X (1990), 137-148. Sosik, H. M., “Storage of marine particulate samples for light-absorption measurements”, Limnol. Oceanogr., 44(4), 1999, 1139-1141 M. Belz, K. Larsen, K.-F. Klein, “Fiber optic sample cells for polychromatic detection of dissolved and particulate matter in natural waters”, Proc. SPIE, Vol. 6377, Oct 2006, 63770X SPEC TROS CO PY Detector and light source requirements The optical throughput of QFT1 equipped with a classical GF/F filter is very low and requires a matched light source / spectrometer system. WPI’s TIDAS E in combination with WPI’s FO-6000 tungsten light source or D4H deuterium/halogen light source can be used in the 380–730 nm and 280–730 nm wavelength range, respectively. The QFT1 can also be interfaced to any 89575 QFT1, Fiber Optic Holder for Glass Fiber Filters In-Line Fiber Optic Filter Holder This In-Line Fiber Optic Filter Holder allows the insertion of optical filters within a fiber optic pathway. The connectors of the filter holder assembly are compatible with WPI’s range of fiber optic jumper cables and can be coupled using SMA or ST connectors. Filters with outer diameters from 8 to 25.4 mm and thicknesses from 2 to 10 mm can be accomodated. The design limits lateral and axial movement of the filter when secured in the holder. Two fiber optic collimators are internally mounted in the holder to pass collimated light through the filter and then refocus the filtered light into the aperture of the output fiber. Spectral range will be largely limited by the bandpass of the optical fibers (from UV to near IR using WPI UV-enhanced cables). 56200 In-Line Fiber Optic Filter Holder (SMA) UK: Tel: +44 (0)1462 424700 • wpiuk@wpi-europe.com World Precision Instruments www.wpiinc.com Germany: Tel: +49 (0)30-6188845 • wpide@wpi-europe.com US: Tel: 941-371-1003 • sales@wpiinc.com 199