ElectroHolography Laboratory

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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

ElectroHolography Laboratory

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