def test_extract_amplitude_real_data(file_path):
test_data = pd.read_csv(file_path + '/data/photovoltage_data.csv',
skiprows=1)
lia = LIA(test_data)
actual_amplitude = lia.extract_signal_amplitude()
desired_amplitude = (-0.0185371754 - 4.60284137e-11) * ureg.mV
assert_equal_qt(actual_amplitude, desired_amplitude)
def test_with_large_dc():
test_data = pd.DataFrame({
'time (ms)': [1, 2, 3, 4, 5, 6],
'val (V)': 10000 + np.array([1, 0, -1, 0, 1, 0]),
'Sync': [1, 0, 0, 0, 1, 0]
})
lia = LIA(test_data)
desired_amplitude = 1 * ureg.V / np.sqrt(2)
actual_amplitude = lia.extract_signal_amplitude(sync_phase_delay=np.pi / 2)
assert_allclose_qt(actual_amplitude, desired_amplitude, atol=1e-6)
def test_extract_minus_pi_2_offset():
test_data = pd.DataFrame({
'time (ms)': [1, 2, 3, 4, 5, 6, 7],
'val (V)': [1, 0, -1, 0, 1, 0, -1],
'Sync': [1, 0, 0, 0, 1, 0, 0]
})
lia = LIA(test_data)
desired_amplitude = 1 * ureg.V / np.sqrt(2)
actual_amplitude = lia.extract_signal_amplitude(sync_phase_delay=np.pi / 2)
assert_allclose_qt(actual_amplitude, desired_amplitude, atol=1e-6)
def test_extract_zero_with_offset():
test_data = pd.DataFrame({
'time (ms)': [0, 1, 2, 3, 4, 5, 6, 7],
'val (V)': [1, 1, 1, 1, 1, 1, 1, 1],
'Sync': [0, 0, 1, 0, 0, 0, 1, 0]
})
lia = LIA(test_data)
desired_amplitude = 0 * ureg.V
actual_amplitude = lia.extract_signal_amplitude(sync_phase_delay=np.pi)
assert_allclose_qt(actual_amplitude, desired_amplitude, atol=1e-6)
def modulated_photocurrent(data, cond):
"""
Returns the RMS value of the modulated photocurrent given the system gain and a dataset using lock-in amplification.
"""
lia = LIA(data=data)
if 'sync_phase_delay' in cond:
sync_phase_delay = cond['sync_phase_delay']
else:
sync_phase_delay = np.pi
extracted_voltage = lia.extract_signal_amplitude(
mode='amplitude', sync_phase_delay=sync_phase_delay)
extracted_current = (extracted_voltage / cond['gain']).to(ureg.pA)
return extracted_current
def fit_lia(data, n_points=101, fit=True):
"""
Generates amplitude vs. phase for lock-in-amplifier type data. Optionally fits that phase to a cosine function and returns the fit parameters.
:param data: pandas DataFrame which contains a 'Sync' column with synchronization points
"""
def cos_func(x, a=1, phase=0.1):
return a*np.cos(x - phase)
ylabel = data.columns[1]
lia = LIA(data)
phase_delays = np.linspace(-np.pi, np.pi, n_points)
test_value = lia.extract_signal_amplitude(sync_phase_delay=0)
extracted_v_np = np.vectorize(lia.extract_signal_amplitude)
all_values = np.array([])
for phase in phase_delays:
retval = lia.extract_signal_amplitude(sync_phase_delay=phase)
if isinstance(retval, pint.Quantity):
retval = retval.m
all_values = np.append(all_values, retval)
if fit:
try:
(amp, phase), pcov = curve_fit(cos_func, phase_delays, all_values)
if amp < 0:
amp *= -1
phase -= np.pi
phase = np.mod(phase, 2*np.pi)
except RuntimeError as e:
breakpoint()
else:
(amp, phase) = (None, None)
full_data = pd.DataFrame({
'Phase (rad)': phase_delays,
ylabel: all_values
})
return full_data, (amp, phase)