May 7, 2015
Today was our last meeting of the semester. We talked about everything we need to do to in order to wrap up our work. I am working on editing my report.
April 29, 2015
URECA was today!! It was very fun and exciting. I presented my project to many people, so I got to work on my speaking skills. I also got to see of other projects. I looked at a lot of the physics and astronomy posters. It is really interesting to see what other students are doing for research. I also looked at my friend’s Cancer Research Center project. It was really cool, though I did not understand a lot of it. URECA was a good learning experience, I hope I get to participate again next year.
April 26, 2015
I finished my poster! Max, Zheni, and I met with Dr. Noé to make some final changes to our posters, and tomorrow he is going to get them printed. I have never made a poster like this before, and I am really excited to see it printed!
April 24, 2015
Today I met with Dr. Noé to go over my poster. I have never made this kind of scientific poster before, but Dr. Noé said my first draft was pretty good. I have to rearrange some of the boxes, and get rid of some text. I also have to look up some applications of the Maltese cross pattern. The poster is due on Monday, and I think I can get it done by then. I am very excited that I had the opportunity to do this project, and that I am going to present at URECA!
April 23, 2015
We had our regular meeting today. It is almost URECA, so Dr. Noé gave on some tips on our posters. I am meeting with him again tomorrow in order to more thoroughly go over my poster.
April 22, 2015
I finished the first draft of my poster. I have never made a scientific poster for an even like URECA before. It was challenging, but I think I eventually figured out how to make a good first draft.
URECA is in a week and I have a list of what I need to bring:
April 21, 2015
I met with Dr. Noé today. He told Zheni, Max, and I about what we need to do for our projects. I got a clearer picture of how to structure my project. I have started working on it, and I think I am making good progress. Hopefully, I will have a good rough draft by our meeting on Thursday.
April 16, 2015
Today we spent our class presenting to each other the projects that we are working on. Zheni presented about the difficulties of the Lunar Ranging project. She told us about diffraction and how that works, and what she did in lab with the retroreflector. I presented what I have on my report so far, which is pictures, and Rachel showed us the sodium lab. The sodium lamp was cool, and she is trying to figure out what else is it in except for sodium. From now until URECA, which is in about a week and a half, I need to focus on writing my report and making my poster. I need to organize all my information so that I know what needs to go on the poster. Hopefully, the report will help me do that.
April 14, 2015
Dr. Noé email me yesterday with an idea of trying to recreate what Jacob Chamoun did in his project in the summer of 2010 as part of an REU program at Stony Brook University. He used triangular piece of overhead projector plastic to create radial polarization. This produces half of a Maltese cross. Dr. Noé wanted me to try creating a full Maltese cross using overhead projector plastic. I had to cut off a piece of the plastic and then cut out alternating triangles with 45 ° angles. I then arranged them into a circle, and looked at it through crossed polarizers. I was able to arrange it so that when there was extinction between the polarizers, there was also an extinction Maltese cross pattern. It was so cool. I was able to take an idea, actually make it happen, and then test it. This is my first experiment with real research. Even though it is a really simple idea, I was able to understand it and create something with it. My plan since high school was to get my PhD in either physics or chemistry field and do research. (Obviously I chose physics, and I have recently added astronomy as a double major). Until now I had never actually done research. I definitely want to keep doing it!
April 13, 2015
I met with Dr. Noé today in order to try to create radial birefringence in Saran wrap and make a Maltese cross pattern. First we just stretched the Saran wrap linearly and induced linear birefringence. We then tried to stretch the Saran wrap across a roll of packing tape, which has a circular shape. When this was put in between the crossed polarizers, it looked birefringent, but it was not uniform. We try to put something under the Saran wrap to stretch it more uniformly. That did not induce a Maltese cross pattern either. Dr. Marty Cohen came by and we tried to stretch the Saran wrap over a piece of metal that had a spherical shape on the top. This still did not create a Maltese cross, and eventually we just broke the Saran wrap. It was not able to stretch enough to produce the Maltese cross pattern without breaking. I am going back to the LTC tomorrow, maybe I will have more luck then.
