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Magnetron as a source of laser spectroscopy


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I was looking into microwave gun and I found magnetron as a source of directed microwave.

Now, is it possible to combine this with laser spectroscopy having magnetron being the power source(we all know how a radar works, it is just somewhere on the nanometer scale to visualize the brain) to visualize the brain? I have not worked out the power and wavelength required

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44 minutes ago, fredreload said:

Good call, all maser are powered by magnetron right? At least the sort of wide range maser device(multiple lasers), not a single maser build(single laser).

So far as I know, magnetrons are not coherent. They produce microwaves continuously in a process that does not lend itself to coherent production>
The radiating particles that generate the microwaves are free electrons.

Magnetrons produce directed radiation because of the focusing effect of their geometry.
But focused or directed is not the same as coherent.
Coherent radiation is produced when lots of tiny individual generators all act to produce their little wave packets so the packets are in phase with each other.
This can either be a pulsed or a continuous effect.

Laser and maser radiation is coherent.

Magnetron radiation may be turned on and off, but is continuous whilst on.

The coherence in a laser or maser comes from the fact that the generating particles are excited atoms or ions that can be 'triggered' to return to a lower state in unison, establishing the coherence of the emitted radiation that results from de-excitation. Of course the part of the atom that is excited and de-excited is an electron, but these are bound electrons, not free electrons.

Edited by studiot
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I imagine magnetrons were uses as sources of excitation when better sources we not (yet) available, but a better question might be whether spectroscopy tells you anything interesting, regardless of the source. Why limit your options?

 

Also, using “powered” or “power source” seems wrong in this context. 

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3 hours ago, swansont said:

I imagine magnetrons were uses as sources of excitation when better sources we not (yet) available, but a better question might be whether spectroscopy tells you anything interesting, regardless of the source. Why limit your options?

 

Also, using “powered” or “power source” seems wrong in this context. 

Hmm, my idea of spectroscopy imaging has to do with hyperspectral imaging, sort of like having a radar system mapping out a landscape. Of course depending on the type of radiation(say infrared) and the reflective index of the object(say neurons) you could generate slices of spectral image with depth.

5 hours ago, studiot said:

So far as I know, magnetrons are not coherent. They produce microwaves continuously in a process that does not lend itself to coherent production>
The radiating particles that generate the microwaves are free electrons.

Magnetrons produce directed radiation because of the focusing effect of their geometry.
But focused or directed is not the same as coherent.
Coherent radiation is produced when lots of tiny individual generators all act to produce their little wave packets so the packets are in phase with each other.
This can either be a pulsed or a continuous effect.

Laser and maser radiation is coherent.

Magnetron radiation may be turned on and off, but is continuous whilst on.

The coherence in a laser or maser comes from the fact that the generating particles are excited atoms or ions that can be 'triggered' to return to a lower state in unison, establishing the coherence of the emitted radiation that results from de-excitation. Of course the part of the atom that is excited and de-excited is an electron, but these are bound electrons, not free electrons.

Cool, about the coherent radiation coming from tiny individual generators, is there a device for this type of thing? (I kept thinking about the movie eraser with that theoretical pulse weapon lol)

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48 minutes ago, fredreload said:

Hmm, my idea of spectroscopy imaging has to do with hyperspectral imaging, sort of like having a radar system mapping out a landscape. Of course depending on the type of radiation(say infrared) and the reflective index of the object(say neurons) you could generate slices of spectral image with depth.

Sounds more like (horizontal) photogrammetry to me. Have you heard of it ?

https://www.google.co.uk/search?source=hp&ei=U-H0X9HwN-eOlwSx8JiQDA&q=photogrammetry&oq=photogramm&gs_lcp=CgZwc3ktYWIQARgAMggIABCxAxDJAzICCAAyAggAMgIIADICCAAyAggAMgIIADICCAAyAggAMgIIADoFCAAQsQM6CAgAELEDEIMBOggILhCxAxCDAToICC4QxwEQowI6CwguELEDEMcBEKMCOgsILhCxAxDHARCvAToCCC46BQguELEDOgsILhCxAxDJAxCTAjoICC4QxwEQrwE6BAgAEApQpAdYki9gokJoAnAAeAGAAdIHiAG0GJIBCTEuOC4xLjYtMpgBAKABAaoBB2d3cy13aXo&sclient=psy-ab

 

50 minutes ago, fredreload said:

Cool, about the coherent radiation coming from tiny individual generators, is there a device for this type of thing? (I kept thinking about the movie eraser with that theoretical pulse weapon lol)

I see you spotted the tiny individual generators.

