First Pizza Lunch Meeting
Wednesday 2 July 2014
Presentations by LTC
Students and Mentors
Alex Kelser,
Simons Fellow
Characterizing IR Transmission of Materials Using a Novel
Thermo-Mechanical Detector
Bimetallic strips convert a temperature change into a
mechanical displacement. I sought to investigate the possibility of using
a bimetallic strip as a practical means of detecting heat from infrared
light. To optically characterize the deflection of a bimetallic strip, I
glued a small mirror onto the end of the strip and directed a laser off of
the mirror into a position sensitive detector (PSD). Thus, the position of
the laser varied as a function of the deflection angle of the bimetallic
strip. The data recorded by the PSD was DC coupled and fed into an
oscilloscope. After analyzing the sensitivity of this configuration, I
discovered that fluctuations in room temperature were causing baseline
thermal drift. To correct for this problem, I chopped the radiation from
the infrared source to match the natural frequency of the bimetallic
strip. This caused the bimetallic strip to go into thermally induced
resonance. The Q-Factor for this resonance was 300. I then AC-coupled the
signal from the PSD, and set the oscilloscope to trigger off of a signal
from the optical chopper. The result was an apparatus capable of measuring
heat from an infrared source, but which filtered out external fluctuations
in temperature. This device has proved capable of detecting 0.5 mw/cm2,
comparable to the sensitivity of commercially available thermopiles.
Jon Gill,
Simons Fellow An Interference Lithography Technique for
Creating Ultra-high Resolution Patterns
Thomas Young demonstrated the wave nature of light by
creating interference patterns with light coming from two slits. A recent
application of this idea is nonlinear interference lithography. Last
fall, I participated in research with Dr. Sean Bentley at Adelphi
University whose goal is to use interference lithography to create
arbitrary ultra-high resolution patterns. The technique depends on the
interaction of intense laser pulses with a substrate activated by three
photon absorption. By slightly shifting the fringe pattern between
multiple exposures narrow bands of unactivated material can be created.
My work last year involved a simplified apparatus in which an
interference pattern ablates a conventional substrate such as dark nail
polish. It took considerable trial-and-error effort to properly overlap
the focussed beams and position the substrate at their common focal point.
With a properly aligned setup I was able to observe periodic fringe
patterns recorded into the substrate under a microscope.
Andrea O'Brisky, Commack
High School Single Bubble Sonoluminescence: The Star in a Jar
This past school year I have been investigating Single
Bubble Sonoluminescence (SBSL) under the guidance of my dedicated science
research teacher at Commack High School, Mr. Kurtz. Sonoluminescence is
the process in which intense high frequency sound waves are used to induce
cavitation in tiny bubbles trapped in a degassed liquid medium. Under just
the right conditions, the temperature of the gas inside the cavitating
bubble exceeds 10,000 K and the bubble to become a tiny point of light.
The standard setup for SBSL is a 100 mL spherical flask with
piezo-electric transducers (PZTs) attached on opposite sides. Another
smaller PZT on the bottom of the flask acts as a microphone to monitor the
response of the flask and the sound of the collapsing trapped bubble,
which contains many high harmonics of the driving frequency. In my setup
the fundamental resonant mode of the flask (largest microphone signal) was
found at 24.5 kHz. Unfortunately as yet I have not been able to achieve SL
or even trap a single bubble with my setup. In retrospect this was
because the home audio amplifier I used could not provide enough voltage
to the PZT, which was then unable to create a sufficiently intense sound
pressure wave.
Ikaasa Suri, Simons Fellow Examining the Behavior of
Non-Newtonian
Fluids Under Stress
It is important to understand how raw materials flow,
especially for industrial applications. Last summer I conducted research
at UC Santa Barbara on the behavior of polymer solutions under stress to
better understand the physical phenomenon known as spurt. Spurt is the
sudden increase in flow rate through a pipe or channel when the pressure
is increased beyond a certain value. I simulated fluid flow in a pipe or
channel by using two parallel plates and found that at random times there
were reductions in resistance, similar to increases in flow rate.
Elizabeth (Libby) Sutton, SB WISE program, sophomore physics major My
First Research Experience in
the Laser Teaching Center
This past semester I had the opportunity to work in the LTC
alongside several other undergraduates; this was my first research
experience of any kind. One thing I learned is that finding a suitable
project topic can be harder than it sounds. I found many possible topics,
but most would have been unrealistic given the amount of time and
resources available. One of these was optical cloaking with
metamaterials. Optical cloaking refers to the cloaking or hiding of an
object by manipulating the electromagnetic waves around said object. Over
the past decade there have been many advances in this field of research. I
later learned that it's possible to create simple optical cloaking devices
without specialized metamaterials ( John Howell, University of Rochester).
Howell used mirrors, tanks filled with water, and lenses to create
cloaked areas. I lacked time and materials to make my own cloaking tank,
but this idea of using everyday objects inspired my final project of
demonstrating optical properties of some optics toys we have in the
lab.
Melia Bonomo, LTC Mentor My
Personal Path to a Third Summer in the LTC
For the past couple of summers I’ve had the opportunity to
work in the
Laser Teaching Center alongside some very talented students and
mentors. My initial exposure to the LTC’s unique educational
environment as an NSF-REU Fellow during summer 2012 created a solid
foundation that has served me well during a variety of subsequent
research and teaching experiences. I carried out a project on
creating Bessel beams with a 4-f spatial filter that gave me my first
experience with the methodology and presentation of physics research.
The following academic year I completed an honors senior thesis at
Dickinson College, analyzing the singularities that form at the tip of
freezing water droplets. Then, with a firsthand understanding of how
the LTC operates, I returned to the lab for the summer to take on a
new role as mentor. This past academic year I was a high school
teaching assistant in Italy, where I tackled the challenge of
designing and executing physics and math lessons for non-native
English speakers. Now I’m back in the LTC, looking forward to being a
mentor once again.
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