## What microscope has this style?

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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portbon
Posts: 21
Joined: Wed Nov 18, 2020 12:54 am

### Re: What microscope has this style?

microb wrote:
Fri Nov 20, 2020 12:12 pm
Scarodactyl wrote:
Fri Nov 20, 2020 6:58 am
microb wrote:
Fri Nov 20, 2020 4:12 am
I still don't understand how wavenumber is supposed to make comparable numbers independent of the nm laser used.
Raman spectroscopy looks at the shift between the input wavelength and what bounces back, which is independent of input wavelength. So what you're graphing is the spectrum of the raman shift in inverse centimeters.
I've read that too, and like a bad manual that spends pages on how to plug the product into an outlet, the details on the internet on this are lacking. And I assume it's not actually complicated, but no one's willing to write it down anywhere.

Apparently a normal spectrometer can be used.

But if I have n samples 200nm to 800nm, and the laser let's say at 532nm plus or minus 10nm of data is ignored, the Raman graph has to involve manipulating (intensity,nm) pairs. So it appears we're just going to re-order the nm's and keep the intensities at the same levels.

The graphs are normally 0 to 4000.

Ok, so I found a posting to answer the above:

"As for data processing, one starts by converting the laser wavelength to wavenumbers. I use a simple trick: wavenumbers (cm-1) = 1e7 / wavelength (nm). Say your laser is at 532nm. Converting that to wavenumbers: laser wavenumber = 1e7/532 = 18797 (cm-1). Now using that same formula convert all the other wavelength data over to wavenumbers. In a final step, subtract all the wavenumbers of the spectrum data from the laser wavelength wavenumber. All the data that falls on the positive side of zero are the Stokes line data. All the data that falls on the negative side of zero are the anti-Stokes line data. One normally drops the anti-Stokes data, but not always. Normally, the wavenumber data are displayed on a 0 to 4000 cm-1 scale, similar to a standard IR spectrum.
Now you have a vibrational spectrum (similar to an IR spectrum) where the peaks are in terms of wavenumber shift from the excitation (the laser). Hence one often speaks of the "Raman shift" of a vibrational line."
This is how the 4000 cm-1 come out from the 532nm Raman spectrometer.
I used this url to convert between nm and cm-1

https://convert.impopen.com/index.php

532nm = 18796.99 cm-1
18796.99 cm-1 – 4000 cm-1
14797cm-1 = 675.81nm
So my Raman system has range of 532nm to 675.81nm giving difference of 4000 cm-1

It can only measure strokes shift. A strokes shift is lower in frequency so higher in wavelength hence 532nm to 675.81nm and not lower.

My raman has converging laser focused 20mm from front of lens. Does anyone know what kind of lens I should use to convert it to parallel (or whatever required by microscope)? so it can be used in a transmitted microscope? And what is the least expensive transmissive microscope I can insert the parallel laser (after it becomes parallel via some kind of lens)?

Also a Raman setup has simple parts. Mine has the above parts too. How can it cost \$15000? Maybe the parts cost only \$1000 or less? What you think? Even though I own a Raman. I'm still a beginner in it.

microb
Posts: 449
Joined: Wed Mar 27, 2019 6:39 am

### Re: What microscope has this style?

portbon wrote:
Sun Nov 22, 2020 12:52 am
My raman has converging laser focused 20mm from front of lens. Does anyone know what kind of lens I should use to convert it to parallel (or whatever required by microscope)?
Thanks for the info on the Raman set up.

For lens assembly, you want to take light that is focused 20mm from your existing set up and collimate the beam to work with an infinity focus system. Here are three options. Please anyone else that knows better than me speak up. I'd like to know too:

1) Hard to find option: So If you add a plano concave (https://www.edmundoptics.com/f/experime ... ses/14468/ -- click the technical images tab to see the diagram) theoretically you could do what you want in one additional lens. It might be hard to find though. Lets say you find one of focal length -15mm, point the flat side to the Raman lens of 20mm FL so the concave side points out and is placed about 5mm away from the Raman existing lens (approximate because the center point P in the Edmunds diagram mentioned above is inside somewhere, you'll need the spec) . Basically look at the technical images tab of this page (https://www.edmundoptics.com/f/experime ... ses/14468/) and put the FL point given to coincide with your 20mm FL point. The light will now be collimated -- infinity focus. Use an achromat lens -- a doublet. And if you use a high power high freq laser maybe the laser will fry the cement as someone else pointed in another post, but probably not. You're using a green laser pointer level laser with some extra umph I assume.

2) Cool and interesting option: Finding a plano concave doublet to work with option 1 above with such a small FL number might be hard. So you can bend that 20mm FL out a bit more, and in fact customize to what you need. Look at the section called "Adding negative lens elements" from this page: (https://www.flickr.com/groups/homemadel ... 612617105/). That math can be used to find lenses to send your 20mm FL out several more millimeters, let's say 110mm. Now you get yet another lens, let's say the lens added to stretch things out to 110mm is -- I don't know -- 10mm in front of your existing 20mm FL lens. So you get a second lens, a plano concave, that's -70mm FL. Place that 70mm back from the 110mm focal point and it will collimate the light to infinity focus as described in option 1 above.

