8/7/15 yesterday Scott helped me through the math of how we going to find out where focal point should be when we shoot a laser at the Big Display wafer while sending in a chirped signal. The code/math we used is documented below, with “%” denoting a comment. The graph the is plotted shows the focal point in mm.
clear all;
L_mirror = 2.5; %in mm. L_mirror (length of the mirror on the wafer)
in_angle = 20*pi/180 % must be in radians
current_pos = L_mirror.*(1-[0:.1:1]); %"current_pos" is the y-intercept.
out_angle = asin(635e-6.*[50e6:10e6:150e6]./3900000 + sin(in_angle));
%defraction equation for out_angle taken from the textbook "Holographic
%Imaging" by Stephen A. Benton and V. Michael Bove Jr., Chapter 8 pg. 78
%equation 8. Equation is sin(out_angle) = wavelength*frequency + sin(in_angle);
current_slope = tan(out_angle);
x = [0:1000];
for i=[1:11]
y(i,:) = current_slope(i).*x + current_pos(i);
%y = mx + b
end
plot(x,y);
%the higher the frequency, the higher the out_angle
%the greater the range of frequencies, the shorter the focal length.
%the lower the frequency, the shorter the focal length
%as L_mirror goes down, f_length goes down