Hartridge Reversion Spectroscope on Ebay

[G4Lab]

here is a Hartridge Reversion Spectroscope. The finest hand spectroscope ever made. Made only in England by R & J Beck (with an earlier version built by the venerable old English optical firm of Bellingham and Stanley) this unit has a micrometer drum that allows you to read wavelength. To 0.2nm

This unit will go for between 300 and 500 I would think. It looks to be in perfect condition. My experience has been that mahogany and other nice wood boxes usually do a pretty good job of protecting such instruments from environmental degradation such as humidity and dust.

Furthermore I can't recall ever receiving an instrument that was cosmetically as pretty as this one, which didnt also work perfectly.

The Hartridge Reversion scopes work by displaying two spectra in the ocular. The two spectra are arrayed in opposite directions one a mirror image of the other. You decide which line or band you want to know about and you turn the micrometer till the same band on both spectra are lined up adjacent to one another. Then you look at the micrometer and read the wavelength to 0.2nm. They are dead on accurate. If it isnt I'll fix it for you.
All the goodies with it are very nice but all you need is the spectroscope. Of course the mahogany case is very nice.

I am currently the high bidder but if anyone wants this please PM me and I will step aside. If you want anything at all more than an OPL THIS is it. Way better than a Zeiss or ANY wavelength model. And the stand that comes with it is almost suitable for gemology (Transmitted light use) as it is. It could use upgrading to quartz halogen and a black plate for reflected through the pavilion technique. (There IS a black shade with a hole in it to keep the light source from dazzling you. Its in the lid.)Complete no brainer. Somebody go for it.
This is a rare tool of the trade that you will always be able to get your money back out of and you wont regret buying if you use a spectroscope at all.

Gene step down from soapbox now.

[Jung Kee]

It says that it isn't complete, do you see which parts which is absent? Or if you can't, do you think it is any important parts? Also, do you know if it possible to adjust focus? I'm nearsighted and have astigmatism so there is always a lot o problem with spectroscopes for me.

[G4Lab]

The important part is the spectroscope itself which doesnt have anything that comes off easily. The photographs all look very good to me. The seller mentions that the screw knob to anchor the unit to the stand is missing. It is merely a 1/4 -20 camera type thread. Very easy to substitute. These outfits came with various different sample cells and lamps for different voltages.
The ONLY thing that is critical is the spectroscope itself. The broken piece of the case is present and will glue back perfectly with white wood glue.

There is no reason I can see not to buy this particular unit , except that I already have two of them. And that you might need to bid hard to win it.

In the late seventies I used to look at an Ealing Beck catalog that showed this item. It cost around $3500 new back then. I never expected to ever see one in person.

I think setting a snipe of $1,000 to insure getting it would not be unreasonable.

It has a calibrated micrometer adjustable slit on the front which has a cylindrical lens to gather light and focus it on the slit. The slit height is also adjustable. There is enough eye relief to use the unit with glasses which I do, using 2.75 diopter reading lenses. The ocular is not a focusing one but you could have a corrective lens installed in it if you wanted by a good optician.

[Jung Kee]

Thank you very much Gene! Hadn't a clue about that this instrument even existed so even if I don't buy it, which is unlikely by looking at how rapidly it has ticked away the last few hours, I'll know that it is out there to look for. How come you've so vast knowledge about obscure physical instruments?

[G4Lab]

This instrument IS mentioned in Peter D. Reads' Gemmological Instruments book which I got a copy of in 1980. However I did already happen to know about this instrument, pretty much by accident. I was already a professional labrat and did alot of microscopy and was studying up on it. I ran across some reflecting objectives made by the same company (R&J Beck of England) A friend of mine in a lab down the hall had an Ealing Beck catalog (Ealing optical bought R&J Beck) and I made him give me the catalog. (He owed me lots of favors ) And when I saw the Hartridge spectroscope it was love at first site. Then I got Peter Reads' book and saw he mentioned them. But I never really expected to ever see one. I can't imagine they sold too many cause they were expensive. ($3500 or so in the late seventies)

The minute I got interested in gemology and jewelry making I always tried to keep an eye out for things that could be useful.

Like this.

[Bojan]

Hi guys,
I recently obtained Hartridge reversing spectrometer... Does anyone know how this instrument works?
What I have in mind is optical layout.. How the reversed (rotated) spectrum is obtained?
I googled quite a bit for the answers to those questions, and, apart from this forum and some medical applications (some papers are from Dr Hartridge himself) , I could not find anything useful.
My unit needs a bit of cleaning and I would like to dismantle it, but I don't want to do it before I know what I will find inside.
Any help will be greatly appreciated, thanks in advance!

[G4Lab]

Thank you (Full) Professor Brian for pointing me to this thread.
For those that don't know, when you go from assistant professor to associate professor, they usually can't fire you. At that point many academics quit working. If you continue to work really hard , like you didn't notice the previous, AND you are fortunate, they make you a full Professor. Congratulations Dr. Brian!!


