def calc_radiance(wavenumber, emissivity, Tgas, unit="mW/sr/cm2/nm"):
"""Derive radiance (mW/cm2/sr/nm) from the emissivity.
Returns
-------
radiance: mW/sr/cm2/nm
"""
radiance = emissivity * planck(cm2nm(wavenumber), Tgas, unit=unit)
return radiance
def calc_radiance(wavenumber, emissivity, Tgas, unit='mW/sr/cm2/nm'):
''' Derive radiance (mW/cm2/sr/nm) from the emissivity
Returns
-------
radiance: mW/sr/cm2/nm
'''
radiance = emissivity * planck(cm2nm(wavenumber), Tgas, unit=unit)
return radiance
def calc_radiance(wavenumber, emissivity, Tgas, unit="mW/sr/cm2/nm"):
"""Derive radiance (:math:`mW/cm^2/sr/nm`) from the emissivity.
.. math::
I(\lambda) = \epsilon(\lambda) \cdot L_0(\lambda, T)
Returns
-------
radiance: array in :math:`mW/sr/cm2/nm`
unless ``unit`` is different
See Also
--------
:py:func:`~radis.phys.blackbody.planck`
"""
radiance = emissivity * planck(cm2nm(wavenumber), Tgas, unit=unit)
return radiance
def test_planck_nm(verbose=True, plot=True, *args, **kwargs):
''' Test blackbody with Wien's law, Stefan's law and tabulated data
of maximum
Reference
---------
Tabulated intensity (75.987...) was checked to match SpectraPlot and
manually calculated values
'''
if plot:
import matplotlib.pyplot as plt
plt.ion() # dont get stuck with Matplotlib if executing through pytest
T = 2200
eps = 0.36
s = sPlanck(wavelength_min=300, wavelength_max=8000, T=T, eps=eps,
wstep=0.1)
w_nm = s.get_wavelength(medium='vacuum')
w_cm = s.get_wavenumber()
Iunit_per_nm = 'W/sr/nm/m2'
Iunit_per_cm = 'W/sr/cm_1/m2'
if plot:
s.plot('radiance_noslit', Iunit=Iunit_per_nm)
I_nm = s.get_radiance_noslit(Iunit=Iunit_per_nm)
I_cm = s.get_radiance_noslit(Iunit=Iunit_per_cm)
# Check Wien's law
w_nm_max = w_nm[I_nm.argmax()]
assert np.isclose(2898/T*1e3, w_nm_max, rtol=1e-4)
if verbose:
print('Maximum emission at T={0}K: {1:.2f}nm'.format(T, w_nm_max))
print(".. test_planck_nm.py: Wien's law: OK")
# Check Stefan's law
sigma = 5.67e-8 # Stefan-Boltzmann constant (W/m2/K-4)
P_theory = eps*sigma*T**4 # Stefan's law (W/m2)
P_calc = pi*s.get_power('W/m2/sr') # Lambert's cosine law
assert np.isclose(P_theory, P_calc, rtol=1e-1)
if verbose:
print(
'Blackbody radiant intensity (Stefan law): {0:.2f} W/m2'.format(P_theory))
print(
'Blackbody radiant intensity (calculated): {0:.2f} W/m2'.format(P_calc))
print(".. test_planck_nm.py: Stefan's law: OK")
# Check that max is correct
# hardcoded for 2200 K, epsilon = 0.36 (~1.3 µm)
assert I_nm.max() == 75.98733181512608
# Test planck and planck_wn
assert np.allclose(planck(w_nm, T, eps, unit=Iunit_per_nm), I_nm)
assert np.allclose(planck_wn(w_cm, T, eps, unit=Iunit_per_cm), I_cm,
rtol=1e-2) # higher tolerance because of numerical error
# during conversion Iunit_per_nm to Iunit_per_cm
return True