April 10, 2015
My abstract for URECA is almost finished. We are just putting on the final touches. I have been thinking about what I am going to want to put on the poster. I am obviously going to need to put on diagrams. I have been playing around with this website called Creately. It’s a website that lets you create diagrams and figures. I think I will be able to use it to create what I need to for my poster.
April 9, 2015
We talked about our abstracts today. Zheni has a more completed one than I do, so I looked at hers. I need to edit mine so it focuses more concisely on my project. For the experimental part of the project, we are going to try to create a Maltese cross pattern in plastic wrap by stretching it over a ring and looking at it through crossed polarizers. URECA is coming up soon and we have to be done with our posters in about 2 weeks. I have started to plan mine out, but I need to decide exactly what will go on it. That will be the next step in the project for me. After I figure out what I want on it, I can start creating diagrams and taking pictures of polarization patterns in the lab. To do: Make “story boards” of the poster Research applications of Maltese cross patterns Either learn how to use a program to make figures or decide to draw them by hand
April 2, 2015
Rachel Sampson joined our meeting today. She worked in the LTC in the spring and summer of 2013, and then again in the spring of 2014. She does other research at Stony Brook now, and she has participated in a couple REU(Research Experience for Undergraduates) programs. She knows a lot about optics. Zheni, Rachel, and I presented our project ideas to her and Dr. Noé. I got to show Zheni my Maltese cross demonstration. I showed her the Maltese cross pattern using linearly polarized light, and then the no Maltese cross pattern using circularly polarized light. I think I have a good handle on what is happening; hopefully writing the abstract for URECA will solidify my understanding.
March 31, 2015
Today, I met with Dr. Noé in order to get a better handle on what I will do for my project. From my previous journal entry, Dr. Noé noticed that I misunderstood the concept of a Maltese cross pattern. We talked a lot about this kind of pattern, and now I understand it. My project is going to be based around looking at Maltese cross patterns in plastic with birefringent properties, which is produced when linearly polarized light is used. I will probably also look at the pattern produced when using circularly polarized light. Now I have to write my abstract for URECA, so Dr. Noé has told me to write down words and phrases that will be important to use in the abstract, so that we can meet and write the abstract together.
March 28, 2015
The Maltese cross is an interesting pattern that can be seen when polymer crystals are looked at through crossed polarizers under polarized light. This pattern is produced because polymers are birefringent. As polymers grow, the growth is faster along one axis than is it along the other two. The part of the polymer growing along the slower axes is able to grow in strands that look like a helix. When polarized light is shown through a polymer crystal, light that is perpendicular to a carbon chain will not be able to go through. When looked at using crossed polarizers, only light not perpendicular to the polarizer and the analyzer make it through.
When looking at the Maltese cross pattern, it can also be observed that, because of birefringence, there is also a banded appearance along with the Maltese cross pattern. Because polymers grow in the fashion of a helix twist along two axes, there are places in the polymer chain, which are orthogonal to the x-z plane of the polarized light, which creates the alternating dark and light areas.
March 27, 2015
I have done some more investigating into the optical properties of calcite. Calcite demonstrates the principal of double refraction. A beam of light vibrates in two directions, which are perpendicular to each other, at the same time. The horizontal component is the ordinary ray, and the vertical component is the extra-ordinary ray. As light, from the sun or an incandescent light bulb, passes through the calcite, the ordinary ray and the extra-ordinary ray are refracted at different speeds, causing two beams of light to come out the other side. The light that comes out is polarized. The cause for the difference in the speeds of the beams of light is the atomic make-up of calcite. There are many more atoms that interfere with the extra-ordinary beam of the light than with the ordinary beam of light. Therefore, the extra-ordinary beam of light slows down more than the ordinary beam of light.
March 26, 2015
Today was a fun day in the LTC. I got to actually see the birefringent effects of calcite in person. I looked through the calcite at some words, and saw two images of the same words. I then took a polarized filter and looked through that at the words under the piece of calcite. When the polarized filter was at a certain angle, only the light waves from one of the images could get through, and I only saw one image. When I turned the polarized filter 90°, I could only see the other filter. Dr. Noé even gave me a piece of calcite to take home. I would like to study calcite further, but I do not know if the complexity of how it works in 3-dimensions is too complicated for the scope of what I have time for in this class, and for the amount of time in which I have to do the project.
