Report by Amy Sullivan
Agnes Scott College’s Beam Me Up Scottie! Event on October 8, 2010 was a big success! We had over one hundred members of the community, including students, staff, and local residents. The event consisted of three rooms of laser demonstrations, one for Lasers in the Movies, one for Lidar, and one large room for the Laser Telephone, Hands on Optics, and Laser Spectroscopy/Guidestar demonstrations. In addition to these events, visitors had the opportunity to attend a planetarium show and view the sky through the college’s telescope. There were student and faculty volunteers from Agnes Scott at each of the demonstrations to help visitors. Pictures of the demonstrations can be found at
http://picasaweb.google.com/amy.c.sullivan/Laserfest?authkey=Gv1sRgCJ7avc6hqeO8IQ#.
A website has been set up to advertise the event as well as to provide an educational site containing information on lasers and their applications. This can be found at
http://ecademy.agnesscott.edu/~asullivan. The site has been linked to the Physics & Astronomy Department website at Agnes Scott and is listed in the information for the event on the Laserfest website. In addition to general background information, the website contains information, pictures, and/or videos on each module that we built. There are five short videos, filmed by students at Agnes Scott, which describe our Lidar system, our hands-on-optics demonstrations, our Lasers in the Movies demonstrations, laser spectroscopy, and our laser telephone. These videos are available on the front page of our Laserfest website and are also linked from our Department of Physics & Astronomy website. This report contains more details each of the demonstrations at our Laserfest event.
Figure 1. Clockwise from upper left: laser telephone laser
and circuit, fish tank demonstrating total internal
reflection, Tardis, British phone booth, large plastic
waveguide.
Our laser communications demonstrations were very popular with visitors of all ages. The demonstration included a laser telephone, two hands-on demonstrations of total internal reflection, and a fiber patch cord. The telephone consisted of two telephone booths, one designed as a British telephone booth, and the other modeled after the Tardis from the television show “Dr. Who.” Each booth had a computer headset that visitors could use to talk to one another across the room. The signal went to a circuit built in-house to amplify and then send the signal to a modulatable red diode laser. The laser traveled through free space to the other side of the room, where it was detected by a photodetector and sent through another circuit to clean up and amplify the signal before entering the second headset. Visitors could talk to each other through the headsets and could block the laser beam with their hands to see that the sound was coming through the laser beam. In between these booths was some printed information on optical communications along with a large plastic optical waveguide and small fish tank with laser pointers to demonstrate total internal reflection. A standard fiber patch cord was included for visitors to see what a real optical fiber looks like. Pictures of these demonstrations are shown in Figure 1 above.
Figure 2. Clockwise from upper left: full spectroscopy
system, close up of diode laser, hydrogen lamp,
spectrum of room lights through hand-held
spectrometer.
The laser spectroscopy and laser guidestar demonstration consisted of a hydrogen lamp and hand-held spectrometers along with a Doppler-free spectroscopy of Rubidium experiment (Figure 2). The lamp and spectrometers allowed visitors to get a feel for how light is made up of many colors before they came by the Rb experiment. This experiment consisted of a tunable diode laser that is tuned to the Rb resonance, an Rb cell, and an IR camera. The laser had an open top so that visitors could see inside and the wavelength could be adjusted by hand to demonstrate the workings of the laser to the participants. The laser was tuned on and off the Rb resonance, showing how the atoms glow when hit with the appropriate wavelength of light. Printed information and a volunteer explained this process to visitors and showed how this experiment could be used to learn more about Rb atoms and also how laser guidestars work in astronomy.
Figure 3. Clockwise from upper left: white light rays
through a single lens, laser rays through multiple
lenses, white light rays through a rectangular plastic
block, laser rays showing total internal reflection in a
prism, laser maze.
The hands-on-optics demonstrations were the most interactive and some of the most popular demonstrations at our Laserfest event (Figure 3). The demonstrations included a white light source that had color filters on one end for visitors to explore how light colors add, and a multiple slit on the other end to produce three rays that could be used to explore how light travels through lenses, reflects off of mirrors, and reflects and refracts at surfaces. There was also a laser ray box with a separate set of optical elements, such as lenses, an adjustable curved mirror, glass plates, and prisms that could also be used to explore light propagation. Visitors of all ages had fun trying different components and combinations of components. There was also a laser maze (the white box shown above) with a HeNe laser input and a series of mirrors (and a beamsplitter) that could be rotated to steer the beam around inside the box. There were four targets of increasing difficulty for visitors to practice their skills at aligning light beams. All of our visitors enjoyed the challenge of this game.
