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Raman-spectroscopy

chloderic

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Hello,

the entire project is considered in detail quite complex and therefore not in a slip here to describe.
So I apologize for the fact that there are quite a few individual postings here,
but even the processing of all descriptions is associated with a lot of work
and the number of pictures would blow up the frame of a single post.

Here's the next part:

In addition to the already described component of the IR holder further side walls are equipped with functions.
The used DPSS laser has to be attached to the module in a stable position,
for this I have constructed a traverse.

1.jpg

This is flanged to the pre-existing threads and holes in front of the inlet (IR filter side).

2.jpg

3.jpg

The internally positioned dichroic does not reflect the total laser power at right angles to the subject.
I would not like to leave the rest (partly polarized) inside the ucube and therefore I just placed a side wall with a central hole on this opposite side.
Here I also see if the laser is placed in about centric position.

4.jpg

The stoke signal used for the evaluation must be bundled on the side opposite the objectiv and fed to the fiber.
For this I use again the collimator from the already known assembly of the beamsplitters of B & W-Tek.
Of course, other solutions are also easily feasible here, because almost any technical solution can be printed in 3D.
This collimator has a special fine thread, which I could actually print.
5.jpg

6.jpg

This assembly is placed in front of the long-pass filter inside and already described on the assembly side of the dice opposite the lens.
I have mounted several types of filters in such 30 x 30 x 10 mm holders,
which I can later try out or combine.

7.jpg

Once again a reminder of a picture of the functional whole assembly,
this can now be modified in further steps, that the handling of objects to be examined is guaranteed.

8.jpg

Finally, for this log a picture of the first functional result.
A clean clear signal in the strength of about 5000 counts exactly 1332cm-1 in stoke direction, so diamond.
So much in advance ..... there is still a lot more possible ....

9.jpg
 
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chloderic

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Hello,

In the next step, I significantly increased the efficiency of the assembly.
For this I had to find out which type of lens is most suitable for this compilation.
So that the comparison can take place under the same conditions I replaced the last used lens objectiv by a used microscope objective changer.
In this case, the changer has four positions with RMS thread.
So I can use at least some of my existing lenses from a cheap microscope.

1.jpg

The rear connection also has an RMS thread in this case, there are of course many other connection constructions.

2.jpg

Because of the eccentric change construction, I had to design a new side wall with an expansive cylindrical thread connection.
The necessary internal thread for this is now known and printable.

3.jpg

The fourth of the test objectives should be the already known from the beam splitter of B & W-Tek, because it has certain "characteristics" ...
In order to use this, I first measured this thread.

4.jpg

5.jpg

Now I have to print an adapter ring for this lens,
that had also worked quite well and the objective can easily be screwed to the revolver.

6.jpg

Now equipped with 4 different lenses, the unit can simply be tested by rotating the revolver under the same conditions.
The overall structure of ucube allows you to simply swap one side panel or one insert for other functions.

7.jpg

8.jpg

By far the best are the results with the B & W-Tek lens, because this has a convex surface inside, so that the laser reflections
expand and, together with the antireflex coating, give the least amount of reflection in the direction of the spectrometer.
In addition, the opening ratio is quite large and scattered reflections in the interior are minimized if the laser is not exactly centered.

Here is the result, left the rest of the laser with about 22,600 counts, which can be eliminated by a second filter and
right the raman signal from the diamond at stoke 1332cm-1 with 62.500 (!) counts and a resolution of MWHM 0.8nm.
Now I want to say here, that you can not get out more with such equipment. (Compare it with the last posted spec obove...).

9.jpg

Finally, then a preview of the next experimental setup (follows),
Here you can see the objective revolver described here.
The final assembly in a microscope I show later.

10.jpg


Bernd
 

chloderic

Active member
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For those of you, who have an ocean optics usb spectrometer i found a free software to examine gem.

It should run with Ocean Optic’s OmniDrive

Link: www.gemmoraman.com/Downloads.aspx

I have no such device and can not test it ..... maybe Paul ?

Unbenannt.JPG
 
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Joined
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Messages
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Points
43
Hello,

since I was asked here how the project is going on, i have decided to skip a few intermediate and test series as a posting.

Here are the essential parts for a complete device.

The various components should be attached to a microscope in one of the possible configurations.
At this microscope the objective tube is attached with a dove-tail connection.

After some attempts and irritations between zeiss-west and zeiss-east I printed such a dove-tail for the cube.

1.jpg

Of course, this connection as a side wall can be adapted modularly to the described cube.

2.jpg

The flanged laser has a certain weight, so I needed some support, which should also be screwed to the cube

3.jpg

4.jpg

The spectrometer board should also be attached to the cube here, also printed in 3D.

5.jpg

Together with the already known SMA adapter and a fiber optic it looks like this.

6.jpg

Now here the whole assembly mounted on the microscope, it is a cheap lomo biolam bought used for 25 Eur.
This is quite enough as a mechanical stable component for this function, because optically only the printed parts and the recycled parts from the B & W TEK as well as the various filters and dichros are installed.

7.jpg

8.jpg

This entire unit works perfectly with very high sensitivity in terms of the technical possibilities of the individual components.
Here is an additional spectrum of sulfur; as with spectra almost always the case, you can see in the spectrum the usual additional fluorescences.
I need to add a few Mw more of laser power to generate a raman signal from this mineral.
On the far left is still residual radiation 532nm to see, also because only one edge filter is installed, left of it the useful signal.

9.jpg

There will be a few additional attachments to follow if anyone is interested.

Greeting

Bernd
 
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