.. auto-generated by dev_tools.docs.nxdl from the NXDL source base_classes/NXmonochromator.nxdl.xml -- DO NOT EDIT

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

.. _NXmonochromator:

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

**Status**:

  base class, extends :ref:`NXcomponent`

**Description**:

  .. collapse:: A  wavelength defining device. ...

      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:`NXaperture`, :ref:`NXcrystal`, :ref:`NXdata`, :ref:`NXgeometry`, :ref:`NXgrating`, :ref:`NXoff_geometry`, :ref:`NXvelocity_selector`

.. index:: NXaperture (base class); used in base class, NXdata (base class); used in base class, NXgeometry (base class); used in base class, NXoff_geometry (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/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/energy_dispersion-field:

  .. index:: energy_dispersion (field)

  **energy_dispersion**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=eV/mm} 

    Energy dispersion at the exit slit.

  .. _/NXmonochromator/wavelength_dispersion-field:

  .. index:: wavelength_dispersion (field)

  **wavelength_dispersion**: (optional) :ref:`NX_FLOAT <NX_FLOAT>` {units=nm/mm} 

    Wavelength dispersion at the exit slit.

  .. _/NXmonochromator/depends_on-field:

  .. index:: depends_on (field)

  **depends_on**: (optional) :ref:`NX_CHAR <NX_CHAR>` :ref:`⤆ </NXcomponent/depends_on-field>`

    .. collapse::   Add a definition for the reference point of a monochromator. ...

        .. todo::
          Add a definition for the reference point of a monochromator.

  .. _/NXmonochromator/entrance_slit-group:

  **entrance_slit**: (optional) :ref:`NXaperture` 

    Size, position and shape of the entrance slit of the monochromator.

  .. _/NXmonochromator/exit_slit-group:

  **exit_slit**: (optional) :ref:`NXaperture` 

    Size, position and shape of the exit slit of the monochromator.

  .. _/NXmonochromator/distribution-group:

  **distribution**: (optional) :ref:`NXdata` :ref:`⤆ </NXobject/DATA-group>`


  .. _/NXmonochromator/geometry-group:

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


    .. index:: deprecated


    **DEPRECATED**: Use the field `depends_on` and :ref:`NXtransformations` to position the monochromator and NXoff_geometry to describe its shape instead


  .. _/NXmonochromator/OFF_GEOMETRY-group:

  :bolditalic:`OFF_GEOMETRY`: (optional) :ref:`NXoff_geometry` 

    This group describes the shape of the beam line component

  .. _/NXmonochromator/CRYSTAL-group:

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

    Use as many crystals as necessary to describe

  .. _/NXmonochromator/VELOCITY_SELECTOR-group:

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


  .. _/NXmonochromator/GRATING-group:

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

    For diffraction grating based monochromators


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

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


* :ref:`/NXmonochromator/CRYSTAL-group </NXmonochromator/CRYSTAL-group>`
* :ref:`/NXmonochromator/depends_on-field </NXmonochromator/depends_on-field>`
* :ref:`/NXmonochromator/distribution-group </NXmonochromator/distribution-group>`
* :ref:`/NXmonochromator/energy-field </NXmonochromator/energy-field>`
* :ref:`/NXmonochromator/energy_dispersion-field </NXmonochromator/energy_dispersion-field>`
* :ref:`/NXmonochromator/energy_error-field </NXmonochromator/energy_error-field>`
* :ref:`/NXmonochromator/energy_errors-field </NXmonochromator/energy_errors-field>`
* :ref:`/NXmonochromator/entrance_slit-group </NXmonochromator/entrance_slit-group>`
* :ref:`/NXmonochromator/exit_slit-group </NXmonochromator/exit_slit-group>`
* :ref:`/NXmonochromator/geometry-group </NXmonochromator/geometry-group>`
* :ref:`/NXmonochromator/GRATING-group </NXmonochromator/GRATING-group>`
* :ref:`/NXmonochromator/OFF_GEOMETRY-group </NXmonochromator/OFF_GEOMETRY-group>`
* :ref:`/NXmonochromator/VELOCITY_SELECTOR-group </NXmonochromator/VELOCITY_SELECTOR-group>`
* :ref:`/NXmonochromator/wavelength-field </NXmonochromator/wavelength-field>`
* :ref:`/NXmonochromator/wavelength_dispersion-field </NXmonochromator/wavelength_dispersion-field>`
* :ref:`/NXmonochromator/wavelength_error-field </NXmonochromator/wavelength_error-field>`
* :ref:`/NXmonochromator/wavelength_errors-field </NXmonochromator/wavelength_errors-field>`

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