.. index:: 
   single: Parameters; 1D Field Centre 50

1D Field Centre 50
==================

The field centre (*FC*) is defined as the distance in cm from the centre of the detector to the centre of the field and is calculated as the half the difference between the distance from the profile centre to the :ref:`right<1D Field Edge Right 50>` and :ref:`left<1D Field Edge Left 50>` field edge:

.. math:: FC = \cfrac {d(RE) + d(LE)} {2}

Where *d(RE)* and *d(LE)* are the linear distances from the profile centre to the right and left field edges respectively.

**Protocol invocation name**: 1D Field Centre 50