FRP reflectance probes consist of a bundle of 7 optical fibers in a stainless steel ferrule. This probe utilizes a fiber core diameter of 400 µm and the spectral range is 275-2100 nm. This configuration allows for much higher throughput into you spectrometer, as opposed to simply using a larger core fiber. When a large core fiber is placed in front of the entrance slit of a spectrometer, the majority of the light is vinyetted and doesn’t make it into the spectrometer. By contrast, when the smaller fibers are stacked along the entrance slit, significantly more light enters into the spectrometer. This allows for much higher sensitivity and signal to noise, while maintaining resolution, since the slit can remain relatively narrow. It is important to note that proper alignment of the stacked fiber to the spectrometer’s slit is crucial for the fiber to work correctly and must be done every time the fiber is connected.