Diffuse Reflectance

Near–IR has been used for the analysis of agricultural products and other scattering solids for many decades. In the past, most applications have involved either loading the product onto a specialized sampling stage or the use of probes based on large diameter fiber–optic bundles. In contrast, Hellma Axiom’s diffuse reflectance probes are designed to be used with small diameter bundles or even single fibers. This provides greater flexibility, much lower transmission cost, and optimum coupling to the newer generations of spectrometers such as those employing charged–coupled detector arrays, FT–NIR, and tunable laser diodes. For further discussions of diffuse reflectance analysis, see Technical Notes AN–911 , AN–916 , and AN-922 .8, 9, 10


Immersion Probes

FDR–700 Series Diffuse Reflectance probes1, 11 are designed for insertion into a sample medium. They provide for the contact spectroscopic analysis of optically scattering materials such as pharmaceutical powders, polymers, and food products. Key characteristics of these probes are high collection efficiency, low stray light, robust construction, and excellent chemical resistance.

FDR-700 Features

  • Compatible with single fibers and small bundles
  • Suitable for immersion in aggressive chemicals
  • Compatible with high temperatures and pressures
  • Large depths of field
  • Purely passive and non–hazardous

FDR-700 Data Sheet (.pdf)


Non-Contact Probes

FDR-800 Series diffuse reflectance probes have been designed to provide optimum performance in the non-contact analysis of powders and other diffusely reflecting materials. These probes are characterized by high collection efficiencies, large depths of field, adjustable offset and collection area, and low stray light.

FDR-800 Series Features

  • Target offsets of typically 12 – 15 mm
  • Immune to reflection from window surfaces
  • Viewed spot diameters of typically 8 mm
  • Purely passive (employs separate optical source)
  • Large depth of field

FDR-800 Data Sheet (.pdf)