I also looked through a polaroid filter and saw that when you look in a mirror through the polaroid filter, you can see the reflection of your face in the mirror. When you flip the polaroid filter and look through the other side you cannot see anything, it is just black. This was very cool. I also want to research more about how this works.
March 22, 2015
Dr. Noé has suggested to me that I look into double refraction and photoelasticity. Double refraction is a very interesting topic. It occurs when light goes through a material and the light that is vibrating vertically is separated from the light that is vibrating horizontally. These two light waves are refracted at two different angles. This is also called birefringence. One substance, among many, that has the ability of do this calcite. The light that comes out of the calcite is polarized, which can be seen if a polarized light filter is places on top of the calcite. Turning the filter will make the calcite lighter and darker depending on how much light it is letting through. The bierfringent effect can be seen if the calcite is placed on something like a dot. When looking through the calcite at the dot, an observer would be able to see the original dot, and another dot next to it. This demonstrates the birefringent property of calcite.
Photoelasticity is a property of some transparent solids, by which they doubling refract light due to stress in the material. This can especially be seen in plastic. Double refraction occurs because of the different indices of refraction in a stressed material. Using the fact that a stressed plastic is birefringent, the stress can actually be calculated using the relation that stress is equal to the retardation divided by thickness times the stress-optical constant. Retardation is the phase difference between the two different light vectors that travel through the material and can be calculated by multiplying the thickness of the material by the difference in the indices of refraction.
The stress in a material like plastic can also be seen visually when looked at through a polarized light filter. The intensity of the color seen is inversely proportional to the retardation. This is only helpful in qualitative analysis, and takes a very skilled eye to be able to get anything useful out of just looking at the colors seen when a polarized filter is held up to stressed plastic with a light source going through it. There are machines, analyzers, which help to quantitatively measure the stress on plastic. An analyzer can measure the retardation of the light waves, which can be used to find the stress.
March 19, 2015
Today, I researched a lot about polarized filters. Light can become polarized by other means as well. There is polarization by reflection, refraction, and scattering. Depending on the angle of the light, nonmetallic surfaces can reflect unpolarized light as polarized light. The amount of light polarized depends on the angle of incidence of the unpolarized light and the material it is being reflected off of. It would be interesting to find out what substances are better at polarizing light by reflection, and what angle light needs to hit the substance at in order to be polarized.
There is also polarization by refraction. During refraction, light leaving one medium and entering another changes the direction of the light, and this can lead to some degree of polarization of the light. Light can also be polarized through scattering. As light enters the atmosphere, it strikes atoms and causes vibration in the electrons. This vibration creates an electromagnetic wave that radiates in all directions, causing vibrations in other electrons in other atoms. This process continues, and accounts for the scattering of light in the atmosphere. Because of the scattering, some light can become partially polarized, which is why sunlight is partially polarized.
March 13, 2015
Today I met with Dr. Noé to specifically discuss ideas for my project. We talked about how sunlight is polarized. We went outside with a polarized filter, and looked at the sky. Using the filter, it is possible to look at the blue parts of the sky, and see that the light is polarized. We also found a spot, a patch of mud, where light is reflected off, and observed the polarization of light there also. Even though the sun is only in one spot of the sky, the sunlight is polarized everywhere. Dr. Noé asked me why the sky is blue, and I did not know, but now I do. The sky is blue because as light from the sun enters Earth’s atmosphere, it is scattered in all directions. Blue light is scattered the most because it travels in shorter, smaller wavelengths than the other colors of light. Because it scatters the most, the sky always appears to be blue. This logic can also be applied to why sunsets are red. This is because when the sun is setting, it is lower in the sky. Light from the sun has to pass through more of our atmosphere, causing the blue light to be scattered even more, to a point when it no longer reaches the observer. This allows red and yellow light to shine through, making the sunset appear red and yellow.
Another interesting concept about polarized light, is that if you put two polarizers on top of each other, at a 90° angle, all of the light coming from them is cancelled out. These are called crossed polarizers. If polarizers are placed on top of each other at angles other than 90°, then the intensity of the light that goes through both polarizers obeys Malus’s Law. Malus’s Law states that the intensity of light that goes through the polarizers equals the initial intensity of the light multiplied by the cosine of the angle squared. By plugging in 90° for the angle, this law proves that the intensity of light going through crossed polarizers is 0.
