# Source code for ggf.stress

```
from . import boyde2009
from .geometry import fiber_distance_capillary # noqa: F401
VALID_MODELS = ["boyde2009"]
[docs]def get_stress(model, semi_major, semi_minor, object_index, medium_index,
effective_fiber_distance=100e-6, mode_field_diameter=3e-6,
power_per_fiber=.6, wavelength=1064e-9, n_points=100,
verbose=False):
"""Compute the optical stress profile in the optical stretcher
Parameters
----------
model: str
Model to use, one of: `boyde2009`
semi_major: float
Semi-major axis of an ellipse fit to the object perimeter [m]
semi_minor: float
Semi-minor axis of an ellipse fit to the object perimeter [m]
object_index: float
Refractive index of the object
medium_index: float
Refractive index of the surrounding medium
effective_fiber_distance: float
Effective distance between the two trapping fibers relative
to the medium refractive index [m]. For an open setup, this is
the physical distance between the fibers. For a closed setup
(capillary), this distance takes into account the refractive
indices and thicknesses of the glass capillary and index
matching gel. For the closed setup, the convenience function
:func:`ggf.fiber_distance_capillary` can be used.
mode_field_diameter: float
The mode field diameter MFD of the fiber used [m]. Note that
the MFD is dependent on the wavelength used. If the
manufacturer did not provide a value for the MFD, the MFD
can be approximated as ``3*wavelenth`` for a single-mode
fiber.
power_per_fiber: float
The laser power coupled into each of the fibers [W]
wavelength: float
The laser wavelength used for the trap [m]
n_points: int
Number of points to compute.
verbose: int
Increases verbosity
Returns
-------
theta: 1d ndarray of length `n_points`
Polar angles [rad]
sigma: 1d ndarray of length `n_points`
Radial stress profile along `theta` [Pa]
"""
if model not in VALID_MODELS:
msg = "`model` must be one of {}, got '{}'".format(VALID_MODELS, model)
raise ValueError(msg)
if model == "boyde2009":
func = boyde2009.get_stress
return func(
semi_major=semi_major,
semi_minor=semi_minor,
object_index=object_index,
medium_index=medium_index,
effective_fiber_distance=effective_fiber_distance,
mode_field_diameter=mode_field_diameter,
power_per_fiber=power_per_fiber,
wavelength=wavelength,
n_points=n_points,
verbose=verbose)
```