3) This is the you'll-probably-do-it-this-way option: Another option is 4F. Check the googles for 4F lens assembly and click the image tab. You'll see the optical diagrams pop up fast. You're 20mm FL lens is the first lens. The second is some other lens you buy. Get a doublet, plano convex (www.surplusshed.com has cheap stuff) and put it at it's focal length (FL) away from your existing lens (flat side away from your existing lens) but add 20mm. Position to get the new lens to focus on the focus point of your existing lens. Technically the image flips here, but you are doing a light source so who cares. Now the two lenses (old and newly bought) work together to collimate the beam. But it also means your laser light hits a tiny point 20mm away from your existing lens, which in this case is fine. But if you use more powerful lasers in the future for LIBS for example, I'm told you can sizzle the air making it pop at that focal point so it's best to use a beam expander that avoids the 4F set up (option 2 above but that's not needed here). But you're using a lower power non-q-switched laser. So 4F is easiest.

portbon
Posts: 21
Joined: Wed Nov 18, 2020 12:54 am

### Re: What microscope has this style?

microb wrote:
Sun Nov 22, 2020 2:00 am
portbon wrote:
Sun Nov 22, 2020 12:52 am
My raman has converging laser focused 20mm from front of lens. Does anyone know what kind of lens I should use to convert it to parallel (or whatever required by microscope)?
Thanks for the info on the Raman set up.

For lens assembly, you want to take light that is focused 20mm from your existing set up and collimate the beam to work with an infinity focus system. Here are three options. Please anyone else that knows better than me speak up. I'd like to know too:

1) Hard to find option: So If you add a plano concave (https://www.edmundoptics.com/f/experime ... ses/14468/ -- click the technical images tab to see the diagram) theoretically you could do what you want in one additional lens. It might be hard to find though. Lets say you find one of focal length -15mm, point the flat side to the Raman lens of 20mm FL so the concave side points out and is placed about 5mm away from the Raman existing lens (approximate because the center point P in the Edmunds diagram mentioned above is inside somewhere, you'll need the spec) . Basically look at the technical images tab of this page (https://www.edmundoptics.com/f/experime ... ses/14468/) and put the FL point given to coincide with your 20mm FL point. The light will now be collimated -- infinity focus. Use an achromat lens -- a doublet. And if you use a high power high freq laser maybe the laser will fry the cement as someone else pointed in another post, but probably not. You're using a green laser pointer level laser with some extra umph I assume.

2) Cool and interesting option: Finding a plano concave doublet to work with option 1 above with such a small FL number might be hard. So you can bend that 20mm FL out a bit more, and in fact customize to what you need. Look at the section called "Adding negative lens elements" from this page: (https://www.flickr.com/groups/homemadel ... 612617105/). That math can be used to find lenses to send your 20mm FL out several more millimeters, let's say 110mm. Now you get yet another lens, let's say the lens added to stretch things out to 110mm is -- I don't know -- 10mm in front of your existing 20mm FL lens. So you get a second lens, a plano concave, that's -70mm FL. Place that 70mm back from the 110mm focal point and it will collimate the light to infinity focus as described in option 1 above.

3) This is the you'll-probably-do-it-this-way option: Another option is 4F. Check the googles for 4F lens assembly and click the image tab. You'll see the optical diagrams pop up fast. You're 20mm FL lens is the first lens. The second is some other lens you buy. Get a doublet, plano convex (www.surplusshed.com has cheap stuff) and put it at it's focal length (FL) away from your existing lens (flat side away from your existing lens) but add 20mm. Position to get the new lens to focus on the focus point of your existing lens. Technically the image flips here, but you are doing a light source so who cares. Now the two lenses (old and newly bought) work together to collimate the beam. But it also means your laser light hits a tiny point 20mm away from your existing lens, which in this case is fine. But if you use more powerful lasers in the future for LIBS for example, I'm told you can sizzle the air making it pop at that focal point so it's best to use a beam expander that avoids the 4F set up (option 2 above but that's not needed here). But you're using a lower power non-q-switched laser. So 4F is easiest.
Wait. The focal length of my Raman is 75mm. What I meant by 20mm was the distance from edge of ring to sample. But the focal length is 75mm as shown in the following specification. How would it change the above? Would it become easier or harder? Thanks.

Again. If you guys will assemble it from scratch. Will it cost \$15,000? What is the cheapest Raman out there and how is it?

