class_docstr: Ray Transfer Matrix for refraction.
  
  Parameters
  ==========
  
  n1 :
      Refractive index of one medium.
  n2 :
      Refractive index of other medium.
  
  See Also
  ========
  
  RayTransferMatrix
  
  Examples
  ========
  
  >>> from sympy.physics.optics import FlatRefraction
  >>> from sympy import symbols
  >>> n1, n2 = symbols('n1 n2')
  >>> FlatRefraction(n1, n2)
  Matrix([
  [1,     0],
  [0, n1/n2]])
code: def __new__(cls, n1, n2):
      n1, n2 = map(sympify, (n1, n2))
      return RayTransferMatrix.__new__(cls, 1, 0, 0, n1 / n2)
  
imports: from sympy.core.expr import Expr
  from sympy.core.numbers import I, pi
  from sympy.core.sympify import sympify
  from sympy.functions.elementary.complexes import im, re
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.elementary.trigonometric import atan2
  from sympy.matrices.dense import Matrix, MutableDenseMatrix
  from sympy.polys.rationaltools import together
  from sympy.utilities.misc import filldedent
label_desc: Use image node_id 1 for calling the FlatRefraction obj's underlying member method code with example usage: obj.__new__(cls, n1, n2) and returns: RayTransferMatrix