Tilting filter

The samples had dry matter over 85% and were ground to pass through a 1 mm screen and then packed in a quartz-windowed cup. The unit was demonstrated at the 1971 Illinois State Fair. After the success of this instrument, Neotec (later Pacific Scientific, then NIR Systems, then Perstorp, then FOSS) built a rotating (tilting) filter instrument. Both instruments were dedicated, analog systems, neither of which was considered user-friendly. ... 

C) tilting filter mount (continuously moving) with detectors on four sides of sample cup. 

Figure 4.1.9. Schematic of a tilting-fllter spectrometer. The three tilting filters provide for wavelength isolation in three regions of the NIR spectrum.

FIGURE 4.4 Two types of tilting filter instrument designs. 

One of the important goals of NIRS analysis has been uniformity of analysis, in otherwords, a sample should obtain the same analysis value from all instruments. The first effort by instrument manufacturers was to accomplish this goal using a slope-and-bias adjustment applied to analysis values. In 1986 a second method was developed that could be used with instruments generating spectra [97], in otherwords, monochromator or tilting filter instruments. This method adjusted the... 

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