ONLINE>
scan/q
ONLINE>
*
= fc_qx()
ONLINE>
*
= fc_qy()
ONLINE>
*
= fc_qz()
ONLINE>
fc_qx() = value
ONLINE>
fc_qy() = value
ONLINE>
fc_qz() = value
ONLINE>
move[/fc_qx=val1][/fc_qy=val2][/fc_qz=val3][/fc_psi=val4]
The names of the functions that control the diffractometer begin with the letters FC (four circle) in order to avoid any mismatches with user defined names. The components of the scattering vector are understood as indices although they can have any fractional value.
ONLINEThe diffractometer angles are defined following the convention of Busing and Levy with the exception of>
scan/two_theta
ONLINE>
scan/omega
ONLINE>
scan/chi
ONLINE>
scan/phi
ONLINE>
scan/psi
The angles are calculated from motor positions using offsets which are part of the UB matrix. The offsets can be determined e.g. by RAFIN (17).
The angle psi denotes the rotation around the scattering vector. It is zero for the bisecting position.
ONLINE>
*
= fc_filter()
ONLINE>
fc_filter() = value
ONLINE>
*
= fc_two_theta()
ONLINE>
*
= fc_omega()
ONLINE>
*
= fc_chi()
ONLINE>
*
= fc_phi()
ONLINE>
*
= fc_psi()
ONLINE>
fc_two_theta() = value
ONLINE>
fc_omega() = value
ONLINE>
fc_chi() = value
ONLINE>
fc_phi() = value
ONLINE>
fc_psi() = value
ONLINE>
move/fc_two_theta=val1/fc_omega=val2
/fc_chi=val3/fc_phi=val4
The diffractometer angles are transformed to q-space with the help of the UB matrix, coded by Th. Brückel (now at Forschungszentrum Jülich). ONLINE supplies the code that allows you to create and modify a UB matrix for a specific crystal. The command
ONLINE>
create/ub name
creates a new queue element of the type UB. It does not
contain only the values of the matrix element but also further
information which will be described below. A UB queue element can
be read from a file:
ONLINEThe UB matrix queue elements should always be kept in/online_dir. A modified UB queue element is written to disk by:>
read/gqeonline_dir
ub_matrix_name
ONLINE>
write/gqe/file=online_dir:ub_matrix_name internal_name