Scarodactyl
Posts: 1046
Joined: Sat Mar 03, 2018 9:09 pm

### Re: What microscope has this style?

I have a handheld raman (an Ahura Firstdefender) which my dad and I figured out how to insert custom libraries into so we could use it for gem ID (along with some custom software and hardware for positioning). I also sell these to gemologists and they cost a lot less than 15k all in, though they might not be as suitable for what you want to do. I have not yet figured out getting one hooked up to a microscope, but I found a -18mm lens in front of the 18mm focusing lens seems to collimate the red reference laser fine--this is a 780nm system so we can't directly see the actual laser, and as such our tests were pretty brief and careful. but I think it should be plenty possible to collimate the laser and hook it up to a coaxial illuminator in a microscope.
You can get a Nikon infinity coaxial illuminator pretty inexpensively, which would be what I vaguely plan to use for this.

microb
Posts: 449
Joined: Wed Mar 27, 2019 6:39 am

### Re: What microscope has this style?

portbon wrote:
Sun Nov 22, 2020 2:53 am

Wait. The focal length of my Raman is 75mm. What I meant by 20mm was the distance from edge of ring to sample. But the focal length is 75mm as shown in the following specification. How would it change the above? Would it become easier or harder? Thanks.
Probably easier since you can probably find a negative 20 to 40-something FL plano-concave lens that will fit between the existing lens and the focus point.

Still don't know what the 20mm was then.

As for parts, seems like the first two items here are the expense things. Could go for a good narrow notch filter for \$300 instead, but the beamsplitter with a hard edge sends 100% laser to the sample compared to a normal beam splitter with notch filter:

Ocean spectrometer (pretty good quality even used) \$600 to \$800
Beamsplitter with hard edge (https://www.semrock.com/filters.aspx?id ... =0&recs=10) \$500 to \$600
Lenses (Edmund Optics, Thorlabs) \$10 to \$80 depending
Fiber (Thorlabs fancy \$120 or ebay \$20 to \$30)

Software maybe to automatically ID materials maybe? Price? Don't know.

portbon
Posts: 21
Joined: Wed Nov 18, 2020 12:54 am

### Re: What microscope has this style?

microb wrote:
Sun Nov 22, 2020 5:23 am
portbon wrote:
Sun Nov 22, 2020 2:53 am

Wait. The focal length of my Raman is 75mm. What I meant by 20mm was the distance from edge of ring to sample. But the focal length is 75mm as shown in the following specification. How would it change the above? Would it become easier or harder? Thanks.
Probably easier since you can probably find a negative 20 to 40-something FL plano-concave lens that will fit between the existing lens and the focus point.

Still don't know what the 20mm was then.

As for parts, seems like the first two items here are the expense things. Could go for a good narrow notch filter for \$300 instead, but the beamsplitter with a hard edge sends 100% laser to the sample compared to a normal beam splitter with notch filter:

Ocean spectrometer (pretty good quality even used) \$600 to \$800
Beamsplitter with hard edge (https://www.semrock.com/filters.aspx?id ... =0&recs=10) \$500 to \$600
Lenses (Edmund Optics, Thorlabs) \$10 to \$80 depending
Fiber (Thorlabs fancy \$120 or ebay \$20 to \$30)

Software maybe to automatically ID materials maybe? Price? Don't know.
What I meant by 20mm is the distance between the edge of the ring holder and the focus. When I put any object in front of this (the center has a small hole), it is in focus. So the 75mm focal length means there is 50mm inside to another lens?

Without the front attachment, the lens is almost in the edge of the ring. So I need to find a plano concave lens with focal length of 20mm. Here seems to be one.
https://www.amazon.com/Diameter-Plano-c ... B013SL7W08

Why is 20mm plano concave lens so hard to find?

Do you have any idea what kind of lens is the above? The focal length is 75mm. But there is a lens just 20mm from focus. I wonder if the lens is just a glass protecting the inside and no divergent or converging function. How do you test what kind of lens is it?

So Raman spectrometer is overpriced? But note the \$15,000 seems to be the cheapest. The Thermo Fisher RMX handheld is being sold for more than \$25,000.
Last edited by portbon on Sun Nov 22, 2020 1:35 pm, edited 3 times in total.

Scarodactyl
Posts: 1046
Joined: Sat Mar 03, 2018 9:09 pm

### Re: What microscope has this style?

The ones I sell are used surplus, so a pretty different msrket. New they were 48k or so. The rmx is typically a lot more than 25k from the purchase orders I've seen (sometimes available from public budgets when fire departments and such buy them), though I haven't ever bought one new.
So I wouldn't say it's overpriced if you're buying new and it does what you want. Raman spectrometry is an incredible tool, and if you're in the gem business it can practically change your life.

portbon
Posts: 21
Joined: Wed Nov 18, 2020 12:54 am

### Re: What microscope has this style?

portbon wrote:
Sun Nov 22, 2020 8:04 am
microb wrote:
Sun Nov 22, 2020 5:23 am
portbon wrote:
Sun Nov 22, 2020 2:53 am

Wait. The focal length of my Raman is 75mm. What I meant by 20mm was the distance from edge of ring to sample. But the focal length is 75mm as shown in the following specification. How would it change the above? Would it become easier or harder? Thanks.
Probably easier since you can probably find a negative 20 to 40-something FL plano-concave lens that will fit between the existing lens and the focus point.

Still don't know what the 20mm was then.

