Method (polarization):
This feature is available whether or not the "Unpolarized" option is checked. It selects the method used to determine the S and P vectors based on the ray vector. For a discussion of this feature, see "Defining the Initial Polarization". The polarization is defined using a Jones vector:
where Jx and Jy have both a magnitude and a phase, and the symbol J is used instead of E to distinguish the 2D Jones vector from the 3D electric field vector E. OpticStudio normalizes the specified Jx and Jy values to have unity magnitude, and then scales the intensity as appropriate if any pupil apodization has been specified. The Jx and Jy values are therefore measured in terms of relative electric field amplitude.
Let the ray vector be K, which has X, Y, and Z direction cosines (l, m, n). For rays traveling parallel to the Z axis, or K = (0, 0, 1), the electric field in the Z direction is zero, and the conversion from the Jones vector to the Electric field is trivial: Ex = Jx, Ey = Jy, and Ez = 0.
For a more general ray, the conversion of the Jones vector (Jx, Jy) to the 3D electric field values (Ex, Ey, Ez) is ambiguous. It is not possible to interpret the Jx and Jy values as meaning that for any ray, the Jx value should be applied in such a way to leave the Ey zero, and for the Jy to be applied so that the Ex is zero. The reason is that the E resulting for the Jones vectors (Jx = 1, Jy = 0) and (Jx = 0, Jy = 1) must be orthogonal to both K and to each other.
OpticStudio allows user selection of three different methods to perform the conversion from J to E. In each method, the vector K refers to the ray vector, the Jx value is the field along a vector S, and the Jy value is the field along a vector P. Note that K, S, and P must all be unit vectors and orthogonal to each other. The three methods are:
X Axis Reference The P vector is determined from K cross X, and S = P cross K. This method is the default.
Y Axis Reference The S vector is determined from Y cross K, and P = K cross S.
Z Axis Reference The S vector is determined from K cross Z, and P = K cross S.
When the object is at infinity, the method selected will change the polarization orientation of S and P for different fields, but all rays from the same field will have the same polarization since all rays are parallel to each other. For finite conjugates, especially when the object space numerical aperture is large, the S and P vector orientations will vary for different rays in the pupil. No matter which method is selected, the transmission results for unpolarized light will be unaffected because any two orthogonal rays may be traced to compute transmission. For systems where a particular polarization is desired, care should be taken to verify that the conversion from J to E yields the intended polarized ray.
To review the detailed conversion results, see Polarization Ray Trace.
Next: