def iv__sim900__sweep_current__read_voltage(current_range, current_step,
bias_resistance,
measurement_delay):
from instruments.srs_sim970 import SIM970
from instruments.srs_sim928 import SIM928
voltage_meter = SIM970(
'GPIB0::2',
7) #voltmeter = SIM970(visa_name = 'GPIB0::2', sim900port = 2)
voltage_source = SIM928('GPIB0::2', 5)
current_applied_vec = np.arange(current_range[0],
current_range[1] + current_step,
current_step)
#SIM928 max voltage = [-20,20]V
voltage_applied_vec = current_applied_vec * bias_resistance
if 1 > 0: #np.abs(voltage_applied_vec[0]) >= 20 or np.abs(voltage_applied_vec[-1]) >= 20:
warnings.showwarning(
'The SIM928 can only output in the range [-20,20]V. You have attempted to exceed this range.',
UserWarning, os.path.basename(__file__),
inspect.currentframe().f_back.f_lineno)
voltage_read_vec = []
voltage_source.reset()
voltage_source.set_output(True)
for ii in range(len(voltage_applied_vec)):
voltage_source.set_voltage(voltage=voltage_applied_vec[ii])
time.sleep(measurement_delay)
voltage_read_vec.append(voltage_meter.read_voltage(channel=1))
voltage_source.set_output(False)
return voltage_read_vec
def iv_curve(v_min=0.0, v_max=0.5, Z_in=1e5, num_meas=501):
""" Calculates values germane to producing an i-V curve of an SNSPD using
the SRS SIM928 voltage source and SIM970 digital voltmeter.
Parameters
----------
v_min : float, startpoint of voltage ramp (generally 0)
v_max : float, peak of voltage ramp
Z_in : float, value of current-limiting resistor
num_meas : int , number of values between start and peak (actual
experiment will run 4 times the length of this number)
Returns
-------
(V,I) : tuple, voltage across DUT and bias current
"""
# Initialising
s28 = SIM928('GPIB0::4::INSTR', 4)
s70 = SIM970('GPIB0::4::INSTR', 7)
v_in = np.linspace(v_min, v_max, num_meas)
v_in = np.append(v_in, np.flip(v_in, 0)) # Sweep voltages (triangle wave)
v_in = np.append(v_in, -v_in) # Adding negative voltages
I = []
V = [] # Bias current and V device
s28.reset()
s70.reset()
s70.set_impedance(gigaohm=True, channel=2)
# Measuring
for i in range(len(v_in)):
s28.set_voltage(voltage=v_in[i]) # Setting sweep voltage [V]
time.sleep(1)
v = s70.read_voltage(channel=1) # Reading DVM 1 [V]
V.append(s70.read_voltage(channel=2)) # Reading DVM 2 [V]
I.append((v - V[i]) * 1e6 / Z_in) # Calculating current [μA]
s28.close()
s70.close()
return (V, I)
sys.path.append(snspd_measurement_code_dir)
sys.path.append(dir1)
sys.path.append(dir2)
sys.path.append(dir3)
#%%import modules
from instruments.srs_sim970 import SIM970
from instruments.srs_sim928 import SIM928
#%% setup
volt_channel = 1
set_voltage = 5.0
voltage_resistance = 10000
output_current = 2 * set_voltage / voltage_resistance
voltmeter = SIM970('GPIB0::4', 7)
source1 = SIM928('GPIB0::4', 1)
source2 = SIM928('GPIB0::4', 4)
voltmeter.set_impedance(True, volt_channel)
source1.set_voltage(voltage=set_voltage)
source2.set_voltage(voltage=set_voltage)
volt_sum = 0
volt_count = 0
#%%begin testing
source1.set_output(True)
source1.set_output(True)
while volt_count < 100:
volt_count = volt_count + 1
volt_sum = volt_sum + voltmeter.read_voltage(volt_channel)
from tqdm import tqdm
import datetime
import pickle
from matplotlib import pyplot as plt
from standard_measurements.iv_sweep import run_iv_sweeps, setup_iv_sweep
from instruments.rigol_dg5000 import RigolDG5000
from instruments.lecroy_620zi import LeCroy620Zi
from instruments.switchino import Switchino
#%%
from instruments.srs_sim970 import SIM970
from instruments.srs_sim928 import SIM928
from instruments.agilent_53131a import Agilent53131a
dmm = SIM970('GPIB0::4', 7)
dmm.set_impedance(gigaohm=True, channel=1)
vs_led = SIM928('GPIB0::4', 1)
vs_nw = SIM928('GPIB0::4', 4)
vs_led.reset()
vs_nw.reset()
counter = Agilent53131a('GPIB0::5::INSTR')
counter.reset()
counter.set_trigger(trigger_voltage=0.050, slope_positive=True)
counter.set_impedance(ohms=50)
counter.set_coupling(dc=True)
counter.setup_timed_count()
counter.write(':EVEN:HYST:REL 100') # Set hysteresis (?)
def dark_counts(v_min=0.35,
v_max=0.5,
Z_in=1e5,
num_meas=50,
t_int=60,
trig_volt=0.03,
attenuation=0,
show_plot=False,
data_name='dark'):
""" Measures dark counts detected for a ramp of I bias values using the SRS
SIM928 voltage source and SIM970 digial voltmeter and the Agilent 53131A
counter.
Parameters
----------
v_min : float, startpoint of voltage ramp
v_max : float, peak of voltage ramp
Z_in : float, value of current-limiting resistor
num_meas : int , number of values between start and peak
t_int : int , integration time of the counter
trig_volt : float, trigger voltage of the Agilent counter
attenuation : int , (optional) attenuation through JDSHA9 if using laser
show_plot : bool , show data plot within this function or return data
Returns
-------
(I,counts) : tuple, bias current and number of counts
"""
# Setting up instruments
s28 = SIM928('GPIB0::4::INSTR', 4)
s70 = SIM970('GPIB0::4::INSTR', 7)
ag = Agilent53131a('GPIB0::5::INSTR')
att = JDSHA9('GPIB0::15::INSTR')
s28.reset()
s70.reset()
ag.basic_setup()
ag.set_trigger(trigger_voltage=trig_volt, slope_positive=True)
if attenuation != 0:
att.set_beam_block(beam_block=False)
att.set_attenuation_db(attenuation)
att.close()
s28.set_voltage(0)
s28.set_output(True)
ag.pyvisa.timeout = t_int * 1000 + 5000 # Stop timeout on longer integrations
# Initialising vectors
v_in = np.linspace(v_min, v_max, num_meas) # Voltage ramp
I = []
counts = [] # Bias current and counts
# Counting
for i in range(len(v_in)):
s28.set_voltage(voltage=v_in[i]) # Setting ramp voltage
time.sleep(0.5) # Letting voltage settle
v = s70.read_voltage(channel=1) # Reading source voltage
V = s70.read_voltage(channel=2) # Reading DUT voltage
I.append((v - V) * 1e6 / Z_in) # Calculating I bias
counts.append(ag.timed_count(t_int)) # Number of counts
s28.set_voltage(0) # Resetting I bias
time.sleep(0.5) # Letting voltage settle
s28.close()
s70.close()
ag.close()
if show_plot:
make_plot((I, counts),
xlab='Bias Current (uA)',
ylab='Countrate (Hz)',
title='Dark Counts',
d_name='dark')
else:
return (I, counts)