Figure 4. Clockwise from right: laser security system,
Michelson interferometer, Blu-ray player.
Another popular set of demonstrations was our Lasers in the Movies room (Figure 4). This room had three demonstrations. There was a display set up with information on how DVD and Blu-ray players work along with a 405 nm laser pointer to demonstrate the color of the Blu-ray laser. Visitors could see both the color of the laser on a regular background and explore fluorescence by pointing the laser at a white piece of paper. We also had a laser espionage demonstration. For clarity of the demonstration, especially in a loud and busy room, we used a Michelson interferometer with a window in one arm. We had a speaker that could be turned on and off, or visitors could talk near the window and see how the interference pattern changed. A student volunteer explained how this could be used to record audio signals from the interference pattern. Finally, we had a laser security system set up with both red and green lasers with movie clips playing in the background from popular movies that show laser security systems. Our volunteer demonstrated how the system looked normally, when the visitors could not see the lasers and could not successfully navigate the laser security system. Then we used fog in a can and chalk dust to show the laser beams and challenged the visitors to try to make it through the lasers without breaking the beam path. This was especially popular with our younger crowd.
Figure 5. From left to right: lidar beam
shooting into the sky, lidar framework in the
lab.
Our final room at the Beam Me Up Scottie! event housed Agnes Scott’s laser radar system (Figure 5). This instrument is supported by an NSF CCLI grant and internal Agnes Scott funding, which allowed us to collect a large amount of data on the atmosphere above Decatur, Georgia over the summer. A summary of the data collected can be found at
http://earlobservations.weebly.com, which is also linked to our Beam Me Up Scottie! website. We had two volunteers, one faculty member and one student, who demonstrated how the instrument works and explained to visitors what properties of the atmosphere we can measure. We had posters on the wall showing the details of the operation of the laser radar system and summaries of some of the summer data. Fortunately, the weather cooperated, and visitors could watch the instrument collect data and view the green laser beam (Figure 5) shooting out into the clear night sky.
Though our Laserfest event is over, we are continuing our focus on lasers in the physics and astronomy department at Agnes Scott. Our students set up a nice display in the physics wing of our science building that describes lasers and their applications. The display includes a DVD and Blu-ray player and information that discusses how they are different. There is also a fiber optic patch cable and a fiber magnifier with information on fibers and optical communications. Finally, there is a clear HeNe laser so visitors can see into the laser and find information on how lasers work. A picture of the display is shown in Figure 6.
Figure 6. Display in the physics wing at Agnes
Scott.
In addition to on-campus activities, we have offered activities developed for Laserfest to local schools interested in physics and physical sciences field trips. We are in conversations with teachers and science club mentors at the middle school and high school in our local public school system to schedule Laserfest field trips during class and for after-school enrichment during the spring term 2011. We have also just recently begun talking with a Cub Scout leader about the possibility of doing a version of the demonstrations that would be appropriate for a younger crowd. We are excited to have these demonstrations to be able to share our enthusiasm and knowledge of lasers with our local community and students and generating more interest in optics.
The Beam Me Up Scottie! outreach event was a big success and the demonstrations that we developed with the Laserfest funds will allow us to continue our outreach both on- and off-campus in the future. Both building the demonstrations and the event itself generated a great deal of enthusiasm among our students for lasers and laser related research. The projects allowed many of our students to get hands-on experience with building demonstrations and explaining their work to our local community as well. This was a great opportunity for us at Agnes Scott, and we are excited to have been able to be a part of the larger Laserfest celebration.
Acknowledgements
The work on Beam Me Up Scottie! would not have been possible without the help of many people at Agnes Scott College. I would like to acknowledge our faculty members, Art Bowling and Chris De Pree, who not only consulted from time to time on planning for the event, but both worked as volunteers during our Laserfest event. Two of our students, Mary Hinkle and Sophia Newton, planned, filmed and edited all the videos that are up on our website now. They also did much of the construction of our demonstrations. Other students, Ethan Sudan, Hannah Marlowe, and Melissa Meister also worked in the early stages of designing and building several of our demonstrations. The Lidar instrument that was highlighted as part of Beam Me Up Scottie! was funded by NSF grant #6026975 and the laser spectroscopy of Rb experiment was made possible by a generous donation of equipment from Bates College.
