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Ghost data in buffer

Posted: Thu Jul 06, 2023 4:52 pm
by Dave_VUB
Hi, I am trying to get decent results from the build kit but I am getting some strange results. It seems like some unwanted data keeps getting through the data accumulation. The data that I am talking about is still visible even when the laser is turned off. Is this correct or is there some kind of problem here?

Re: Ghost data in buffer

Posted: Fri Jul 07, 2023 3:45 pm
by Luc
different origin are possible but I'm thinking of those two first:
  • stray light in the room, in particular if you use fluorescent lamps or if your setup is close to a computer monitor or TV
  • hot pixels; some pixels will have higher response than others
In both case you can compensate by using a blank taken in the same operating conditions with the same exposure/gain settings. I always use a blank for my measurements, even when calibrating with a Neon lamp.

Re: Ghost data in buffer

Posted: Mon Jul 17, 2023 12:41 pm
by Dave_VUB
Is a blank just the environment (with or without the laser source turned on) or is it taken with an empty cuvet for example to simulate everything that is reflected onto the sensor apart from the sample itself?

Re: Ghost data in buffer

Posted: Mon Jul 17, 2023 2:14 pm
by Luc
My recommendation is to take the blank exactly like how you'd do the measurement but just switch the laser off - then switch the laser back on, wait for stabilization if required, and perform all your measurements.

So I do it with the test tube in place :) And I even try to stay at the same position in the room in case I would block some light from PC monitor or else. It's a bit overkill but I prefer doing more than not enough!

Re: Ghost data in buffer

Posted: Tue Jul 18, 2023 9:12 am
by Dave_VUB
Hi I tried the blank removal as you mentioned for Methanol. The results I get with and without the blank removal are as follows (filenames with 1100 is with blank removal, filenames with 1105 are without blank removal)

Re: Ghost data in buffer

Posted: Tue Jul 18, 2023 9:17 am
by Dave_VUB
some settings I used are:
- exposure 4s
- gain 2dB
- baseline removal alg enabled

Re: Ghost data in buffer

Posted: Tue Jul 18, 2023 2:11 pm
by Luc
Is the setup at the VUB main campus in Etterbeek?

If so, maybe we can arrange a visit so that I have a look at your setup directly. Contact me via private message if you're interested.

Re: Ghost data in buffer

Posted: Thu Jul 20, 2023 12:20 pm
by Dave_VUB
Hi, I would love to have a personal visit if possible