KB Mirror control and focusing¶
A Kirkpatrick-Baez mirror, or KB mirror for short, focuses beams of X-rays by reflecting them at grazing incidence off a curved surface, usually coated with a layer of a heavy metal. It is named after Paul Kirkpatrick and Albert Baez (father of Joan Baez), the inventors of the X-ray microscope.
Although X-rays can be focused by compound refractive lenses, these also reduce the intensity of the beam and are therefore undesirable. KB mirrors, on the other hand, can focus beams to small spot sizes with minimal loss of intensity. Typically they are used in pairs - one to focus horizontally and one for vertical focus. When the horizontal and vertical focuses coincide, the X-ray beam is focused to a small spot.
This chapter presents KB mirror control and focusing with BLISS.
These features are implemented as a
KbController class offering:
- a focusing procedure (
- a calculation motor (
- plugin: bliss package: bliss.controller.kb class: KbController name: kb saving: True <- Save or not data during slits scans focus: - device: $hfocus - device: $vfocus - plugin: bliss package: bliss.controller.kb class: KbFocus name: hfocus offset_motor: $kbho <- Slit offset motor in front of the KB system offset_start: 0.0 <- Start position of the iterative dscan bender_upstream: $kbh1 bender_downstream: $kbh2 bender_increment: 20 <- def. val., can be set when calling focus counter: $diagbpm.bpm.x - plugin: bliss package: bliss.controller.kb class: KbFocus name: vfocus offset_motor: $kbvo offset_start: 0.0 bender_upstream: $kbv1 bender_downstream: $kbv2 bender_increment: 20 counter: $diagbpm.bpm.y # KB Motors - plugin: emotion class: KbMirrorCalcMotor name: kbmirror # distance in mm distance: 85 <- distance between the 2 rotation points in mm axes: - name: $kbvrot <- Main rotation tags: real rot - name: $kbvecrot <- eccentric rotation tags: real ecrot - name: kbvry <- tilt rotation tags: tilt - name: kbvtz <- vertical/horizontal translation tags: height