Diffraction Grating I Need: Where to Buy

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linuxusr
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Diffraction Grating I Need: Where to Buy

#1 Post by linuxusr » Sat Jun 19, 2021 12:04 pm

After Peter Evennett's lectures on conjugate planes and some readings on optics in Matsumoto and Roullard's An Introduction to Digital Photomicography, I want to see various diffraction orders and their relationship to NA and resolution for myself.

But I need the same grating, a slide, one of opaque lines and spaces, that Abbe used and Evennett uses in his demonstrations.

Does anyone know where I can buy one? Ads on Amazon are ambiguous and hard to know what I'm buying.
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Re: Diffraction Grating I Need: Where to Buy

#2 Post by MichaelG. » Sat Jun 19, 2021 2:07 pm

Sorry, I have no idea where you might buy the slide used by Peter Evennett [unless Zeiss sells it] … but I would just mention that this is not what is commonly termed a ‘Diffraction Grating’

For the benefit of those who have not seen it: The slide is illustrated about 28 minutes into Peter’s video demonstration.
https://youtu.be/60_jgZtyR6U

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Re: Diffraction Grating I Need: Where to Buy

#3 Post by lagoonatic » Sat Jun 19, 2021 2:33 pm

Check out the calibration and stage micrometers section of Electron Microscopy Sciences - the micrometer standards section looks like it contains the same type of slides used in the video.
https://www.emsdiasum.com/microscopy/pr ... aspx#stage

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Re: Diffraction Grating I Need: Where to Buy

#4 Post by MichaelG. » Sat Jun 19, 2021 5:39 pm

The whole ‘Abbe Diffraction Apparatus’ is illustrated here:

https://www.nms.ac.uk/explore-our-colle ... tus/647239

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Edit: __ See p18 et seq of this : https://www.zeiss.co.uk/content/dam/Cor ... sue_15.pdf

Edit: __ and this : https://www.diatomshop.com/files/Beyond ... lities.pdf
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Re: Diffraction Grating I Need: Where to Buy

#5 Post by linuxusr » Sun Jun 20, 2021 12:57 pm

lagoonatic wrote:
Sat Jun 19, 2021 2:33 pm
Check out the calibration and stage micrometers section of Electron Microscopy Sciences - the micrometer standards section looks like it contains the same type of slides used in the video.
https://www.emsdiasum.com/microscopy/pr ... aspx#stage
I think that if any of these items were a diffraction grating, that would be stated. Here are measurement devices, each as expensive as a student microscope, measuring to three decimal places, to be used for research and publication. I think that diffraction gratings are for heuristic purposes and have no functionality in the lab.
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Re: Diffraction Grating I Need: Where to Buy

#6 Post by linuxusr » Sun Jun 20, 2021 1:34 pm

MichaelG. wrote:
Sat Jun 19, 2021 5:39 pm
The whole ‘Abbe Diffraction Apparatus’ is illustrated here:

https://www.nms.ac.uk/explore-our-colle ... tus/647239

MichaelG.
.

Edit: __ See p18 et seq of this : https://www.zeiss.co.uk/content/dam/Cor ... sue_15.pdf

Edit: __ and this : https://www.diatomshop.com/files/Beyond ... lities.pdf
I'm happy that "too many projects" doesn't exclude this one! MichaelG. you are a gem for finding these rich resources, which I will now digest. A cursory look tells me that a diffraction grating slide on the stage is not used at all. My assumption of a slide-on-the-stage diffraction grating might be incorrect. Instead, here, in the last article you cited, an objective is swapped out and replaced with an identically threaded "diffraction funnel" into which can be inserted various back focal plane diaphragms indicating 0 or 0 + orders of diffraction depending on the diaphragm.

I'm also interested in obtaining H. Hselmann's Teaching Microscopy: Part 2. Didactic Methods in Teaching Microscopy from RMS Proceedings 2, 1967 that was cited in the Abbe apparatus from the museum in Scotland that you discovered. I Googled, Binged, and went to rms.org.uk to no avail, so I have emailed the RMS at info@rms.org.uk and asked if they could provide this article as well as Part 1.

Meanwhile, Amazon does sell diffraction gratings in the form of slides but with zero documentation, so I have no idea what they do. Maybe I'll buy one and find out. Meanwhile, more reading is ahead.
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Re: Diffraction Grating I Need: Where to Buy

#7 Post by MichaelG. » Sun Jun 20, 2021 4:09 pm

You're welcome, linuxusr

I am a big fan of Peter Evennett, and was fortunate to get a 1:1 version of his tutorial, at MMC in 2019

That said: You might also find this alternative video [by Kurt Thorn] useful: https://youtu.be/d8Tqoo0S6gc

I can assure you that, as mentioned earlier, the Abbe ‘striped specimen’ is not what is commonly termed a ‘Diffraction Grating’ … Kurt Thorn specifically terms it ‘approximately equal to’ on his presentation, and that seems very reasonable.
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The sort of diffraction grating that you will find on ebay or Amazon is better described by this:
https://en.wikipedia.org/wiki/Diffraction_grating


Enjoy the journey!

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Re: Diffraction Grating I Need: Where to Buy

#8 Post by MichaelG. » Sun Jun 20, 2021 10:33 pm

For clarity: https://www.alamy.com/archive-image-fro ... 86849.html

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Edit: There is a very brief summary of Abbe’s experiment on the final page of this:
https://www.med.unc.edu/microscopy/wp-c ... lenses.pdf
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Re: Diffraction Grating I Need: Where to Buy

#9 Post by patta » Mon Jun 21, 2021 5:55 am

The SRATE and other shops on Aliexpress (maybe also on ebay or Amazon) has several diffraction grating with (hopefully correct) specifications.
They sell also the "slits" for classoroom experiments, with larger spacing than the true diffraction gratings, which may be similar to what you're looking for.

A fast way to go: a CD or DVD are a fine grating, showing 2-3 color sequences.
Also hologram labels, like on credit cards, banknotes, brand packages, are pretty excellent diffraction gratings.
Both are made for reflection, but may work in transmission too if the backing is removed.

It is also possible to get diffraction effects with crude home methods:
Slit: paint a microscope slide black (or glue aluminium foil to it); score the slit with a knife.
Otherwise, with a laser printer, print the slit on a transparent sheet, like acetate "paper".
Use a razor blade to make a sharp half-dark slide
Use one or more needles, or hairs, to get a line obstacle

From the video at minute 28, the slide he's using, a "calibration slide" with spacing 10 micron (0,01 mm) is basically identical, as post #3, they cost like 10$

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Re: Diffraction Grating I Need: Where to Buy

#10 Post by linuxusr » Tue Jun 22, 2021 11:35 pm

@MichaelG

Remember the link you gave for the Zeiss Innovation issue on Abbe and his experiments?

It's a good thing I browsed through that because I found out that my assumptions about how I would employ a diffraction grating were completely wrong. If you recall the beginning of Evennett's lecture on LM, he points out that the older Zeiss microscope he is using for demonstration has the benefit of modularity but during the presentation, of course, we do not see his various manipulations of the hardware.

I had assumed, incorrectly, that I would be opening and closing the condenser aperture. Instead, I must open and close the field illumination aperture. Further, I must remove the condenser!

This quote is from page 15 of the Zeiss journal:
. . . the condenser is removed so that the light source lies at infinity and can be made to adopt a point-shaped structure by closing the luminous-field diaphragm. Removal of the eyepiece . . . permits viewing of the images produced in the back focal plane of the objective
Where the grating should be placed in another question. In the Abbe kit, it looks like a "funnel device" is swapped in for an objective and that various annuli are slid into that device. I, of course, will be using my stage to place the grating on, well, the optical axis of the objective should be centered on it.

I'm still playing with what to use for a grating. The idea of painting a slide black and scoring lines with a razor or scalpel is one idea. Another is from my book An Introduction to Digital Photomicography which uses the pores of a diatom frustule, specifically, Pleurosigma This produces a hexagon of six second order spots with the first order spot in the center. This is with the aperture open (But which aperture???). With the aperture closed, the second order spots disappear and looking at the specimen you lose the resolution between the pores.
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Re: Diffraction Grating I Need: Where to Buy

#11 Post by MichaelG. » Wed Jun 23, 2021 5:07 pm

I think we really need to read and understand the early work

… I have never seen the full Zeiss Abbe kit ‘in the flesh’ and have no idea what the ‘funnel device’ consists of.

Peter Evennett certainly uses the late version of the Zeiss slide in his demonstration, and it is mounted in the obvious place [on the stage of his much modified microscope] … The slide is visible in the grab from his video, that I posted earlier, and is [so far as I recall] exactly like the one in the NMS collection.
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Re: Diffraction Grating I Need: Where to Buy

#12 Post by MichaelG. » Wed Jun 23, 2021 10:30 pm

It is really important to follow Peter Evennett’s description of his modified microscope
[starting about 21 minutes into the video]

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