As for parts, seems like the first two items here are the expense things. Could go for a good narrow notch filter for \$300 instead, but the beamsplitter with a hard edge sends 100% laser to the sample compared to a normal beam splitter with notch filter:

Ocean spectrometer (pretty good quality even used) \$600 to \$800
Beamsplitter with hard edge (https://www.semrock.com/filters.aspx?id ... =0&recs=10) \$500 to \$600
Lenses (Edmund Optics, Thorlabs) \$10 to \$80 depending
Fiber (Thorlabs fancy \$120 or ebay \$20 to \$30)

Software maybe to automatically ID materials maybe? Price? Don't know.
What I meant by 20mm is the distance between the edge of the ring holder and the focus. When I put any object in front of this (the center has a small hole), it is in focus. So the 75mm focal length means there is 50mm inside to another lens?

Without the front attachment, the lens is almost in the edge of the ring. So I need to find a plano concave lens with focal length of 20mm. Here seems to be one.
https://www.amazon.com/Diameter-Plano-c ... B013SL7W08

Why is 20mm plano concave lens so hard to find?

Do you have any idea what kind of lens is the above? The focal length is 75mm. But there is a lens just 20mm from focus. I wonder if the lens is just a glass protecting the inside and no divergent or converging function. How do you test what kind of lens is it?

So Raman spectrometer is overpriced? But note the \$15,000 seems to be the cheapest. The Thermo Fisher RMX handheld is being sold for more than \$25,000.
microb, please don't miss the major edit above after I spents hours reviewing about optics.

In the following, are you sure that when you coincide the focal points even of another focal length instruments (like 75mm) vs 20mm.. the green rays coming from the right will become parallel at the left?? I haven't seen this kind of illustration anywhere.

microb
Posts: 449
Joined: Wed Mar 27, 2019 6:39 am

### Re: What microscope has this style?

portbon wrote:
Sun Nov 22, 2020 8:04 am
So Raman spectrometer is overpriced? But note the \$15,000 seems to be the cheapest. The Thermo Fisher RMX handheld is being sold for more than \$25,000.
For DIY, I'm assuming a cheapo laser. So maybe that's where the extra parts costs are.

So you could have what a Leica confocal system has in it: stable power supply, high end continuous running laser, and maybe an acousto-optic modulator (AOM) to stabilize the the light frequency by piezoing a piece a quartz to optically select only one frequency to shoot to a target (https://en.wikipedia.org/wiki/Acousto-optic_modulator). So the AOM would need another power supply and high frequency clock/controller. The power supply would do 0 to 300 vdc to run the piezo.

The cheaper 532nm lasers emit green and an IR. So if yo do try a cheapo green remember to buy an IR filter because it's probably not safe otherwise. But then the cheapo green lasers do shift about in frequency depending on temperature.

For the most part, I'm assuming the commercial price is because the item is low volume, and high expertise R&D to make a product to sell.

For a cheaper set up that I didn't buy it and it may not work as well, failing horribly -- don't know. I only bought the spectrometer before switching to Oceans. But those ThunderOptics guys on ebay are also selling a Raman setup, but for \$1k to \$3k depending on options. The probe they sell \$1k. Maybe it has that \$600 high edge dichroic mirror.

As for lenses:
For lens details I thought plano concave would work, but maybe double concave is better according to Thorlabs here (https://www.thorlabs.com/tutorials.cfm? ... 11DDBB9099) (https://www.lockhaven.edu/~dsimanek/scenario/lenses.htm)

Search for " increase the divergence of converging light" seems to bring up diagrams. I have lenses and maybe can show a set up. But it's supposed to work. Buy some \$10 doublets and try it out. You can probably get even cheaper. I've bought from this site before: https://www.surplusshed.com/ Something worth experimenting with.
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Scarodactyl
Posts: 1046
Joined: Sat Mar 03, 2018 9:09 pm

### Re: What microscope has this style?

Ramans are not something you DIY if you want a working raman, not yet anyway. There are some projects online but nothing with extremely great results. They're just a huge pita if you don't just directly buy all the correct compinents, which are expensive new.
The thunder optics raman setups seem to be more like kits. They do some cool looking stuff but I'm not confident if you bought one of their ramans that you'd have a complete system ready for serious usage. That said I've never bought one either.

microb
Posts: 449
Joined: Wed Mar 27, 2019 6:39 am

### Re: What microscope has this style?

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microb
Posts: 449
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### Re: What microscope has this style?

portbon wrote:
Sun Nov 22, 2020 8:04 am
Without the front attachment, the lens is almost in the edge of the ring. So I need to find a plano concave lens with focal length of 20mm. Here seems to be one.
https://www.amazon.com/Diameter-Plano-c ... B013SL7W08

Why is 20mm plano concave lens so hard to find?
I just saw this mixed in among the images. At this point the "20mm" anything has nothing to do with what you have. I thought that was the focal length of your device.

What ever distance the laser is sharpest is approximately the FL of the device. Call it F1.

