New testing fixtures and propagate_fft test

tests/conftest.py

@@ -0,0 +1,12 @@
+# ref: https://gist.github.com/peterhurford/09f7dcda0ab04b95c026c60fa49c2a68?permalink_comment_id=3453153#gistcomment-3453153
+
+from glob import glob
+
+
+def refactor(string: str) -> str:
+    return string.replace("/", ".").replace("\\", ".").replace(".py", "")
+
+
+pytest_plugins = [
+    refactor(fixture) for fixture in glob("tests/fixtures/*.py") if "__" not in fixture
+]

tests/fixtures/airy2.py

@@ -0,0 +1,36 @@
+import pytest
+
+import numpy as np
+import scipy.special
+
+@pytest.fixture
+def airy2():
+
+    def _airy2(diameter, focal_length, wavelength, pixelscale, shape, oversample):
+        # https://en.wikipedia.org/wiki/Airy_disk#Mathematical_Formulation
+
+        f_number = focal_length / diameter
+
+        shape = np.asarray(shape)
+        shape *= oversample
+
+        c = (shape - 1) / 2
+        y, x = np.indices(shape, dtype=float)
+
+        x -= c[1]
+        y -= c[0]
+
+        x *= (pixelscale[0] / oversample)
+        y *= (pixelscale[1] / oversample)
+
+        q = np.sqrt(x ** 2 + y ** 2)
+        X = (np.pi * q) / (wavelength * f_number)
+
+        # if length is odd, the center value will be zero which will throw a
+        # divide by zero error. To avoid this, we'll set any zeros to machine
+        # epsilon (eps)
+        X[X == 0] = np.finfo(X.dtype).eps
+
+        return (2 * scipy.special.jn(1, X) / X) ** 2
+
+    return _airy2

tests/fixtures/pupil.py

@@ -0,0 +1,25 @@
+import pytest
+
+import lentil
+
+@pytest.fixture
+def pupil():
+
+    def _pupil(focal_length, diameter, shape, radius, coeffs=None):
+
+        amplitude = lentil.circle(shape, radius)
+        pixelscale = diameter/(2*radius)
+
+        if coeffs is not None:
+            opd = lentil.zernike_compose(amplitude, coeffs)
+        else:
+            opd = 0
+
+        p = lentil.Pupil(amplitude=amplitude,
+                         phase=opd,
+                         pixelscale=pixelscale,
+                         focal_length=focal_length)
+
+        return p
+
+    return _pupil

tests/test_propagate_fft.py

@@ -0,0 +1,28 @@
+import lentil
+import numpy as np
+
+
+def test_propagate_airy(airy2, pupil):
+    diameter = 1
+    focal_length = 10
+    wavelength = 500e-9
+    pixelscale = (5e-6, 5e-6)
+    shape = (511, 511)
+    oversample = 1
+
+    psf_airy = airy2(diameter, focal_length, wavelength, pixelscale, shape, oversample)
+    psf_airy = psf_airy/np.max(psf_airy)
+
+    p = pupil(focal_length=focal_length,
+              diameter=diameter,
+              shape=(512, 512),
+              radius=256,
+              coeffs=None)
+
+    w = lentil.Wavefront(wavelength=500e-9)
+    w *= p
+    w = lentil.propagate_fft(w, shape=(511,511), pixelscale=5e-6, oversample=1)
+    psf = w.intensity
+    psf = psf/np.max(psf)
+
+    np.all(np.isclose(psf, psf_airy, atol=1e-3))