Did you understand what I mean by in phase ?

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Posted (edited)
38 minutes ago, studiot said:

Ya, coherence, still working out on that part. The magnetron is supposed to create a railgun like effect I think

You excite the electrons and you shoot a photon through the column with mirrors on both side, charging it up. I am not sure if the electron is in an excited state from the thermionic emission though

https://en.wikipedia.org/wiki/Stimulated_emission

Edited by fredreload
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1 hour ago, fredreload said:

Hmm, my idea of spectroscopy imaging has to do with hyperspectral imaging, sort of like having a radar system mapping out a landscape. Of course depending on the type of radiation(say infrared) and the reflective index of the object(say neurons) you could generate slices of spectral image with depth.

What causes the different wavelengths to be emitted, for this imaging?

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1 hour ago, swansont said:

What causes the different wavelengths to be emitted, for this imaging?

The wavelength reflected from Raman Spectroscopy is because of the atomic structure of the atoms examined. Below is an interesting video showing how they find diamond through Raman spectroscopy in identifying the wavelength(toward the end of the video).

Well you see. If I want to examine the bone I use x-ray. Why? Because x-ray pass through the skin but gets reflected off the bones(x-ray has high frequency and short wavelength). Similarly if I want to examine the brain I would be interested in monitoring maybe the sodium concentration of the electrical synapses or map out the individual neurons of the nervous system.

Most conventional method you can find on Google about brain imaging is probably along the line of (drilling a hole on the skull and monitor the brain with a microscope) if you want nanoscale resolution.

So I went with Raman spectroscopy. Using laser somewhere in the infrared range(or ultraviolet https://journals.aps.org/pr/abstract/10.1103/PhysRev.15.110) would perhaps pass through the skin and bounce off the neurons/sodium/potassium of the brain, allowing for their imaging. The hyperspectral imaging would generate a map based on the collected wavelength exhibited.

Believe me they lit up my brain once by exciting the sodium in the brain, turning it into a sodium vapor lamp. But this gives off a wavelength in the visible light range somewhere around 594nm so ya, you cannot see it from the outside. They seem to be able to retrieve the image through the eyes though and that is how I got a glimpse of it.

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10 hours ago, fredreload said:

The wavelength reflected from Raman Spectroscopy is because of the atomic structure of the atoms examined. 

OK, but you didn't say you were doing Raman spectroscopy; how does this give you depth/location information?

 

Quote

Well you see. If I want to examine the bone I use x-ray. Why? Because x-ray pass through the skin but gets reflected off the bones(x-ray has high frequency and short wavelength). Similarly if I want to examine the brain I would be interested in monitoring maybe the sodium concentration of the electrical synapses or map out the individual neurons of the nervous system.

Reflected or absorbed?

 

Quote

Most conventional method you can find on Google about brain imaging is probably along the line of (drilling a hole on the skull and monitor the brain with a microscope) if you want nanoscale resolution.

MRI and PET don't image the brain?

Microscopes give nanoscale resolution?

 

Quote

So I went with Raman spectroscopy. Using laser somewhere in the infrared range(or ultraviolet https://journals.aps.org/pr/abstract/10.1103/PhysRev.15.110) would perhaps pass through the skin and bounce off the neurons/sodium/potassium of the brain, allowing for their imaging. The hyperspectral imaging would generate a map based on the collected wavelength exhibited.

Lasers are not magnetrons. How does the magnetron fit into this scheme? You mentioned power source, which makes no sense.  

 

 

 

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10 hours ago, fredreload said:

The wavelength reflected from Raman Spectroscopy

Enough is Enough !

 

I have tried to be helpful but you seem to be wandering all over the shop without properly understanding anything.

I am particularly worried about continued references to spectroscopy in relation to 'imaging'.
Your idea of imaging seems quite different from mine.

 

Imaging to me refers to creating some sort of pictures of the spatial disposition of the objects being imaged.