Get a planar convex achromat doublet of F2 focal length and put it F1+ F2 away from your device, flat side aimed away. You should then see the beam not expand for ten feet and you can consider it collimated.

https://youtu.be/ac-vVNbQt2I

https://www.edmundoptics.com/knowledge- ... al-length/

microb
Posts: 449
Joined: Wed Mar 27, 2019 6:39 am

### Re: What microscope has this style?

I have a feeling this machine pictured below is slightly expensive. But I'm just guessing. Cool to see all the options:

https://www.edinst.com/us/products/rms1 ... icroscope/
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viktor j nilsson
Posts: 271
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Location: Lund, Sweden

### Re: What microscope has this style?

If that's the "reduced baseplate" I want to see the extended baseplate version...

microb
Posts: 449
Joined: Wed Mar 27, 2019 6:39 am

### Re: What microscope has this style?

viktor j nilsson wrote:
Sun Nov 22, 2020 9:24 pm

If that's the "reduced baseplate" I want to see the extended baseplate version...
This is the reduced base plate:
https://www.edinst.com/us/products/rm5- ... icroscope/
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portbon
Posts: 21
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### Re: What microscope has this style?

microb wrote:
Sun Nov 22, 2020 8:58 pm
portbon wrote:
Sun Nov 22, 2020 8:04 am
Without the front attachment, the lens is almost in the edge of the ring. So I need to find a plano concave lens with focal length of 20mm. Here seems to be one.
https://www.amazon.com/Diameter-Plano-c ... B013SL7W08

Why is 20mm plano concave lens so hard to find?
I just saw this mixed in among the images. At this point the "20mm" anything has nothing to do with what you have. I thought that was the focal length of your device.

What ever distance the laser is sharpest is approximately the FL of the device. Call it F1.

Get a planar convex achromat doublet of F2 focal length and put it F1+ F2 away from your device, flat side aimed away. You should then see the beam not expand for ten feet and you can consider it collimated.

https://youtu.be/ac-vVNbQt2I

https://www.edmundoptics.com/knowledge- ... al-length/
Here the handheld Thermo Scientific First Defender RMX is being sold for \$80,000 (I thought it was \$25,000). I nearly got one at ebay for \$5000 but the problem was there was no warrantee and I have difficulty getting Export License for it (Export License was required for it because it is handheld and can detect explosives at micron quantity and it has library for it). Without Export License, Trump can make the FBI snatch you in any country with extradition treaty.

https://www.fishersci.com/shop/products ... /p-4006497

The internal parts is akin to the following illustration.

I want to focus (pun unintended) for Raman spectroscope in general.

Let's say I can successfully make the laser parallel. But I wonder if the CCD can read the laser back? If it can. Why didn't the manufacturer make them parallel? That way you don't have to worry about focus. The problem I have to get the ring and some attachments from the manufacturer is because their default attachments are off by 2mm and the spectra not optimal.

If the parallel laser will work. At what distance should the sample be put? Because if it can be put anywhere. Then I can put the sample one foot away? And if it can not diverse so much, I can aim it at meters away to sample unknown substances?

portbon
Posts: 21
Joined: Wed Nov 18, 2020 12:54 am

### Re: What microscope has this style?

portbon wrote:
Sun Nov 22, 2020 10:55 pm
microb wrote:
Sun Nov 22, 2020 8:58 pm
portbon wrote:
Sun Nov 22, 2020 8:04 am
Without the front attachment, the lens is almost in the edge of the ring. So I need to find a plano concave lens with focal length of 20mm. Here seems to be one.
https://www.amazon.com/Diameter-Plano-c ... B013SL7W08

Why is 20mm plano concave lens so hard to find?
I just saw this mixed in among the images. At this point the "20mm" anything has nothing to do with what you have. I thought that was the focal length of your device.

What ever distance the laser is sharpest is approximately the FL of the device. Call it F1.

Get a planar convex achromat doublet of F2 focal length and put it F1+ F2 away from your device, flat side aimed away. You should then see the beam not expand for ten feet and you can consider it collimated.

https://youtu.be/ac-vVNbQt2I

https://www.edmundoptics.com/knowledge- ... al-length/
Here the handheld Thermo Scientific First Defender RMX is being sold for \$80,000 (I thought it was \$25,000). I nearly got one at ebay for \$5000 but the problem was there was no warrantee and I have difficulty getting Export License for it (Export License was required for it because it is handheld and can detect explosives at micron quantity and it has library for it). Without Export License, Trump can make the FBI snatch you in any country with extradition treaty.

https://www.fishersci.com/shop/products ... /p-4006497

The internal parts is akin to the following illustration.

I want to focus (pun unintended) for Raman spectroscope in general.

Let's say I can successfully make the laser parallel. But I wonder if the CCD can read the laser back? If it can. Why didn't the manufacturer make them parallel? That way you don't have to worry about focus. The problem I have to get the ring and some attachments from the manufacturer is because their default attachments are off by 2mm and the spectra not optimal.

If the parallel laser will work. At what distance should the sample be put? Because if it can be put anywhere. Then I can put the sample one foot away? And if it can not diverse so much, I can aim it at meters away to sample unknown substances?
Last year I have read so many articles about Raman especially when I was deciding what to buy. But I didn't use it for a year and just remember them now. I guess raman spectrometer doesn't have parallel beam to a target to avoid spectal frequency loss? I read this.

https://eprints.lancs.ac.uk/id/eprint/7 ... nal_BW.pdf

"Although global illumination allows for high quality spectral imaging, this often comes at a cost of spectral quality due to the reduced laser intensities across the sampling area."

