When dust or grim coats mirrors in a double-beam UV-Vis spectrometer, the device's performance degrades. Repair costs can also double because you can't replace one mirror if it needs fixing. Because they work as a pair, you must replace both mirrors. Stray light caused by faulty equipment design and other factors could decrease an instrument's linearity range and reduce the absorbency of the substance it measures. Electronic components in the spectrometer or sample source may also generate noise that decreases measurement accuracy and reduces the device's sensitivity