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Lens

Basic Lens object handling

LensCalcMixin

Source code in tfs/lens.py 
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class LensCalcMixin():
    def __init__(self, *args, **kwargs):
        """
        Mixin class to abstract focal length calculation from a variety of 
        lens devices.

        Relies on the following methods / attributes from the child class:
        - self.radius
        - self.z
        """
        return

    def focus(self, energy):
        return ut.focal_length(self.radius, energy)

    def image_from_obj(self, z_obj, energy):
        """
        Method calculates the image distance in meters along the beam pipeline
        from a point of origin given the focal length of the lens, location of
        lens, and location of object.

        Parameters
        ----------
        z_obj
            Location of object along the beamline in meters (m)

        Returns
        -------
        image
            Returns the distance z_im of the image along the beam pipeline from
            a point of origin in meters (m)
        Note
        ----
        If the location of the object (z_obj) is equal to the focal length of
        the lens, this function will return infinity.
        """
        # Find the object location for the lens
        obj = self.z - z_obj
        # Check if the lens object is at the focal length
        # If this happens, then the image location will be infinity.
        # Note, this should not effect the recursive calculations that occur
        # later in the code
        if obj == self.focus(energy):
            return np.inf
        # Calculate the location of the focal plane
        plane = 1/(1/self.focus(energy) - 1/obj)
        # Find the position in accelerator coordinates
        return plane + self.z

__init__(*args, **kwargs)

Mixin class to abstract focal length calculation from a variety of lens devices.

Relies on the following methods / attributes from the child class: - self.radius - self.z

Source code in tfs/lens.py 
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def __init__(self, *args, **kwargs):
    """
    Mixin class to abstract focal length calculation from a variety of 
    lens devices.

    Relies on the following methods / attributes from the child class:
    - self.radius
    - self.z
    """
    return

image_from_obj(z_obj, energy)

Method calculates the image distance in meters along the beam pipeline from a point of origin given the focal length of the lens, location of lens, and location of object.

Parameters

z_obj Location of object along the beamline in meters (m)

Returns

image Returns the distance z_im of the image along the beam pipeline from a point of origin in meters (m) Note

If the location of the object (z_obj) is equal to the focal length of the lens, this function will return infinity.

Source code in tfs/lens.py 
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def image_from_obj(self, z_obj, energy):
    """
    Method calculates the image distance in meters along the beam pipeline
    from a point of origin given the focal length of the lens, location of
    lens, and location of object.

    Parameters
    ----------
    z_obj
        Location of object along the beamline in meters (m)

    Returns
    -------
    image
        Returns the distance z_im of the image along the beam pipeline from
        a point of origin in meters (m)
    Note
    ----
    If the location of the object (z_obj) is equal to the focal length of
    the lens, this function will return infinity.
    """
    # Find the object location for the lens
    obj = self.z - z_obj
    # Check if the lens object is at the focal length
    # If this happens, then the image location will be infinity.
    # Note, this should not effect the recursive calculations that occur
    # later in the code
    if obj == self.focus(energy):
        return np.inf
    # Calculate the location of the focal plane
    plane = 1/(1/self.focus(energy) - 1/obj)
    # Find the position in accelerator coordinates
    return plane + self.z

LensConnect

Data structure for a basic system of lenses

Parameters

args : Lens Lens objects

Source code in tfs/lens.py 
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class LensConnect:
    """
    Data structure for a basic system of lenses

    Parameters
    ----------
    args : Lens
        Lens objects
    """
    def __init__(self, *args):
        """
        Parameters
        ----------
        args
            Variable length argument list of the lenses in the system, their
            radii, z position, and focal length.
        """
        self.lenses = sorted(args, key=lambda lens: lens.z)

    @property
    def effective_radius(self):
        """
        Method calculates the effective radius of the lens array
        including prefocusing lens 

        Returns
        -------
        float
            returns the effective radius of the lens array.
        """
        if not self.lenses:
            return 0.0
        return 1/np.sum(np.reciprocal([float(l.radius) for l in self.lenses]))


    @property
    def tfs_radius(self):
        """
        Method calculates the effective radius of the lens array
        excluding prefocusing lens 

        Returns
        -------
        float
            returns the effective radius of the lens array.
        """
        if not self.lenses:
            return 0.0
        return 1/np.sum(np.reciprocal([float(l.radius) for l in self.lenses[1:]]))


    def image(self, z_obj, energy):
        """
        Method recursively calculates the z location of the image of a system
        of lenses and returns it in meters (m)

        Parameters
        ----------
        z_obj
            Location of the object along the beam pipline from a designated
            point of origin in meters (m)

        Returns
        -------
        float
            returns the location z of a system of lenses in meters (m).
        """
        # Set the initial image as the z object
        image = z_obj
        # Determine the final output by looping through lenses
        for lens in self.lenses:
            image = lens.image_from_obj(image, energy)
        return image

    @property
    def nlens(self):
        """
        Method calculates the total number of lenses in the Lens array.

        Returns
        -------
        int
            Returns the total number of lenses in the array.
        """
        return len(self.lenses)

    def _info(self):
        """
        Create a table with lens information
        """
        # Create initial table
        pt = prettytable.PrettyTable(['Prefix', 'Radius', 'Z'])
        # Adjust table settings
        pt.align = 'l'
        pt.float_format = '8.5'
        for lens in self.lenses:
            pt.add_row([lens.prefix, lens.radius, lens.z])
        return pt

    def show_info(self):
        """
        Show a table of information on the lens
        """
        print(self._info())

    @classmethod
    def connect(cls, array1, array2):
        """
        Create a new LensConnect from the combination of multiple
        """
        return cls(*array1.lenses, *array2.lenses)

effective_radius property

Method calculates the effective radius of the lens array including prefocusing lens

Returns

float returns the effective radius of the lens array.

nlens property

Method calculates the total number of lenses in the Lens array.

