.. _concepts.diffract:

==================
Diffractometer
==================

.. index::
    !design; diffractometer
    !diffractometer
    !geometry
    !mode

Diffractometers are built as a subclass of
:class:`~hklpy2.diffract.DiffractometerBase()`, adding a variety of
positioners as ophyd Components.  In an instance of that subclass, user
sets :attr:`~hklpy2.diffract.DiffractometerBase.backend_solver` by calling
:func:`~hklpy2.misc.solver_factory`.  In this call, the user specifies the solver,
the geometry, and defines which Components (of the diffractometer) are to be used as
pseudos and reals.  The backend implements
:meth:`~hklpy2.backends.base.SolverBase.forward`,
:meth:`~hklpy2.backends.base.SolverBase.inverse`, and all related support, for
only the pseudos and reals that are identified.

Parts of `DiffractometerBase`
=============================

A :class:`~hklpy2.diffract.DiffractometerBase` object has several parts:

The :class:`~hklpy2.diffract.DiffractometerBase()` class should
be a thin interface. Most real diffractometer capability should be
provided in the :class:`~hklpy2.ops.Core()` class (or one of
its attributes, such as :attr:`~hklpy2.ops.Core.solver`
and :attr:`~hklpy2.ops.Core.sample`)

.. rubric:: Core-related methods and properties
.. autosummary::

    ~hklpy2.diffract.DiffractometerBase.forward (method)
    ~hklpy2.diffract.DiffractometerBase.inverse (method)
    ~hklpy2.diffract.DiffractometerBase.position (method)
    ~hklpy2.diffract.DiffractometerBase.pseudo_axis_names (property)
    ~hklpy2.diffract.DiffractometerBase.real_axis_names (property)
    ~hklpy2.diffract.DiffractometerBase.wh (method)

.. rubric:: Sample-related methods and properties
.. autosummary::

    ~hklpy2.diffract.DiffractometerBase.add_reflection (method)
    ~hklpy2.diffract.DiffractometerBase.add_sample (method)
    ~hklpy2.diffract.DiffractometerBase.sample (property)
    ~hklpy2.diffract.DiffractometerBase.samples (property)

.. rubric:: Related methods and properties from other classes
.. autosummary::

    ~hklpy2.ops.Core.assign_axes (method)
    ~hklpy2.backends.base.SolverBase.extra_axis_names (property)
    ~hklpy2.blocks.sample.Sample.lattice (property)
    ~hklpy2.blocks.sample.Sample.refine_lattice (method)
    ~hklpy2.ops.Core.refine_lattice (method)
    ~hklpy2.blocks.sample.Sample.reflections (property)
    ~hklpy2.ops.Core.set_solver (method)
    ~hklpy2.blocks.sample.Sample.U (property)
    ~hklpy2.blocks.sample.Sample.UB (property)

.. seealso::

   :ref:`guide.diffract` for step-by-step instructions on defining a
   diffractometer object and using it with the bluesky RunEngine.