Does anyone have instructions for the Zeiss Linnik microscope?

[Bradscopegems]

Does anyone know how to set up the Carl Zeiss West germany version of the Linnik microscope, which is a massive cube of metal designed for
measuring the contours of reflective specimens such as metal surfaces to sub-wavelength accuracy. I bought one of these on eBay some years ago and have just started to set it up. I can get a focussed image and I can get the two apertures which seem to correspond to the main and comparison objective to coincide, but there are too many controls for adjusting the fringe separation and angle, so I have not been able to get any fringes as yet. I have attached a photo which may jog someone's memory, if they have worked in metallurgy or materials science. There seems to be nothing in the Zeiss archives.

[MichaelG.]

Sorry ... I have never seen one, and that is clearly my loss !!
I look forward to learning something about it.

Welcome to the forum
MichaelG.

.

Edit: I presume that you know this much already ... but others may not:
https://en.m.wikipedia.org/wiki/Linnik_interferometer

[Bradscopegems]

US06721094.jpg (117.6 KiB) Viewed 4706 times

Thanks for your reply. Unfortunately, the Wiki image is not helpful, because it shows an interferometer modified for other purposes so that it is
no longer recognizable as a Linnik. I am attaching a better basic diagram from a US patent. The Zeiss instrument contains a lot of extra optics not shown in the diagram, which are used to align the system and shift the fringes to any desired angle and spacing. This is what makes it so difficult to align.

[microb]

Found a paper on upgrading one: http://www.mate.tue.nl/mate/pdfs/1628.pdf
The microscope looks impressive.

"THE MICROSCOPE The Carl Zeiss microscope, type number ZXAPA, is of the Linnik type. It has objectives of 10 x, 25x and 60 x with numerical apertures of 0.16, 0.32 and 0.64 respectively, and an 8x eyepiece, giving a 2 mm exit pupil at maximum. The field of view on the object is 2 mm, 0.8 mm and 0.3 mm diameter respectively. Each reference objective can be supplied with a reference surface with a reflectance of 30%, 60% or 90%. It operates on a Thallium spectral lamp with λ = 540 nm with a coherence length of about one tenth of a millimeter."

[MichaelG.]

Unfortunately, the Wiki image is not helpful, because it shows an interferometer modified for other purposes so that it is no longer recognizable as a Linnik. I am attaching a better basic diagram from a US patent. The Zeiss instrument contains a lot of extra optics not shown in the diagram, which are used to align the system and shift the fringes to any desired angle and spacing. This is what makes it so difficult to align.

Thanks Brad ... I will have a look at the patent

MichaelG.
.

Edit: Here, for seekers of knowledge, is that patent:
https://worldwide.espacenet.com/publica ... cale=en_EP
The final sentence of the Abstract may, or may not, be relevant to your difficulty ...
I don't know where the Zeiss instrument sits, in the evolution of such things.

[MichaelG.]

Found a paper on upgrading one: http://www.mate.tue.nl/mate/pdfs/1628.pdf

An excellent find
Today will be a 'learning day'

MichaelG.

[Bradscopegems]

Linnik optical diagram (Kingslake).jpg (181.99 KiB) Viewed 4662 times

Dear Microb and MichaelG,
Thank you for your suggestions. I have sent an email to the dutch group who modernized a Linnik very similar to mine and
will let you know if they respond. I am attaching here an optical diagram from Applied Optics and Optical Engineering ed. Kingslake, volume 4, which shows
the complexity of the Zeiss design, which allows the angle and spacing of the interference fringes to be varied in a controlled way..... once you can find them! Generally in interference microscopes you use white light initially to find the phase delay approximately, and then switch to something like the monochromatic thallium lamp or a laser shining through a rotating diffuser which both give a measurement correct to a small fraction of a wavelength (but ambiguous without the white light measurement first).

[microb]

To get my Nikon interference set up running (viewtopic.php?f=5&t=7511) , I had to use the right camera c-mount setup. The one pictured in this post was the only one that produced fringing. Any shorter, or longer even with Nikon parts (one c-mount was half as long) and no fringing. So maybe check your camera set up. You might have to set up something that you can adjust in length to find the focus plan where different light frequencies are actually planar.