new user- wind tunnel

zaynah · Post by **zaynah** » Tue Feb 26, 2013 10:03 am

hi world,

this is my first time with holograms.

i have designed a wind tunnel 1 metre length by 80 cm width by 30 cm height.
I wish to do its hologram to visualise.
Can anyone point me in the right direction.ie wat to do? how to start? what material to buy etc..

An advance thanks to anyone who reply me..

cheers
zaynah

holomaker · Post by **holomaker** » Tue Feb 26, 2013 12:44 pm

This will be tough to make an actual hologram of the air currents with out using a pulse laser. You could set up an interferometer to see the air movments ..........

zaynah · Post by **zaynah** » Wed Feb 27, 2013 1:15 am

dear Holomaker

can you tell me more?

In my wind tunnel, smoke are being sent to view the air currents..
I wish to use the laser beams..

Thanks in advance

Ed Wesly · Post by **Ed Wesly** » Wed Feb 27, 2013 9:16 am

So it seems that you want to make holograms of the smoke in the wind tunnel? Then definitely you will need a pulsed laser, either a frequency doubled Nd:YAG as they are called, or a ruby laser.

I do have such a device, a JK/Lumonics HLS-2, output one Joule, which would be capable of recording such an event. Where are you located?

Jem · Post by **Jem** » Wed Feb 27, 2013 10:51 am

Or is he(?) wanting to use 'real time' interferometry to see the stress patterns on objects in the tunnel?

Have I got the correct terminology there?, i've seen it done with a 'wing' as wind speed increases you can see the stress points. Similar to cross polarisation, but different

. If I knew what I was talking about it'd be a good suggestion, lol

holomaker · Post by **holomaker** » Wed Feb 27, 2013 12:01 pm

Holographic Interferometry........... or as the old guys say "nondestructive testing", Ed I’m sure has got all tight info , but its possible in theory to shoot (make hologram) wiith the tunnel and object in static mode, then process in place(no shrinking) with a wet tank film holder, or have a good repeatable plate holder, then start up your tunnel with hologram lit and placed exactly back in position, to then see possible stress fringes. You need a heck of a lot of light and some badass equiptment to make it work , That’s why we mentioned Pulsed type laser .
Using a Pulsed laser and exposing few mili-seconds apart (double exposing), will show you the fringes drapped aroung the object in the wind tunnel's viewable surface (stress areas).

Jem · Post by **Jem** » Wed Feb 27, 2013 1:11 pm

Haha... Thanks Dave... I sort of knew what I wanted to say, but the brain wouldn't process the info. You nailed it though, thanks

zaynah · Post by **zaynah** » Thu Feb 28, 2013 2:48 pm

dear holomaker.

I live in MAuritius..
I am completely new to hologram. can you tell me if i can mode this? and also how to proceed??

thank you for all.

holomaker · Post by **holomaker** » Thu Feb 28, 2013 6:01 pm

Ah yes Mauritius the home of the now long gone Dodo bird ! So using air currents, you could try an interferometer possibly with one arm across the wind tunnel, then could do a side by side picture of the distorted fringes ............. look to the internet for information on this subject and return with you questions !

BobH · Post by **BobH** » Fri Mar 01, 2013 12:23 pm

Might consider a Point Diffraction Interferometer. I build one of those in the Fluid Dynamics Lab at NASA Ames around 1990. It allowed visualization of air pressure around an airfoil, and photographs were made to record it.