Plesty Lightfield Spectrometer Device

A Plesty device for the Princeton Instruments LightField spectrometer. It drives LightField through its .NET automation API via pythonnet, so the server runs on the Windows PC the camera is attached to.

Full documentation: docs/index.md.

Setup the server

On the Windows PC where LightField is installed (camera via USB — PIXIS — or GigE — PyLoN-IR), close all LightField apps: LightField.exe, AddInProcess.exe and the LightField Firmware Assistant. Then in a Terminal/PowerShell:

git clone https://gitlab.com/plesty/hub/devices/princeton_instruments/lightfield_spectrometer.git
cd lightfield_spectrometer
uv sync
copy .env.example .env
:: edit .env — at least DEVICE_DATA_PATH (where frames go, steerable by clients)
uv run python -m plesty.lightfield_spectrometer --tcp-port 5555

Run the server from a normal (non-elevated) desktop shell — not over SSH: Windows OpenSSH gives administrator accounts an elevated token, and LightField's automation IPC refuses mismatched privilege levels. The preflight warns when it detects this.

A GigE camera needs no configuration: the preflight finds the link-local neighbour on the camera NIC, verifies it with a ping, and pins it to .env as CAMERA_HOST.

Starting unattended

Under a supervisor or the bench app there is nobody to answer the confirmation before an open LightField session is closed, so it refuses and the server does not start. Pass --close-lightfield (or set DEVICE_CLOSE_LIGHTFIELD=1) to close it and discard whatever it has not saved. The same flag allows ending the LightField Firmware Assistant, which holds the camera and usually ignores a polite close — check no firmware write is in progress first, since interrupting one can leave the camera unusable.

Long runs

LightField's AddInProcess keeps a share of every acquisition and never releases it: about 0.21 MB per acquisition plus 0.037 MB per second of acquiring, measured on the bench. Idling is free and so are API calls — only acquiring costs — but overnight that is gigabytes, and no exposure setting avoids it.

Nothing in this process can free another process's heap, so the server restarts the LightField session instead, between acquisitions, once the host passes DEVICE_RECYCLE_CEILING_MB (default 1024 MB, 0 to disable). A restart costs about 22 s and the experiment's settings survive it. See Long runs and the automation host in docs/index.md.

Tests

uv run pytest                              # hardware-free; what CI runs
uv run python tests/field_test.py          # the instrument, in-process
uv run python tests/field_test_client.py   # the instrument over ZMQ

The field tests need hardware and are run by hand — the host tier on the LightField PC, the client tier from a machine on the instrument network, against a running server. Run the host tier first; the client tier reads its report to know what to exercise.

Regenerate the manuals

uv run plesty manual generate . --with-pdf