March 23, 2007
Dr. Noe and I met yesterday afternoon and discussed the 'skew angle 'article from Optics Express . We payed close attention to the Shack-Hartmann (SH) wavefront sensor (!PDF file!). Dr. Noe postulated whether or not it were possible to use construct our own SH using a single aperture on a screen in front of a larger lense and translating the hole across the lens to record one at a time the same points on the CCD each small lens of the standard SH does at once. This would eliminate 'industrial' reliance on factory production of the very small lenses. We discussed possible problems his postulation would have from diffraction of the beam by the aperture. We discussed ray optics and lenses and saw how a focuse object through a lens has a limited size. One example is the sun, moon, and solar eclipses. A good reference is here . A qualitative analysis to ascertain the constraints of diffraction dependent on distance of the screen aperture from the lense was suggested. We put a beam through a screen aperture and tried several lenses to see the effects of beam focusing with lenses. It seems. at first, that this method might not work. I s there anyone else who has tried this? More exploration is needed.
March 22, 2007
I read an article in the 11 December 2006/ Vol. 14, No. 25 issue of Optics Express by Miles Padgett's optics group at the University of Glasgow titled "Direct Measurement of the skew angle of the Poynting vector in a helically phased beam." It describes a technique to directly measure the topological number (l-hbar) of an optical vortex using a method other than interferometric. It was very interesting to read and think about the quantitative and qualitative differences between interferometric methods and this 'direct' method.
March 20, 2007
Dr. Noe invited Lyuba Kuznetsova from the University of Cornell Applied Science and Engineering department to tour the lab this morning. Lyuba is a member of Dr.Frank Wise's Optical Physics, Quantum Electronics, and Photonics group. The day before she gave a seminar titled 'Turning Nonlinearity to Advantage in High Energy Yb-Doped Fiber Amplifiers.' To my limited understanding, this is like lasing thourgh a fiber optic cable rather than a cavity. Very interesting.
March 13, 2007
Dr. Noe and I discussed the mathematical and physical aspects of how two Laguerre-Gaussian beams superimpose on eachother in phase, and out of phase. We utilized the GNUPLOT editor to graph several examples of this. I have provided some links below of examples. We also demonstrated how interference patterns are created using an interferometer and how the relative phase of the beams can be changed and how that changes the resulting intensity pattern. Plot commands Plot
March 7, 2007
I have decided on a topic for my research project. I will begin to study the properties of optical vortices. In particular, I will see how the topological number of the vortex relates to method by which the vortex is created. The vortex can be created using a 'fork' diffraction grating. How does the topological number depend on the slits of the grating? To begin, Dr. Noe and I looked at a simple two-slit diffracion pattern to see how the resulting position of the intensity pattern depends on the slits. Can I expand this idea to the 'fork' grating? Ultimately, I would like see the limits and controls of the vortices' topological number based on the method of the vortex production. The topological number is a convention for measuring the angular momentum. So, this will in turn show how we can control the angular momentum of the vortex.
February 14, 2007
Dr. Noe and I have been discussing possible topics for my research this semester in the Laser Teaching Center. I am mainly interested in topics related to the angular momentum of light, such as polarized Light and optical tweezers, and optical vortices. Some other topics I am considering, in relation to Dr. Schneble's PHY 452 Lasers course are Fabry-Perot Laser Measurements, and the study of mode stability in a laser cavity. I will begin researching many of these ideas and find a suitable project to present at the April research celebration.
Laser Teaching Center