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FrozenGate by Avery

Laser "microscope"

I tried the pond scum thing with limited success.

I went out and collected some brackish pond water. I put the water in empty Tobasco jars. Focused my DIY 635nm (15-20 mW - want to illuminate, not toast, the beasties) pointer down to a tiny sub mm speck where it railed the jar. After the passing through the jar I used a 10 mm telescope eyepiece to expand the laser stripe. Projected onto a wall 1-2 meters away.

Here's a picture of the setup:
PondScumProjector.jpg


There were a lot of little critters visible to the naked eye in the water. No doubt lots of bacteria also. All I got was shimmering of the laser spot. It would blank out when something larger passed in front the beam. Note the water had settled so whatever was causing the shimmering was not turbulence.

I think I need a different approach than this.
 
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Try a wet mount microscope slide. Shine the laser through the bottom, displaying an image on the ceiling. There's plenty of room under a cover slip for bacteria. There are probably so many bacteria in the large amount of water in the bottle it's all a blur due to overlap. [holy runon] Also, try a green laser. It may work better, but i'm not sure on that.
 
This is what I did:


bacteria%20experiment.png


I used a 30mW green to do it, projected onto a white screen about 5m away. The reason I think it is in those locations is because the particles and the bacteria that you see on the screen seem to get larger and smaller as they move, implying moving closer or further away from the focal point, respectively. I only saw one every 15 seconds or so, the rest was just dust.
 
It's worth noting that microscopes work until the objects get so small that light goes around it... moving to lasers won't change that. I asked my teacher about this a while back he told me it wouldn't work for this reason. You have to go to X-rays to get much smaller.
 
Well, common bacteria range in size up to about 10µm long, the largest being something like 750µm.

Although those sizes seem tiny, when you think that 10µm is a hundredth of a millimeter, it's not as small as you first think.
 
ossumguywill said:
It's worth noting that microscopes work until the objects get so small that light goes around it... moving to lasers won't change that. I asked my teacher about this a while back he told me it wouldn't work for this reason. You have to go to X-rays to get much smaller.
Click to expand...

A blu ray on a florescent screen would be better than.
 
flogged. Dont forget there are imperfections in glass. It could possibly be a problem that you are using a Tabasco bottle. Like another member suggested try a microscope slide or another flat piece of glass. Your experiment may actually work but the volume of water is so great that there is too much bacteria/scum in the water to actually project an image.

This is just my own theory as to why i did not work so don't flame me if i am wrong :P
 
So today i found an old bottle of methylene blue. After eating some and watching my urine and eyes turn blue, i decided it was time for science. When i get around to it later tonight, i'll stain some skin cells and see if i can get a decent image. I'll try it with some bucket water too. Plenty of ring worms so i suppose it's got all sorts of microbes in it. I'll also try staining some plant cells with some iodine. I'll get back to you people with (hopefully) some images later.
 
Limited success. I couldn't cut plant layers thin enough without a microtome, and i had apparently no bacteria in the water. However, i did manage to get an image of my cheek cell. I placed the wet mount slide directly on the OC of the laser, and here's what i got. You can see the membrane and nucleus, although in not much detail. There is a lot of diffraction too. An interesting note, i used my high power laser, so when the cell was placed in the beam, i could see it swell due to heating. Rather quickly too. When the laser was turned off and on again, the cell would swell each time, indicating it shrunk while the laser was off.
 
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Here is the experiment done by Arbor Scientific. The narrator unfortunately misidentifies the wavelength of the laser; but the experiment works perfectly. The water acts as a small lens and assists in magnification. Bill

YouTube - Green Laser Microscope
 
I'll try it that way next! However i must do it with a "dead" battery else my laser will incinerate the poor creatures.
 
My 5mw is on loan to a friend. Maybe i could use my Hene, but it would have to be in a dark room.
 
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