pyavaspec-tspspi 1.0.2a2

Unofficial library and tool to communicate with AvaSpec-2048-2 spectrometer

Python script to access AvaSpec 2048-2 spectrometer

This is a (unofficial) library and tool to access basic functions (not all data types are supported) of the Avaspec 2048-2 spectrometer from Python on platforms that are not supported by the software supplied by the manufacturer. This has been developed for a project where I wanted to use the spectrometer on FreeBSD (note that no reverse engineering of the original software took place so I can not be sure this is the proper way to talk to the spectrometer - the results just make sense). This project is in no way associated with the manufacturer of this device!

Warning: This project currently applies a fixed calibration to the spectrometers data. This might not be suited to any other spectrometer than the one used by the original author of this software. There will be a configuration option some time in future.

The library interface

The spectrometer is exposed by the PyAvaSpec_2048_2 class from the pyavaspec.pyavaspec module. To use this class use

from pyavaspec.pyavaspec import PyAvaSpec_2048_2

To connect to a device one can simply instantiate the PyAvaSpec_2048_2 class. This tries to locate the USB spectrometer by the vendor id 0x1992 and product ID 0x0666.

with PyAvaSpec_2048_2() as spec:

When not using the with construct one should close the spectrometer manually in the end to prevent lingering resources:

spec = PyAvaSpec_2048_2()

# ...

spec.close()

Function	Description
cmdMeasure(integrationTime = 1000, averageCount = 1)	Performs a measurement
cmdMeasureSoftAverages(integrationTime = 1000, softAverages = 1, hardAverages = 1)	Performs a measurement and applies software averaging
dumpData(data, filename = None, calibration = [0.546875, 299.67])	Dump the supplied data into a data file or to stdout
```plotData(data, peaks = [], peakFwhmLine = False, xrange = None, calibration = [ 0.546875, 299.67 ], filename = None, fileformat = 'png', title = "Spectrometer output", showtimeout = 0)	Plots the supplied data. One can add peaks previously found via searchPeaks, zoom into a specific area via xrange, supply ones own plot title, store the result in a file or display the plot only for a given time
indexToWavelength(pixelIndex, calibration = [ 0.546875, 299.67 ])	Converts an index in the data array to a wavelength
applyMovingAverage(data, windowSize = 10)	Applies a moving average filter to the data and returns a new data array.
searchPeaks(data, maxPeaks = 10)	Performs peak search in the supplied data. One should already have done background subtraction and applied a moving average filter for this to work. Returns a list of peaks.
loadData(filename)	Loads a datafile and returns the data array
getVersionInformation()	Will later be used to query version information from the spectrometer. Currently not functional

The CLI utility

The CLI utility supports a set of options that one can supply:

Commands

The spectrometer is controlled via a sequence of arbitrary commands that set the status and execute actions.

Command	Action
measure	Performs a measurement with the previous supplied settings as foreground data
measurebg	Performs a measurement with previous supplied settings as background data
inttime N	Sets the integration time (in milliseconds, default 1000)
avgsoft N	Sets the number of software averages (default 1)
avghard N	Sets the number of hardware averages (default 1)
peakmaxcount N	Sets the maximum number of peaks (default 10) to search while performing peak search
peakavgwindow N	Sets the size of the averaging window (default 10) while performing peak search
dump	Dump data of foreground signal to stdout
dumpbg	Dump data of background signal to stdout
dumppeak	Dump peak data to stdout
dumpf [filename]	Dumps the foreground data (corrected or uncorrected) into the supplied data file
dumpfbg [filename]	Dumps the background data into the supplied data file
dumpfpeak [filename]	Dumps information about peaks into the supplied data file
loadf [filename]	Loads the specified datafile into the foreground data buffer
loadfbg [filename]	Loads the specified datafile into the background data buffer
loadfpeaks [filename]	Loads peak data from the specified data file
plotformat [svg,png]	Selects the plot format to be png or svg
plotf [filename] [title]	Plots the current available foreground data (corrected or uncorrected, found peaks if available) into the specified (PNG or SVG) file
plot [title]	Plots the current available foreground data and shows it to the user
plotfbg [filename] [title]	Plots the current available background data into the specified (PNG or SVG) file
plotbg [title]	Plots the current available background data and shows it to the user
moveavg	Apply a moving average filter to the foreground data
bgsub	Performs background subtraction on the currently available foreground data if background data is available and background subtraction has not happened up until now
peaks	Performs peak search using the previously set parameters and stores information for the current foreground data (discarded on next foreground measurement)
gateon	Enabled the external gate (for ex. SDG1032X)
gateoff	Disable the external gate (for ex. SDG1032X)

Settings: External SDG1032X control

The software allows one to control an external function generator (SDG1032X) to enable or disable a light source. The communication is handled via the sdg1032x Python library. It's assumed that most parameters (such as waveform, etc.) have already been set up since it does not make much sense to scan those parameters while running the spectrometer in most cases. This might be extended in later versions.

Option	Description
--sdg1032xdev	Supplies the hostname or IP address of the SDG1032X, enabled the SDG1032X module
--sdg1032xch	Selects the channel (1 or 2) to gate, default 1
--sdg1032xfrq	Sets the frequency of the selected channel (in Hz)
--sdg1032xperiod	Sets the period of the selected channel (in Hz)

Sample invocations

Simple measurement and display

To simply run a measurement with default settings and display the result run:

avacli measure plot

Measurement with background supression, store everything

The following command:

• Uses channel 2 of a SDG1032X function generator on 10.0.0.14 as gate
• Measures background
  • Stores the background data in background.dat
  • Stores a plot of the background in background.png
• Measures the signal
  • Stores the uncorrected raw signal in dataraw.dat
  • Plots the uncorrected raw signal in dataraw.png
• Performs background subtraction
  • Stores the intermediate result in datasub.dat
  • Plots the intermediate result in datasub.png
• Applies a moving average filter
  • Stores the intermediate result in dataavg.dat
  • Plots the intermediate result in dataavg.png
• Performs peak search
  • Stores peak data in peaks.dat
  • Plots the corrected signal including the found peak in peaks.png
  • Shows the plot to the user

avacli --sdg1032xdev 10.0.0.14 --sdg1032xch 2 gateoff measurebg dumpfbg background.dat plotfbg background.png "Background" gateon measure gateoff dumpf dataraw.dat plotf dataraw.png "Raw signal" bgsub dumpf datasub.dat plotf datasub.png "Background subtracted" moveavg dumpf dataavg.dat plotf dataavg.png "Averaged and subtracted signal" peaks plotf peaks.png "Peaks" dumpfpeak peaks.dat plot "Peaks"

Loading previous data and generating SVGs

avacli loadfbg background.dat loadf dataraw.dat plotformat svg plotf dataraw.svg "Raw signal" plotfbg background.svg "Background" bgsub plotf datasub.svg "Background subtracted" moveavg plotf dataavg.svg "Averaged and subtracted signal" peaks plotf peaks.svg "Peaks"