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Sunday, May 29, 2011

Follow Up: Chromatic Dispersive Light Schlieren

For the last couple of weeks I have been tinkering with the Chromatic Dispersive Light Schlieren that I built. If you haven't read the other couple of posts about this setup check them out HERE and HERE. To summarize the only difference between this setup and the other ones that I have built is the light source. As the title suggests this uses a Chromatic Dispersive Light source for the Schlieren illumination or CDLS as I like to call it. To make this I placed a prism and a collimating lens right after the LED light source to break the white light from the white diode into all the colors of the rainbow (at least as many as a white LED can produce anyway!). Check out the first link above to see what I mean.
The reason I decided to try this is getting a Schlieren stop in just the right place, at the focus of the mirror, with a camera that has a zoom lens is difficult and sometimes impossible. My hope was the Chromatic Dispersive Light Schlieren would eliminate the need for a Schlieren stop and so far it seems to work.
Above is a short video showing the results that i got with a candle. The reason I am using a candle to test this is because it's a easy thing to photograph because of all the wonderful hot air it makes ;-)

Below is a picture of the setup that I used to make the video. I don't have a whole lot of new information to write about this week because I didn't have a lot of time to work on this. I did update the picture of the setup that I posted last week with the location of the prism and the lens because a few people emailed me and asked about it. Without further adu here it is!

Schlieren Setup With Chromatic Dispersive Light

Hopefully you can click on the picture to get a better view but for some reason that doesn't always work. Email me at if you want the original or have any questions. Here is a picture of the setup to hold the LED and the prism.

CDLS Setup With Diode and Prism
The diode is mounted behind the small aluminum bracket on the left and obviously the prism is on the right. Both of them are mounted to small brackets that have threaded pins that extend through the metal bracket in the vise. There are a couple of belleville washers on the shafts to keep tension on the brackets, adding friction so they can be adjusted (rotated) but not freely spin around. Most of these parts I salvaged and modified from junk I had laying around. Others I fabricated from odds and ends.
As I mentioned I don't have a lot to write about so check out the video and let me know what you think.

1 comment:

  1. hi there
    i am also doing some schlieren but mainly for industrial R&D. i am impressed by your capabilities!
    please see me on youtube
    and Wiki:Schlieren imaging
    (feel free to add them as references...)
    i would be happy to discuss technical issues
    shmuel.benezra @