Crystal metadata change

src/dodal/beamlines/i22.py

@@ -11,9 +11,13 @@
 )
 from dodal.common.beamlines.beamline_utils import set_beamline as set_utils_beamline
 from dodal.common.beamlines.device_helpers import numbered_slits
+from dodal.common.crystal_metadata import (
+    MaterialsEnum,
+    make_crystal_metadata_from_material,
+)
 from dodal.common.visit import RemoteDirectoryServiceClient, StaticVisitPathProvider
 from dodal.devices.focusing_mirror import FocusingMirror
-from dodal.devices.i22.dcm import CrystalMetadata, DoubleCrystalMonochromator
+from dodal.devices.i22.dcm import DoubleCrystalMonochromator
 from dodal.devices.i22.fswitch import FSwitch
 from dodal.devices.i22.nxsas import NXSasMetadataHolder, NXSasOAV, NXSasPilatus
 from dodal.devices.linkam3 import Linkam3
@@ -170,17 +174,12 @@ def dcm(
         fake_with_ophyd_sim,
         bl_prefix=False,
         temperature_prefix=f"{BeamlinePrefix(BL).beamline_prefix}-DI-DCM-01:",
-        crystal_1_metadata=CrystalMetadata(
-            usage="Bragg",
-            type="silicon",
-            reflection=(1, 1, 1),
-            d_spacing=(3.13475, "nm"),
+        crystal_1_metadata=make_crystal_metadata_from_material(
+            MaterialsEnum.Si, (1, 1, 1)
         ),
-        crystal_2_metadata=CrystalMetadata(
-            usage="Bragg",
-            type="silicon",
-            reflection=(1, 1, 1),
-            d_spacing=(3.13475, "nm"),
+        crystal_2_metadata=make_crystal_metadata_from_material(
+            MaterialsEnum.Si,
+            (1, 1, 1),
         ),
     )
 

src/dodal/beamlines/p38.py

@@ -10,9 +10,13 @@
 )
 from dodal.common.beamlines.beamline_utils import set_beamline as set_utils_beamline
 from dodal.common.beamlines.device_helpers import numbered_slits
+from dodal.common.crystal_metadata import (
+    MaterialsEnum,
+    make_crystal_metadata_from_material,
+)
 from dodal.common.visit import LocalDirectoryServiceClient, StaticVisitPathProvider
 from dodal.devices.focusing_mirror import FocusingMirror
-from dodal.devices.i22.dcm import CrystalMetadata, DoubleCrystalMonochromator
+from dodal.devices.i22.dcm import DoubleCrystalMonochromator
 from dodal.devices.i22.fswitch import FSwitch
 from dodal.devices.linkam3 import Linkam3
 from dodal.devices.slits import Slits
@@ -227,17 +231,11 @@ def dcm(
         fake_with_ophyd_sim,
         bl_prefix=False,
         temperature_prefix=f"{BeamlinePrefix(BL).beamline_prefix}-DI-DCM-01:",
-        crystal_1_metadata=CrystalMetadata(
-            usage="Bragg",
-            type="silicon",
-            reflection=(1, 1, 1),
-            d_spacing=(3.13475, "nm"),
+        crystal_1_metadata=make_crystal_metadata_from_material(
+            MaterialsEnum.Si, (1, 1, 1)
         ),
-        crystal_2_metadata=CrystalMetadata(
-            usage="Bragg",
-            type="silicon",
-            reflection=(1, 1, 1),
-            d_spacing=(3.13475, "nm"),
+        crystal_2_metadata=make_crystal_metadata_from_material(
+            MaterialsEnum.Si, (1, 1, 1)
         ),
     )
 

src/dodal/common/crystal_metadata.py

@@ -0,0 +1,61 @@
+import math
+from dataclasses import dataclass
+from enum import Enum
+from typing import Literal
+
+
+@dataclass(frozen=True)
+class Material:
+    """
+    Class representing a crystalline material with a specific lattice parameter.
+    """
+
+    name: str
+    lattice_parameter: float  # Lattice parameter in meters
+
+
+class MaterialsEnum(Enum):
+    Si = Material(name="silicon", lattice_parameter=5.4310205e-10)
+    Ge = Material(name="germanium", lattice_parameter=5.6575e-10)
+
+
+@dataclass(frozen=True)
+class CrystalMetadata:
+    """
+    Metadata used in the NeXus format,
+    see https://manual.nexusformat.org/classes/base_classes/NXcrystal.html
+    """
+
+    usage: Literal["Bragg", "Laue"]
+    type: str
+    reflection: tuple[int, int, int]
+    d_spacing: tuple[float, str]
+
+    @staticmethod
+    def calculate_default_d_spacing(
+        lattice_parameter: float, reflection: tuple[int, int, int]
+    ) -> tuple[float, str]:
+        """
+        Calculates the d-spacing value in nanometers based on the given lattice parameter and reflection indices.
+        """
+        h_index, k_index, l_index = reflection
+        d_spacing_m = lattice_parameter / math.sqrt(
+            h_index**2 + k_index**2 + l_index**2
+        )
+        d_spacing_nm = d_spacing_m * 1e9  # Convert meters to nanometers
+        return round(d_spacing_nm, 5), "nm"
+
+
+def make_crystal_metadata_from_material(
+    material: MaterialsEnum,
+    reflection_plane: tuple[int, int, int],
+    usage: Literal["Bragg", "Laue"] = "Bragg",
+    d_spacing_param: tuple[float, str] | None = None,
+):
+    d_spacing = d_spacing_param or CrystalMetadata.calculate_default_d_spacing(
+        material.value.lattice_parameter, reflection_plane
+    )
+    assert all(
+        isinstance(i, int) and i > 0 for i in reflection_plane
+    ), "Reflection plane indices must be positive integers"
+    return CrystalMetadata(usage, material.value.name, reflection_plane, d_spacing)

