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

.. index::
    ! NXmonochromator (base class)
    ! monochromator (base class)
    see: monochromator (base class); NXmonochromator

.. _NXmonochromator:

===============
NXmonochromator
===============

**Status**:

  base class, extends :ref:`NXobject`

**Description**:

  A  wavelength defining device.

  This is a base class for everything which
  selects a wavelength or energy, be it a 
  monochromator crystal, a velocity selector,
  an undulator or whatever.

  The expected units are:

  * wavelength: angstrom
  * energy:     eV


**Symbols**:

  No symbol table

**Groups cited**:
  :ref:`NXcrystal`, :ref:`NXdata`, :ref:`NXgeometry`, :ref:`NXgrating`, :ref:`NXvelocity_selector`

.. index:: NXdata (base class); used in base class, NXgeometry (base class); used in base class, NXcrystal (base class); used in base class, NXvelocity_selector (base class); used in base class, NXgrating (base class); used in base class

**Structure**:

  .. _/NXmonochromator@default-attribute:

  .. index:: default (file attribute)

  **@default**: (optional) :ref:`NX_CHAR <NX_CHAR>`

    .. index:: plotting

    Declares which child group contains a path leading 
    to a :ref:`NXdata` group.

    It is recommended (as of NIAC2014) to use this attribute
    to help define the path to the default dataset to be plotted.
    See https://www.nexusformat.org/2014_How_to_find_default_data.html
    for a summary of the discussion.

  .. _/NXmonochromator/wavelength-field:

  .. index:: wavelength (field)

  **wavelength**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_WAVELENGTH <NX_WAVELENGTH>`}

    wavelength selected

  .. _/NXmonochromator/wavelength_error-field:

  .. index:: wavelength_error (field)

  **wavelength_error**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_WAVELENGTH <NX_WAVELENGTH>`}


    .. index:: deprecated


    **DEPRECATED**: see https://github.com/nexusformat/definitions/issues/820

    wavelength standard deviation

  .. _/NXmonochromator/wavelength_errors-field:

  .. index:: wavelength_errors (field)

  **wavelength_errors**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_WAVELENGTH <NX_WAVELENGTH>`}

    wavelength standard deviation

  .. _/NXmonochromator/energy-field:

  .. index:: energy (field)

  **energy**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_ENERGY <NX_ENERGY>`}

    energy selected

  .. _/NXmonochromator/energy_error-field:

  .. index:: energy_error (field)

  **energy_error**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_ENERGY <NX_ENERGY>`}


    .. index:: deprecated


    **DEPRECATED**: see https://github.com/nexusformat/definitions/issues/820

    energy standard deviation

  .. _/NXmonochromator/energy_errors-field:

  .. index:: energy_errors (field)

  **energy_errors**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=\ :ref:`NX_ENERGY <NX_ENERGY>`}

    energy standard deviation

  .. _/NXmonochromator/distribution-group:

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


  .. _/NXmonochromator/geometry-group:

  **geometry**: (optional) :ref:`NXgeometry`


  .. _/NXmonochromator/CRYSTAL-group:

  **CRYSTAL**: (optional) :ref:`NXcrystal`

    Use as many crystals as necessary to describe

  .. _/NXmonochromator/VELOCITY_SELECTOR-group:

  **VELOCITY_SELECTOR**: (optional) :ref:`NXvelocity_selector`


  .. _/NXmonochromator/GRATING-group:

  **GRATING**: (optional) :ref:`NXgrating`

    For diffraction grating based monochromators


Hypertext Anchors
-----------------

Table of hypertext anchors for all groups, fields,
attributes, and links defined in this class.


========================================================================================== ==========================================================================================
documentation (reST source) anchor                                                         web page (HTML) anchor                                                                    
========================================================================================== ==========================================================================================
:ref:`/NXmonochromator/CRYSTAL-group </NXmonochromator/CRYSTAL-group>`                     :ref:`#nxmonochromator-crystal-group </NXmonochromator/CRYSTAL-group>`                    
:ref:`/NXmonochromator/distribution-group </NXmonochromator/distribution-group>`           :ref:`#nxmonochromator-distribution-group </NXmonochromator/distribution-group>`          
:ref:`/NXmonochromator/energy-field </NXmonochromator/energy-field>`                       :ref:`#nxmonochromator-energy-field </NXmonochromator/energy-field>`                      
:ref:`/NXmonochromator/energy_error-field </NXmonochromator/energy_error-field>`           :ref:`#nxmonochromator-energy-error-field </NXmonochromator/energy_error-field>`          
:ref:`/NXmonochromator/energy_errors-field </NXmonochromator/energy_errors-field>`         :ref:`#nxmonochromator-energy-errors-field </NXmonochromator/energy_errors-field>`        
:ref:`/NXmonochromator/geometry-group </NXmonochromator/geometry-group>`                   :ref:`#nxmonochromator-geometry-group </NXmonochromator/geometry-group>`                  
:ref:`/NXmonochromator/GRATING-group </NXmonochromator/GRATING-group>`                     :ref:`#nxmonochromator-grating-group </NXmonochromator/GRATING-group>`                    
:ref:`/NXmonochromator/VELOCITY_SELECTOR-group </NXmonochromator/VELOCITY_SELECTOR-group>` :ref:`#nxmonochromator-velocity-selector-group </NXmonochromator/VELOCITY_SELECTOR-group>`
:ref:`/NXmonochromator/wavelength-field </NXmonochromator/wavelength-field>`               :ref:`#nxmonochromator-wavelength-field </NXmonochromator/wavelength-field>`              
:ref:`/NXmonochromator/wavelength_error-field </NXmonochromator/wavelength_error-field>`   :ref:`#nxmonochromator-wavelength-error-field </NXmonochromator/wavelength_error-field>`  
:ref:`/NXmonochromator/wavelength_errors-field </NXmonochromator/wavelength_errors-field>` :ref:`#nxmonochromator-wavelength-errors-field </NXmonochromator/wavelength_errors-field>`
:ref:`/NXmonochromator@default-attribute </NXmonochromator@default-attribute>`             :ref:`#nxmonochromator-default-attribute </NXmonochromator@default-attribute>`            
========================================================================================== ==========================================================================================


**NXDL Source**:
  https://github.com/FAIRmat-Experimental/nexus_definitions/tree/fairmat/base_classes/NXmonochromator.nxdl.xml