.. auto-generated by script ../../../../utils/nxdl2rst.py from the NXDL source NXgrating.nxdl.xml

.. index::
    ! NXgrating (base class)
    ! grating (base class)
    see: grating (base class); NXgrating

.. _NXgrating:

=========
NXgrating
=========

**Status**:

  base class, extends :ref:`NXobject`

**Description**:

  A diffraction grating, as could be used in a soft X-ray monochromator

**Symbols**:

  No symbol table

**Groups cited**:
  :ref:`NXdata`, :ref:`NXshape`, :ref:`NXtransformations`

.. index:: NXshape (base class); used in base class, NXdata (base class); used in base class, NXtransformations (base class); used in base class

**Structure**:

  .. index:: angles (field)

  **angles[2]**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_ANGLE <NX_ANGLE>`}

    Blaze or trapezoidal angles, with the angle of the upstream facing edge listed first. Blazed gratings can be identified by the low value of the first-listed angle.

  .. index:: period (field)

  **period[]**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}

    List of polynomial coefficients describing the spatial separation of lines/grooves as a function of position along the grating, in increasing powers of position. Gratings which do not have variable line spacing will only have a single coefficient (constant).

  .. index:: duty_cycle (field)

  **duty_cycle**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_UNITLESS <NX_UNITLESS>`}


  .. index:: depth (field)

  **depth**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}


  .. index:: diffraction_order (field)

  **diffraction_order**: (optional) :ref:`NX_INT <NX_INT>` {units=\ :ref:`NX_UNITLESS <NX_UNITLESS>`}


  .. index:: deflection_angle (field)

  **deflection_angle**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_ANGLE <NX_ANGLE>`}

    Angle between the incident beam and the utilised outgoing beam.

  .. index:: interior_atmosphere (field)

  **interior_atmosphere**: (optional) :ref:`NX_CHAR <NX_CHAR>`


    Any of these values: ``vacuum`` | ``helium`` | ``argon``

  .. index:: substrate_material (field)

  **substrate_material**: (optional) :ref:`NX_CHAR <NX_CHAR>`


  .. index:: substrate_density (field)

  **substrate_density**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_MASS_DENSITY <NX_MASS_DENSITY>`}


  .. index:: substrate_thickness (field)

  **substrate_thickness**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}


  .. index:: coating_material (field)

  **coating_material**: (optional) :ref:`NX_CHAR <NX_CHAR>`


  .. index:: substrate_roughness (field)

  **substrate_roughness**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}


  .. index:: coating_roughness (field)

  **coating_roughness**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}


  .. index:: layer_thickness (field)

  **layer_thickness**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}

    An array describing the thickness of each layer

  **shape**: (optional) :ref:`NXshape`

    A NXshape group describing the shape of the mirror

  **figure_data**: (optional) :ref:`NXdata`

    Numerical description of the surface figure of the mirror.

  **(transformations)**: (optional) :ref:`NXtransformations`

    "Engineering" position of the grating

**NXDL Source**:
  https://github.com/nexusformat/definitions/blob/master/base_classes/NXgrating.nxdl.xml