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Convenience wrapper of Toptica Laser SDK for controlling a Toptica CTL with a DLCpro

Word of caution: This module controls potentially Class 4 lasers. Use is entirely on your own risk.

API documentation available here. Docs can be built with python3 -m pdoc --html -o ./docs dlccontrol.py (needs pdoc3 to be installed).

The DLCcontrol class can read and control:

• laser current on/off
• wavelength setpoint for lasers that have this option
• laser diode setpoint for lasers that have this option
• analogue remote control settings (can control laser current and/or piezo simultaneously)
  • enable/disable
  • select input channel
  • set multiplier factor of the input voltage
• internal scan settings (both for scanning the piezo and laser current)
  • scan start
  • scan end
  • scan offset
  • scan amplitude
• user level (normal, maintenance, service)
• any other setting using the DLCcontrol.client attribute

The class will check that the wavelength/temperature setpoint and internal scan settings are within acceptable ranges (and raise a OutOfRangeError if not).

The module also provides some convenient dictionaries with all the settings it can modify, these dictionaries can be saved with measurement data to make sure all settings are recorded. The DLCcontrol class can dump these dicts to json files.

Here are the parameters that can be saved, queried from the instrument and printed with DLCcontrol.get_all_parameters(verbose=True):

-------------------------------------------------------
timestamp      : 2021-11-29 22:42:02.707762
scan:
 | enabled       : True
 | output channel: OutputChannel.PC
 | frequency     : 50.0000290562942
 | amplitude     : 21.0
 | offset        : 61.0
 | start         : 50.5
 | end           : 71.5
analogue remote:
 | cc:
 |  | enabled: False
 |  | factor : 10.0
 |  | signal : InputChannel.Fine1
 | pc:
 |  | enabled: False
 |  | factor : 10.0
 |  | signal : InputChannel.Fine2
wavelength:
 | wl setpoint: 1550.46
 | wl actual  : 1550.460841087153
temperatures:
 | temp setpoint: None
 | temp actual  : None
-------------------------------------------------------

The module uses properties extensively (listed as Instance variables in the docs), which means class attributes have setter and getter functions, which can be used like this:

import dlccontrol as ctrl

with ctrl.DLCcontrol("xx.xx.xx.xx") as dlc:
    # Change wavelength or laser diode temperature depending on how the unit is
    # controlled
    if dlc.wl_setting_present:
        dlc.wavelength_setpoint = 1550
        actual_wl = dlc.wavelength_actual
    if dlc.temp_setting_present:
        dlc.temp_setpoint = 20
        actual_temp = dlc.temp_actual
    # Set up a the analogue remote control sweeping the current with the
    # on input Fine1
    dlc.remote_select = "CC"
    dlc.remote_signal = "Fine1"
    dlc.remote_factor = 10
    dlc.remote_enable = True
    # Use the internal voltage scan and gradually increase the scan amplitude
    dlc.scan_output_channel = "PC"
    initial_amplitude = dlc.scan_amplitude
    dlc.scan_frequency = 20
    for i in range(10):
        dlc.scan_amplitude = i
      dlc.scan_amplitude = initial_amplitude

Doing the same with the Toptica SDK would look like this (and this module is providing other features in addition to simplifying the syntax)

import toptica.lasersdk.dlcpro.v2_4_0 as toptica
import toptica.lasersdk.decop as decop

with toptica.DLCpro(toptica.NetworkConnection("xx.xx.xx.xx")) as dlc:
    try:
        dlc.laser1.ctl.wavelength_set.set(float(1550))
        actual_wl = dlc.laser1.ctl.wavelength_act.get()
    except decop.DecopError:
        pass
    try:
        dlc.laser1.dl.tc.temp_set(float(20))
        actual_temp = dlc.laser1.dl.tc.temp_act.get()
    except decop.DecopError:
        pass
    # Set up a the analogue remote control sweeping the current with the
    # on input Fine1
    dlc.laser1.dl.cc.external_input.signal.set(0)
    dlc.laser1.dl.cc.external_input.factor.set(10)
    dlc.laser1.dl.cc.external_input.enable.set(True)
    # Use the internal voltage scan and gradually increase the scan amplitude
    dlc.laser1.scan.output_channel.set(50)
    initial_amplitude = dlc.laser1.scan.amplitude.get()
    dlc.laser1.scan.frequency.set(20)
    for i in range(10):
        dlc.laser1.scan.amplitude.set(float(i))
    dlc.laser1.scan.amplitude.set(initial_amplitude)

If you want to access other settings than what the wrapper conveniently offers, the DLCcontrol.client attribute is useful as it can give you access to any other setting:

import dlccontrol as ctrl
with ctrl.DLCcontrol("xx.xx.xx.xx") as dlc:
    print(dlc.client.get("serial-number"))
    # Need higher privilige to access the following commands
    dlc.set_user_level(1, "password from manual")
    dlc.client.set("laser1:dl:cc:current-clip", 250)
    dlc.client.set("laser1:dl:factory-settings:cc:current-clip", 250)
    dlc.client.exec("laser-common:store-all")

Note also the DLCcontrol.set_user_level() function to elevate the connection for access to protected settings.

More examples are in the examples.py module.

• The upper frequency limit for internal scan is set very low, find out what the actual limits are for the voltage and current scan
• Handle limits for scan outputs to OutA and OutB (they can currently be used, just no checks on the range)
• Make update of interdependent scan settings update all relevant private dictionary entries
• Set parameters from dict/file
• Add property for setting the laser current when not scanning
• Tests would be helpful...

The source is available on Github, please report issues there. Contributions are also welcome. The source code is licensed under the MIT license.

• v0.2.0 Nov 2021:
  • Added support for temperature tuned lasers, automatic discovery of whether the laser is wavelength or temperature controlled
  • Adding a client attribute to the DLCcontrol class to access any laser attribute
  • Methods for setting and getting the user level for enabling change of restricted parameters
  • Parameters dictionary now includes timestamp of the parameter set
  • Black formatting