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# -*- coding: utf-8 -*- |
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""" |
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This file contains basic pulse extraction methods for Qudi. |
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Qudi is free software: you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation, either version 3 of the License, or |
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(at your option) any later version. |
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Qudi is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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You should have received a copy of the GNU General Public License |
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along with Qudi. If not, see <http://www.gnu.org/licenses/>. |
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Copyright (c) the Qudi Developers. See the COPYRIGHT.txt file at the |
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top-level directory of this distribution and at <https://github.com/Ulm-IQO/qudi/> |
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""" |
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import numpy as np |
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from scipy import ndimage |
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from logic.pulsed.pulse_extractor import PulseExtractorBase |
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class BasicPulseExtractor(PulseExtractorBase): |
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""" |
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""" |
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def __init__(self, *args, **kwargs): |
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super().__init__(*args, **kwargs) |
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def gated_conv_deriv(self, count_data, conv_std_dev=20.0): |
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""" |
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Detects the rising flank in the gated timetrace data and extracts just the laser pulses. |
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The flank detection is based on an image edge detection technique performed in 1D. |
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There is no information about the data needed. |
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Only the gaussian filter width to reduce shot noise can be given as parameter. |
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@param 2D numpy.ndarray count_data: the raw timetrace data from a gated fast counter |
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dim 0: gate number; dim 1: time bin |
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@param float conv_std_dev: The standard deviation of the gaussian filter used for smoothing |
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@return dict: The extracted laser pulses of the timetrace as well as the indices for rising |
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and falling flanks. |
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""" |
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# Create return dictionary |
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return_dict = {'laser_counts_arr': np.zeros(0, dtype='int64'), |
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'laser_indices_rising': -1, |
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'laser_indices_falling': -1} |
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# sum up all gated timetraces to ease flank detection |
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timetrace_sum = np.sum(count_data, 0) |
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# apply gaussian filter to remove noise and compute the gradient of the timetrace sum |
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try: |
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conv = ndimage.filters.gaussian_filter1d(timetrace_sum.astype(float), conv_std_dev) |
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except: |
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conv = np.zeros(timetrace_sum.size) |
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try: |
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conv_deriv = np.gradient(conv) |
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except: |
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conv_deriv = np.zeros(conv.size) |
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# get indices of rising and falling flank |
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rising_ind = conv_deriv.argmax() |
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falling_ind = conv_deriv.argmin() |
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# If gaussian smoothing or derivative failed, the returned array only contains zeros. |
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# Check for that and return also only zeros to indicate a failed pulse extraction. |
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if len(conv_deriv.nonzero()[0]) == 0: |
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laser_arr = np.zeros(count_data.shape, dtype='int64') |
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else: |
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# slice the data array to cut off anything but laser pulses |
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laser_arr = count_data[:, rising_ind:falling_ind] |
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return_dict['laser_counts_arr'] = laser_arr.astype('int64') |
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return_dict['laser_indices_rising'] = rising_ind |
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return_dict['laser_indices_falling'] = falling_ind |
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return return_dict |
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def ungated_conv_deriv(self, count_data, conv_std_dev=20.0): |
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""" Detects the laser pulses in the ungated timetrace data and extracts |
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them. |
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@param numpy.ndarray count_data: 1D array the raw timetrace data from an ungated fast counter |
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@param dict measurement_settings: The measurement settings of the currently running measurement. |
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@param float conv_std_dev: The standard deviation of the gaussian used for smoothing |
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@return 2D numpy.ndarray: 2D array, the extracted laser pulses of the timetrace. |
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dimensions: 0: laser number, 1: time bin |
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Procedure: |
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Edge Detection: |
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--------------- |
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The count_data array with the laser pulses is smoothed with a |
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gaussian filter (convolution), which used a defined standard |
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deviation of 10 entries (bins). Then the derivation of the convolved |
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time trace is taken to obtain the maxima and minima, which |
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corresponds to the rising and falling edge of the pulses. |
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The convolution with a gaussian removes nasty peaks due to count |
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fluctuation within a laser pulse and at the same time ensures a |
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clear distinction of the maxima and minima in the derived convolved |
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trace. |
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The maxima and minima are not found sequentially, pulse by pulse, |
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but are rather globally obtained. I.e. the convolved and derived |
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array is searched iteratively for a maximum and a minimum, and after |
