Question: Is it possible to output a serial port command (CL Acquisition)?

[RIKO]

John,

Update, I got the probe time  to try the QE-Pro, the software able to detect it, and detect the emission spectrum.
Instead of using a longer count time, I found averaging -average of multiple short period acquisition -  is better to improve the signal to noise ratio.

My problem now, how do I export the CL spectrum out from the db?

[John Donovan]

John,

Update, I got the probe time  to try the QE-Pro, the software able to detect it, and detect the emission spectrum.
Instead of using a longer count time, I found averaging -average of multiple short period acquisition -  is better to improve the signal to noise ratio.

My problem now, how do I export the CL spectrum out from the db?

Hi Riko,
Awesome.  What exactly did you do to acquire the best spectra?

From the Run menu use the CL display menu and use the EMSA format export-  I don't have an OEM export method implemented at the moment.
john

[RIKO]

Hi John,

Got it. Now I need to figure out how to read emsa format.
Am I correct to say that the first column (after keyword #spectrum) is the wavelength, and the second one is the intensity?
If yes, the number seems to be too large. Should they multiply by some factor?

To get a clean signal, I did the following steps manually:
1. Get the dark spectra with 500ms integration time, and
2. Repeat (1) four times (or as necessary), save them separately.
3. Average the dark spectra
4. Get the  CL spectra with 500ms integration time (should be the same as dark ref)
6. Subtract the CL spectra with the dark spectra.
6. Repeat (3) and (4) four times
7. Average of all four (CL minus dark) is the final spectra.

[John Donovan]

Hi John,

Got it. Now I need to figure out how to read emsa format.
Am I correct to say that the first column (after keyword #spectrum) is the wavelength, and the second one is the intensity?
If yes, the number seems to be too large. Should they multiply by some factor?

To get a clean signal, I did the following steps manually:
1. Get the dark spectra with 500ms integration time, and
2. Repeat (1) four times (or as necessary), save them separately.
3. Average the dark spectra
4. Get the  CL spectra with 500ms integration time (should be the same as dark ref)
6. Subtract the CL spectra with the dark spectra.
6. Repeat (3) and (4) four times
7. Average of all four (CL minus dark) is the final spectra.

The first column in the dark spectrum intensities and the second column is the light spectrum intensities.

The thing is I'm surprised that you need to average them manually because the way I acquire them is by summing a number of short integration times.

For example, let's say you specify 10 seconds for the CL acquisition time.  The software divides that into intervals based on the RealTimeInterval specified in your Probewin.ini file which is usually around 400 milliseconds or so. It then adds those 400 ms integrations together for the total spectra.

So summing or averaging fractional second integrations, one should get the same results I would think!

[RIKO]

For example, let's say you specify 10 seconds for the CL acquisition time.  The software divides that into intervals based on the RealTimeInterval specified in your Probewin.ini file which is usually around 400 milliseconds or so. It then adds those 400 ms integrations together for the total spectra.

So summing or averaging fractional second integrations, one should get the same results I would think!

John,

I think there are small difference between those two methods. On my method, the the random noise is cancelling each other, while your implementation seem to be not.

On my methods, I've subtracted the light spectrum intensities with the dark references before summing it up. In this way, I will end up with some pixels to have positive and some negative value. This is useful to remove some random noise, particularly  for some non-emitted wavelengths. Averaging those positive and negative value should give me a zero average. I've also make sure to take the dark ref with the same acquisition time with the light spectrum to get the same noise characteristic for both.

On the other hand, on your implementation, it seem that you are summing all the short acquisition. Since all the pixels are having a positive value, we will end up accumulate the random noise if we just simply sum them up.

[John Donovan]

For example, let's say you specify 10 seconds for the CL acquisition time.  The software divides that into intervals based on the RealTimeInterval specified in your Probewin.ini file which is usually around 400 milliseconds or so. It then adds those 400 ms integrations together for the total spectra.

So summing or averaging fractional second integrations, one should get the same results I would think!

John,

I think there are small difference between those two methods. On my method, the the random noise is cancelling each other, while your implementation seem to be not.

On my methods, I've subtracted the light spectrum intensities with the dark references before summing it up. In this way, I will end up with some pixels to have positive and some negative value. This is useful to remove some random noise, particularly  for some non-emitted wavelengths. Averaging those positive and negative value should give me a zero average. I've also make sure to take the dark ref with the same acquisition time with the light spectrum to get the same noise characteristic for both.

On the other hand, on your implementation, it seem that you are summing all the short acquisition. Since all the pixels are having a positive value, we will end up accumulate the random noise if we just simply sum them up.

Hi Riko,
I don't quite get why your method of performing the net intensity subtraction for each integration would provide better data than performing the net intensity subtraction after summing them.   Mathematically they are exactly equivalent...

Unless there is some non-linearity with the spectromotor that changes with each sub second interval acquisition?

But still I'd like to try and figure out how to make your net (light - dark) method an option in my software.  The problem is, I want to keep both the dark and the light spectra stored separately, not just the net intensities.  Storing the dark and light spectra for each sub second interval would be an excessively large amount of data.  Also doing a light - dark net subtraction would require inserting the faraday cup for each integration!  We don't want to interrupt the WDS/EDS acquisition!

Maybe I could just add a third storage array for the net spectra. That way I could perform a net subtraction for each sub second acquisition and store that as an accumulation, instead of calculating it on the fly after all acquisitions are complete...  I would have to add it as a third column in the EMSA file.

I guess I don't quite understand why your net method would work better.  Random noise should still average out over time.  Can you provide some examples here of the two methods compared?
john

[RIKO]

John,

Yes they should be the same. But just to be sure, when I set the count time set at 40 sec and  "dark fraction time" to 0.5, does that means it will use 20 sec for the dark ref, and 20 sec for light spectrum? If that is the case, then you are right, both method should be the same.

Another thing on the emsa file. The first pixel, the dark ref is larger than the light spectrum. Don't you think that is kind of odd?

[John Donovan]

Yes they should be the same. But just to be sure, when I set the count time set at 40 sec and  "dark fraction time" to 0.5, does that means it will use 20 sec for the dark ref, and 20 sec for light spectrum? If that is the case, then you are right, both method should be the same.

Hi Riko,
No, the dark fraction time only applies to the dark spectrum acquisition.  So if you set the count time to 40 and the dark fraction time to 0.5, it will acquire the dark spectrum for 20 seconds and the light spectrum for 40 seconds.

I did this because I assume some people won't care too much about the dark spectrum and so would want a shorter time spent on the dark spectrum.

Another thing on the emsa file. The first pixel, the dark ref is larger than the light spectrum. Don't you think that is kind of odd?

I had it backwards.  The light spectrum is the first column, the dark spectrum is the second column.  Sorry.
john