src/dodal/devices/dcm.py

@@ -1,7 +1,15 @@
-from ophyd_async.core import StandardReadable
+import numpy as np
+from numpy.typing import NDArray
+from ophyd_async.core import StandardReadable, soft_signal_r_and_setter
 from ophyd_async.epics.motor import Motor
 from ophyd_async.epics.signal import epics_signal_r
 
+from dodal.common.crystal_metadata import (
+    CrystalMetadata,
+    MaterialsEnum,
+    make_crystal_metadata_from_material,
+)
+
 
 class DCM(StandardReadable):
     """
@@ -17,7 +25,11 @@ def __init__(
         self,
         prefix: str,
         name: str = "",
+        crystal_metadata: CrystalMetadata | None = None,
     ) -> None:
+        cm = crystal_metadata or make_crystal_metadata_from_material(
+            MaterialsEnum.Si, (1, 1, 1)
+        )
         with self.add_children_as_readables():
             self.bragg_in_degrees = Motor(prefix + "BRAGG")
             self.roll_in_mrad = Motor(prefix + "ROLL")
@@ -36,4 +48,16 @@ def __init__(
             self.perp_temp = epics_signal_r(float, prefix + "TEMP6")
             self.perp_sub_assembly_temp = epics_signal_r(float, prefix + "TEMP7")
 
+            self.crystal_metadata_usage, _ = soft_signal_r_and_setter(
+                str, initial_value=cm.usage
+            )
+            self.crystal_metadata_type, _ = soft_signal_r_and_setter(
+                str, initial_value=cm.type
+            )
+            reflection_array = np.array(cm.reflection)
+            self.crystal_metadata_reflection, _ = soft_signal_r_and_setter(
+                NDArray[np.uint64],
+                initial_value=reflection_array,
+            )
+            self.crystal_metadata_d_spacing = epics_signal_r(float, "DSPACING:RBV")
         super().__init__(name)

src/dodal/devices/i22/dcm.py

@@ -1,6 +1,4 @@
 import time
-from dataclasses import dataclass
-from typing import Literal
 
 import numpy as np
 from bluesky.protocols import Reading
@@ -14,24 +12,13 @@
 from ophyd_async.epics.motor import Motor
 from ophyd_async.epics.signal import epics_signal_r
 
+from dodal.common.crystal_metadata import CrystalMetadata
+
 # Conversion constant for energy and wavelength, taken from the X-Ray data booklet
 # Converts between energy in KeV and wavelength in angstrom
 _CONVERSION_CONSTANT = 12.3984
 
 
-@dataclass(frozen=True, unsafe_hash=True)
-class CrystalMetadata:
-    """
-    Metadata used in the NeXus format,
-    see https://manual.nexusformat.org/classes/base_classes/NXcrystal.html
-    """
-
-    usage: Literal["Bragg", "Laue"] | None = None
-    type: str | None = None
-    reflection: tuple[int, int, int] | None = None
-    d_spacing: tuple[float, str] | None = None
-
-
 class DoubleCrystalMonochromator(StandardReadable):
     """
     A double crystal monochromator (DCM), used to select the energy of the beam.
@@ -45,8 +32,8 @@ class DoubleCrystalMonochromator(StandardReadable):
     def __init__(
         self,
         temperature_prefix: str,
-        crystal_1_metadata: CrystalMetadata | None = None,
-        crystal_2_metadata: CrystalMetadata | None = None,
+        crystal_1_metadata: CrystalMetadata,
+        crystal_2_metadata: CrystalMetadata,
         prefix: str = "",
         name: str = "",
     ) -> None:
@@ -74,63 +61,37 @@ def __init__(
 
