|
May 5 , 2008 Today I presented my WSE 187 project. Dr. Noe and I settled on the project title " Calibrating the Optical Tweezers Imaging System Using Diffraction". At first I was quite nervous mainly because I did not realize how fast this semester went by and the fact that today was the day to present was quite a shock. However, the presentation was not too bad. On Friday, Hamsa, one of Dr. Noe's students who is quite familiar with optical tweezing came into the lab and I was able to see some tweezing of yeast cells. That was just an awesome experience! Simply from viewing the tweezing I was able to put more things in context and I believe this helped liven up my talk. From this experience I have learned quite a bit more on public speaking, presentation formatting, and over all the nature of research.May 2 , 2008 After a bit of brainstorming Dr. Noe suggested that I work on a project that involves calibrating the optical tweezers imaging system. This being the case we ended up using diffraction to calibrate the tweezers imaging system. Essentially, we used "rainbow glasses" as our diffraction gratings. We employed equations used for Young's double split experiments to calculate the distance between modes ( in constructive interference). We also used the image of the dots from the "rainbow glasses" to obtain the magnifications for a 20x objective and a 50x objective. Ultimately, having obtained these magnifications we were able to determine the proportion of these lenses, which in this case was 5/2. Our calculated magnifications were consistent with this value, we obtained a magnification of 1600 for the 20x objective and 4000 for the 50x objective. During our experiment we obtained some interesting results. Having calculated the magnification of the 50x objective we decided to see how we could use this information. One of the ways we did the latter was by attempting to find the acutal diameter of yeast cells we imaged in the lab. In the past, several of Dr.Noe's students determined, by calibration of the tweezer imaging system, that the actual diameter of yeast cells they had imaged was about 10 microns. However, my caculations yielded the diameter to be 5 microns. This difference is quite interesting for after searching several websites we came across information that yeast cells are highly variable and that their diameters at times can range from 5-10 microns. This information helped to assert my calculations , however, it is still intriguing that several students have consistedly calculated diameters of 10 microns.May 1, 2008 On Tuesday I was back in the lab experimenting with the CCD camera. As I did this I used some basic optics equations to calculate the magnification,image distance, and focal point. In many ways this was helpful because I was able to see a real life example of how these formulas such as the thin lens equation works. April 28, 2008Exactly one week from today I will be presenting. It is kind of nerve racking to be the first person, out of all the groups to present. I can't do anything about it so I will just have to be brave and get it done. This week hopefully I will be very productive and I will have more hands on experience with tweezers and be able to write my abstract. I know I also need to start my power point presentation. It is going to be crucial for me to map out what I want to do within this week so I will meet my expected deadlines. The main thing for me to do is be able to see how the trapping really occurs. I also would like to get some really interesting pictures of the tweezer setup, and also a couple of diagrams displaying how the trapping occurs. This past weekend as I was reflecting on all that has been done in this course thus far I realized how difficult it can be to think up your own project. There are many things that one can be interested in however it is often hard to get the project started. As I reached the stage of finishing touches last year in my High School Science Research internship at the American Museum of Natural History, I must honestly say I did not feel as frazzled as I do now. I think alot of that has to do with the time constraints, I had approximately 6 months for that project, and it also seemed that having that period of time enabled me to really explore what I would like to do( which in that case was a bioinformatics related project). Nonetheless, I have learned valuable lessons from this course: time management, how to be more proactive, and also that it is important to be curiously engaged in what you are doing. Overall, I think all of this will make me a better independent thinker in the long run and in the short term it has definitely prepared me for this summer. April 25, 2008 Today my main goal has been to try to understand what really happens when the trapping of the particles occurs. I have been searching various articles and I found one that has helped to clarify this event. I have learned that the trapping occurs as a result of pressurized radiation from a focused beam exerts minute forces on these particles. The physics behind this is truly remarkable because in this manner scientists are able to measure and manipulate these particles.A site that has been quite helpful to me in understanding the physics behind this is listed below. A major plus about this site are its diagrams: Explanation of Tweezer Trapping( Particle Manipulation) April 14, 2006 One of the first things I did today was get a chance to gain some hands on experience with the tweezer setup.In this interaction I was able to familiarize myself with some of the basic tweezer imaging steps. Some of the things that I was able to do learn more about tweezer imaging via hands on experience. This experience allowed me to personally arrange the setup by ensuring that the right materials were at hand ( i.e. the correct screws, lens, etc). After this step, I proceeded in arranging the setup by ensuring that the lens ( in this case a BPX065 lens) was aligned with the CCD(charged couple device)camera on the rail. Once this was in place I was able to try various forms of imaging with the lens and the CCD. From this I was able to find the focal point and I was able to view an image of text on the monitor. This within itself helped me gain a deeper sense of the functions of the tweezer setup. The next step in my tweezer journey will hopefully be imaging other things perhaps polystyrene balls. April 1, 2008 Today,I found out that my project will most probably entail learning about the various uses of optical tweezers. This I believe is important because from this step I will have a background in hands on tweezer applications. Such knowledge will definitely be useful in future tweezer projects. This is getting exciting. I can't wait to go to the lab with Dr. Noe and start. March 28, 2008 Today I read a paper titled: " Inexpensive optical tweezers for undergraduate laboratories" from the American Journal of Physics. An interesting apsect of this paper was the section on several experiments that one could possibly conduct in an undergraduate lab. Out of the six experiments listed two caught my eye. These experiments pertained to the distortion on cells. The first experiment, in particular, dealt with the flexibilty of cells and the way tweezers measurement can highlights this effect. The second experiment dealt with the morphology of cells which can be observed via tweezer measurements. The main reason that both intrigued me was the direct involvment of tweezers in a bioscience related experiment. They also intrigue me because for certain cells their flexbility, distortion, shape etc... can serve important roles in the cell's function. March 24, 2008 Today is my first day back from spring break. Over spring break I began to learn more about one of the central components of my project. As I say this I am refering to a question I had for quite sometime,this question pertains to what exactly are optical tweezers. From searching various places I was able to discover that optical tweezers are" a laser based technique that utilizes minute gradient forces exerted by light waves to measure and manipulate micro-molecules. Essentially, it seems that these forces form a trap of sorts that enable one to manipulate these micro-molecules. Now if any of you are like me you might be wondering in what settings are optical tweezers really used. To my delight I found out that they are often used in manipulating bio-molecules such as small strands of DNA and viruses.Several sites that I found very helpful in giving me a solid idea of what optical tweezers are and current research that they are being utilized in have been: Stanford Information on Optical Tweezers Background information on Art Askin the "father" of the optical trap Harvard Information on Optical Tweezers More Information On Tweezers, their uses, etc... An interesting MIT tweezers lab March 7, 2008 Today is the 7th of March but more importantly today marks the" birth" of my LTC journal. At this point I am still trying to acquaint myself with the Linux setup and the various codes that come along with it.
|