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Sunday, September 19, 2010

Schlieren with Anamorphic Lens and Blue LED

I am still really busy this last week but I managed to try something that I was wondering about. Specifically I wanted to try using an anamorphic lens with the Schlieren parabolic mirror setup to see if it increased the resolution. As I mentioned already I have been really busy so I only had time to build a lens and give it a quick try. The results were interesting but not quite what I wanted. I think that with more tinkering around I could make it work.
Schlieren of candle with anamorphic lens and blue light source
Another thing that I also wanted to try again was using a blue LED instead of a white one. I gave this a try back when I was using a convex lens instead of a parabolic mirror to reduce / eliminate chromatic aberrations. It didn't help so I switched to the parabolic mirror.

An anamorphic lens is usually used in movie theatre's to give that wide aspect ratio or to get rid of it. They mostly just stretch or widen an image. They do this using a couple of prisms. HERE is a good link that explains it all pretty well with some cool pictures.
What I have been wondering is what would happen if you place a colored filter of a "Schlieren stop" razor edge between the prisms and put the lens in front of a camera in a Schlieren setup? My thinking is that as the light enters the first prism it's refracted out into the primary colors. The incidence of refraction is based on the frequency of the light and the angle the light is entering the prism. Then the second prism re-combines the light back into a "correct looking" image (although stretched a bit).
In a Schlieren setup the light is being refracted by the different densities of air so when it gets to the first prism it is hitting it at a slightly different angle. I'm wondering if the prism will 'spread out' the slightly refracted light even more... then if it passes through a colored filter the recombined there might  be a more pronounced 'Schlieren effect'.
I'm not a optical expert or a photographer so I don't know if this is going to work. What I am good at is building things so I figured instead of thinking about it too much why not build one and see what happens?
That is exactly what I did. I took two prisms out of one of THESE security door peep hole's and mounted them to a plate in front of the camera lens. Unfortunately I don't have a lot of spare time this weekend so to do that I had to take off my homemade telephoto lens. Without the telephoto lens I had to use the digital zoom on my camera and all the images are fuzzy.

Above is a video I made using the setup I just described. About half way through I switched over from a white LED to a blue one. I also added some text right in the middle of the video showing a link to my blog. It's annoying but I had to do it because I notice most of my videos get copied to other peoples sites...
Anyway that is the update of the things that I am doing for this week. I'm going to mess around more with the anamorphic lens that I made and also add the telephoto lens to the setup so I don't have those grainy unfocused shots. Once I do that I'll write a post detailing the anamorphic lens and whatever I happen to see while using it.

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