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finding those the array entries within the 4 times |
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self.conv_std_dev (2*self.conv_std_dev to the left and |
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2*self.conv_std_dev) are set to zero. |
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The crucial part is the knowledge of the number of laser pulses and |
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the choice of the appropriate std_dev for the gauss filter. |
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To ensure a good performance of the edge detection, you have to |
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ensure a steep rising and falling edge of the laser pulse! Be also |
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careful in choosing a large conv_std_dev value and using a small |
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laser pulse (rule of thumb: conv_std_dev < laser_length/10). |
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""" |
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# Create return dictionary |
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return_dict = {'laser_counts_arr': np.empty(0, dtype='int64'), |
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'laser_indices_rising': np.empty(0, dtype='int64'), |
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'laser_indices_falling': np.empty(0, dtype='int64')} |
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number_of_lasers = self.measurement_settings.get('number_of_lasers') |
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if not isinstance(number_of_lasers, int): |
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return return_dict |
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# apply gaussian filter to remove noise and compute the gradient of the timetrace sum |
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try: |
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conv = ndimage.filters.gaussian_filter1d(count_data.astype(float), conv_std_dev) |
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except: |
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conv = np.zeros(count_data.size) |
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try: |
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conv_deriv = np.gradient(conv) |
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except: |
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conv_deriv = np.zeros(conv.size) |
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# if gaussian smoothing or derivative failed, the returned array only contains zeros. |
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# Check for that and return also only zeros to indicate a failed pulse extraction. |
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if len(conv_deriv.nonzero()[0]) == 0: |
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return_dict['laser_counts_arr'] = np.zeros((number_of_lasers, 10), dtype='int64') |
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return return_dict |
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# use a reference for array, because the exact position of the peaks or dips |
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# (i.e. maxima or minima, which are the inflection points in the pulse) are distorted by |
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# a large conv_std_dev value. |
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try: |
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conv = ndimage.filters.gaussian_filter1d(count_data.astype(float), 10) |
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except: |
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conv = np.zeros(count_data.size) |
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try: |
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conv_deriv_ref = np.gradient(conv) |
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except: |
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conv_deriv_ref = np.zeros(conv.size) |
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# initialize arrays to contain indices for all rising and falling |
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# flanks, respectively |
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rising_ind = np.empty(number_of_lasers, dtype='int64') |
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falling_ind = np.empty(number_of_lasers, dtype='int64') |
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# Find as many rising and falling flanks as there are laser pulses in |
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# the trace: |
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for i in range(number_of_lasers): |
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# save the index of the absolute maximum of the derived time trace |
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# as rising edge position |
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rising_ind[i] = np.argmax(conv_deriv) |
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# refine the rising edge detection, by using a small and fixed |
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# conv_std_dev parameter to find the inflection point more precise |
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start_ind = int(rising_ind[i] - conv_std_dev) |
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if start_ind < 0: |
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start_ind = 0 |
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stop_ind = int(rising_ind[i] + conv_std_dev) |
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if stop_ind > len(conv_deriv): |
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stop_ind = len(conv_deriv) |
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if start_ind == stop_ind: |
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stop_ind = start_ind + 1 |
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rising_ind[i] = start_ind + np.argmax(conv_deriv_ref[start_ind:stop_ind]) |
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# set this position and the surrounding of the saved edge to 0 to |
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# avoid a second detection |
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if rising_ind[i] < 2 * conv_std_dev: |
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del_ind_start = 0 |
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else: |
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del_ind_start = rising_ind[i] - int(2 * conv_std_dev) |
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if (conv_deriv.size - rising_ind[i]) < 2 * conv_std_dev: |
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del_ind_stop = conv_deriv.size - 1 |
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else: |
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del_ind_stop = rising_ind[i] + int(2 * conv_std_dev) |
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conv_deriv[del_ind_start:del_ind_stop] = 0 |
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# save the index of the absolute minimum of the derived time trace |
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# as falling edge position |
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falling_ind[i] = np.argmin(conv_deriv) |
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# refine the falling edge detection, by using a small and fixed |
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# conv_std_dev parameter to find the inflection point more precise |
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start_ind = int(falling_ind[i] - conv_std_dev) |
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if start_ind < 0: |
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start_ind = 0 |
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stop_ind = int(falling_ind[i] + conv_std_dev) |
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if stop_ind > len(conv_deriv): |
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stop_ind = len(conv_deriv) |
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if start_ind == stop_ind: |
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stop_ind = start_ind + 1 |
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falling_ind[i] = start_ind + np.argmin(conv_deriv_ref[start_ind:stop_ind]) |