The above sentence appears to be vague. It mentions high quality spectral imaging then at a cost of spectral quality? How do you reword it?

Whatever, I think making the beam parallel to a sample won't affect the slit width. I read.

https://www.spectroscopyonline.com/view ... ectroscopy

Now this is a microscope forum. Ok. What kind of microscope where I can put the rectangular box and inject the parallel beam to reach the sample? I'd not look at the eyepiece to avoid the laser but use camera on top of the microscope.

portbon
Posts: 21
Joined: Wed Nov 18, 2020 12:54 am

### Re: What microscope has this style?

microb wrote:
Sun Nov 22, 2020 8:58 pm
portbon wrote:
Sun Nov 22, 2020 8:04 am
Without the front attachment, the lens is almost in the edge of the ring. So I need to find a plano concave lens with focal length of 20mm. Here seems to be one.
https://www.amazon.com/Diameter-Plano-c ... B013SL7W08

Why is 20mm plano concave lens so hard to find?
I just saw this mixed in among the images. At this point the "20mm" anything has nothing to do with what you have. I thought that was the focal length of your device.

What ever distance the laser is sharpest is approximately the FL of the device. Call it F1.

Get a planar convex achromat doublet of F2 focal length and put it F1+ F2 away from your device, flat side aimed away. You should then see the beam not expand for ten feet and you can consider it collimated.

https://youtu.be/ac-vVNbQt2I

https://www.edmundoptics.com/knowledge- ... al-length/
Why is the 20mm not relevent? I'll explain. Just a while ago the blue sediment filter housing arrived and I'm trying to determine what exact plastic it is made of. I didn't buy the library because it is so expensive so I have to match from existing database.

In the following, the 20mm is distance between front lens to the blue housing. But the Raman is 75mm focal lenght so it starts from inside.

This is front of it.

So because of the lens at front between the 75mm focal length and the lens is 20mm from focus (the blue housing). Then I can just put a 20mm plano concave lens right at the front of existing lens so the laser can become parallel right? I can't put a 30mm plano concave because it is inside the box. What do you think? Thanks so much for the assistances.

Scarodactyl
Posts: 1046
Joined: Sat Mar 03, 2018 9:09 pm

### Re: What microscope has this style?

Maybe try one of these as a first effort?
https://www.surplusshed.com/pages/item/L3803.html

microb
Posts: 449
Joined: Wed Mar 27, 2019 6:39 am

### Re: What microscope has this style?

portbon wrote:
Tue Nov 24, 2020 2:08 am

So because of the lens at front between the 75mm focal length and the lens is 20mm from focus (the blue housing). Then I can just put a 20mm plano concave lens right at the front of existing lens so the laser can become parallel right? I can't put a 30mm plano concave because it is inside the box. What do you think? Thanks so much for the assistances.

Even if you had a -20mm lens, the point the negative 20 is measured from is inside the lens, so it won't physically fit as the glass will have to be inside your black box as you noted with your -30mm lens example. So you'd need something like a -15mm lens to give room for the glass and that would theoretically give collimated light.

But the easiest method would be to do the last half of a relay lens. Get an achromatic doublet (plano-convex) with a focal length of F2 (lens shown in white receiving your black box focused light), then get an infinity objective or another lens F3 to act like a simple objective.

The distance between the white lens and the orange lens (or objective) can vary drastically since it would be infinity space to use the microscope term.

In the other diagram the light blue is the F2 lens. The green is an objective or F3 lens. The fold mirror and all that is just because this was the best diagram available quickly. That part doesn't matter here.

The issue will be the size of the beam. If you get a 500mm F2, the widening beam from your black box will expand out and is going to have a larger diameter than if you got an F2 of 50mm. For the infinity space, like a RMS 10x objective you will want something like 8mm to 10mm. The distance F2 that get the beam size you want will define the lens you want to buy. Of course the beam size you want would be defined by the objective (or just another lens) you decide to use.
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Last edited by microb on Tue Nov 24, 2020 5:21 am, edited 2 times in total.

portbon
Posts: 21
Joined: Wed Nov 18, 2020 12:54 am

### Re: What microscope has this style?

Scarodactyl wrote:
Tue Nov 24, 2020 2:50 am
Maybe try one of these as a first effort?
https://www.surplusshed.com/pages/item/L3803.html
What kind of lens is it? Is it a plano concave lens?

I live in Asia and it will take 2 weeks for anything shipped from the US to arrive. That's why the Kodak ring I ordered from Ebay hasn't arrived and I don't want to piss off the manufacturer lest they won't send me any extra ring or even sell me anything. They are only a few personnel and the technical engineer warned me never to open the box or they won't service the \$15,000 equipment (maybe they didn't want me to find out the inside only cost less than \$1000).

