Source code for easistrain.func_conicalslit

# -*- coding: utf-8 -*-
"""
Created on Thu May 20 17:32:56 2021

@author: slim
"""
import numpy


# This function determine the distance between the centre of the silt and the conical aperture
# lss is the distance between the slit and the sample
# r is the radius (distance between the centre of the silt and the aperture)




def slitradius(a, lss, tth):
    r = lss * numpy.tan(2 * tth)
    return r



# This function determine the depth resolution of the conical slit (length of the gauge volume)
# dpr is the depth resolution (length of the gauge volume)
# lsd is the distance between the slit and the detector
# lss is the distance between the slit and the sample
# dss is the distance travelled by the diffraction cone before imtersectiong the slit
# dsd is the distance travelled by the diffraction between the slit and the detector
# dslit is the opening of the slit
# dfoc is the defocus of the beam
# dpsd is the spatial resolution of the detector (pixel size)
# The formula was extracted from the paper of Lienet et al [Lienert,Mat.Res.Soc.Symp.Proc,vol.590,2000]


def lengthgv(tth, lss, lsd, dslit, dfoc, dpsd):
    dss = lss / numpy.cos(2 * tth)
    dsd = ((lss + lsd) / numpy.cos(2 * tth)) - dss
    dpr = (1 / numpy.tan(2 * tth)) * numpy.sqrt(
        ((((dss + dsd) * dslit) / dsd) ** 2) + (dfoc**2) + (((dss * dpsd) / dsd) ** 2)
    )
    return dpr



# This function determine the depth resolution of the conical slit (length of the gauge volume)
# lss is the distance between the slit and the sample
# rs is the radius of the slit (distance between the centre of the slit and the opening)
# bs is the beam size in the veritical direction
# dslit is the opening of the slit
# I write this formula (It is an approximation if the Lienert formula)


def gvlength(rs, dslit, bs, lss):
    gvl = ((dslit + bs) * lss) / (rs + (dslit / 2))
    return gvl