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# set this position and the sourrounding of the saved flank to 0 to |
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# avoid a second detection |
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if falling_ind[i] < 2 * conv_std_dev: |
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del_ind_start = 0 |
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else: |
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del_ind_start = falling_ind[i] - int(2 * conv_std_dev) |
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if (conv_deriv.size - falling_ind[i]) < 2 * conv_std_dev: |
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del_ind_stop = conv_deriv.size - 1 |
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else: |
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del_ind_stop = falling_ind[i] + int(2 * conv_std_dev) |
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conv_deriv[del_ind_start:del_ind_stop] = 0 |
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# sort all indices of rising and falling flanks |
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rising_ind.sort() |
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falling_ind.sort() |
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# find the maximum laser length to use as size for the laser array |
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laser_length = np.max(falling_ind - rising_ind) |
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# initialize the empty output array |
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laser_arr = np.zeros((number_of_lasers, laser_length), dtype='int64') |
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# slice the detected laser pulses of the timetrace and save them in the |
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# output array according to the found rising edge |
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for i in range(number_of_lasers): |
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if rising_ind[i] + laser_length > count_data.size: |
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lenarr = count_data[rising_ind[i]:].size |
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laser_arr[i, 0:lenarr] = count_data[rising_ind[i]:] |
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else: |
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laser_arr[i] = count_data[rising_ind[i]:rising_ind[i] + laser_length] |
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return_dict['laser_counts_arr'] = laser_arr.astype('int64') |
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return_dict['laser_indices_rising'] = rising_ind |
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return_dict['laser_indices_falling'] = falling_ind |
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return return_dict |
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def ungated_threshold(self, count_data, count_threshold=10, min_laser_length=200e-9, |
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threshold_tolerance=20e-9): |
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""" |
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@param count_data: |
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@return: |
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""" |
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""" |
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Detects the laser pulses in the ungated timetrace data and extracts them. |
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@param numpy.ndarray count_data: 1D array the raw timetrace data from an ungated fast counter |
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@param measurement_settings: |
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@param fast_counter_settings: |
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@param count_threshold: |
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@param min_laser_length: |
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@param threshold_tolerance: |
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@return 2D numpy.ndarray: 2D array, the extracted laser pulses of the timetrace. |
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dimensions: 0: laser number, 1: time bin |
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Procedure: |
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Threshold detection: |
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--------------- |
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All count data from the time trace is compared to a threshold value. |
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Values above the threshold are considered to belong to a laser pulse. |
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If the length of a pulse would be below the minimum length the pulse is discarded. |
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If a number of bins which are below the threshold is smaller than the number of bins making the |
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threshold_tolerance then they are still considered to belong to a laser pulse. |
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""" |
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return_dict = dict() |
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number_of_lasers = self.measurement_settings.get('number_of_lasers') |
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counter_bin_width = self.fast_counter_settings.get('bin_width') |
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292
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|
|
if not isinstance(number_of_lasers, int): |
|
293
|
|
|
return_dict['laser_indices_rising'] = np.zeros(1, dtype='int64') |
|
294
|
|
|
return_dict['laser_indices_falling'] = np.zeros(1, dtype='int64') |
|
295
|
|
|
return_dict['laser_counts_arr'] = np.zeros((1, 3000), dtype='int64') |
|
296
|
|
|
return return_dict |
|
297
|
|
|
else: |
|
298
|
|
|
return_dict['laser_indices_rising'] = np.zeros(number_of_lasers, dtype='int64') |
|
299
|
|
|
return_dict['laser_indices_falling'] = np.zeros(number_of_lasers, dtype='int64') |
|
300
|
|
|
return_dict['laser_counts_arr'] = np.zeros((number_of_lasers, 3000), dtype='int64') |
|
301
|
|
|
|
|
302
|
|
|
# Convert length in seconds into length in time bins |
|
303
|
|
|
threshold_tolerance = round(threshold_tolerance / counter_bin_width) |
|
304
|
|
|
min_laser_length = round(min_laser_length / counter_bin_width) |
|
305
|
|
|
|
|
306
|
|
|
# get all bin indices with counts > threshold value |
|
307
|
|
|
bigger_indices = np.where(count_data >= count_threshold)[0] |
|
308
|
|
|
|
|
309
|
|
|
# get all indices with consecutive numbering (bin chains not interrupted by values < threshold |
|
310
|
|
|
index_list = np.split(bigger_indices, |
|
311
|
|
|
np.where(np.diff(bigger_indices) >= threshold_tolerance)[0] + 1) |
|
312
|
|
|
for i, index_group in enumerate(index_list): |
|
313
|
|
|
if index_group.size > 0: |
|
314
|
|
|
start, end = index_list[i][0], index_list[i][-1] |
|
315
|
|
|
index_list[i] = np.arange(start, end + 1) |
|
316
|
|
|
consecutive_indices_unfiltered = index_list |
|
317
|
|
|
|
|
318
|
|
|
# sort out all groups shorter than minimum laser length |
|
319
|
|
|
consecutive_indices = [item for item in consecutive_indices_unfiltered if |
|
320
|
|
|
len(item) > min_laser_length] |
|
321
|
|
|
|
|
322
|
|
|
# Check if the number of lasers matches the number of remaining index groups |
|
323
|
|
|
if number_of_lasers != len(consecutive_indices): |
|
324
|
|
|
return return_dict |
|
325
|
|
|
|
|
326
|
|
|
# determine max length of laser pulse and initialize laser array |
|
327
|
|
|
max_laser_length = max([index_array.size for index_array in consecutive_indices]) |
|
328
|
|
|
return_dict['laser_counts_arr'] = np.zeros((number_of_lasers, max_laser_length), dtype='int64') |
|
329
|
|
|
|
|
330
|
|
|
# fill laser array with slices of raw data array. Also populate the rising/falling index arrays |
|
331
|
|
|
for i, index_group in enumerate(consecutive_indices): |
|
332
|
|
|
return_dict['laser_indices_rising'][i] = index_group[0] |
|
333
|
|
|
return_dict['laser_indices_falling'][i] = index_group[-1] |
|
334
|
|
|
return_dict['laser_counts_arr'][i, :index_group.size] = count_data[index_group] |
|
335
|
|
|
|
|
336
|
|
|
return return_dict |
|
337
|
|
|
|