Anyway. Before I order. I need to know first the theory works. The other day I sent the following illustration.

I asked whether if you could coincide the focal points of the say 20mm lens and 75mm focal lens beam (green), you can get a parallel beam. microb hasn't confirmed it or anyone. So please clarify if this is accurate and true and work.

Here is video i took of the laser diverging from focus to 2 meters away. If the lens above will work. Does it mean the parallel beam coming out of the lens will be the same diameter as the beam coming from the laser diode?

Scarodactyl
Posts: 1046
Joined: Sat Mar 03, 2018 9:09 pm

### Re: What microscope has this style?

It has a -20 focal length anyway. Even if it has a wait it's a cheap thing to try.
Last edited by Scarodactyl on Tue Nov 24, 2020 6:05 am, edited 1 time in total.

microb
Posts: 449
Joined: Wed Mar 27, 2019 6:39 am

### Re: What microscope has this style?

Given your video, that beam is expanding fast after focusing at 20mm out where it image inverts to widen out. Since this is a light source, image inversion doesn't matter. So odds are, you'll want another short focal length doublet. So if you have an objective you want to use, get the size on that paper that fits the needed diameter of field view. I'm assuming you want to match this device up to an objective like these guys did: (http://aseq-instruments.com/ASEQ_Raman.html) They of course left the laser as collimated. You're trying to undo that and have infinity space like they have. That one optic left of the fan is probably a focusing lens to shoot into the spectrometer.

If you are in Asia, the lens manufacturers are right there. You can get doublets and objectives on ebay India for example or aliexpress. Buy a cheapo objective for \$10 to \$15 and a lens for a \$4 to \$10. Then try it out. To be honest, buy a few and experiment.

For the light coming back, you'll want a doublet. If you were just shooting a laser out, the one frequency light means a lens with chromatic aberrations would not be an issue. But you want a quality spectrum focus back at your sensor, so doublet. Asian websites are listing them for \$2 to \$5.

portbon
Posts: 21
Joined: Wed Nov 18, 2020 12:54 am

### Re: What microscope has this style?

microb wrote:
Tue Nov 24, 2020 4:05 am
portbon wrote:
Tue Nov 24, 2020 2:08 am

So because of the lens at front between the 75mm focal length and the lens is 20mm from focus (the blue housing). Then I can just put a 20mm plano concave lens right at the front of existing lens so the laser can become parallel right? I can't put a 30mm plano concave because it is inside the box. What do you think? Thanks so much for the assistances.

Even if you had a -20mm lens, the point the negative 20 is measured from is inside the lens, so it won't physically fit as the glass will have to be inside your black box as you noted with your -30mm lens example. So you'd need something like a -15mm lens to give room for the glass and that would theoretically give collimated light.

But the easiest method would be to do the last half of a relay lens. Get an achromatic doublet (plano-convex) with a focal length of F2 (lens shown in white receiving your black box focused light), then get an infinity objective or another lens F3 to act like a simple objective.

The distance between the white lens and the orange lens (or objective) can vary drastically since it would be infinity space to use the microscope term.

In the other diagram the light blue is the F2 lens. The green is an objective or F3 lens. The fold mirror and all that is just because this was the best diagram available quickly. That part doesn't matter here.

The issue will be the size of the beam. If you get a 500mm F2, the widening beam from your black box will expand out and is going to have a larger diameter than if you got an F2 of 50mm. For the infinity space, like a RMS 10x objective you will want something like 2mm diameter field of view according to one table -- but I'd thought it would be more like 8mm to 10mm. Supposedly that table was for RMS. Anyway, the distance F2 that get the beam size you want will define the lens you want to buy. Of course the beam size you want would be defined by the Diameter Of Field Of View of the objective you decide to use.
Thanks for the illustration. So for a 20mm plano concave lens. EFL (Effective Focal Length) is the 20mm and not the BFL (Back Focal Length)?

For now I just want to try to target water molecule with parallel laser beam. I want it to be as big as the original laser beam. What size is laser diode beam usually? The following is my water spectra.

Stellarnet has this explanation of the peaks.

"Figure 2. Raman scattering spectrum of pure water. The shoulder at ~3250 cm-1 corresponds to the asymmetric –OH stretch, and the most intense feature at ~3410 cm-1 corresponds to the symmetric –OH stretch. Even more intriguing, there is a small shoulder at ~3630 cm-1 which corresponds to the –OH stretch of a water molecule which is only partially involved in hydrogen bonding – a particularly rare event."

I wonder what would happen if I hit the water with parallel beam. More water molecules will be covered. Will it make the counts higher? Will it improve or diminish the spectral resolution? If the counts would get lower or spectral resolution poorer. Then I'd just forget about parallel beams.

I still don't see cheaper microscope that can also allow transmitted parallel light from a Raman. What microscope is there like the OMAX but with transmitted laser injection capability.

