The following Python script uses the SR830 to output an AC voltage across a device and then measures the amplitude and phase of current that passes through the device. This information can be used to calculate the impedance. The script performs this measurement for a range of frequencies.

from StanfordResearchSystems import SR830
import visa
import math
import matplotlib.pyplot as plt
import time
import csv
import datetime

######################################################################
# Connect to the lock-in amplifier
######################################################################

# connect to the SR830 Lock In Amplifier
sr830 = SR830()
sr830.connect("GPIB0::8::INSTR")
# Enable debug output so we see the commands that are sent to the instrument
sr830.enable_debug_output()
# Reset the device
#sr830.reset()

######################################################################
# Setup of the SR830 Lock-in Amplifier
######################################################################

sr830.use_internal_reference()

# disable line filters
sr830.disable_line_filters()
#sr830.enable_line_filters()

# set the input to measure 
#sr830.set_input_mode_A_1uA()
sr830.set_input_mode_A()
sr830.set_input_shield_to_floating()
sr830.set_input_coupling_ac()

# set the reserve
#sr830.set_reserve_low_noise()
sr830.set_reserve_normal()

# set the displays to interesting things
sr830.display_ch1_r()
sr830.display_ch2_phi()

######################################################################
# define the parameters for the measurement
######################################################################

amplitude = 0.004
sr830.set_sine_output_level(amplitude)
#sr830.set_reference_frequency(freq)

# define the sweep parameters
f_start = 1000
f_stop =  100000
f_step = 1000       
delay = 3

# define variables we store the measurement in
data_impedance = []                # impedance
#data_BiasVoltage = []            # Bias voltage we set
data_phi = []                       # phaseshift
#data_1_over_C_squared = []  # to save one over Capacity^2
freq = []                               # frequency

# Creat unique filenames for saving the data
time_for_name = datetime.datetime.now().strftime("%Y_%m_%d_%H%M%S")
filename_csv = 'semshort' + time_for_name +'.csv'
filename_pdf = 'semshort' + time_for_name +'.pdf'

# Header for csv
with open(filename_csv, 'a') as csvfile:
        writer = csv.writer(csvfile, delimiter=';',  lineterminator='\n')
#       writer.writerow(["f / Hz :" , str(freq)])
        writer.writerow(["Ue / V :" , str(amplitude)])
        writer.writerow(["Frequency / Hz" , "Impedance / Ohm", "Phase / °"])

# Some parameters for the SR830
sr830.set_time_constant(0.1)
sr830.set_sensitivity(1)
sr830.set_reference_frequency(f_start)
time.sleep(delay)

######################################################################
# step through the frequencies
######################################################################

# positive sweep
steps = int((f_stop - f_start)/f_step)
for nr in range(steps):
    f = f_start + nr * f_step
    sr830.set_reference_frequency(f)
    time.sleep(1)
    # read the data from the SR830
    value_r = sr830.read_r()
    phi = sr830.read_phi()
    #sr830.set_sensitivity(2*value_r)

# skip the data point if value_r = 0 so that division by zero is avoided
    if (value_r != 0):
        freq.append(f)
        Z = amplitude/value_r
        data_impedance.append(Z)
        data_phi.append(phi)

# Write the data in a csv
        with open(filename_csv, 'a') as csvfile:
            writer = csv.writer(csvfile, delimiter=';',  lineterminator='\n')
            writer.writerow([f, Z, phi])

######################################################################
# Plot the Data and save the figure as a .pdf
######################################################################

# plot the data
f, fig = plt.subplots(2, sharex = True)
fig[0].plot(freq, data_impedance,'o-')
fig[1].plot(freq, data_phi,'*')

# set labels and a title
plt.xlabel('Frequency / Hz')
plt.axes(fig[0])
plt.ylabel('Z / Ohm')
plt.axes(fig[1])
plt.ylabel('Phi / °')
#plt.title('Characteristic curve of a diode')

plt.savefig(filename_pdf)
plt.show()

######################################################################
# Clean up
######################################################################

# reset and disconnect the SR830
sr830.reset()
sr830.disconnect()

SR830_Impedance.py

Frequency dependent impedance measurements with the Stanford 830 lock-in amplifier

Python script for conducting the impedance measurements