Description

This repository contains the datasets and analysis code for the 3rd Year laser spectroscopy experiment.

Datasets

Datafiles are located in the data folder. Current files and short descriprors:

• PD1_1.csv/PD2_1.csv: Oscilloscope output of PD1/PD2 with the doppler broadened spectrum.
• PD2_2.csv: Oscilloscope output of PD2 with the pump beam introduced into the system. PD2 is the probe beam. PD1's output is lost due to an error.
• PD1_3.csv/PD2_3.csv: Oscilloscope output for PD1(reference), and PD2(probe). Setup is just as above.
• PD1_4.csv/PD2_4.csv: Oscilloscope output for PD1(reference), and PD2(probe). Setup is just as above.
• PD1_5.csv/PD2_5.csv/PD3_5.csv: Oscilloscope output for PD1(reference), PD2(probe) and PD3(etalon). Note that this dataset has a negative time-energy dependence.
• PD3_S5_S/E/F.CSV: The etalon measurements at the start middle and end of the session.
• PD1_6.csv/PD2_6.csv: Datasets taken as usual, with etalon blocked. Taken right after PD3_S5_S.
• PD1_7.csv/PD2_7.csv: Datasets taken as usual, with etalon blocked. Taken right after PD3_S5_E.
• PD1_8.csv/PD2_8.csv: Datasets taken as usual, with etalon blocked. Taken right after PD3_S5_F.
• PD2_8_B.csv: PD2 data with the pump beam blocked. Taken after PD1/2_8.
• PD1_9/PD2_9/PD2_9_B/PD3_9: Same naming convention as above. New etalon alignment.

Analysis code

The analysis code included in the repository and their usages are:

• plot_rough_data.py dataset [E_scaling]: Plots the rough data with a moving average applied to it, as well as allows fitting to it using the fit_line(xmin,xmax) method afterwards. The E_scaling can be supplied to transform Time into frequency for x axis. A secondary function called fit_splitting(amin.amax,bmin,bmax) is included. This can be used to get the splitting between the lines characterised by bounds [amin,amax] and [bmin,bmax].
• plot_rough_data_etalon.py dataset [etalon]: Same as plot_rough_data.py, but instead of E_scaling the etalon dataset can be provided. The etalon's data is plotted and found peaks are marked as a sanity check.
• plot_hyperfine.py probe reference cull_low cull_high [E_scaling]: Code used to remove the background of the probe beam measurement. The cull_low and cull_high parameters remove the first cull_low datapoints and the last cull_high datapoints, so they are not fitted. This is so that variation on doppler absorption depth variance is less of an issue. The fit(xmin,xmax) function is still present and now fits the background removed hyperfine structure. E_scaling can still be applied with the same effect. fit_splitting(amin.amax,bmin,bmax) is included with the same effect as before. fit_structure(xmin,xmax,m1=0,m2=0,m3=0,p0=None) is included to provide an optimisation of the structure. It fits the true and cross-over peaks. The initial values are either the true peak's rough location (m1-3) or, the optimisation parameter's initial guess (p0).
• plot_hyperfine_etalon.py probe reference cull_low cull_high etalon: Same as plot_hyperfine.py, but instead of E_scaling the etalon dataset can be provided. The etalon's data is plotted and found peaks are marked as a sanity check. Unlike in plot_rough_etalon.py here the etalon peaks are interpolated to give an accurate scaling. This also has an extra method fit_total(amin,amax,bmin,bmax,am1,am2,am3,bm1,bm2,bm3), which fits a paired hyperfine structure and determines the S1/2 spliting as well. Note that while the parameters are the same as for fit_structure, it needs that am1<am2<am3<bm1<bm2<bm3 to work. This file has these methods and general plotting improved.

Setup

A schematic view of the setup used.