Joseph's End of Week 2 and Start of Week 3

Since it's already Monday, I might as well throw today in as well as last Thursday and Friday. So, as I mentioned in my last post, both Cory and Brittany were not there Thursday, but my external advisor Dr. Blanche was, so I was able to go into the lab, but I didn't really do anything with the lasers. I worked on the presentation that I was going to present on Friday, did some research. Then, I went to a seminar, and it was awesome! Sure, I probably understood 30% of the thing, but still! It talked about how you could trap particles just using lasers and nanowires (which are like fiber-optic cables that you stretch until you get very thin wire, sort of like how you stretch bubble gum). I'm probably not allowed to go any deeper than that, but it was cool. Also, before the seminar, these people gave out cookies and punch! YES!

Anyways, on Friday, I learn that the meeting that I was supposed to present at was cancelled! Too few people were there or something. I was like, "WHAT? ALL THAT HARD WORK FOR NOTHING?!?" Ah, well. So, instead, I did some more research, helped Brittany with some tests, and went to something called "Community Speakers." Community Speakers apparently is where this group get I assume important people to come in and talk about their field and what they do. Oh, and did I mention that they had free pizza and soda?!? So of course I went! One of the topics was internships, and the speaker was a university student that interned all over the place, and it was interesting listening to what he did and his pros and cons of working for small vs. large companies. For instance, in a large company, you have more resources, but in a small company you get to know everyone in the company, making for a better atmosphere. I also started researching for my next assignment: testing for the sensitivity of a photopolymer.

Monday was really cool! Why? BECAUSE I MADE MY FIRST HOLOGRAM! AW YEAH! So, after doing some calculations and whatnot, I made my setup for making the hologram, turned on my laser, dimmed the lights, and started the recording. It takes time for the light from the laser to "energize" the photopolymer (holographic film). For the photopolmer to record anything, you have to pass a threshold exposure, and the exposure can be expressed in the equation "Exposure = Energy (from the laser) * Time (that the laser is shining on the photopolymer)." In terms of an analogy, you can think of the exposure as a bucket, the energy as a hose, and time as, well, time. For the hologram to work, the bucket needs to be full. Now, to fill the bucket, you can either have the hose be fully open (high energy laser), filling the bucket in a short amount of time, but you also run a greater risk of overflowing the bucket (overexposure); or you can have a slow stream of water from the hose (low energy), that would take a long time to fill the bucket, but also more leeway for overexposure. Depending on your setup, you pick the method that works for you. Anyways, my laser was relatively weak, so I needed to wait a minute for the hologram to record. Also, during the recording process, you need to be VERY still. Holograms work because they record according to interference, but interference only happens when everything is still. You don't move, you don't breathe heavily, you don't nervously move your foot, you don't even look at the hologram funny. You pretend to be frozen for a minute, and then you're done recording! I developed the hologram, and it worked! YEAH! However, it wasn't THAT great (due to a bad choice of object), so I'm not showing it to you :-p. However, more's to come, so I can't wait!

Some random stuff:

I learned about something called Hysteresis. What in the world is that, you ask? Hysteresis is the problem where there is a "lag" distance before something moves. For instance, recall that huge contraption from my last post (or go back and look at at). Say I'm doing my experiment, turning my knob by each increment, and I accidentally overshoot a little. I just need to turn back to get them aligned and take the measurement, right? WRONG! Why? Because even though I moved the knob, it might not necessarily move the platform. Think of it as a gear moving over a notched surface, and you control the notched surface. As I move the surface to the left, the gear moves as well. Now what happens if after that I move the surface to the right? Does the gear move? Well, not at first. I need to get the notches to hit the other side of the gear first before the gear will move in the other direction. However, even though the gear didn't move, my measurement of the surface's displacement changed, which means my distance is wrong. That error is due to hysteresis, or that "lag" effect.

I also saw a Tie Fighter Hologram! Here you go, the one picture of this post:

Too bad you can't see the 3D-ness of it, but trust me when I say that it was cool!