August 1, 2003
This is my last journal entry because tomorrow I am returning home to Texas. I've been very busy this week preparing for the presentation and finishing my paper. Monday through Wednesday I worked long hours taking my last data and making graphs, preparing my power point presentation, and writing my paper. The entire day Thursday was spent at the REU presentations, and today I finished my paper. To sum up the summer, I have learned a lot, and not just about my project. I have learned more about what goes into research. The experience has reaffirmed my ambition to pursue physics in graduate school. I have enjoyed working (and having fun and laughing a lot) with all of the people in the lab and will miss each one of them. July 28, 2003
Last week was quite a busy one. On Wednesday we had our weekly lunch with Professor Metcalf. A past Laser Teaching Center student, Alex Ellis, came to talk about the research he did here last summer. On Thursday the other REU physics students came for a tour of our lab. James, Jose, Tom, and I each explained our projects at the board and then showed our setups. Friday Dr. Noe took us all out for sushi. We were all a little nervous about eating raw fish, but everyone ate at least a little bit. There was also a physics keg party Friday afternoon, but I did not go for very long. Besides all of these events, I was working hard on my project trying to get it finished up. I saved many pictures from the CCD camera on the computer and attempted to make an animation of the Talbot effect, but it did not turn out to be very effective. Instead, Dr. Noe put the pictures online. I also took more data and made more graphs. I still have a few more things to do before I write my paper, but I hope to finish those today so that I can write my paper tomorrow. I only have 3 days until my presentation, and then 2 days after that I return to Texas. July 21, 2003
This week I was finally able to take data. I took several measurements of the different image distances and made graphs comparing those distances to those predicted by the formula in Silverman's book, which I have mentioned in previous journal entries. I also calculated the standard deviation of the measurements to determine the error and see if the values the formula predicts are within this margin of error. For my REU presentation next week I plan on using Power Point, so I want to have several pictures for the presentation. I am going to save the images projected onto the CCD camera for about 100 different distances so that I can show what the effect looks like at different distances. I will do that this week, however last week I began working on trying to figure out what exposure time I will need at different distances from the light source. Other than working on my project, several other events kept me busy last week. On Tuesday, students from the Physics and Chemistry REU programs went to Brookhaven National Labs for a tour. We saw the synchrotron, Relatvisitic Heavy Ion Collider (RHIC), and the PHENIX. I enjoyed the tour and learned a lot from it. On Wednesday we had our usual lunch with Professor Metcalf. We each spoke about the progress of our projects. We also discussed the Physics Regents exam. The Regents exam is a statewide New York exam. Thursday Professor Metcalf gave us an introduction to quantum mechanics. Next week he will give us another lecture on quantum mechanics. Finally, on Friday the Physics, Chemistry, and Marine Science REU programs went on a "Discovery Boat Cruise" in Stony Brook. Outside of the lab, I have been attending the Stony Brook Film Festival. I have enjoyed seeing several independent films, especially the short films. July 11, 2003
While waiting for my Ronchi ruling to arrive, I worked on ideas for my setup and further researching background information. I want to begin writing my paper about the Talbot effect soon so that at the end I won't be rushed to finish. I also made some theoretical predictions for the location of images for a particular rulingdistance as well as for the magnification of the images. During the weekly REU luncheon on Tuesday, we toured the Van De Graaff. Then on Wednesday those of us in the Laser Teaching Center ate pizza for lunch with Professor Metcalf and discussed each of our projects and interests. My Ronchi ruling arrived Thursday so I tried it out on my setup. When I held up a screen to view the image of the ruling, expecting to see horizantal lines, I actually saw concentric circles. At first I thought that I may have been sent the wrong thing, but after looking under a magnifying glass I saw horizantal lines on the ruling as I should have. I found out today, with the help of Dr. Noe and Professor Metcalf, that the circles were interference fringes caused by the reflection of light from the back of the ruling interfering with light reflected from the front of the ruling. I spent the rest of the day learning about Fresnel equations for reflection. Also, since Maanit needs a more powerful laser for his experiment, I switched lasers today and learned how to align laser light through a fiber optic cable. Dr. Noe took Patrick, Sandy, Tom and me to lunch at The Curry Club for some good Indian food. I also briefly attended the Physics keg party. July 7, 2003
Last Monday and Tuesday I worked on learning Fourier transforms. I found it difficult to find a book with a good explanation of them and examples of how to work problems, but finally came across a good one called Mathematical Physics: Applied Mathematics for Scientists and Engineers by Bruce Kusse and Erik Westwig. Wednesday we began to set up my project. I will use a device on which I will be able to put most of the set up. Each object, including the grating, screen, and CCD camera, will have a platform that slides on the device. I will be able to make accurate measurements up to 100 microns because the device measures in millimeters and each platform has a ruler that may be matched up with a position on the ruler on the main device. The rulers on the platforms have 10 marks for every 9 millimeters, which enables the accurate measurement. I will have to send a couple of the platforms into the machine shop to be adapted for the size of the equipment