March 12, 2015
Today we talked more about refraction. I presented what I wrote about in my research notebook. I calculated the critical angles of light passing through glass surrounded by several substances with different indices of refraction using Snell’s Law. I made a graph of the critical angles vs. the ratio of the indices of refraction. From this I discovered that as the graph approached a ratio of 1, the angle approached 90°. Dr. Noé pointed out that if you graph a sin curve, it levels off at (90° ,1). This means that a small change in the index of refraction can mean a big change in the critical angle, because the function has a very small slope.
We also talked about a potential project for Zheni, which is working with a retroreflector. Retroreflectors are what have been put on the moon so that we can bounce lasers off of it and determine the distance between the Earth and the moon. The LTC has a retroreflector, and we shined a light at it to see what happened. The light was reflected back at us, and it looked like a bright star in the night sky. Retroreflectors reflect back all the light that has been shown onto it. When a laser beam is reflected off the retroreflectors on the moon, it seems like all the light is not reflected back, because detectors only pick up a very low intensity of light. This is not because the all the light is not reflected back, but rather because the beam of light scatters and widens on its journey to the moon and back. I found this very interesting, and I am excited to know what Zheni does for her project.
We also talked briefly about polarized light today. We talked about what happens when left-handed and right-handed polarized light overlap. All of the light would cancel out, because it is going in opposite directions, except for one direction. This creates linearly polarized light.
February 26, 2015
We talked a lot about refraction and reflection today. Dr. Noé introduced us to the idea of total internal reflection. Total internal reflection occurs when light is moving from one substance medium to another, but it hits the second substance at an angle greater than the critical angle, so it gets reflected back into the first substance. Dr. Noé also mentioned Snell's Law, which can be used to calculates the angle of refraction when light hits a medium at a certain angle: n1sinθ1= n2sinθ2 . n is the index of refraction of each substance.
After the class, I also found an article from Advanced Materials Research Vols. 912-914 about using polarized light in automobile lighting systems. ("Application of Linearly Polarized Light in Automobile Lighting System") The authors discuss how vehicle headlights can be dangerous at night because of their brightness, and that the use of polarized light can change the amount of light received by other drivers. They also discuss that the angle of the windshield on the car receiving the light can impact the intensity of the light received by the driver. I think it would be an interesting project to first shine non-polarized and polarized light through glass and measure the intensity of the light on the other side, and then to shine polarized light on glass at different angles and measure the intensity of the light that makes it through the glass. The authors also discuss how giving the windshield polarizers makes a difference. This is a topic that can also be explored further.
One other topic that I am interested in is spectroscopy. I found an article titled "Noninvasive Detection of Concealed Complex Mixed Solution Using Raman Spectroscopy" which concerns the difficulty of using spectroscopy on substances inside fluorescent bottles. The authors of this paper use a method called Spatially Offset Raman Spectroscopy. This kind of spectroscopy is able to suppress fluorescence, which cannot be done with Raman spectroscopy. I think spectroscopy is interesting, especially since I am interested in astronomy.
February 19, 2015
Today was my first meeting in the Laser Teaching Center. For an hour we talked to Dr. Noé about project ideas, and he told us about some journals in which we could look for ideas. I am going to look in the American Journal of Physics to see if I can find any inspiration for a project to do this semester.
I am also doing another research class this semester. It is through the WISE (Women in Science and Engineering) program at Stony Brook. I get to be put into 3 different research roations. The first one is about using computational methods to do astronomy research. My project is to write a Python code to calculate orbits of astrophysical systems. I am learning a lot about program and what it is like to be a computational scientist. I am really excited to have these opportunities. The second rotation has to do with topology optimization. As of right now, that is all I know about the rotation. It does not start until after the current rotation is over. The third rotation takes place at Brookhaven Naitonal Laboratory (BNL). The rotation I am doing is called "Fast Field Trip of Partical Accelerators". I am hoping to learn about some basics of how particle accelerators work. I cannot wait to start my project with Dr. Noé ; I just need to figure out what it is first.