ws6-200-wvm 0.2.0

Python client for the HighFinesse WS/6-200 wavemeter (wlmData wrapper).

ws6-200-wvm

Python client for the HighFinesse WS/6-200 wavemeter (and other WS/6 variants that share the same wlmData library).

The HighFinesse stack is a shared-memory client/server: the vendor's wlm_ws6 application owns the USB device and publishes measurements into shared memory; this package loads wlmData.dll (Windows) or libwlmData.so (Linux) via ctypes and reads from that shared memory. Reads are microsecond-scale memory operations.

Constraints:

• The vendor library is x86_64 only — this package will not work on a Raspberry Pi / ARM host. Run on a Windows or Linux x86_64 PC attached to the wavemeter over USB.
• The vendor server (wlm_ws6.exe) must be running locally. On Windows, this package can autostart it for you (default).

Install

pip install ws6-200-wvm

or with uv:

uv add ws6-200-wvm

Prerequisites

1. HighFinesse "Wavelength Meter" application installed from the USB stick that shipped with your WS6. The installer is calibration-keyed to your unit's serial, so use the one for your device. It places wlmData.dll under C:\Windows\System32\ and wlm_ws6.exe somewhere on PATH.

   Linux equivalent: request the Linux bundle from HighFinesse support; it installs libwlmData.so and a wlm_ws6 daemon binary.

2. USB connection from the host to the WS6, and the wavemeter powered on. First time, run the vendor "Wavelength Meter" GUI to confirm it sees the device.

If you are integrating this package into a larger application and need to write an adapter, see docs/wrapping.md.

Quickstart

from ws6200_wvm import Ws6200

with Ws6200(channel=1) as wm:
    print(wm.idn)
    print(wm.measure_frequency_thz(), "THz")
    print(wm.measure_wavelength_nm(), "nm")

Or without the context manager:

wm = Ws6200(channel=1)
wm.connect()
try:
    freq_thz = wm.measure_frequency_thz()
finally:
    wm.disconnect()

Configuration

Ws6200Config is a pydantic model that you can populate from YAML / JSON / env vars and call .make() on to get a driver:

from ws6200_wvm import Ws6200Config

cfg = Ws6200Config(channel=1, autostart_server=True, start_timeout_s=10.0)
wm = cfg.make()

Fields:

field	default	meaning
channel	1	1-indexed switcher channel.
dll_path	None	Override path to wlmData.dll / libwlmData.so. Auto-detected if unset.
autostart_server	True	On Windows, launch wlm_ws6.exe via ControlWLMEx if not running.
start_timeout_s	10.0	Seconds to wait for wlm_ws6 to come up.

CLI

A console script ws6200-wvm is installed for first-install smoke tests:

ws6200-wvm measure                       # one reading, then exit
ws6200-wvm measure --watch --interval 0.5
ws6200-wvm measure --channel 2 --dll-path "C:\path\to\wlmData.dll"

Errors

Library / setup problems raise RuntimeError:

• "could not load HighFinesse wlmData library …" — install the vendor software, or pass dll_path=... to point at it.
• "HighFinesse wlm server is not running …" — start wlm_ws6.exe manually, or pass autostart_server=True on Windows.

Wavemeter-reported measurement errors raise WavemeterError with a label from wlmData.h:

label	meaning
noval	No measurement available yet
nosig	No input signal
badsig	Signal present but uncomputable
under	Underexposed
over	Overexposed
nowlm	No wavemeter server running
outofrange	Outside calibrated range
noresponse
div0
outofresolution

NotConnectedError (subclass of WavemeterError) is raised if you call a measure_* method before connect().

Calibration

HighFinesse units use an internal reference but the factory absolute calibration drifts over time. Check the recommendation that came with your unit (typically 12–24 months) and send it back in cycle to keep the 200 MHz absolute spec.