Another way: POLA, IPOLA and diffracted beam graphite monochromator
Set IPOLA to 1 (POLA should now be cos2 2? of the monochromator.)
In the case of Graphite 002 reflection: 2? = 26.603 (d=3.3480Å). cos2 2?=0.80
Mainly due to problems such as mosaic spread - POLA refines on this diffractometer (again using annealed Y2O3) to 0.911