Can I apply a new OD calibration to old data?


Is there a way to apply a new OD calibration fit to raw OD readings from old experiments? It seems like a new fit could be applied to the raw OD values in an old experiment folder, but I can’t quite figure out how to do it. Any recommendations or ideas?

Thank you,

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I haven’t done this before but here is the equation in the DPU script that converts the raw OD values to OD. If you have the calibration constants, you should be able to just iterate through all the OD readings to the new ODs.

If you do this, do you mind sharing your script? :slight_smile:


I’ve done this before. Here’s an adaptation of the script I use:

To use it, you just have to download the calibrations.json from your eVOLVER machine:

## (In eVOLVER Computer) ##
# Download the file from the eVOLVER
scp pi@<evolver-ip>:evolver/evolver/calibrations.json calibrations.json

edit the custom variables inside, and create a folder “NewOD” inside your experiment folder.

Also, you may also want to use the blank of your initial experiment. In that case, you have to get it from your experiment.pickle file, as it is done here:

and then subtract it from your newly calculated OD.

I hope it will be useful.



Now that I think about this twice, if you want to apply a blank to your newly calculated OD, you wouldn’t do it with the data inside the pickle file, since it comes from the old calibration.

Instead, you would subtract each OD value minus the initial OD value:

data[i,1] -= data[0,1]

Hope it helps!

Alternatively, you can calculate an average blank with the first 5 OD values or however you think it’s best.

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Thank you Daniel! This is super helpful!

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