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RAMAN-spectroscopy

chloderic

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Yes sir ... now i see it here ... thanks a lot for sharing.
 

kecked

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Finally got my 538nm edge filter. Is it normal to still see a little light directly through the filter. I put 50mw directly in and see like 1mw out. Pretty good but had hoped to see nothing.
 

chloderic

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Finally got my 538nm edge filter. Is it normal to still see a little light directly through the filter. I put 50mw directly in and see like 1mw out. Pretty good but had hoped to see nothing.
Interesting .... could you please post the type of this filter and the source , maybe a datasheet ?
In the first i would think about the beam-structure .. is it colominated ...?
 

kecked

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https://www.ebay.com/itm/283010042988?ul_noapp=true

I put 50mw in and see barley 1 mw out so indirect I think it will work for raman. Will let you know. So far All I have is the laser and filter. Have not done anything else yet.

I plan to let the laser illuminate the sample and then collect the light with a microscope objective. The filter will be on the back of the objective and go out via fiber to the spec. I would try using the filter as dichro to put the beam and signal coplanar but am unsure of the leaking. I don't think it will matter how I illuminate the sample since the scatter is in all direction so I can get a bit of isolation by not using the filter as a bounce mirror.
 

chloderic

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https://www.ebay.com/itm/283010042988?ul_noapp=true

I put 50mw in and see barley 1 mw out so indirect I think it will work for raman. Will let you know. So far All I have is the laser and filter. Have not done anything else yet.

I plan to let the laser illuminate the sample and then collect the light with a microscope objective. The filter will be on the back of the objective and go out via fiber to the spec. I would try using the filter as dichro to put the beam and signal coplanar but am unsure of the leaking. I don't think it will matter how I illuminate the sample since the scatter is in all direction so I can get a bit of isolation by not using the filter as a bounce mirror.
Hello, wow, that was a quick answer!

This will certainly be an interesting project, please keep us informed about the progress ... maybe with some pictures?
From this ebayer (probably reseller of Thunder Optics) I have already bought a filter,
this was a little bit bigger, cut on a bit longer wave but steeper and the transmission curve is smoother,
Raman SharpEdge Filter for 532nm Laser, 540nm CutOn 25mm Research Grade; but, as you can see on the graph, Raman collected light can pass from 535nm. This is equivalent to 105cm-1 in Raman shift.

Have a look here:

https://www.ebay.de/itm/Raman-Sharp...095086?hash=item41eb6453ee:g:q2AAAOSwNRdX2tl9

Take a look at the third picture, can it possibly be that your laser above 532nm has another emmission?
If so, then you need a clean up filter ...

Because of your profile, I actually thought that you have already realized a raman system ...?

Please let us participate in your progress.

greetings

Bernd
 

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kecked

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I got them working but they were all duct tape quality units. Get spectrum move on. This is the final design for use in my algae toxin research. The Zeiss isn't mine but I use it here at the university. That's a 100k unit. This design is meant for doing materials testing of graphene 2d 3d for some battery work I'm playing with. Making electrodes.

My dpss does produce a second line but its very close in. Think your right and I'll add a clean up filter on it. I was just surprised to see anything pass through from the laser. Iwanted to measure the 808 1064 leaking from it and figured this would really knock down the primary so I can see some detail in the smaller peaks. For 65.00 I'm not complaining and for graphene this will be fine.
 

paul1598419

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@chloderic

I was surprised to see the shipping cost of your sharp edge filter. Maybe that is the shipping to me, but $60.00 for a 1 inch filter seems excessive. I can certainly ship it to France for less than that.
 

chloderic

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@chloderic

I was surprised to see the shipping cost of your sharp edge filter. Maybe that is the shipping to me, but $60.00 for a 1 inch filter seems excessive. I can certainly ship it to France for less than that.
Because of this i contacted Thunder Optics directly and we found a solution ouside of ebay for less shipping cost. But .... it was not easy ...
 

paul1598419

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Good for you. I would also try to find a way around such a ridiculous shipping charge.
 

chloderic

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Good for you. I would also try to find a way around such a ridiculous shipping charge.
Hello Paul,

if you are interested in special filters on this topic, the reseller of Thunder optics is certainly not the 1st choice for you.
He also sources his filters from the USA, therefor the high freight costs he sells in his auctions and on the online shop on his homepage.

Based on the published transmission data sheets, I assume that he sells some of the products from the aforementioned bjomejag there.

In the webshop of bjomejag in the bay one finds many such filters from overproduction of Omega Optical (Welcome to Omega Optical | Omega Optical) at very reasonable prices.

Here is his shop on ebay:

https://www.ebay.de/usr/bjomejag?_trksid=p2047675.l2559

greetings

Bernd
 
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paul1598419

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Thanks, Bernd. I was thinking about maybe trying to set up a Raman spectrometer, but I think I could get these filters cheaper here in the US. I don't currently have a use for this, but did want to follow how everyone here got to make their own version of these.
 
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I subscribed to the thread without writing anything. But it annoys me to see all capitals in Raman when I receive emails about new posts. It's not an acronym, it's a person name. Would it be possible to change/correct it?

Hopefully someone will not create a thread about CARS LOL
 

kecked

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Well the filter does work. There is a tiny bit of leakage but it's workable. The filter is really sensitive to angle for the leaking so it is important to align the laser source and the filter. Not too hard but unexpected. I did check the laser for a second line and did NOT find one. Laser is 532-534 depending on temperature. That's a lot to ask for a 538 edge filter.

I noticed I just crossed the 10 million line for rep+ thank you all. Given my sub 242 posts that seems pretty quick. Anyone ever do it faster? Looks like chloderic is not far behind.
 
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chloderic

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Well the filter does work. There is a tiny bit of leakage but it's workable. The filter is really sensitive to angle for the leaking so it is important to align the laser source and the filter. Not too hard but unexpected. I did check the laser for a second line and did NOT find one. Laser is 532-534 depending on temperature. That's a lot to ask for a 538 edge filter.
Yes kecked, we talked about this here, you can shift the wavelenght of the filter a litte bit by rotating , therefor it is needed to have a collimated beam ....

Maybe have a look at this , there is a formula to calcutate it:

https://www.semrock.com/filter-spectra-at-non-normal-angles-of-incidence.aspx
 

paul1598419

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Nice work, guys. Just wanted to give chloderic some + rep. I need to spread some more before getting back to you, kecked.
 

chloderic

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Hello everybody,

in the last few weeks, I've been working on a new Raman device for a while.
I wanted to illustrate this in the first commissioning of the prototype.
I printed my construction of the optical unit with my 3-D printer.
In the cube with edge length 58mm are IR filter, laser line cleaning filter 0.9nm,
dichro beam splitter 50/50, microscope objective, longpass changeable filter,
collimator optics and sma connection integrated.
Adapted a traverse for a 532nm DPSS LASER and an analog / digital control.
If interested, I will also like to detail the construction here,
but , as you know, this is connected with a little work and therefore can only be done gradually.


1.jpg
2.jpg 3.jpg 5.jpg

Greetings

Bernd
 




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