Читать книгу Continuous Emission Monitoring - James A. Jahnke - Страница 143

A White cell is a type of sample cell developed by John White (White 1942) that increases the pathlength of the light beam by reflecting it from three spherical, slightly misaligned concave mirrors (Figure 4‐13). The cell shown in the figure shows the beam making eight traverses across the cell to increase the pathlength eightfold from that of a cell containing only windows. The number of passes can be adjusted by adjusting the mirror positions. White cells can be designed with pathlengths from less than a meter to hundreds of meters (Vidrine 2000; Doussin et al. 1999).