Journal
7/1 | 7/6 | 7/7 | 7/8 | 7/12 | 7/14 | 7/16 | 7/21 | 7/23 | 7/26 | 7/28 | 7/30 | 8/2 | 8/4 | 8/5 | 8/6 | 8/11 | 11/1
Monday, November 1
The summer has now concluded and I apologize for the length of time it took me to update my journal. Upon leaving Stony Brook I immediately had to go to Clarkson University to begin my first year of college. Since I arrived here I have been extremely busy, taking 18 credits this semester to fulfill my high school diploma requirements and keep up with the rest of the freshmen here.
The Simons presentation went well. My poster was finally printed after some confusion between operating systems. I arrived and set up my poster early, and gave my family an overview of my project as a final practice before the actual presentations started. I spoke to several professors and students during the event, explaining my experiment and the benefits of liquid mirror telescopes. Most people seemed interested by my idea and the ceremony went well.
I feel that the Simons fellowship was a success for me, I enjoyed working with Dr. Noe and the REU and Simons students, and I definitely learned a lot throughout the summer, not just about optics and physics, but about how to think and question. Dr. Noe encouraged us not to take things for granted and through the summer I saw and used that idea many times, and I found that every time something good came out of it. I would like to thank the Simons Foundation, Dr. Noe, Harold Metcalf, Marty Cohen, and my fellow students for the opportunity to work in the Laser Teaching Center this summer.
Wednesday, August 11
This week has been rather hectic here at the LTC, and I have sadly been running short on time to post here in my journal. My laptop with all of the files I need to be working on is currently malfuntioning however, so I have a bit of time to write while that is sorted out.
Monday I worked to collect data about the shape of the liquid surface of my mirror. I also spent a sizeable portion of the day working on my abstract and going over it with Dr. Noe. Tuesday I spent a long time with Dr. Noe getting the abstract closer to perfection, and today we put the finishing touches on it. Yesterday Pradyoth, Annie, and I gave a tour of the Laser Teaching Center to the other Simons Students. Today and yesterday I have been collecting data and locating focal lengths for different spin speeds, as well as working on my poster, which I have to print tomorrow evening. Unfortunately, both the spreadsheets I was using to analyze my data and my poster files are on my computer which I cannot access right now. All I know about that little issue at this point is that it is going to be a long night.
Update: Good to go. Ubuntu manages to save the day and somehow recover the files I was working on. This has been an extremely stressful two hours or so, and it is still going to be a long night, but a much better one than it could have been.
Friday, August 6
Today we said goodbye to the REU students, which was sad. We watched them all give their talks and then they left, wishing us luck with our projects and our college experiences. After our goodbyes we went back to work. I continued changing the focal length of the mirror and recording the changes in the image projected on to the ceiling. When the image was brought in to focus well enough to see the filament, it was apparent that the filament was located on the edge of a ring of light. We soon saw that this light was coming from the edges of the mirror, where the interaction of the water with the side of the container deformed its parabolic shape. Following Dr. Noe's advice, I made a mask from a ring of cardboard placed on top of the mirror. This covered the part of mirror causing the ring and the filament could then be seen almost perfectly and with barely any other light around it. This discovery although the mask I made does reduce the total light collected by the mirror, so some more work is needed to prevent it from blocking too much light.
Thursday, August 5
Today I actually built the telescope! Pictures of it will be up here very soon. The telescope is built with a record player and a dish sitting on a turntable. There is also a movable stand above it to hold a screen, CCD, light bulb, etc. at a movable point in space. The first model used a nine inch diameter plastic tub on top of a lens holder to keep it above the record player's pin. This containter was extremely difficult to center and made a poor mirror, although it demonstrated the concept of the liquid mirror well. We were able to view magnified images an off-axis light by looking at the mirror from an angle. During lunch, Dr. Noe got supplies for a better, larger mirror, which I constructed after lunch with some help from Jeff from the Machine Shop. I used a combination of two plastic pots, and Jeff put a hole in the exact center of the small one for me in less than five minutes. The larger pot has an indent that fits on the top of that one, and that larger one holds the mirror, with a diameter of twelve inches. Using this larger mirror I was able to project light like a search light by placing a light bulb at the focal point and projecting it on to the cieling with the mirror. This was very exciting and I hope to make more progress and upload pictures tomorrow.
