Light reflected from a solid surface can be either diffuse, specular or both (total reflectance). Diffuse reflectance is based upon the collection of radiation that has been diffusely scattered from the sample. The Selector diffuse reflectance accessory P/N 19900 uses an optimized off-axis optics configuration which selectively collects and maximizes the diffusely reflected components of light whilst minimizing the specular component. The off-axis design also allows for the expansion of use of the Selector optics with an alternative specialized baseplate - the Environmental Chamber P/N 19930 Series.
Various sampling cups provided for sample study include a standard 11mm diameter cup, a micro 4mm diameter cup and a tilted cup. The tilted cup can be used for the collection of total reflectance if desired (diffuse and specular components). In addition there are abrasive sample mounts used with 12mm diabraze pads. The diabraze material is rubbed against the surface of an intractable solid and this becomes deposited on the abrasive pad surface. The diabraze pad on its sample mount is then placed in the sampling position of the Selector accessory.
The optical design of the Selector means that it is a beam direction dependant accessory. A left to right or right to left beam direction (source to detector) Selector will only fit on to its appropriate beam direction dependant baseplate. The baseplate is supplied with the Selector and when ordering you should give the name and make of spectrometer to receive the correct baseplate for the Selector. The Selector can be installed into different spectrometer systems by change of the baseplate only, but the spectrometer systems must have the same common beam direction.
so both has their adventages and disadvantages.
