Making a Laser Projection Microscope

We learned about this awesome project from The Happy Scientist (subscription required for this video). He gave a great, simple explanation about what to do, and we had no trouble getting it to work. And it was so cool! You can probably find other tutorials for this project online, also. (Yes. Here is one.)

Basically, what you're doing is creating a little loop in which a drop of water can be suspended by surface tension. The water acts like a lens for the laser light to shine through. The light is then projected onto a screen and, voila!, you can see tiny little microorganisms in the water. It is amazing. We used pond water to make sure there would be lots of life in it, and there was! We saw all types of different protazoa, flagellates, etc., with all types of movement going on. Some things zipped across the screen quickly, some sort of lurched along, others were definitely swimming. So cool! This is one of the most impressive activities we did this entire unit, and the children LOVED it. They wanted to show it to everyone who came to our house for the next several days.

It's hard to see anything very clearly in the picture above, but this video is really cool. You can see several organisms moving around in the drop of water, and observe the different ways they move. You should definitely try this project yourself!

Lasers

I can't even describe to you how much the children delight in saying "light amplification through stimulated emission of radiation." They think they're so funny. And we loved learning about lasers! They are cool.

This is the laser pointer we have. We really like it.

Here's a good, simple explanation with pictures of how lasers work and what they are.

Lots of good videos about lasers here.

This video was okay—better in conjunction with the others, though, as we didn't think it explained the process very clearly.

This video has no narration, but just text. We liked it because it described semiconductor lasers, which are slightly different than the solid state, gas, dye, or other lasers. (We learned about semiconductors earlier, during our electricity unit, and our favorite video then was this one.)

This one is less about the lasers themselves, but more about laser cutters. Still interesting though.

This was interesting because it showed an open cavity laser, which makes it easy to see what is going on. This is a helium-neon laser.

Very clear and well-explained. Shows why a ruby is often used in a solid-state laser. This video really helped us realize why "pumping" is needed before the laser actually starts working (something we didn't understand before).

Just screens of text. But a good analogy.

Another video that is quite clear about how stimulated emission of radiation is created. Good animations (except the one of Einstein!) :)