DIY Anamorphic Two Elements Jet Cut from Single Block, Zero Back Focus Distance ?

[Mustafa Umut Sarac]

I want to order laser or water jet cut two cylinderical lens elements from single block of plexiglass or glass without need of mount because remaining block would carry the elements and could be painted light tight.

Yes , it is an anamorphic lens. I inspired with Elcan Leitz IMAX lenses and want to be the back focus distance might be zero , film would be slided traveled on surface of lens flat back element.

Here is the drawing of lens , because of they have same common vertical axis , laser or waterjet would be able to cut in short time.

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Surface would be problem with laser plexi but not water jet glass.

Is it possible to design above lens with zero back focus distance or what would be needed to do ?

What is the secret of zero back focus distance ?

Mustafa Umut Sarac
Istanbul

[Jac@stafford.net]

Is it possible to design above lens with zero back focus distance or what would be needed to do ?

What is the secret of zero back focus distance ?

A square pyramid element with a shaped, truncated apex. I owe you more detail and will look for my strange lens that uses what I wish to describe. A picture might help. I recall a comment here from another person who has the same lens. It is a Metrogon with the big block of glass below the rear element. With luck I'll have more later.
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[Mustafa Umut Sarac]

Thank you Jac and all,

I think I saw an french lens with truncated cone glass at the back side. How does it help ? Is it the only solution ?

I think coming rays hitting to cone , focus to cone bottom and reflects back to back of the lens ? Is it correct ?

Umut

[Jac@stafford.net]

Thank you Jac and all,
I think I saw an french lens with truncated cone glass at the back side. How does it help ? Is it the only solution ?
I think coming rays hitting to cone , focus to cone bottom and reflects back to back of the lens ? Is it correct ?

Umut

Do not thank me because now that I have handled the unusual lens I have, I cannot account for the massive glass lens behind the Planigon (earlier I said it was a Metrogon). Here is a post on APUG (http://www.apug.org/forums/viewpost.php?p=1607437) in which richard ide mentions the same lens with extra glass, but it gives no clue as to what the 1 1/2" additional rear glass is for. I can only tell you that it seems to reduce the distance to the film but does not behaved as a pressure plate. Sorry.

When I have time I will mount the lens on an 8x10" camera, but that drifts us into a different topic.

[Mustafa Umut Sarac]

Jac,

I think you mentioned that pyramid lens which was a document lens where ibm parc published attached paper on it. Now the question , does it solve the zero back focus distance problem ? I think not , its a thick piece of glass , you put on paper and flat glass shows the paper normal when pyramid shows the other pages distorted. They hoped to user to sense group of larger number of documents on desk .

Is there any other solution anyone knows about zero back focus distance ?

Find the attached pdf.

Umut

[Jac@stafford.net]

That's a very cool paper. Thank you. I have coded digital solutions, but the old lens approach is enlightening.
I will follow this thread but have no knowledge to contribute.

Best of luck!

[Dan Fromm]

Interesting pdf but completely irrelevant to the OP's problem. The lens isn't a glass pyramid, it is a computer display device with software to drive it, exactly what one would expect from Xerox PARC. And it doesn't exist.

The paper says, on p. 5:


We have implemented a version of the Document Lens in the Information Visualizer. There are at least two ways to implement the truncated pyramid that results from moving the lens toward you, and get real time response. If you could produce a high resolution image of the 2D layout, you could use either software or hardware texture mapping to map the image onto the truncated pyramid. Currently, we kow of no way to produce the required high resolution texture to make either of these approaches practical.

[Jac@stafford.net]

Interesting pdf but completely irrelevant to the OP's problem. The lens isn't a glass pyramid, it is a computer display device with software to drive it, exactly what one would expect from Xerox PARC. And it doesn't exist.

The paper says, on p. 5: Currently, we kow of no way to produce the required high resolution texture to make either of these approaches practical.

That's the best part!