def test_lsst_y_focus():
# Check that applying reasonable focus depth (from O'Connor++06) indeed leads to smaller spot
# size for LSST y-band.
rng = galsim.BaseDeviate(9876543210)
bandpass = galsim.Bandpass("LSST_y.dat", wave_type='nm')
sed = galsim.SED("1", wave_type='nm', flux_type='flambda')
obj = galsim.Gaussian(fwhm=1e-5)
oversampling = 32
photon_ops0 = [
galsim.WavelengthSampler(sed, bandpass, rng=rng),
galsim.FRatioAngles(1.234, 0.606, rng=rng),
galsim.FocusDepth(0.0),
galsim.Refraction(3.9)
]
img0 = obj.drawImage(
sensor=galsim.SiliconSensor(),
method='phot',
n_photons=100000,
photon_ops=photon_ops0,
scale=0.2/oversampling,
nx=32*oversampling,
ny=32*oversampling,
rng=rng
)
T0 = img0.calculateMomentRadius()
T0 *= 10*oversampling/0.2 # arcsec => microns
# O'Connor finds minimum spot size when the focus depth is ~ -12 microns. Our sensor isn't
# necessarily the same as the one there though; our minimum seems to be around -6 microns.
# That could be due to differences in the design of the sensor though. We just use -6 microns
# here, which is still useful to test the sign of the `depth` parameter and the interaction of
# the 4 different surface operators required to produce this effect, and is roughly consistent
# with O'Connor.
depth1 = -6. # microns, negative means surface is intrafocal
depth1 /= 10 # microns => pixels
photon_ops1 = [
galsim.WavelengthSampler(sed, bandpass, rng=rng),
galsim.FRatioAngles(1.234, 0.606, rng=rng),
galsim.FocusDepth(depth1),
galsim.Refraction(3.9)
]
img1 = obj.drawImage(
sensor=galsim.SiliconSensor(),
method='phot',
n_photons=100000,
photon_ops=photon_ops1,
scale=0.2/oversampling,
nx=32*oversampling,
ny=32*oversampling,
rng=rng
)
T1 = img1.calculateMomentRadius()
T1 *= 10*oversampling/0.2 # arcsec => microns
np.testing.assert_array_less(T1, T0)
bd = galsim.BaseDeviate(12)
depths = np.linspace(-25, 25, 41) # microns
obj = galsim.Gaussian(sigma=1e-4)
sed = galsim.SED("1", wave_type='nm', flux_type='flambda')
fig, ax = plt.subplots()
oversampling = 16
for filter in ['g', 'z', 'y']:
bandpass = galsim.Bandpass("LSST_{}.dat".format(filter), wave_type='nm')
Ts = []
for depth in depths:
depth_pix = depth / 10
surface_ops = [
galsim.WavelengthSampler(sed, bandpass, rng=bd),
galsim.FRatioAngles(1.234, 0.606, rng=bd),
galsim.FocusDepth(depth_pix),
galsim.Refraction(3.9) # approx number for Silicon
]
img = obj.drawImage(
sensor=galsim.SiliconSensor(),
method='phot',
n_photons=1_000_000,
surface_ops=surface_ops,
scale=0.2 /
oversampling, # oversample pixels to better resolve PSF size
nx=32 * oversampling, # 6.4 arcsec stamp
ny=32 * oversampling,
)
Ts.append(img.calculateMomentRadius())
Ts = np.array(Ts) / 0.2 * 10 * oversampling # convert arcsec -> micron
ax.scatter(depths, Ts, label=filter)
def test_focus_depth():
bd = galsim.BaseDeviate(1234)
for _ in range(100):
# Test that FocusDepth is additive
photon_array = galsim.PhotonArray(1000)
photon_array2 = galsim.PhotonArray(1000)
photon_array.x = 0.0
photon_array.y = 0.0
photon_array2.x = 0.0
photon_array2.y = 0.0
galsim.FRatioAngles(1.234, obscuration=0.606,
rng=bd).applyTo(photon_array)
photon_array2.dxdz[:] = photon_array.dxdz
photon_array2.dydz[:] = photon_array.dydz
fd1 = galsim.FocusDepth(1.1)
fd2 = galsim.FocusDepth(2.2)
fd3 = galsim.FocusDepth(3.3)
fd1.applyTo(photon_array)
fd2.applyTo(photon_array)
fd3.applyTo(photon_array2)
np.testing.assert_allclose(photon_array.x,
photon_array2.x,
rtol=0,
atol=1e-15)
np.testing.assert_allclose(photon_array.y,
photon_array2.y,
rtol=0,
atol=1e-15)
# Assuming focus is at x=y=0, then
# intrafocal (depth < 0) => (x > 0 => dxdz < 0)
# extrafocal (depth > 0) => (x > 0 => dxdz > 0)
# We applied an extrafocal operation above, so check for corresponding
# relation between x, dxdz
np.testing.assert_array_less(0, photon_array.x * photon_array.dxdz)
# transforming by depth and -depth is null
fd4 = galsim.FocusDepth(-3.3)
fd4.applyTo(photon_array)
np.testing.assert_allclose(photon_array.x, 0.0, rtol=0, atol=1e-15)
np.testing.assert_allclose(photon_array.y, 0.0, rtol=0, atol=1e-15)
# Check that invalid photon array is trapped
pa = galsim.PhotonArray(10)
fd = galsim.FocusDepth(1.0)
with np.testing.assert_raises(galsim.GalSimError):
fd.applyTo(pa)
# Check that we can infer depth from photon positions before and after...
for _ in range(100):
photon_array = galsim.PhotonArray(1000)
photon_array2 = galsim.PhotonArray(1000)
ud = galsim.UniformDeviate(bd)
ud.generate(photon_array.x)
ud.generate(photon_array.y)
photon_array.x -= 0.5
photon_array.y -= 0.5
galsim.FRatioAngles(1.234, obscuration=0.606,
rng=bd).applyTo(photon_array)
photon_array2.x[:] = photon_array.x
photon_array2.y[:] = photon_array.y
photon_array2.dxdz[:] = photon_array.dxdz
photon_array2.dydz[:] = photon_array.dydz
depth = ud() - 0.5
galsim.FocusDepth(depth).applyTo(photon_array2)
np.testing.assert_allclose(
(photon_array2.x - photon_array.x) / photon_array.dxdz, depth)
np.testing.assert_allclose(
(photon_array2.y - photon_array.y) / photon_array.dydz, depth)
np.testing.assert_allclose(photon_array.dxdz, photon_array2.dxdz)
np.testing.assert_allclose(photon_array.dydz, photon_array2.dydz)