Wednesday, August 4
Today and yesterday I have been working on the math that allows a parabolic shape to form on the surface of a rotating liquid. Today we also went over our abstracts and watched the first run-through of the undergraduates' talks. In the next week I have to complete my actual experiment, edit and complete my abstract, and complete my final poster to prepare for the Simons presentation. I also have to prepare for a brief presentation and tour of the lab for the Simons students which will take place next Tuesday.
Monday, August 2
Today I worked on trying to figure out how the math of determining the focal length based on the spin speed works. I am looking at several papers in an effort to do so. I also began working on my final Simons poster, which has to be done by thursday. Tomorrow I need to keep working on the poster and construction and the math, and I also need to write my abstract to go over on Wednesday. On top of that the REU students are giving a tour of the lab tomorrow, so it should be a busy day.
Friday, July 30
I finally have decided on a project, which I am very excited about. I will be building and testing a liquid mirror telescope. I spent yesterday and today figuring out the project and learning in detail how to go about calculating the focal length of the mirror based on several factors, and then actually calculating it. I plan to actually build it and start testing it early next week.
Wednesday, July 28
Yesterday and today have been spent focused primarily on project ideas. Further looking in to the liquid mirror telescope, the idea that I had come up with is extremely complicated, much too complicated for the final two weeks of the summer. In lieu of this, I am exploring other ideas. One of these ideas continues with the liquid mirror telescope, but on a much simpler scale answering much more basic questions. I would build a small liquid mirror telescope and demonstrate its changing focal length, and figure out how much and how precisely it could be changed. I would experiment with different liquids with varying viscosities and properties, and see the change in the focal length range, as well as the change in ripples in the liquid. Another project idea is an interesting phenomenon that occurs when veiwing an object through a lense at a distance. As Dr. Noe and I quickly figured out, what you see at first is not at all what you would expect. This is rather puzzling and would be interesting to look in to.
Aside from that, yesterday the three Simons fellows attended a workshop on creating a poster for the end of the Simons program. It made me realize how close we are to the end and that I really need to come up with a project, even though it feels like I just got to the Laser Teaching Center. Today at our LTC lunch we had a guest speaker who was a high school student who had veiwed standing sound waves using microbeads in a tube. This was interesting because I am interested in sound, and because I had carried out a similar experiment last year. After that, as a group we went over the undergraduates' abstracts for their papers, and we were able to see how much detail and fine tuning it takes to write a paper. In all, it has been a busy two days but I should have a project nailed down by tomorrow.
Monday, July 26
Today was a very busy day. The morning was mostly spent preparing for the vortex party, and the entire rest of the day was spent at the vortex party. Kiko Galves from Colgate University and Giovanni Milione from City College of New york both gave presentations about vector beams. Following that, Annie, Pradyoth, and I gave our presentation on our mini-project: Profiling a Gaussian Laser Beam. After that, Josh Lieber, a former Simons fellow in the LTC presented his work from last year, four high school students from New York city presented their results from experiments this summer, and then Heather and Jacob each presented their summer work. Following the lectures, most of the students and professors went out to dinner together, which was a good way to unwind after the intensive afternoon schedule. In all, it was a long, but very interesting day.
Friday, July 23
Thursday and Friday we did a lot of work on our report. We worked together and with Dr. Noe to get a good report together, and now we are close to finishing it, and it will be on this website within a day or two. Our graphs and data analysis are completed however, and we are very pleased with the results. The final graph is shown below. All of the widths we found are plotted together, along with the best fit hyperbola, and it can be seen that the path of the laser beam is in fact hyperbolic.
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The widths we found are in blue, the best fit hyperbola is shown in orange |
I also had some time to work on my actual project idea a little today and I am very excited. Today I downloaded Beam 4, a software designed to make ray-trace diagrams. I began using it and in trying to learn about it I decided to make a basic telescope with a parabolic mirror, as a liquid mirror would be. It was very simple to use the forward-facing telescope to focus incoming rays to a film, where they could be captured by a CCD.
