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

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

.. _NXmonochromator:

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

**Status**:

  base class, extends :ref:`NXobject`, version 1.0

**Description**:

  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:`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

**Structure**:

  .. index:: wavelength (data field)

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

    wavelength selected

  .. index:: wavelength_error (data field)

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

    wavelength standard deviation

  .. index:: energy (data field)

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

    energy selected

  .. index:: energy_error (data field)

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

    energy standard deviation

  **distribution**: :ref:`NXdata`


  **geometry**: :ref:`NXgeometry`


  **(crystal)**: :ref:`NXcrystal`

    Use as many crystals as necessary to describe

  **(velocity_selector)**: :ref:`NXvelocity_selector`


**Source**:
  Automatically generated from https://github.com/nexusformat/definitions/blob/master/base_classes/NXmonochromator.nxdl.xml