Omni-Diff™ Diffuse Reflection Probe

The Omni-Diff™ diffuse reflectance probe interfaces to virtually any spectrometer via fiber optics. This compact accessory is equipped with input and output SMA connectors that readily attached to a fiber optic coupler, like the Harrick FiberMate2. It is ideal for diffuse reflectance analysis of samples up to 1.5 meters away from the spectrometer. The Omni-Diff™ measures the radiation diffusely reflected from the sample, deflecting the specular component away from the collection optics. A selection of fiber optics is available for use in the UV-Vis, NIR and mid-IR, as well as a digital imaging system for photographic documentation of the sample.

The Omni-Diff™ is ideal for examining neat powders in addition to rough surfaced solids which are too large to fit into the spectrometer.

Diffuse reflection fiber optic probe
Model No.
NOTE: A Model No. ending in "XXX" denotes spectrometer code.

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  • Compact and convenient to use.
  • Suitable for use from the UV to the IR. For best performance, use with an MCT detector in the infrared.
  • Maximizes the collection of the diffusely reflected light, while minimizing the specular component.
  • Two standard 905 SMA connectors for connecting suitable fiber optic cables.
  • Optical fiber optics available seperately in 1.5m long sets:
    • VIS/Near-IR fiber optics for use from 350nm to 2250nm.
    • Near/Mid-IR fiber optics for use from 6500cm-1 to 1700cm-1.
    • Mid-IR fiber optics for use from 2000cm-1 to 600 cm-1.
  • Optional video imaging and illumination system.
  • Optional references for Mid-IR and UV-VIS/Near-IR studies.
  • Interfaces with a fiber optic coupler, such as the Harrick FiberMate2.
Model No. Product Description Price
FM2-XXX FiberMate2

Fiber optic coupler

OMN-SPC Omni-Spec™

Specular reflection fiber optic probe

Model No. Product Description Price
OMN-CAM Digital Camera for Omni-Spec, Omni-Diff Magnifier with USB interface N/A
OMN-DIF-R Spectralon and InfraGold for Omni-Diff Vis and IR diffuse reflectance references N/A
Model No. Product Price
OMN-F-CIR Near/Mid-IR Fiber Set (CIR) N/A
OMN-F-UVN Vis-NIR Fiber Set N/A
OMN-F-PIR Mid-IR Long Wavelength Fiber Set (PIR) N/A

The Omni-Diff™ is excellent for diffuse reflectance measurements of samples outside of the sample compartment. The Omni-Diff™ is a fiber optic probe that is designed for measurements of powders and rough-surface solids up to 1.5m away from the spectrometer. It interfaces to the spectrometer using two fiber optics and a fiber optic coupler, such as the FiberMate2. The Omni-Diff™ features all front-surface Al mirrors on its interior, allowing operation over a wide spectral range. It comes enclosed in a box, which serves as a light shield in the UV-VIS and a purge enclosure in the IR. Fibers are available for the VIS, NIR, and mid-IR. However, an MCT detector is recommended for mid-IR applications.
The Omni-Diff™ is available with an optional digital camera for real-time viewing of the sample. This is a useful aid in positioning the accessory over small spots and for photographic documentation.

Figures 1 and 2 show the spectra recorded from several different locations on a granola bar box. Figure 3 shows the photographic images from those sites. Note that Figure 3a has a bright section in the center. This photograph was taken with the visible source from the UV-VIS spectrometer on and it shows the actual area sampled. From the spectra, it is clear that the infrared mostly detects the glossy coating on the paper with a small contribution from the underlying cardboard on the outside of the box. The glossy coating and its characteristic peak around 3670cm-1 is not observed from the inside of the box (blue spectra). From the UV-VIS spectra, it is clear that the sections sampled are different colors.

Figure 1. UV-VIS diffuse reflectance spectra of a Quaker Chewy Granola Bar box, recorded using the UV-VIS/NIR fibers.


Figure 2. Infrared diffuse reflectance spectra of a Quaker Chewy Granola Bar box, recorded using the CIR fibers with a DTGS detector.

Figure 3. Photographs of the different sections of the Quaker Chewy Granola Bar box sampled. Shown with the color-code for the spectra in Figures 1 and 2.