README

Generalized Lorenz Mie Repository

This repository holds code for calculating optical fields
and forces on spherical particles in generalized Lorenz-Mie theory.

There are two main tasks of the code: first it calculates the 
field of the beam, and second it calculates the force on a spherical 
particle at some position in the beam.

1. Calculating the field
  First we write the field in terms of vector spherical harmonics. We
need the coefficients of the field in this basis. The following 
codes give these coefficients for Bessel beams, plane waves, and 
angled planewaves:
besselcoefficients.pro
planewavecoefficients.pro
planewavecoefficientsangled.pro
 
  Next we can input the beam coefficients into efield_vsh_sum.pro which
gives the electric field vectors at specified points in the beam.

 We have some test code(in /tests) that runs this for a conveyor beam which is a
superposition of two Bessel beams. Run testconveyorxy.pro and 
testconveyorxz.pro to get crosssections of the beam. This agrees with 
Cizmar's paper.

2. Calculating the optical force
 You need to calculate the beam coefficients using the above codes making 
sure that you are centered on the particle. Once you have the coefficients
of the beam then you send these to normbartonforce.pro which gives
you the force efficiency Q on the particle. 

We also have test code(in /tests) for this. Running 
testbartonforcevska3fast.pro gives the force on a particle in a 
plane wave versus particle size. This compares well to Irvine 1964 paper.
Finally running testconveyoraxialforce.pro gives the axial force along one
period of an optical conveyor. This agrees with Cizmar's paper.