Beck Spectroscope

I acquired this thing, alongside a nice boxed travelling microscope, as part of an auction lot. The only connection I can see between the two is that the support pin for the microscope is the same diameter as the pin on this gadget.

Online research tells me that the bottom piece is a Beck prism spectroscope.

The other piece is clearly supposed to contain a light source and has a lens in the end to collimate the light. It does seem to work, as shining a bright light down the collimator tube and reflecting it through the slit makes a spectrum visible at the eye tube.

However the spectroscope is missing its eyepiece, and although the eye tube is 23.2mm in diameter, which seems fairly standard, there is a locating key on one side that will stop a circular eyepiece from entering.

Which raises a couple of queries which I am hoping the optics experts might be able to help with.

Does anyone know what focal length (or magnification) the eyepiece would have been - or have a method that would allow me to measure what it should be? I can't see any examples of eyepieces online with a flat on one side so I suspect I will have to get a lens and make a mount.

All the Beck spectrometers I can find online seem to be stand alone devices. Has anyone got any pointers to a picture that might show me the sort of specimen holding stage that this would have originally fitted?

Thanks in advance for any ideas.

You might find pages numbered 31 et seq. of this catalogue of interest, Peter: **LINK**

https://ia800702.us.archive.org/18/items/illustratedprice00beck/illustratedprice00beck.pdf

MichaelG.

Thank you Michael most interesting.- where do you find these things!! Now to work through the diagrams an d descriptions and try and figure out the similarities and differences.

Thanks again.

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I remembered that I had a copy on file, from some previous search for a Beck item [Richard Beck being an heroic name in microscopy] … so it was only a matter of re-locating source from the file-name.

MichaelG.

Nice to see in 1882 who was guilty of flooding the UK with cheap rubbish:

Of late years the Microscope having been greatly popularized, there has arisen a demand for cheap instruments, and a demand that has been mainly filled by literally worthless articles of French manufacture, made to look well and to sell, but as instruments of precision or research utterly useless.

One of Beck's microscopes is listed in their US Catalogue at $1600, about £28,000 today. No wonder amateurs looked for more affordable microscopes, even if they were unspeakably French!

Dave

Just for closure and to thank Michael for the pointers.

I dredged up a 1925 patent on the spectroscope Espacenet – search results which shows the same compound prism in my unit when I stripped it down.

The patent says that the surface between the two sections of the prism should be half silvered, and the face of the prism should have a diffraction grating either applied or engraved on it.

Unfortunately the half silvering looks rather badly damaged, and is well beyond my abilities to repair, and I can't see the grating - although I have seen a spectrum through the device so I might one day persevere. But for now it goes on the bottom shelf. It came for free with a very useful travelling microscope to nothing is lost.

Thanks again Michael for the pointers.

Thanks for sharing the patent, Peter … Well-found

At that vintage, I would expect the grating to probably be diamond-engraved [see edit]

… If you have seen a spectrum, it would suggest that very close inspection might be worthwhile.

Sorry, I currently have no idea what ‘ruling engine’ Beck might have used … but I will have a dig-around.

MichaelG.

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Edit: __ on second thoughts … have a look at this:
http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artapr11/dw-grating.html

Edited By Michael Gilligan on 14/02/2023 18:18:18

[ Caution: Rabbit-Hole Ahead ]

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**LINK**

https://www.researchgate.net/figure/H-A-Roland-with-his-ruling-engine-for-diffraction-gratings-Jones-1988_fig3_279264596

MichaelG.

Note the typo in the previous link

Rowland [not Roland] was the man

**LINK**

https://jps.library.utoronto.ca/index.php/aestimatio/article/view/25736/18882

MichaelG.

Edited By Michael Gilligan on 15/02/2023 08:12:59