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The light from a source directly over the telescope focuses perfectly on the detector |
After re-drawing the rays to mimick light coming from a point other than directly above the telecscope, it became apparent that the light was not going to focus as nicely as it had before, and this is the trouble with liquid mirror telescopes. They are unable to tilt because they rely on gravity for their shape, and so are unable to look anywhere but directly overhead.
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The light coming in from a different place is not even able to focus on the secondary mirror because of its incidence angl |
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As I was playing with the software, I decided to change the curvature of the mirror, and I noticed something very interesting. If you changed the curvature of the mirror, which can easily be done with a liquid mirror, you would move the focal length in such a way so that at each different focal length, a different ray would pass over the detector.
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The focal point has been changed and one of the drawn rays is making it to the detector |
Using this and a program that takes into account the exact rate of change of the curvature of the mirror, a CCD could take many pictures and combine them, or use a technique similar to drift scanning to form a usable image of something not directly above telescope while keeping the telescope aimed directly upward. This could be used as a method for aiming liquid mirror telescopes, which would benefit them greatly as their lack of movement is their most pronounced shortcoming.
Wednesday, July 21
Today and the past two days have been spent working extensively on our mini-project. We've been collecting and analyzing a lot of data, as well as working on the report. Dr. Noe has been offering advice and helpful pointers and we've been working to accommodate his suggestions. The full report will be available from my journal shortly, but essentially we are mapping a gaussian laser beam as accurately as possible to find the waist and divergance, and from these numbers you can find the exact way in which the beam propogates through space, and even deduce the wavelength of the beam. We are now done taking data, and all that is left is the final touches on the report, which should be here within a day or two.
Of course, besides just data taking, we've also attended several talks on various topics. On Tuesday, Marty Ligare gave a fascinating talk about an interesting approach to thermodynamics in a trap by deriving equations from newtonian physics. Then, on Wednesday, we were visited by two former LTC students, Greg Caravelli and Rebekah Schiller, both of whom are now high school science teachers. Both of them gave interesting talks about what it is like to be a physicist teaching in a school, as opposed to a teacher teaching physics. They have both had interesting careers up to this point, Rebekah moving from teaching in a difficult school to one of the Nation's best schools, and Greg teaching at a private Jewish school where the sciences are seen with little value. Both of them from very different positions encouraged bright young physicists to get in to education, because they have seen first-hand that teachers of the sciences in many instances are woefully under-prepared to explain physics. Rebekah told a story of her first year when she co-taught a class with another teacher. The other teacher when describing Newton's second law wrote F=m/a. Rebekah tried to explain the mistake but he had difficulty realizing his error. These stories are upsetting and I do believe that we need better physics educators, and science teachers in general, because poor representation at a young age often turns people off of the sciences all together.
As far as projects go, I am still doing a lot of reasearch, although I have some much firmer ideas now. I am thinking of making a liquid mirror telescope, which uses a liquid reflecting surface as a primary mirror. This greatly reduces the cost of the telescope, allows for bigger mirrors, and, its most interesting property, it allows for a continuously adjustable focal length. I have some more research to do, but it would be very exciting to model this adjustable focal length and possibly build a mount that could take advantage of this.
Friday, July 16
Yesterday and today have been busy. Pradyoth, Annie and I have spent most of the past two days taking measurements with the HeNe laser. We are measuring the width at different points along the beam and plotting them to find the waist. To measure the width, we measure the beam intensity with a photodetector at a series of fifty to eighty points as we move a razor blade across the laser. Plotting these yeilds an erf curve as expected, and we have to plot an erf curve as close as possible to our results in order to determine the width. To do this, we plot a point on the erf curve at each data point we took. We then subtract this number from the data point and square the result, to prevent positive and negative errors from cancellling out, which would lead to a misleading result. We do this for each of the data points collected at a given distance, and add up the results. We then change the parameters of the erf curve to get the most accurate result. Once this is done, we take the width of the erf curve that we have come up with and plot it against other widths.
