A trichromat lens changing its phase delay over time looks precisely like an infinite loop. For odak visit: https://github.com/kunguz/odak

trichromat lens with a phase delay

import torch
import sys
import math
from odak.learn.wave import propagate_beam, generate_complex_field, wavenumber, calculate_phase, calculate_amplitude, quadratic_phase_function
from odak.learn.tools import save_image, convolve2d
from odak.tools import check_directory, shell_command
from tqdm import tqdm


def generate(resolution, delay, distance=0.15, wavelength = 532e-9, pixel_pitch = 8e-6, propagation_type='TR Fresnel'):
    k = wavenumber(wavelength)
    field = torch.zeros(resolution[0], resolution[1])
    field[int(field.shape[0]/2.), int(field.shape[1]/2.)] = 1
    qwp = quadratic_phase_function(field.shape[0], field.shape[1], k, focal=-distance, dx=pixel_pitch).to(field.device)
    qwp_phase = calculate_phase(qwp) + delay * 2 * math.pi
    phase = convolve2d(field, qwp_phase)
    return phase % (2* math.pi) / (2 * math.pi) * 255.


def main(resolution=[480, 640], output_directory='./output', n_iterations=50):
    check_directory(output_directory)
    amplitude = torch.rand(resolution[0], resolution[1], 3)
    t = tqdm(range(n_iterations), leave=False)
    delays = torch.linspace(0, 1, n_iterations)
    wavelengths = [440e-9, 532e-9, 640e-9]
    for i in t:
        delay = torch.ones(3) / n_iterations * i
        for ch in range(3):
            delay = delays[i] + ch * 1. / n_iterations * i
            wavelength = wavelengths[ch]
            amplitude[:,:,ch] = generate(resolution, delay, wavelength=wavelength) 
        description = '{0}/output_{1:04d}.png'.format(output_directory, i)
        t.set_description(description)
        save_image('{0}/output_{1:04d}.png'.format(output_directory, i), amplitude)
    create_gif(output_directory)
    return True

def create_gif(output_directory):
    cmd = [
           'ffmpeg',
           '-y',
           '-i',
           '{}/output_%4d.png'.format(output_directory),
           '{}/animation.gif'.format(output_directory)
          ]
    shell_command(cmd)
    return True

if __name__ == '__main__':
    sys.exit(main())