Reports: UR649348-UR6: Measurement of the Refractive Index of Highly Turbid Media

Samir Bali , Miami University

As in 2010, my students and I published three papers in top-quality refereed journals this year. In addition, four new manuscripts are being written up for publication.

Funding by Petroleum Research Fund is gratefully acknowledged in all works.

Work published - THREE PAPERS TOTAL

In our first work, published in the August 2011 issue of Optics Letters, we reply to a comment made by another research group on our Optics Letters paper published in 2010. The appearance of oscillations in our 2010 data was criticized in a Comment by a group in Finland. We respond to their criticism, and provide new insights into total internal reflection (TIR) from turbid media, showing that there are not one but two oscillations in the data, depending on whether the particle size is less than or more than the laser wavelength.

According to the Journal of Citation Reports, Optics Letters is the 2nd most cited out of 70 refereed journals in the field of "Optics", and is the 4th highest in its 5-year impact factor (3.3). This work will be presented, along with other important recent findings, in a talk this October at the premier annual meeting in optics "Frontiers in Optics / Division of Laser Science" (FiO/DLS) hosted by the Optical Society of America. The presenter is an undergraduate student, Ms. Kashika Goyal.

As is the custom in publishing a Reply to a Comment on a publication, the 3 student co-authors on the above work are the same as on the original 2010 publication. Please refer to my 2010 report for their whereabouts after graduation.

In addition, we completed two more experiments, accepted for publication in American Journal of Physics. According to Journal of Citation Reports AJP is the topmost education journal in Physics, and the 3rd most cited out of 33 journals in education across all scientific disciplines. In these works we uncover subtle yet important fundamental aspects of laser-atom interaction via cutting-edge demonstrations suitable for the advanced undergraduate laboratory. I am indebted to the Petroleum Research Fund for enabling us to purchase optics and laser-related equipment for the refractive index sensing lab that is freely shared with our laser-cooling lab.

The first of these two works describes the broadening of an atomic energy level owing to the presence of light and was performed by seniors and MS students enrolled in my lecture/lab course "Optics and Lasers":

  • Andrew Hachtel, Jeff Kleykamp, John Camenisch (BS Physics 2012), and Matt Gillette (BS Physics 2013) are the 1st, 2nd, 8th, and 9th authors respectively.
  • Don Kane, Megan Marshall, and Brad Worth (BS Physics 2011) are the 3rd, 4th, and 5th authors respectively. Don is now pursuing graduate studies in computer science at University of Illinois, Urbana-Champaigne, and Brad is enrolled in the MS physics program here at Miami University. Because of her involvement in research with our group, Megan was awarded a highly prestigious national-level Astronaut scholarship in 2011. She is now pursuing graduate studies in physics and astronomy at University of Maryland, College Park.
  • Jason Barkeloo and Jay Kangara (MS Physics 2012) are the 6th and 7th authors respectively. They are both 1st year graduate students in our two-year terminal Master's program in physics.

    The second of these two works, describes the shift in an atomic energy-level caused by the presence of light and is an adaptation for the advanced undergraduate lab of a similar experiment we had previously published in Laser Physics Letters, highlighted in my 2010 progress report. Several undergraduate students and one MS student worked together:

  • Jeff Kleykamp and Andrew Hachtel (BS Physics 2012), Don Kane and Megan Marshall (BS Physics 2011), are the 1st, 2nd, 3rd, and 4th authors respectively. For details on Don and Megan's whereabouts after graduation please see above.
  • Peter Harnish (BS Physics 2009) and Nathan Souther (MS Physics 2009) are part of the team of students who worked on the original version of the experiment in 2010, published in Laser Physics Letters.


First, please recall from my 2010 progress report that we were testing in detail our model for TIR from a turbid medium by studying aqueous suspensions of mono-sized polystyrene microspheres. We have now devised a method that proves beyond a doubt the validity of the model developed in our Optics Letters of 2010 and 2011. We will submit our new results to Optics Letters. Proposals are being prepared for submission later this month to NSF Physics, and early next year to NSF Engineering.

Second and Third, please recall from my 2010 progress report, that we had measured refractive index changes in auto-engine oil of slightly varying states of degradation, and that we had made the first ever accurate measurement of refractive index of Intralipid – a human intravenous nutrient also known as "optical tissue". We have taken more data, and further improved our curve-fitting procedure, and will within this year submit our results to Sensors and Actuators B and to Journal of Biomedical Letters.

Fourth, we have prepared a critique on the method of "differentiation of the reflectance curve to obtain the refractive index" which though widely used is manifestly flawed for turbid media. We will submit our analysis to Reviews of Scientific Instruments.

The student co-authors on these works with Prof. L. M. Bali and myself are below:

  • Kashika Goyal (BS Zoology 2013) is 1st author on 3 of the above manuscripts. She started working with me as a freshman, including full-time for 9 weeks this summer.
  • Bradley Worth (BS Engineering Physics 2011, MS 2013) graduated this year from Miami (see 2010 progress report) and is now in our MS physics program.
  • Millie Dong (BS Chemical Engineering 2013) is the 1st author on the auto-engine oil work. She started as a freshman. She is working with me full-time in summer 2012.
  • Sorab Makkar (BS Zoology 2013) is a co-author on 3 works.

The upcoming four manuscript submissions should positively impact the likelihood for my proposals to NSF and PRF.

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