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The orange line is the closest possible erf curve to our data, represented by the blue points. |
Our final graph of the widths is not quite complete as we have to take several more width measurements on Monday. Hopefully after we take those, we will be able to plot them and determine the equation by which this particular HeNe laser propagates through space.
Wednesday,July 14
Yesterday all of the Simons Fellows went to Brookhaven National Laboratory for the day. We were not able to get any work done, but it was a very interesting and educational day. We were first given a speech introducing us to the Laboratory, then a tour of the phenix detector, which was fascinating. We were able to go right up to and see the detector which was really cool. After that we were given a talk on Atlas, one of the detectors at the LHC (Large Hadron Collider). Brookhaven Laboratory processes and stores a lot of the data collected there. After that, we actually got a lecture on and a tour of the super computer at the lab, New York Blue. It is an IBM Blue Gene computer and currently the sixty-seventh most powerful super-computer in the world, with a peak performance of over one hundred teraflops (one trillion floating point operations per second). It is air-cooled, and extremely energy efficient as well.
Today we spent most of the day in the lab experimenting for our mini-project. We repeatedly passed the laser blade in front of the laser beam to try to determine the diameter of the beam at different distances from the laser. This proved to be difficult because a laser beam is Gaussian and it is extremely difficult to discern just where it starts and ends, and we ended up getting a seemingly jumbled mass of data. At the end of the day of experimenting, Marty pointed out something interesting, explaining to us that because it is difficult to define where a Gaussian beam begins and ends, often the edge of the beam is considered to be either the point where the intensity is e^(-2) or the point where it is half as intense as it is at the peak. We decided that it would be best to use e^(-2), because it is a larger diameter and we would like to find the waist of the beam, or its most narrow point, and a larger diameter would be most helpful in this endeavor. Tomorrow we will begin taking measurements looking for this point and hopefully get some useable data.
When we weren't in the lab today we were at the weekly LTC lunch, and our guest speaker this week was John Marburger, a physicist who was president of Stony Brook for fourteen years, as well as President George W. Bush's Science Advisor, and is currently Vice President of Research at Stony Brook. He talked about optics in general, and he was very interesting. He described how optics fits in to a sub-feild of studying propagating systems, and how many different areas of physics come together in optics. He talked about modelling different systems with optics because the math in the wave equation is very similar to many different observable phenomena. He even brought in a fifty year-old tape recorder and used the amplifier to set up a standing sound wave. It was a very informative talk and offered a new angle to looking at optics and how it fits in to physics as a whole.
Back to the topMonday, July 12
Friday was a fairly busy day, we worked a long time trying to visualize and mathematically show just what happens as a laser beam propagates. We thought about the properties of a gaussian beam and tried to explain mathematically what would happen if a razor blade was passed in front of the beam while it was pointed at a photodetector. We then derived the equation of the hyperbola that models a propogating laser beam from the its geometric definition; the board looked like this when we were done:
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This is the second layer, the first had to be erased before we could finish. |
Today, we completed at least rudimentary experimentation on our "mini project." We continued the ideas we had discussed friday and tested them. Using a HeNe laser, a photodetector, a lense and a translation stage, we were able to measure the light intensity when the laser beam was blocked at various points. We then plotted these points and determined the erf function that was closest to them essentially by integrating a Gaussian equation in Open Office Spreadsheet, then minimizing the difference between the curve and the points by adjusting several parameters. We used an erf curve because it is the integral of a Gaussian equation and we predicted that the laser beam's light intensity as the razor blade moved across it should follow this function because the laser beam's intensity from one side of a diameter to the other is represented by a Gaussian equation. The final results of this stage of the experiment are posted below so it can be seen how closely the data matches our prediction at a short (.147m) and a medium (3.5m) distance.
