# scriptfile: tweezer_position.lsf
# 
# description: This script calculates
#   the force on a rod as a function
#   of rod x position relative to the 
#   beam focal point.
load("tweezer");
save("temp");

source_offset=0;            # source position
pos=linspace(-5e-6,5e-6,22);      # partical X position relative to beam focus
Force=matrix(length(pos),3);      # initialize Force variable

for (i=1:length(pos)) {

  switchtolayout;
  # set particle position. (0,0) corresponds to focal point
  select("circle");
  set("x", 0);
  set("y",-50e-9);

  # set beam focus.  correct for source position offset
  select("beam");
  set("distance from focus",pos(i) + source_offset);  

  # run in non-graphical mode
  run;                    

  # get the force
  F = getresult("optical_force_MST","F_total");  
  f = F.f;
  SP = sourcepower(f);  
  Force(i,1:3) = F.F_total/SP;  # normalize to source power. Important in this case becuase different beam size contains different amounts of power
}

# plot results
plot(pos*1e6,Force,"X position (um)","Force (N/W)");
legend("Fx","Fy","Fz");

load("tweezer");