The internal optical path of the Hartridge involves a cylindrical front lens and variable slit.
Inside there is a grating or prism (depending on vintage and manufacturer. They were made both by Beck, and by Bellingham and Stanley, both venerable UK optics firms) and on a rotary platform operated by the wavelength micrometer,
you will find a single thin wedge which splits the spectrum into two opposite moving trains of lines even though the wedge itself only rotates in one direction.

You may take the top cover off without fear of doing too much damage. Have some Kodak lens cleaner and a brand new microfiber cloth to clean things with. DO NOT TRY TO CLEAN a GRATING. YOU WILL RUIN IT. The only thing you can do to a grating is give it a toot with an a blower , one the blows CLEAN oil free gas. THere are CO2 ones available that are good. Sometimes the halocarbon ones sold at office supply stores have residual oil in them,or even irritant nauseants, to prevent kids from "huffing" them. A squeeze bulb might be better. A brand new fine sable brush can be used to dislodge dust. Anything else is not advisable, unless the grating is completely unusable as it is, and is going to be replaced anyway.

Watch out for and recover any flecks of the blacking paint that come loose. The wedge can be cleaned like a camera lens surface as can all the other optics. If there is a mirror it is probably first surface and needs to be cleaned very delicately and only if really necessary.

I have emailed another list member about this. He has a Hartridge with a prism for dispersion and sent me innard photos while he spruced it up. I have asked him to post them, or give me permission to do so. He was kind enough to say yes.

[Bojan]

Thank you.. Now I know my specimen is with prism.
I still don't get it, how the spectrum is reversed.. It must be inside eyepiece barrel, as this is the only part that moves (with micrometer).
Also, the eyepiece actually consists of two parts, I can see it is cut in two halves along optical axis - one half for each spectrum? Two halves are not identical, from what is visible from outside..

[Bojan]

The only explanation (for my specimen) as to how two spectra (one of them rotated by 180°) are produced is, one half of the eyepiece reverses the image (simple plossl eyepiece lens perhaps), and the other one doesn't (terrestrial eyepiece.. it has to have similar magnification but field of view is visibly narrower).

[G4Lab]

Yours looks like a later model. I can't see the wedge in yours.
But a split ocular would do the job.

Were you able to clean the dirt that made you open it in the first place? If it is inside the prism train it will be a difficult and advanced job. Almost impossible.

[Bojan]

Thanks..
So, split eyepiece is known to be used like this? Interesting.. I will try (gently) to remove it and have a look. If this is so, there is not much attenuation in the light path, which means the image is as bright as it gets..
There was just a bit of dust on the slit (visible on spectrum), it's clean now.
Well, I am happy now

Actually, the reason I picked up this unit has not much to do with gemology, but more with astro-spectroscopy.
But, spectrometer is spectrometer, right ?

[G4Lab]

That ocular is definitely replacing the wedge. And you can see that there has been
an update of the micrometer linkage too. I had pictures from another guy who had a Bellingham and Stanley and that was different too. So I there was design creep over the decades that this toy was built.

The only problem with using it for astronomy is the amount of light available.
You can point it at the moon and see Frauenhoefers' lines. But if you want to use it on stars you will need a big telescope I think. But it ought to work as well as any other star spectroscope. Many of these have construction that is substantially the same as the spectroscopes we use. Most of them use a transmission grating I think.

The dispersion on the Hartridge is 33 degrees. Most visual spectroscopes disperse seven to 15 degrees. So the light is spread a bit thinner and in the absence a a bright source lamp (as in gemstone or other transmission measurements) the spectrum might be very dim.

Let us know how it works out for that purpose.

Gene

[Bojan]

The only problem with using it for astronomy is the amount of light available.

Yes, I know... but I have the necessary equipment (computerised 10" reflector)
All I need now is couple of adapters made so that I can mount in on the telescope and fit the small camera on the H eyepiece...
I will certainly let you know how it went.
Thanks for your all your helpful comments and replies - I learned a lot

[Barbra Voltaire, FGG]

Looks like the item Gene originally pointed to has been removed.

[G4Lab]

This is similar to the one I linked to. All those ebay links go away after about 90 days or so.
Owen and Frank, you should look this gentleman up.

The three other hand specs are Beck wavelength prism spectroscopes which were often put on the GIA spectroscope outfit. Beck really was THE hand spectroscope company. Although there have been others nobody ever really made the variety of interesting hand specs that Beck did. The Zeiss has nothing over the three in this picture.

The Hartridge may be overkill for many gemologists. Tim sold his, but he was being ruthless about raising money to get back down under. They have really high toy value. You can look at all kinds of lights and colors and get direct ACCURATE readouts of wavelength. Actually more accurate than many fiber optic spectrometers and less trouble. The wavelength calibration tics are 0.2nm and are easily that readable.