Scarodactyl
Posts: 1046
Joined: Sat Mar 03, 2018 9:09 pm

### Re: What microscope has this style?

You won't find a cheap one with that capability built in. You'd probably need to adapt a coaxial illuminator meant for normal light.
My plan for one is to use a Nikon optiphot with infinity-corrected optics, maybe with a customized stage to get more working distance. I haven't specced it out entirely and certainly haven't tested it, so putting together a whole spec for it isn't something I can do right now. The long and short though is that this model of illuminator serves as an adapter between older finite optiphots and infinity ones, fitting into finite nikon microscopes below but accepting infinity eclipse-series heads above. The objective will get the collimated laser light, focus it onto the sample, then should recollimate it on the way back to the spectrometer. Better yet, some of these illuminators come only with a brightfield prism, so the 'darkfield' position is just empty space. I plan to black out the top and side of the prism so the laser can't go up into the head at all while inserted as one safety feature (in addition to a barrier filter).

microb
Posts: 449
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### Re: What microscope has this style?

portbon wrote:
Tue Nov 24, 2020 5:26 am
I wonder what would happen if I hit the water with parallel beam. More water molecules will be covered. Will it make the counts higher? Will it improve or diminish the spectral resolution? If the counts would get lower or spectral resolution poorer. Then I'd just forget about parallel beams.
This paper used parallel mirrors to get more laser contact: https://www.researchgate.net/figure/Sch ... _285505653
“For these investigations, the authors have created a typical multi-pass optical cuvette,… These angles α and β may be preliminary adjusted in some intervals and were chosen in the way that the exciting beam passes a maximum possible length in a medium under study up to its full absorption.”

"Multipass Cuvettes for Luminescence Spectroscopy" https://link.springer.com/chapter/10.10 ... -04947-1_6

Multipass Cell Using Spherical Mirrors While Achieving Dense Spot Patterns
“It is easy to understand that if a beam is passed through a very long tube containing a sample of gas that the instruments requiring Such a long tube would be extremely cumbersome and therefore not easily portable. To overcome this problem, others have devised systems wherein a beam of light is repeatedly reflected between opposed mirrors to thereby extending the length of exposure of the beam to a gas sample in a way that the size of the instrument can be Sub stantially reduced.”
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portbon
Posts: 21
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### Re: What microscope has this style?

This is the Olympus BX-43/BX51 microscope where the black Raman box is inserted.

How does the insertion part looks like? In normal usage, what equipment do you put there?

Is it an Olympus BX-43 or BX-51, how much is second hand? and new? I was offered \$33,000 which includes the \$15,000 Raman black box. So the microscope is like costing \$18,000 new. It's this the price of a new microscope? I can't find the price anywhere.

microb
Posts: 449
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### Re: What microscope has this style?

portbon wrote:
Wed Nov 25, 2020 12:32 am
Is it an Olympus BX-43 or BX-51, how much is second hand? and new? I was offered \$33,000 which includes the \$15,000 Raman black box. So the microscope is like costing \$18,000 new. It's this the price of a new microscope? I can't find the price anywhere.
That picture looks like a CX41. A BX51 frame looks like this: https://www.ebay.com/itm/Olympus-BX51-B ... 4413393681

Don't know the option used in the picture you gave. There is a switchable dual port option from Olympus, but that has telan lenses in it:
https://www.ebay.com/itm/Olympus-U-DPT- ... 4524551768
https://www.ebay.com/itm/Olympus-Micros ... 4465991434

The option you showed looks like a switchable into infinity space light path.

portbon
Posts: 21
Joined: Wed Nov 18, 2020 12:54 am

### Re: What microscope has this style?

microb wrote:
Wed Nov 25, 2020 7:38 am
portbon wrote:
Wed Nov 25, 2020 12:32 am
Is it an Olympus BX-43 or BX-51, how much is second hand? and new? I was offered \$33,000 which includes the \$15,000 Raman black box. So the microscope is like costing \$18,000 new. It's this the price of a new microscope? I can't find the price anywhere.
That picture looks like a CX41. A BX51 frame looks like this: https://www.ebay.com/itm/Olympus-BX51-B ... 4413393681

Don't know the option used in the picture you gave. There is a switchable dual port option from Olympus, but that has telan lenses in it:
https://www.ebay.com/itm/Olympus-U-DPT- ... 4524551768
https://www.ebay.com/itm/Olympus-Micros ... 4465991434

The option you showed looks like a switchable into infinity space light path.
The ebay shows this picture.

This is not present in the following.

What are you talking about? I have been trying to ponder it for days. Thanks.

microb
Posts: 449
Joined: Wed Mar 27, 2019 6:39 am

### Re: What microscope has this style?

portbon wrote:
Fri Nov 27, 2020 12:36 am
This is not present in the following.
Didn't say it was. The dual port option I gave links to is the only switchable light path I could think of from Olympus for the BX. But as I mentioned, it has a telan lens in it where as the unit you pictured is in infinity space side of the telan lens. There is also another version (https://www.ebay.com/itm/Olympus-Micros ... 4545007260) which seems to involve a 50/50 sharing which you don't want.

You appear to be looking for something that would allow you to use an objective to find the target, pull a lever out to switch a mirror to allow the Raman unit access, but then not send blinding light to the eye pieces or camera.