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

.. index::
    ! NXdetector_module (base class)
    ! detector_module (base class)
    see: detector_module (base class); NXdetector_module

.. _NXdetector_module:

=================
NXdetector_module
=================

**Status**:

  base class, extends :ref:`NXobject`

**Description**:

  Geometry and logical description of a detector module.

  Many detectors consist of multiple
  smaller modules. Sometimes it is important to know the exact position of such
  modules.
  This is the purpose of this group. It is a child group to NXdetector.

  Note, the pixel size is given as values in the array fast_pixel_direction and slow_pixel_direction.

**Symbols**:

  No symbol table

**Groups cited**:
  none

**Structure**:

  .. index:: data_origin (field)

  **data_origin**: (optional) :ref:`NX_INT <NX_INT>`

    A dimension-2 or dimension-3 field which gives the indices
    of the origin of the hyperslab of data for this module in the
    main area detector image in the parent NXdetector module.

    The data_origin is 0-based.

    The frame number dimension (np) is omitted.  Thus the
    data_origin field for a dimension-2 dataset with indices (np, i, j)
    will be an array with indices (i, j), and for a dimension-3
    dataset with indices (np, i, j, k) will be an array with indices
    (i, j, k).

    The order of indices (i, j or i, j, k) is slow to fast.

  .. index:: data_size (field)

  **data_size**: (optional) :ref:`NX_INT <NX_INT>`

    Two or three values for the size of the module in pixels in
    each direction. Dimensionality and order of indices is the
    same as for data_origin.

  .. index:: module_offset (field)

  **module_offset**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}

    Offset of the module in regards to the origin of the detector in an
    arbitrary direction.

    .. index:: transformation_type (field attribute)

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


      Obligatory value:  ``translation``

    .. index:: vector (field attribute)

    **@vector**: (optional) :ref:`NX_NUMBER <NX_NUMBER>`

      Three values that define the axis for this transformation

    .. index:: offset (field attribute)

    **@offset**: (optional) :ref:`NX_NUMBER <NX_NUMBER>`

      A fixed offset applied before the transformation (three vector components).

    .. index:: offset_units (field attribute)

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

      Units of the offset.

    .. index:: depends_on (field attribute)

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

      Points to the path of the next element in the geometry chain.

  .. index:: fast_pixel_direction (field)

  **fast_pixel_direction**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}

    Values along the direction of fastest varying pixel direction. Each value in this
    array is the size of a pixel in the units specified. Alternatively, if only one
    value is given, all pixels in this direction have the same value. The direction
    itself is given through the vector attribute.

    .. index:: transformation_type (field attribute)

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


      Obligatory value:  ``translation``

    .. index:: vector (field attribute)

    **@vector**: (optional) :ref:`NX_NUMBER <NX_NUMBER>`

      Three values that define the axis for this transformation

    .. index:: offset (field attribute)

    **@offset**: (optional) :ref:`NX_NUMBER <NX_NUMBER>`

      A fixed offset applied before the transformation (three vector components).

    .. index:: offset_units (field attribute)

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

      Units of the offset.

    .. index:: depends_on (field attribute)

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

      Points to the path of the next element in the geometry chain.

  .. index:: slow_pixel_direction (field)

  **slow_pixel_direction**: (optional) :ref:`NX_NUMBER <NX_NUMBER>` {units=\ :ref:`NX_LENGTH <NX_LENGTH>`}

    Values along the direction of fastest varying pixel direction. Each value in this
    array is the size of a pixel in the units specified. Alternatively, if only one
    value is given, all pixels in this direction have the same value. The direction
    itself is given through the vector attribute.

    .. index:: transformation_type (field attribute)

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


      Obligatory value:  ``translation``

    .. index:: vector (field attribute)

    **@vector**: (optional) :ref:`NX_NUMBER <NX_NUMBER>`

      Three values that define the axis for this transformation

    .. index:: offset (field attribute)

    **@offset**: (optional) :ref:`NX_NUMBER <NX_NUMBER>`

      A fixed offset applied before the transformation (three vector components).

    .. index:: offset_units (field attribute)

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

      Units of the offset.

    .. index:: depends_on (field attribute)

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

      Points to the path of the next element in the geometry chain.

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