Raman spectroscopy is conducted on the randomly scattered light at near right angles to the beam and looses all of this spatial information.

You have not responded to my offering onphotogrammetry, which is what I thought you wanted.

If this is not the case please make clear what you are seeking before I can post again.

 

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On 1/4/2021 at 10:44 PM, fredreload said:

I was looking into microwave gun

Bad idea.

 

21 hours ago, fredreload said:

all maser are powered by magnetron right?

No

I suspect that no laser, or maser,  is powered by a magnetron.
Certainly most are not.

11 hours ago, fredreload said:

Most conventional method you can find on Google about brain imaging is probably along the line of (drilling a hole on the skull and monitor the brain with a microscope) if you want nanoscale resolution.

So I went with Raman spectroscopy.

You can not get nanoscale resolution with Raman spectroscopy.

You can not do Raman spectroscopy with microwaves.
You can not get nanoscale resolution with microwaves.

And, because the skull is in the way, you can't do Raman spectroscopy on the brain.

 

What do you think you are talking about?

11 hours ago, fredreload said:

Believe me they lit up my brain once by exciting the sodium in the brain, turning it into a sodium vapor lamp.

No, they did not.

11 hours ago, fredreload said:

. But this gives off a wavelength in the visible light range somewhere around 594nm so ya, you cannot see it from the outside. They seem to be able to retrieve the image through the eyes though and that is how I got a glimpse of it.

Nonsense.


 

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Posted (edited)
59 minutes ago, studiot said:

Enough is Enough !

 

I have tried to be helpful but you seem to be wandering all over the shop without properly understanding anything.

I am particularly worried about continued references to spectroscopy in relation to 'imaging'.
Your idea of imaging seems quite different from mine.

 

Imaging to me refers to creating some sort of pictures of the spatial disposition of the objects being imaged.

Raman spectroscopy is conducted on the randomly scattered light at near right angles to the beam and looses all of this spatial information.

You have not responded to my offering onphotogrammetry, which is what I thought you wanted.

If this is not the case please make clear what you are seeking before I can post again.

 

Like I said, hyperspectral imaging with spatial scanning. I am not sure what photogrammetry is but probably something similar :D?

https://en.wikipedia.org/wiki/Hyperspectral_imaging#Spatial_scanning

1 hour ago, swansont said:

OK, but you didn't say you were doing Raman spectroscopy; how does this give you depth/location information?

 

Reflected or absorbed?

 

MRI and PET don't image the brain?

Microscopes give nanoscale resolution?

 

Lasers are not magnetrons. How does the magnetron fit into this scheme? You mentioned power source, which makes no sense.  

 

 

 

Spatial scanning or Fourier Transform like MRI, still theorizing on that part.

37 minutes ago, John Cuthber said:

Bad idea.

 

No

I suspect that no laser, or maser,  is powered by a magnetron.
Certainly most are not.

You can not get nanoscale resolution with Raman spectroscopy.

You can not do Raman spectroscopy with microwaves.
You can not get nanoscale resolution with microwaves.

And, because the skull is in the way, you can't do Raman spectroscopy on the brain.

 

What do you think you are talking about?

No, they did not.

Nonsense.


 

Cuz I modded the design = =, I attempt to use the electrons in the magnetron as a laser source, I am just not sure if they are excited for stimulated emission coming from thermionic emission(please refer to how magnetron works video)

Edited by fredreload
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46 minutes ago, studiot said:

Imaging to me refers to creating some sort of pictures of the spatial disposition of the objects being imaged.

Raman spectroscopy is conducted on the randomly scattered light at near right angles to the beam and looses all of this spatial information.

Hyperspectral imaging using Raman microspectroscopy is a thing, the putative benefit being that images of various biochemicals can be acquired without the need for individual staining, as is currently done via immunohistochemistry. It's quite a specialised setup though.

I gather the OP speculates such techniques can be modified to allow brain imaging? If only. I've seen some transcutaneous experiments, mostly for blood glucose monitoring which isn't concerned with spatial information. Going through skin is one thing, i've never come across any set-ups even trying to penetrate bone.

I don't know physics, but one problem that straight away suggests itself is that if you are using longer wavelengths to achieve penetrance, then you are limiting the usefulness of any spatial information (as there is a dependence on wavelength and spatial resolution).

