Millennia eV Laser Control

A small myTk GUI for the Spectra-Physics Millennia eV CW pump laser, driven through PyHardwareLibrary's MillenniaDevice.

The window provides:

• Pump Diodes On/Off — a toggle button (driver ON / OFF, status ?D).
• Shutter Open/Close — a toggle button (SHT:1 / SHT:0, status ?SHT).
• Power Monitor — live output power in watts (?P) plus On/Off and Open/Closed lamps for the diodes and the shutter.

All serial I/O runs on a background worker thread, so the eV's slow write-then-confirm actions never freeze the UI. If the laser's serial port is already in use by another program (on this bench the eV's USB port is routinely captured by Parallels for the Windows Spectra-Physics app), the status line says so explicitly.

Auto-reconnect. If the connection drops (cable pulled, port disappears) — or the laser simply isn't present at launch — the app keeps watching for the port and reconnects automatically as soon as it reappears. During this the status line shows it is monitoring and the button reads Disconnect so you can cancel the auto-retry. An explicit Disconnect is honoured: it will not reconnect on its own until you press Connect again.

Setup

python3 -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt
pip install git+https://github.com/DCC-Lab/PyHardwareLibrary.git

Run

python millennia_ui.py                 # auto-detect the Millennia serial port
python millennia_ui.py --port /dev/cu.usbmodemXXXX
python millennia_ui.py --simulate      # no hardware needed (DebugMillenniaDevice)

Standalone macOS app

A double-clickable bundle can be built with PyInstaller (no Python install needed by the end user, and it launches in the user's own GUI session):

./packaging/build_app.sh        # -> packaging/dist/MilleniaUI.app

See packaging/BUILD.md for details, Gatekeeper notes, and code-signing.

Known issues

• Port busy. If the Spectra-Physics Windows app (or any program) holds the laser's USB/serial port, macOS will not expose a /dev/cu.* node for it and the GUI cannot connect. Quit that app first.
• GUI session. A Tkinter app can only open a window in the GUI login session that owns the screen. Launching it from a shell that belongs to a different logged-in user (e.g. running as dccote while the console is logged in as dcclab) aborts in libxpc before any window appears. Run it as the user logged in at the screen, or launch the .app from Finder.

License

MIT © 2026 Daniel Côté (DCC-Lab)