def test_zeroth_order_diffraction_equals_reflection(self):
plane = Plane()
ray = Rays([(A, B, -1)], [(0, 0, 1)], uniform(100, 1000))
reflection = plane.reflect(ray)
diffraction = plane.diffract(ray, uniform(0.001, 0.002), 0)
self.assertTrue(allclose(reflection.endpoints, diffraction.endpoints))
self.assertTrue(allclose(reflection.directions,
diffraction.directions))
def test_diffract(self):
"""Test that diffraction works for a simple case."""
plane = Plane()
d = 1 / uniform(9e4, 1e5)
order = -1
wavelength = uniform(500e-9, 700e-9)
ray = Rays([(0, -abs(B), 1)],
array([(0, abs(B), -1)]) / sqrt(B ** 2 + 1),
wavelength)
diffraction = plane.diffract(ray, d, order)
inc_angle = atan(abs(B))
exit_angle = asin(sin(inc_angle) + order * wavelength / d)
self.assertTrue(allclose(diffraction.directions[0],
(0, -sin(exit_angle), cos(exit_angle))))