coreDAQ Python API¶

coreDAQ is a low-noise opto-electronic data acquisition system for optical power measurement and programmable capture. py_coreDAQ is the Python driver for it.

The instrument provides four simultaneous measurement channels, a sample rate up to 100 kHz, 32 MB of on-board capture memory, and a BNC trigger input for synchronised acquisition. It connects to the host over USB and is powered from the USB bus.

Full specifications, electrical characteristics, and mechanical drawings are in the datasheet.

If you would like to buy one, visit core-instrumentation.com/coredaq.

If you find any issues with the driver, or anything odd in your measurements, please raise an issue on GitHub and our engineers will look into it as fast as we can.

Quick Hardware Note¶

The instrument comes in four hardware variants, combining two detector types with two amplifier topologies.

Detector type determines the usable wavelength range:

InGaAs — 910–1700 nm. Covers the near-infrared bands used in telecom and fibre-optic work (1310 nm, 1550 nm, O/C/L-band).
Silicon — 400–1100 nm. Covers the visible and near-infrared, suited for free-space, Ti:Sapphire, and 850 nm datacom applications.

Amplifier topology determines how dynamic range is distributed:

Linear (transimpedance) — eight overlapping gain ranges spanning roughly 300 pW to 3 mW. Each range gives fixed, uniform resolution across its window. Switching between ranges is handled automatically by the driver's autoRange algorithm. Best choice for precision tracking of a known power level, noise floor measurements, or any application where absolute resolution at a specific power matters. It is to be noted that autoRanging will not be active while the device is in Capture Mode.
Logarithmic — the full 1 nW to 3 mW span is compressed into a single range by a logarithmic amplifier. There are no ranges to select or switch between. Resolution is highest at low input powers and decreases toward the upper end, matching the way optical power is perceived on a dB scale. Ideal for characterising high-dynamic-range devices — resonators, interferometers, swept-source measurements — where the signal can jump orders of magnitude and stopping to change ranges is not practical.

The driver handles all four variants transparently. You do not need to know which one is connected; it is detected at startup and the appropriate calibration and conversion path is selected automatically. A built-in simulator is included so every code example in this documentation is runnable on a laptop without hardware.

Install¶

pip install py_coreDAQ

Connect and read¶

from py_coreDAQ import coreDAQ

coredaq = coreDAQ.connect(simulator=True)
print(coredaq.read_all())           # [W, W, W, W]
print(coredaq.channels[0].power_w)  # watts, one channel
coredaq.close()

Or use it as a context manager — the port closes automatically on exit:

with coreDAQ.connect(simulator=True) as coredaq:
    print(coredaq.read_all())

On real hardware, pass the port or let the driver find the device:

coredaq = coreDAQ.connect("/dev/tty.usbmodem12401")
coredaq = coreDAQ.connect()   # auto-discovers the first coreDAQ on the bus

Default behavior¶

reads return watts unless changed with set_reading_unit()
autoRange=True on all read*() methods
sample rate: 500 Hz, oversampling: OS 1
LINEAR readings always apply the active zero offset

Hardware variants¶

Instruments differ in amplifier topology — logarithmic or transimpedance — and in detector, which determines the usable wavelength range. The driver detects the variant at connection time and selects the appropriate calibration and conversion path automatically.

Amplifier topology	Detector	Wavelength range
Logarithmic	InGaAs	910 – 1700 nm
Transimpedance (linear)	InGaAs	910 – 1700 nm
Logarithmic	Silicon	400 – 1100 nm
Transimpedance (linear)	Silicon	400 – 1100 nm

Methods that are topology-specific — such as range control on transimpedance instruments — raise coreDAQUnsupportedError on incompatible hardware rather than silently no-opping.

Simulator¶

Every code example in this documentation uses coreDAQ.connect(simulator=True) and is runnable as-is. The simulator supports all four variants and produces deterministic output (seeded RNG, seed=42 by default).

# Default: InGaAs LOG at 1550 nm
with coreDAQ.connect(simulator=True) as coredaq:
    print(coredaq.frontend())   # LOG
    print(coredaq.detector())   # INGAAS

# InGaAs LINEAR
with coreDAQ.connect(simulator=True, frontend="LINEAR", detector="INGAAS") as coredaq:
    print(coredaq.supported_ranges())

# Si LOG at 850 nm
with coreDAQ.connect(
    simulator=True, frontend="LOG", detector="SILICON", wavelength_nm=850.0
) as coredaq:
    print(coredaq.read_channel(0))

Documentation map¶

Page	What it covers
Quickstart	First measurement in under 5 minutes
Read Power	Single-shot reads, `ChannelProxy`, averaging, full-detail reads
Capture Data	Block acquisition with `capture()`, `CaptureResult`
Capture Data	Triggered capture via BNC input, channel masking, `CaptureResult`
Ranges and AutoRange	TIA gain ranges on LINEAR frontends
Units, Sample Rate, and Oversampling	Global device settings, streaming setup
Frames, Masking, and Memory Limits	Channel masks and SDRAM frame limits
Zeroing and Signal Health	Dark zeroing, signal clipping
Device State	Instrument state machine, busy errors
API Reference	Full method table