Nye Optical f1.4 / 150mm UV-VIS-IR mirror lens

[Dr Klaus Schmitt]

A friend told me about it and was able to buy it. Quite a rare beast actually with Nikon-F mount
and very unusual speed of f1.4 (yes, one point four!!) - and made to work from ultraviolet to IR,
precisely 180nm - 4.500nm. Focus works by moving the primary mirror, beyond infinity to about
10ft - I added a helicoid to get it to focus much closer. 



Camera mount is left. Needs a bit TLC, which I will do once I'm back from California.

I have three similar lenses from the same maker, but this one is the most interesting and advanced one.
http://photographyoftheinvisibleworld.blogspot.com/2012/02/uv-vis-ir-lyman-alpha-lenses.html

Too bad the inventor and maker passed away in 2006, his son has sold off all remaining stock since.

[MILLIREHM]

Very interesting lens Klaus!

But yes - the not always wanted doughnut -shape  Bokeh is an intrinsic with reflex lenses

[Frank Fremerey]

Fascinating. Cannot wait to see you in a radiation proof suit taking
photos in the 180 nm to 350 nm range ....

BTW. Which sensor might record this part?

Chemical?

[Dr Klaus Schmitt]

Very interesting lens Klaus!

But yes - the not always wanted doughnut -shape  Bokeh is an intrinsic with reflex lenses

I have quite some experince working with BG bokeh, as I shoot wide open often. Choosing the right BG solves that.

Fascinating. Cannot wait to see you in a radiation proof suit taking
photos in the 180 nm to 350 nm range ....

BTW. Which sensor might record this part?

Chemical?

Well, not really the area that interests me, as flower UV patterns hardly reach beyond 300nm (some do...).

The easiest to use sensor is simply film, but there are digital sensors out there which reach very deep, used by astronomers.

[Akira]

That should be an impressive lens, Klaus!  Do these three siblings use real quartz, not the fused silica?

[Erik Lund]

This one sure looks liker the real thing! What a monster

[Dr Klaus Schmitt]

That should be an impressive lens, Klaus!  Do these three siblings use real quartz, not the fused silica?

There is an important difference between "real quartz" and fused silica - real quatz in optically anisotrope, but fused silica (fused quartz) isn't and also it can be made much more pure, so has much higher transmssion into UV. See https://en.wikipedia.org/wiki/Fused_quartz

So those mirrors are made of fused silica - but if you think about it a bit more, all those mirrors are first surface mirrors and the quartz substrate is just the rear part of it (used because of their very low thermal expansion coefficient), so are irrelevant for transmission. However to protect the first surface mirrors, they are usually overcoated with a very thin layer of fused silica for protection.

The design is a typical catoptic CASSEGRAIN design https://en.wikipedia.org/wiki/Cassegrain_reflector where the seconday, hyperbolic mirror is used to achieve the needed back focal length. (I never really
found out what the exact shape and form of the mirrors are, so it could also be a Ritchey-Chretien etc.)

This one sure looks liker the real thing! What a monster

Not really a monster, just about 1200grams, 150mm front diameter, 200mm lomg (all values approx.).
In terms of performance, what interests most of course is its high speed!

[Akira]

Klaus, yes, I'm aware that the mirror part is on the first surface, and Cassegrain type design uses, unlike the common mirror lenses for the photographic optics, no refractive elements.  That's why I was interested in the use of quartz, which is mentioned in your blog linked in your initial post.  I would suspect that the quartz is more immune to the temperature changes?

[Dr Klaus Schmitt]

Klaus, yes, I'm aware that the mirror part is on the first surface, and Cassegrain type design uses, unlike the common mirror lenses for the photographic optics, no refractive elements.  That's why I was interested in the use of quartz, which is mentioned in your blog linked in your initial post.  I would suspect that the quartz is more immune to the temperature changes?

Yes, exactly that is the reason. The block of the primary is about 1" or 25mm thick

[Dr Klaus Schmitt]

Thanks Eric, interesting reflex lens too, certainly deserves its own thread I guess - and not a hijack here... ;-)

Those lenses have often been used for mil. night sight systems, this one looks like one.

[Akira]

Yes, exactly that is the reason. The block of the primary is about 1" or 25mm thick

Klaus, thanks for the confirmation!

[Alaun]

Akira, quartz has a crystal structure, fused quartz or fused silica has a glass structure. Fused quartz and fused silica is the same stuff. the quartz crystal is not stable beyond about 700 celsius the stable structure then is christobalith, but the change might not happen until you reach about 1200 celsius. with glass, you have a uniform expansion in all directions, when heated, that probably better then with a crystal structure in an application like the lens here. the glass therefor is a good refractory material and used for example for crucibles etc whenn casting aluminium

(sorry for the typewriting here, its done with a mobile, and so i do not correct spelling etc)

[Erik Lund]

I have split the topic

[Akira]

Akira, quartz has a crystal structure, fused quartz or fused silica has a glass structure. Fused quartz and fused silica is the same stuff. the quartz crystal is not stable beyond about 700 celsius the stable structure then is christobalith, but the change might not happen until you reach about 1200 celsius. with glass, you have a uniform expansion in all directions, when heated, that probably better then with a crystal structure in an application like the lens here. the glass therefor is a good refractory material and used for example for crucibles etc whenn casting aluminium

(sorry for the typewriting here, its done with a mobile, and so i do not correct spelling etc)

Werner, thanks for the detailed explanation of the materials.  So, what is the purpose of using quarts for the reflex mirrors in this lens?

[Dr Klaus Schmitt]

1) to form a very stable substrate, regarding very low thermal expansion, for both mirrors
2) to form a very hard and resistant, yet very transparent (UV-IR) overcoating for thr aluminum first surface mirrors