Some thoughts on how to detect the phase of the laser
If CCD imaging is not used, it is unrealistic to directly use photoelectric elements to measure the phase. The light speed is too fast. I consider measuring the phase difference between the laser emission and reflection parts, and then calculus the phase difference to
obtain the phase of the laser.
hold off
clear all
f= 450000;% laser signal frequency Hz
fs=900000;% sampling frequency Hz
N=400;% sampling points
t=(0:N-1)/fs;% sampling time s
for j = 175: 225
x=sin(2*pi*f*t);% signal sampling value
D = j;
x1 = x(1:D);
x2 = x(D+1:N);
for i = 1: D
x3(i) = x1(D+1-i);
end
plot(x2);
hold on
plot( x3);
hold off
pause(0.5);
% Perform calculus calculation on the phase difference of each sub-laser to obtain the sub-laser phase
% According to the phase, the arduion microcontroller drives the phase modulation device I designed to perform phase modulation to make each laser coherent
end 
By the way, the damage caused by laser weapons to objects or human bodies is a thermal effect. When I tested it myself, I was still burned when I wore a 450nm red protective mask. It felt like someone had been cutting you with a knife...