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This is our data at .147m. The blue points are our data recordings, and the yellow line is the erf curve of best fit that we predicted the points would follow. |
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This is our data at 3.50m. The blue points are our data recordings, and the yellow line is the erf curve of best fit that we predicted the points would follow. |
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Thursday, July 8
Today we did our first hands-on experementation in the Laser Lab. Pradyoth, Annie, and I were asked by Dr. Noe to determine the spread of a laser beam and the shape that it takes over a distance. We took several measurements of the laser beam's size at different distances, ranging from a few meters to almost five hundred feet. After gathering the data, we plotted it in a graph and created the most accurate best fit line that we could.
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The graph plots the distance from the laser to the screen versus the diameter of the laser spot. |
There is still work needed to be done with this project. Our measurements this far are very crude, the diameter of the laser beam was measured by eye with a meter stick in a moderately lit environment. The diameter of the beam in this scenario is extremely difficult to measure because a laser beam is Gaussian, so it fades out gradually as you go from the center to the outside. This makes it very difficult to discern the edges of the beam, and the visible edges are effected by ambient light in the room. To overcome this, we have to take several measurements at different distances with a photodetector, which will allow us to get a much better measurement of the diameter because it is not subject to a human eye's interpretation of the beam. Another part of this that Dr. Noe is encouraging us to try is to measure the light intensity that hits the photodetector as an object is passed accross the beam. We have hypothesised what the curve of light intensity will look like and will actually perform this experiment tomorrow.
Wednesday, July 7
Today we had "Laser Sam" from Sam's Laser FAQ come and talk about lasers. He discussed the theory and hazards of lasers as well as the types of lasers that exist and the uses for each different type. I found his talks interesting and have been using his website which is a goldmine of laser information. Earlier in the day I learned how to put pictures in the text of my website, the results of which can be seen in yesterday's entry. You may also have seen the collection of links to journal entries at the top of the journal page, a feature of html that I recently learned how to use. As far as a project goes, I am still doing large amounts of research on several topics and I hope to come up with an idea soon.
Tuesday, July 6
The last few days have been busy and I have been learning about all sorts of optics topics. Last friday was a very exciting day as Pradyoth, Annie and I finally got the Stirling engine to work! We polished it and lubricated it and gave it a bit of time in the sun and it worked. I thought this was really great because we had a small engine chugging along on nothing but sunlight. A Stirling engine uses light energy focused by a parabolic mirror to heat a chamber filled with hydrogen. As this hydrogen expands, it drives a piston which drives a wheel and causes another piston to force cool hydrogen back to the heating chamber. This method is one of the most efficient ways of gathering solar energy, and large-scale Stirling engines are available for commercial use with power outputs up to 24 kilowatts. Unfortunately, as the day went on, the engine stopped working. We tried polishing the mirror again as it seemed dirty, but it didn't help much. We had used a generous amount of lubricant when we began, so we didn't think that could be the problem, although we did notice some squeaking in the wheel as we tried to get it to work again. Another thing that we noticed was that the cooling chamber was at a high temperature. This lowers the efficiency of the engine and if it was too low the engine would stop working all together, so this could be a reason that the engine stopped working. We brought it inside and tried to cool the engine, but it was already too late and the sun was too low for another attempt, and we will need to come back to it another time when there is plenty of sunlight and try to more exactly identify the problem.
Monday was a holiday, the Fourth of July, and Stony Brook's campus was quite, but the three Simons Fellows in the LTC came to the lab anyway. During the day, Dr. Noe showed us how to use gnuplot, an open-source graphing program based in the command line. He challenged us to figure out how to plot an ellipse osculating a parabola, a topic from our first lunch discussion, and important when making precise parabolic mirrors. When two figures are said to be osculating, or "kissing" it means that at a specific point their second derivatives are equal. Before we could do this, we had to figure out how to graph anything osculating, so we began by plotting a circle osculating a parabola.
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The picture looks slightly skewed because of the scale, but the top curve is the circle and the bottom curve is the parabola. |
After this we were able to come up with an ellipse and a parabola that we thought were osculating, but after graphing them we could see that they were not. For the rest of the day and fairly late into the night we tried to see where we went wrong and explain what hadhappened, and eventually concluded that we had made a mathematical error while taking the second derivative of the ellipse. After that, we found the actual obsculating ellipse and parabola, and graphed our results, this time it looked like it should.