Returns

int Returns the total number of lenses in the array.

tfs_radius property

Method calculates the effective radius of the lens array excluding prefocusing lens

Returns

float returns the effective radius of the lens array.

__init__(*args)

Parameters

args Variable length argument list of the lenses in the system, their radii, z position, and focal length.

Source code in tfs/lens.py 
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def __init__(self, *args):
    """
    Parameters
    ----------
    args
        Variable length argument list of the lenses in the system, their
        radii, z position, and focal length.
    """
    self.lenses = sorted(args, key=lambda lens: lens.z)

connect(array1, array2) classmethod

Create a new LensConnect from the combination of multiple

Source code in tfs/lens.py 
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@classmethod
def connect(cls, array1, array2):
    """
    Create a new LensConnect from the combination of multiple
    """
    return cls(*array1.lenses, *array2.lenses)

image(z_obj, energy)

Method recursively calculates the z location of the image of a system of lenses and returns it in meters (m)

Parameters

z_obj Location of the object along the beam pipline from a designated point of origin in meters (m)

Returns

float returns the location z of a system of lenses in meters (m).

Source code in tfs/lens.py 
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def image(self, z_obj, energy):
    """
    Method recursively calculates the z location of the image of a system
    of lenses and returns it in meters (m)

    Parameters
    ----------
    z_obj
        Location of the object along the beam pipline from a designated
        point of origin in meters (m)

    Returns
    -------
    float
        returns the location z of a system of lenses in meters (m).
    """
    # Set the initial image as the z object
    image = z_obj
    # Determine the final output by looping through lenses
    for lens in self.lenses:
        image = lens.image_from_obj(image, energy)
    return image

show_info()

Show a table of information on the lens

Source code in tfs/lens.py 
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def show_info(self):
    """
    Show a table of information on the lens
    """
    print(self._info())

LensTripLimits

Bases: Device

Trip limits for a given pre-focus lens (or lack thereof).

Source code in tfs/lens.py 
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class LensTripLimits(Device):
    """Trip limits for a given pre-focus lens (or lack thereof)."""
    # _table_name = Cpt(EpicsSignalRO, ":STR", doc="Table name for trip information")
    low = Cpt(EpicsSignalRO, ":LOW", doc="Trip region low [um]", auto_monitor=False)
    high = Cpt(EpicsSignalRO, ":HIGH", doc="Trip region high [um]", auto_monitor=False)

MFXLens

Bases: InOutPVStatePositioner, LensCalcMixin

Data structure for basic Lens object

Parameters

prefix : str Name of the state record that controls the PV

str

Prefix for the PVs that contain focusing information

Source code in tfs/lens.py 
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class MFXLens(InOutPVStatePositioner, LensCalcMixin):
    """
    Data structure for basic Lens object

    Parameters
    ----------
    prefix : str
        Name of the state record that controls the PV

    prefix_lens : str
        Prefix for the PVs that contain focusing information
    """
    # StatePositioner information
    _inserted = Cpt(EpicsSignalRO, ':STATE')
    _removed = Cpt(EpicsSignalRO, ":OUT")
    _insert = Cpt(EpicsSignal, ':INSERT')
    _remove = Cpt(EpicsSignal, ':REMOVE')
    _state_logic = {'_inserted': {0: 'defer',  1: 'IN'},
                    '_removed': {0: 'defer', 1: 'OUT'}}
    # Signals related to optical configuration
    _sig_radius = Cpt(EpicsSignalRO, ":RADIUS", auto_monitor=True)
    _sig_z = Cpt(EpicsSignalRO, ":Z", auto_monitor=True)
    _sig_focus = Cpt(EpicsSignalRO, ":FOCUS", auto_monitor=True)
    # Default configuration attributes. Read attributes are set correctly by
    # InOutRecordPositioner
    _default_configuration_attrs = ['_sig_radius', '_sig_z']
    # Signal for requested focus
    _req_focus = Cpt(EpicsSignal, ':REQ_FOCUS')

    def __init__(self, prefix, **kwargs):
        super().__init__(prefix, **kwargs)


    @property
    def radius(self):
        """
        Method converts the EPICS lens radius signal into a float that can be
        used for calculations.

        Returns
        -------
        float
            Returns the radius of the lens
        """
        return self._sig_radius.get()

    @property
    def z(self):
        """
        Method converts the z position EPICS signal into a float.

        Returns
        -------
        float
            Returns the z position of the lens in meters along the beamline
        """
        return self._sig_z.get()

    @property
    def sig_focus(self):
        """
        Method converts the EPICS focal length signal of the lens into a float

        Returns
        -------
        float
            Returns the focal length of the lens in meters
        """
        return self._sig_focus.get()

    def _do_move(self, state):
        if state.name == 'IN':
            self._insert.put(1)
        elif state.name == 'OUT':
            self._remove.put(1)
        # We shouldn't ever get to this line as most calls will have gone
        # through check_value first. Just in case this is here to not fail
        # silently
        else:
            raise ValueError("Invalid State {}".format(state))

radius property

Method converts the EPICS lens radius signal into a float that can be used for calculations.

Returns

float Returns the radius of the lens

sig_focus property

Method converts the EPICS focal length signal of the lens into a float

Returns

float Returns the focal length of the lens in meters

z property

Method converts the z position EPICS signal into a float.

Returns

float Returns the z position of the lens in meters along the beamline