A quartz focusing mirror is used at beamline 6-2 to remove high energy radiation and to focus the x-rays at one spot.  High energy x-rays are filtered from the spectrum by setting the incident beam at a grazing angle.  Since, the critical angle for total reflection increases with increasing x-ray energy, energetic x-rays will penetrate into the mirror while lower energy x-rays are reflected at a given angle.  Focusing is achieved since the mirror is bent in a elliptical shape.