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Here you can see that the ellipse and parabola touch at the bottom, this is osculation. |
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This is the same picture as the one above, but with a much smaller scale so it can more clearly be seen that for a brief period the curves are nearly exactly the same. |
Today was a less hectic day than a lot of days have been here at the LTC. We had a Simons meeting in which Professor Simmerling gave a fascinating talk about his work in computational structural biology. We cleaned the lab in preparation for tomorrow's talks on lasers, and other than that spent most of the day doing research on the internet and in journals for project ideas. I read articles on a wide variety of optics topics from acousto-optics to causality and measuring gravitational forces with photons. I am continuously learning a lot about optics and different related feilds and I hope to have a much clearer idea of a project by the end of this week, and hopefully have an actual idea worked out by sometime next week.
Thursday, July 1
Wow, it's been a busy couple of days. I arrived at Stony Brook on Sunday and have been busy ever since. Monday morning I met with Dr. Noe and the rest of the Simons Fellows who I will be working with in the Laser Teaching Center. After brief introductions we were off to the lab, and subjected to a whirlwind of phenomena and quizzed on how each one works. After that it was off to a lunch full of discussion about optics and physics in general, with topics ranging from laser alignment to spherical aberration to telescope designs to different shaped mirrors to why the sky is blue, all while drawing diagrams and explanations on pizza boxes. What really struck me about this discussion was the structure that Dr. Noe set up. He could easily have simply explained what caused different phenomena and had us take notes on the pizza boxes, but he didn't. He posed questions, handed us pens, and let us figure it out and prove it. On occasion he would point something out or draw a quick sketch, but the majority of the writing on the boxes was my own or one of my fellow students. With this technique, Dr. Noe forced us to learn and understand the concepts much better than we would have had he simply explained it and not made us think. After lunch we returned to the lab and began to see how things in the lab actually worked. We observed as the undergraduate students in the lab began constructing an interferometer, and began research into ideas for our own projects.
The days following were just as full as the previous ones. The undergraduate students in the lab are giving us crash courses in different areas pertaining to optics. Tuesday began with a discussion on math with Heather, covering topics from all years of high school math along with different ways to look at concepts that we had previously been seen. Wednesday we went over the wave nature of light, and today we learned about geometric optics and matrices and their relation to optics. These sessions with the undergraduates have been informal and we have been encouraged to participate and come up with things on our own. Dr. Noe has continuously challenged us as well as the undergraduates during these sessions, and everyone, including Dr. Noe himself, has learned valuable things during them.
After the morning session with the undergraduates, we need to eat, but that is no reason to stop learning. On Tuesday, we attended a lecture with the undergraduates about different physics experiments in which the professor discussed thermal expansion, tides, spinning fluids, and several other interesting topics. On Wednesday we had a Laser Teaching Center lunch, which included a presentation on acoustic waves by Dr. Metcalf. This presentation was fascinating and I am currently researching possible projects in this area. After lunch, we normally return to the lab to consider things that have been talked about in the morning, research project ideas, or mull over new ideas as they come up. Yesterday, for example, Dr. Noe took us outside to do solar work with lenses and mirrors. In doing this large measurements needed to be taken, and were taken by counting off paces. This led to a discussion of the human gait and its relation to a pendulum, which causes all people walking with a natural stride to walk at nearly the same exact pace.
What has really struck me in my first few days at the Laser Teaching Center is a simple quest for knowledge and thought possessed by the people there. The sessions that appear to be taught by the undergraduates to us become discussions of principles that are often taken for granted. This morning for example, we took a long time investigating and trying to explain just why F=R/2 with a spherical mirror. Eventually, with input from everyone in the room, a suitable explanation was found. This spontaneous discussion and more careful consideration of ideas normally not considered has stood out to me in the Laser Teaching Center in just the short time I have been here. Dr. Noe has shown and continues to show that anything can be questioned and should be questioned, and that nothing should be taken for granted. Because of this unique atmosphere and the people here, I look forward to beginning my research project in the Laser Teaching Center.