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27 minutes ago, Prometheus said:

Hyperspectral imaging using Raman microspectroscopy is a thing, the putative benefit being that images of various biochemicals can be acquired without the need for individual staining, as is currently done via immunohistochemistry. It's quite a specialised setup though.

It is also, as far as I can tell, not spatially-resolved process

 

27 minutes ago, Prometheus said:

 I don't know physics, but one problem that straight away suggests itself is that if you are using longer wavelengths to achieve penetrance, then you are limiting the usefulness of any spatial information (as there is a dependence on wavelength and spatial resolution).

Agree. There was mention of nanometer scale imaging, and I don't know how you do that with micron wavelength light.

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Posted (edited)
6 minutes ago, swansont said:

It is also, as far as I can tell, not spatially-resolved process

 

Agree. There was mention of nanometer scale imaging, and I don't know how you do that with micron wavelength light.

Well, Raman spectroscopy works based on reflection, but even then the wavelength of the source could impact the resolution, I'd say something in the infrared/UV range? Or if you guys know of a method I have not considered before @@

Edited by fredreload
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5 minutes ago, swansont said:

It is also, as far as I can tell, not spatially-resolved process

Does spatially-resolved have a specific technical meaning in this context? Spatial information is acquired by taking a spectrum from a defined location then shifting the stage slightly and taking a spectrum from an adjacent location and so on, then computationally stitching them all together.

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33 minutes ago, fredreload said:

Well, Raman spectroscopy works based on reflection, but even then the wavelength of the source could impact the resolution, I'd say something in the infrared/UV range?

Not reflection. It's absorption and emission as the electron drops into a different state. 

33 minutes ago, fredreload said:

Or if you guys know of a method I have not considered before @@

You might investigate what is already done, and why that works.

MRIs work because it's microwaves and magnetic fields, which can penetrate the skull. PET scans work because the ingested material concentrates in the cells under investigation and the positrons can penetrate the skull.

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5 hours ago, Prometheus said:

Hyperspectral imaging using Raman microspectroscopy is a thing, the putative benefit being that images of various biochemicals can be acquired without the need for individual staining, as is currently done via immunohistochemistry. It's quite a specialised setup though.

I gather the OP speculates such techniques can be modified to allow brain imaging? If only. I've seen some transcutaneous experiments, mostly for blood glucose monitoring which isn't concerned with spatial information. Going through skin is one thing, i've never come across any set-ups even trying to penetrate bone.

I don't know physics, but one problem that straight away suggests itself is that if you are using longer wavelengths to achieve penetrance, then you are limiting the usefulness of any spatial information (as there is a dependence on wavelength and spatial resolution).

Thank you for this.

OK so it is 'false colour imaging'

Quote

Coloured images are then generated from the PCs to reveal the spatial organization of the elements isolated as principal components. In our images, pixels with a high positive score for a given PC are assigned a false colour while pixels with high negative score are assigned a second colour, where the colour intensity corresponds to the relative contribution of the score.

So it is not a true photographic picture of what is there but a generated 'image', rather as Xray diffraction picture 'can measure' a lattice spacing.

Very clever work nonetheless.

 

I still maintain that this was not made clear at the outset.

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Posted (edited)
1 hour ago, studiot said:

Thank you for this.

OK so it is 'false colour imaging'

So it is not a true photographic picture of what is there but a generated 'image', rather as Xray diffraction picture 'can measure' a lattice spacing.

Very clever work nonetheless.

 

I still maintain that this was not made clear at the outset.

My bad, I was a bit skeptical to say transform the spatial spectrum to an RGB pixel color, my mind sort of think that is the possibility but it was never revealed in the Wikipedia link @@, so ya, thanks for the clarification. And after reviewing Raman Spectroscopy I will post the video here. I guess I was a bit unclear about the concept

 

Edited by fredreload
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On 1/6/2021 at 6:01 AM, studiot said:

I see you spotted the tiny individual generators.

Did you understand what I mean by in phase ?

Many thanks for the hint. I chose magnetron in the first place because of its wide range of em wave emission. It seems the stimulated emission of the electrons from thermionic emission should be in phase and also covers a wide range. It is just, I do not know the working mechanism for laser for stimulated emission to get the electrons to an excited state. Correct me if I am wrong

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