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

1D Field Size 50
================

The field size (*FS*) is defined as the distance from the :ref:`left field edge<1D Field Edge Left 50>` to the  :ref:`right field edge<1D Field Edge Right 50>`:

.. math:: FS = d(RE) - d(LE)

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 Size 50

|Note| Noisy data can lead to a inaccurate field size being reported.

|Note| The right and left field edges are affected by the set window levels.

.. |Note| image:: _static/Note.png