.. auto-generated by dev_tools.docs.nxdl from the NXDL source base_classes/NXguide.nxdl.xml -- DO NOT EDIT .. index:: ! NXguide (base class) ! guide (base class) see: guide (base class); NXguide .. _NXguide: ======= NXguide ======= .. Contributors List .. |contrib_name| replace:: Aaron Brewster|phyy-nx|https://avatars.githubusercontent.com/u/13471434?v=4|2022-06-15 .. |contrib_name| replace:: Pete R Jemian|prjemian|https://avatars.githubusercontent.com/u/2279984?v=4|2022-01-28 .. |contrib_name| replace:: Peter Chang|PeterC-DLS|https://avatars.githubusercontent.com/u/1381719?v=4|2020-10-20 .. |contrib_name| replace:: Tobias Richter|zjttoefs|https://avatars.githubusercontent.com/u/856440?v=4|2018-05-15 .. |contrib_name| replace:: Joachim Wuttke (o)|jwuttke|https://avatars.githubusercontent.com/u/5262000?v=4|2014-09-03 **Status**: base class, extends :ref:`NXobject` **Description**: .. collapse:: A neutron optical element to direct the path of the beam. ... A neutron optical element to direct the path of the beam. :ref:`NXguide` is used by neutron instruments to describe a guide consists of several mirrors building a shape through which neutrons can be guided or directed. The simplest such form is box shaped although elliptical guides are gaining in popularity. The individual parts of a guide usually have common characteristics but there are cases where they are different. For example, a neutron guide might consist of 2 or 4 coated walls or a supermirror bender with multiple, coated vanes. To describe polarizing supermirrors such as used in neutron reflection, it may be necessary to revise this definition of :ref:`NXguide` to include :ref:`NXpolarizer` and/or :ref:`NXmirror`. When even greater complexity exists in the definition of what constitutes a *guide*, it has been suggested that :ref:`NXguide` be redefined as a :ref:`NXcollection` of :ref:`NXmirror` each having their own :ref:`NXgeometry` describing their location(s). For the more general case when describing mirrors, consider using :ref:`NXmirror`. NOTE: The NeXus International Advisory Committee welcomes comments for revision and improvement of this definition of :ref:`NXguide`. **Symbols**: **nsurf**: number of reflecting surfaces **nwl**: number of wavelengths **Groups cited**: :ref:`NXdata`, :ref:`NXgeometry`, :ref:`NXoff_geometry`, :ref:`NXtransformations` .. index:: NXgeometry (base class); used in base class, NXdata (base class); used in base class, NXoff_geometry (base class); used in base class, NXtransformations (base class); used in base class **Structure**: .. _/NXguide@default-attribute: .. index:: default (file attribute) **@default**: (optional) :ref:`NX_CHAR ` .. collapse:: Declares which child group contains a path leading ... .. 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. .. _/NXguide/description-field: .. index:: description (field) **description**: (optional) :ref:`NX_CHAR ` A description of this particular instance of ``NXguide``. .. _/NXguide/incident_angle-field: .. index:: incident_angle (field) **incident_angle**: (optional) :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} TODO: documentation needed .. _/NXguide/bend_angle_x-field: .. index:: bend_angle_x (field) **bend_angle_x**: (optional) :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} TODO: documentation needed .. _/NXguide/bend_angle_y-field: .. index:: bend_angle_y (field) **bend_angle_y**: (optional) :ref:`NX_FLOAT ` {units=\ :ref:`NX_ANGLE `} TODO: documentation needed .. _/NXguide/interior_atmosphere-field: .. index:: interior_atmosphere (field) **interior_atmosphere**: (optional) :ref:`NX_CHAR ` Any of these values: ``vacuum`` | ``helium`` | ``argon`` .. _/NXguide/external_material-field: .. index:: external_material (field) **external_material**: (optional) :ref:`NX_CHAR ` external material outside substrate .. _/NXguide/m_value-field: .. index:: m_value (field) **m_value**: (optional) :ref:`NX_FLOAT ` (Rank: 1, Dimensions: [nsurf]) .. collapse:: The ``m`` value for a supermirror, which defines the supermirror ... The ``m`` value for a supermirror, which defines the supermirror regime in multiples of the critical angle of Nickel. .. _/NXguide/substrate_material-field: .. index:: substrate_material (field) **substrate_material**: (optional) :ref:`NX_FLOAT ` (Rank: 1, Dimensions: [nsurf]) TODO: documentation needed .. _/NXguide/substrate_thickness-field: .. index:: substrate_thickness (field) **substrate_thickness**: (optional) :ref:`NX_FLOAT ` (Rank: 1, Dimensions: [nsurf]) {units=\ :ref:`NX_LENGTH `} TODO: documentation needed .. _/NXguide/coating_material-field: .. index:: coating_material (field) **coating_material**: (optional) :ref:`NX_FLOAT ` (Rank: 1, Dimensions: [nsurf]) TODO: documentation needed .. _/NXguide/substrate_roughness-field: .. index:: substrate_roughness (field) **substrate_roughness**: (optional) :ref:`NX_FLOAT ` (Rank: 1, Dimensions: [nsurf]) {units=\ :ref:`NX_LENGTH `} TODO: documentation needed .. _/NXguide/coating_roughness-field: .. index:: coating_roughness (field) **coating_roughness**: (optional) :ref:`NX_FLOAT ` (Rank: 1, Dimensions: [nsurf]) {units=\ :ref:`NX_LENGTH `} TODO: documentation needed .. _/NXguide/number_sections-field: .. index:: number_sections (field) **number_sections**: (optional) :ref:`NX_INT ` {units=\ :ref:`NX_UNITLESS `} .. collapse:: number of substrate sections (also called ``nsurf`` as an ... number of substrate sections (also called ``nsurf`` as an index in the ``NXguide`` specification) .. _/NXguide/depends_on-field: .. index:: depends_on (field) **depends_on**: (optional) :ref:`NX_CHAR ` .. collapse:: NeXus positions components by applying a set of translations and rotations ... NeXus positions components by applying a set of translations and rotations to apply to the component starting from 0, 0, 0. The order of these operations is critical and forms what NeXus calls a dependency chain. The depends_on field defines the path to the top most operation of the dependency chain or the string "." if located in the origin. Usually these operations are stored in a NXtransformations group. But NeXus allows them to be stored anywhere. The entry opening of the guide lies on the reference plane. The center of the opening on that plane is the reference point on the x and y axis. The reference plane is orthogonal to the z axis and is the reference point along the z axis. Given no bend in the guide, it is parallel with z axis and extends in the positive direction of the z axis. .. image:: guide/guide.png :width: 40% .. _/NXguide/GEOMETRY-group: **GEOMETRY**: (optional) :ref:`NXgeometry` .. index:: deprecated **DEPRECATED**: Use the field `depends_on` and :ref:`NXtransformations` to position the guid and NXoff_geometry to describe its shape instead TODO: Explain what this NXgeometry group means. What is intended here? .. _/NXguide/reflectivity-group: **reflectivity**: (optional) :ref:`NXdata` Reflectivity as function of reflecting surface and wavelength .. _/NXguide/reflectivity@signal-attribute: .. index:: signal (group attribute) **@signal**: (optional) :ref:`NX_CHAR ` :ref:`⤆ ` Obligatory value: ``data`` .. _/NXguide/reflectivity@axes-attribute: .. index:: axes (group attribute) **@axes**: (optional) :ref:`NX_CHAR ` :ref:`⤆ ` Obligatory value: ``surface wavelength`` .. _/NXguide/reflectivity@surface_indices-attribute: .. index:: surface_indices (group attribute) **@surface_indices**: (optional) :ref:`NX_CHAR ` Obligatory value: ``0`` .. _/NXguide/reflectivity@wavelength_indices-attribute: .. index:: wavelength_indices (group attribute) **@wavelength_indices**: (optional) :ref:`NX_CHAR ` Obligatory value: ``1`` .. _/NXguide/reflectivity/data-field: .. index:: data (field) **data**: (optional) :ref:`NX_NUMBER ` (Rank: 2, Dimensions: [nsurf, nwl]) :ref:`⤆ ` reflectivity of each surface as a function of wavelength .. _/NXguide/reflectivity/surface-field: .. index:: surface (field) **surface**: (optional) :ref:`NX_NUMBER ` (Rank: 1, Dimensions: [nsurf]) {units=\ :ref:`NX_ANY `} .. collapse:: List of surfaces. Probably best to use index ... List of surfaces. Probably best to use index numbers but the specification is very loose. .. _/NXguide/reflectivity/wavelength-field: .. index:: wavelength (field) **wavelength**: (optional) :ref:`NX_NUMBER ` (Rank: 1, Dimensions: [nwl]) {units=\ :ref:`NX_WAVELENGTH `} wavelengths at which reflectivity was measured .. _/NXguide/OFF_GEOMETRY-group: **OFF_GEOMETRY**: (optional) :ref:`NXoff_geometry` This group describes the shape of the beam line component .. _/NXguide/TRANSFORMATIONS-group: **TRANSFORMATIONS**: (optional) :ref:`NXtransformations` .. collapse:: This is the group recommended for holding the chain of translation ... This is the group recommended for holding the chain of translation and rotation operations necessary to position the component within the instrument. The dependency chain may however traverse similar groups in other component groups. Hypertext Anchors ----------------- List of hypertext anchors for all groups, fields, attributes, and links defined in this class. * :ref:`/NXguide/bend_angle_x-field ` * :ref:`/NXguide/bend_angle_y-field ` * :ref:`/NXguide/coating_material-field ` * :ref:`/NXguide/coating_roughness-field ` * :ref:`/NXguide/depends_on-field ` * :ref:`/NXguide/description-field ` * :ref:`/NXguide/external_material-field ` * :ref:`/NXguide/GEOMETRY-group ` * :ref:`/NXguide/incident_angle-field ` * :ref:`/NXguide/interior_atmosphere-field ` * :ref:`/NXguide/m_value-field ` * :ref:`/NXguide/number_sections-field ` * :ref:`/NXguide/OFF_GEOMETRY-group ` * :ref:`/NXguide/reflectivity-group ` * :ref:`/NXguide/reflectivity/data-field ` * :ref:`/NXguide/reflectivity/surface-field ` * :ref:`/NXguide/reflectivity/wavelength-field ` * :ref:`/NXguide/reflectivity@axes-attribute ` * :ref:`/NXguide/reflectivity@signal-attribute ` * :ref:`/NXguide/reflectivity@surface_indices-attribute ` * :ref:`/NXguide/reflectivity@wavelength_indices-attribute ` * :ref:`/NXguide/substrate_material-field ` * :ref:`/NXguide/substrate_roughness-field ` * :ref:`/NXguide/substrate_thickness-field ` * :ref:`/NXguide/TRANSFORMATIONS-group ` * :ref:`/NXguide@default-attribute ` **NXDL Source**: https://github.com/nexusformat/definitions/blob/main/base_classes/NXguide.nxdl.xml