I am using. I am also ordering a different Ronchi grating. The one I was using previously had a ruling of 100 lines/inch, but the new one will have 250 lines/inch, which is closer in size to the one used in Waves and Grains. I will be able to perform my experiment when the new grating comes in and when the machine shop is done with the platforms. Until then, I will continue researching in journal articles. I also plan to read up on the CCD camera so that I will know how to use it when it is time. I need to calculate the theoretical predictions for the Talbot length for the new Ronchi grating as well. So, I have plenty to keep myself busy with until I have all of the equipment I need. Thursday all of us in the laser teaching center had pizza with Dr. Metcalf, who recently returned from a semester in Utrecht. Friday was the 4th of July, so we did not work. I hope everyone enjoyed the holiday weekend. I went to New York City and saw an amazing fireworks display and a couple of great Broadway shows: Cabaret and Long Day's Journey into Night. June 30, 2003
At the beginning of the week, I attempted to take some data for my experiment. Tuesday I was finally able to figure out a problem I had been having mathematically trying to predict the Talbot Effect. When I tried to compare my theoretical prediction with experimental observation, I discovered that with my current setup I did not have a long enough range to observe enough to know if this prediction is correct, so I will have to wait until I have a more permanent setup to find out. While trying to take data, I came up with quite a few questions that I spent most of Thursday trying to answer by both reading several articles on the Talbot Effect and by going back to my setup to compare what I had read and what I observed. One thing that struck my curiosity was that I had seen two different equations for calculating the Talbot length (the distance from the grating at which the image may be seen). One equation has consistently shown up in all the articles I have read. The only place I have seen something else is in Silverman's book Waves and Grains, which is the equation I used to make theoretical predictions. The equation in Silverman's book takes into account the light source to grating distance, while the other equation does not. Through this project, I would like to figure out a connection between the two different equations. I would also like to learn more about the fractional Talbot effect, which I hope to observe by taking light intensity measurements at different distances from the grating. Finally, I would like to find out for how long a distance the Talbot effect occurs and what this depends on. On Friday I decided to start learning how to do Fourier Transforms before I began taking data. I have not quite figured them out yet, so I will work more on that today. We also went out to lunch again on Friday, this time to The Curry Club. It is an Indian food restaurant. After lunch, two boys came down to the lab to see some demonstrations. Then at 4 we went up to the weekly physics department keg party, which was mostly professors and graduate students, but several of the other REU physics students attended as well. I met and talked to a couple of professors. June 20th, 2003
I have spent the last week further researching diffraction and the Talbot effect. I observed the diffraction pattern formed by single, double, and multi slit diffraction. I also observed the Talbot effect as I learned more about it. The Talbot effect is when noncollimated light is passed through an object and then produces an image of that object at periodic distances, called the Talbot length, from the object. I used a helium neon laser passed through an optical fiber so that it was no longer collimated. The object needs to be periodic, so I used a Ronchi grating, which has a period of 100 lines/inch. Then I held a white screen up to the light and observed the image of the grating go in and out of focus as I moved it further from the grating. Next week I plan to observe the effect more quantitatively by measuring the distance at which the object may be viewed. Today, I focused on rereading some things because after observing the Talbot effect and diffraction patterns in the lab, I figured I would better understand what I had previously read. This afternoon, Dr. Noe, James, and I went out to eat at "The Cull House." I had lobster for the first time! It was good to get a break from the cafeteria food and to see more of Long Island. June 16th, 2003
Over the last week, I searched the web and different journal articles to try to come up with a project idea. After looking at past projects done at the laser center, I became interested in doing something with chaos in lasers or fiber optics; however, i was unsuccessful in finding a project in this area that would fit into the limited time frame I have here this summer. Dr. Noe suggested looking into the Talbot Effect and Fourier Optics over the weekend, and after reading up on these I have decided to do a project in this area. The Talbot Effect was discovered by H.F. Talbot while he was studying the diffraction of light. As I research more, I will be able to explain in greater detail exactly what it is, but since I am still learning, I do not want to write anything incorrect here, but if you are interested click here to find out more about it. I am currently deciding exactly what to do in this subject. I have looked at some articles, including one describing the use of the Talbot Effect to measure distance to an object and another using it to make a spectrometer. Both of these sound interesting, but I am still looking around and will decide what is best soon. June 10, 2003
Today is my second day in the Laser Teaching Center. Yesterday I met Dr. Noe and the other REU students working in the laser center. We learned a little bit about Linux and looked at the Van de Graaff accelerator used in the nuclear physics laboratory. Today I have been working on my biography and journal. I do not know exactly what I will be working on this summer, but I hope to figure that out in the next few days. I will update this journal about once a week to talk about where I am in the research process.
