April 2014 – VAOL:Vassar Applied Optics Laboratory

week 6 and 7

“Taking Data”

An expression used by experimenters and scientists regarding the collection and arrangement of data; the steps preceding the analysis of the data.

This week, we took data.

The CCD cameras have proven to be excellent. We drop the worm into the cuvette (through which a green and a blue laser are shining). One CCD camera is trained on the green, and one is trained on the blue.

Upload the data to the computer, and open the movies in LoggerPro (Insert-> movie-> choose movie).
“Set Scale” to 1cm by dragging the mouse from one wall of the shadow of the cuvette to the other.
Set origin at the left end of the “set scale” lin
Choose options-> movie options-> override frame rate 25f/s and advance by 15f/s
“add point” and click on the head/tail of the worm. The movie will progress at 15 f/s as you record the entire trajectory
“add point series” for each new worm to separate data and make it easier to look at.

The whole process is not too difficult to understand, and LoggerPro is relatively easy to navigate. The most difficult part is keeping it organized. For each LoggerPro file, there are two movies (one for each of the colors of laser, one from each CCD camera), and two sets of data (two graphs).

Here is a screenshot of the process. There are two videos open, and two sets of data. I keep note of unusual things that happen during the videos, and label the data sets clearly to minimize confusion. LoggerPro also helps differentiate between the data points by changing the color of each point series (each trajectory is color coded).

What’s next? For now, we have to continue collecting data. In order for a set of data to be at all conclusive or valid, it has to have enough raw data to generate a reasonable average.

Week 5

Although this is not actually week 5 of being in the lab, it is the 5th week of work we have gotten to do. Last week we were unfortunately unable to run any tests due to conflict in timing with the replacement of an air filter in the lab. Although we did not do any testing we did pick worms to put in a new petri dish to grow for the next week.

The first thing that I got to do this week was head into the lab with Tewa and see the finalized version of our test setup. I spent the day taking measurements and drawing a diagram as seen below. This was in the middle of the week and the worms were not mature enough for accurate testing, so the day ended with the measurements and some quick looks at test runs performed by Tewa and Brian the previous week.

The next day was spent in the OLB with Brian and Lily looking for possible UV lasers for testing. After we are done with testing the reactions of the C. Elegans with the blue laser we plan to take it to the next step by replacing it with an ultraviolet laser. It took a lot of looking, but we found a few sites that were selling mounted UV lasers. One sight in particular did not sell mounted lasers, but sold extremely powerful handheld lasers. Although these are dangerous and don’t seem safe for the general populace, the site claims that all of its products are legal under U.S. law.

The final day in the lab we got to run actual tests. The day started out by picking out worms to grow for next week, but the next step was taking them into our actual lab to record some tests. Brian Tewa and I took turns recording each CCD camera and dropping the worms into the cuvette. This new setup is interesting because we no longer have to turn off the lights in the lab to get accurate readings; however, goggles are still needed for safety from the blue laser. The tests seemed to run quite smoothly, and some of the worms seemed as if they were actually fighting against gravity to stay out of the blue light which is what we are looking for. After dropping about 20 worms, the next step was to use chloroform to kill the remaining worms in the petri dish to see if there is a distinct difference between dead and live worms in the cuvette. We walked to a different building to use a fume hood to safely use the chloroform and it took about 10 minutes of waiting to make sure the worms were actually dead. At this point I had to leave the lab, but Tewa and Brian remained to do some more testing.

Next week I will be putting together a table with Brian and Lily regarding the possible UV lasers for Professor Magnes to look at and determine which laser to purchase. I also anticipate more testing with our setup or possibly analyzing the data that we took this week.

week 5

Recall the problem of unfocused images when trying to observe the behavior of the worms when sent through two different wavelengths of light, side by side. The regular digital camera was producing such a tiny image that good data was hard to retrieve from the videos. We solved the problem by purchasing a second CCD camera! Now we are able to take two images (focusing the cameras on the two different colors respectively).

What’s next: We are looking into purchasing a UV laser in earnest. Comparing the price, whether it plugs in, the power, the beam divergence, and the wavelength to find the best option for us. We need it to plug in, for the divergence to be small, and for the wavelength to be mid- 300 nm, possibly adjustable.

In our search for the appropriate UV laser, we have found several inappropriate ones, and one especially scary one. A company called Wicked Lasers is selling handheld lasers that achieve up to 2 Watts of power, one of which has an attachment that makes it into a lightsaber. Although it does come with a disclaimer (“this is not a toy”), it is definitely a little scary that such a powerful laser can be bought for just a few hundred dollars, especially one that (even though it is described as NOT a toy) looks an awful lot like a toy.