         # Soft metadata
         # If supplied include crystal details in output of read_configuration
-        crystal_1_metadata = crystal_1_metadata or CrystalMetadata()
-        crystal_2_metadata = crystal_2_metadata or CrystalMetadata()
         with self.add_children_as_readables(ConfigSignal):
-            if crystal_1_metadata.usage is not None:
-                self.crystal_1_usage, _ = soft_signal_r_and_setter(
-                    str, initial_value=crystal_1_metadata.usage
-                )
-            else:
-                self.crystal_1_usage = None
-            if crystal_1_metadata.type is not None:
-                self.crystal_1_type, _ = soft_signal_r_and_setter(
-                    str, initial_value=crystal_1_metadata.type
-                )
-            else:
-                self.crystal_1_type = None
-            if crystal_1_metadata.reflection is not None:
-                self.crystal_1_reflection, _ = soft_signal_r_and_setter(
-                    Array1D[np.int32],
-                    initial_value=np.array(crystal_1_metadata.reflection),
-                )
-            else:
-                self.crystal_1_reflection = None
-            if crystal_1_metadata.d_spacing is not None:
-                self.crystal_1_d_spacing, _ = soft_signal_r_and_setter(
-                    float,
-                    initial_value=crystal_1_metadata.d_spacing[0],
-                    units=crystal_1_metadata.d_spacing[1],
-                )
-            else:
-                self.crystal_1_d_spacing = None
-            if crystal_2_metadata.usage is not None:
-                self.crystal_2_usage, _ = soft_signal_r_and_setter(
-                    str, initial_value=crystal_2_metadata.usage
-                )
-            else:
-                self.crystal_2_usage = None
-            if crystal_2_metadata.type is not None:
-                self.crystal_2_type, _ = soft_signal_r_and_setter(
-                    str, initial_value=crystal_2_metadata.type
-                )
-            else:
-                self.crystal_2_type = None
-            if crystal_2_metadata.reflection is not None:
-                self.crystal_2_reflection, _ = soft_signal_r_and_setter(
-                    Array1D[np.int32],
-                    initial_value=np.array(crystal_2_metadata.reflection),
-                )
-            else:
-                self.crystal_2_reflection = None
-            if crystal_2_metadata.d_spacing is not None:
-                self.crystal_2_d_spacing, _ = soft_signal_r_and_setter(
-                    float,
-                    initial_value=crystal_2_metadata.d_spacing[0],
-                    units=crystal_2_metadata.d_spacing[1],
-                )
-            else:
-                self.crystal_2_d_spacing = None
+            self.crystal_1_usage, _ = soft_signal_r_and_setter(
+                str, initial_value=crystal_1_metadata.usage
+            )
+            self.crystal_1_type, _ = soft_signal_r_and_setter(
+                str, initial_value=crystal_1_metadata.type
+            )
+            self.crystal_1_reflection, _ = soft_signal_r_and_setter(
+                Array1D[np.int32],
+                initial_value=np.array(crystal_1_metadata.reflection),
+            )
+            self.crystal_1_d_spacing, _ = soft_signal_r_and_setter(
+                float,
+                initial_value=crystal_1_metadata.d_spacing[0],
+                units=crystal_1_metadata.d_spacing[1],
+            )
+            self.crystal_2_usage, _ = soft_signal_r_and_setter(
+                str, initial_value=crystal_2_metadata.usage
+            )
+            self.crystal_2_type, _ = soft_signal_r_and_setter(
+                str, initial_value=crystal_2_metadata.type
+            )
+            self.crystal_2_reflection, _ = soft_signal_r_and_setter(
+                Array1D[np.int32],
+                initial_value=np.array(crystal_2_metadata.reflection),
+            )
+            self.crystal_2_d_spacing, _ = soft_signal_r_and_setter(
+                float,
+                initial_value=crystal_2_metadata.d_spacing[0],
+                units=crystal_2_metadata.d_spacing[1],
+            )
 
         super().__init__(name)
 

tests/common/test_crystal_metadata.py

@@ -0,0 +1,37 @@
+import pytest
+
+from dodal.common.crystal_metadata import (
+    MaterialsEnum,
+    make_crystal_metadata_from_material,
+)
+
+
+def test_happy_path_silicon():
+    crystal_metadata = make_crystal_metadata_from_material(MaterialsEnum.Si, (3, 1, 1))
+
+    # Check the values
+    assert crystal_metadata.type == "silicon"
+    assert crystal_metadata.reflection == (3, 1, 1)
+    assert crystal_metadata.d_spacing == pytest.approx(
+        (0.16375, "nm"), rel=1e-3
+    )  # Allow for small tolerance
+    assert crystal_metadata.usage == "Bragg"
+
+
+def test_happy_path_germanium():
+    crystal_metadata = make_crystal_metadata_from_material(MaterialsEnum.Ge, (1, 1, 1))
+    # Check the values
+    assert crystal_metadata.type == "germanium"
+    assert crystal_metadata.reflection == (1, 1, 1)
+    assert crystal_metadata.d_spacing == pytest.approx(
+        (0.326633, "nm"), rel=1e-3
+    )  # Allow for small tolerance
+    assert crystal_metadata.usage == "Bragg"
+
+
+def test_invalid_reflection_plane_with_negative_number():
+    with pytest.raises(
+        AssertionError,
+        match="Reflection plane indices must be positive integers",
+    ):
+        make_crystal_metadata_from_material(MaterialsEnum.Si, (-1, 2, 3))