Tuesday, September 13, 2011

Work Experience and Photonics - Working with Gold!

A Level Student - Amy Francis - has been working at Physics and Astronomy at the University of Southampton for the last two weeks. Here is her guest blog...

Day 1: I worked with Paul [Venn, post graduate student ed.] on his Quantum Physics Phd project which ultimately aims to find the boundary between classic laws of physics and quantum mechanics. I was investigating the transmission of a He-Ne laser [beam] through [different sized] apertures. I worked in the molecule interferometry laboratory, aligning the lenses, irises, beam splitters and telescope between the laser source and the detectors so the He-Ne beam was focussed onto a hole in the gold sample and onto the detectors. This had to be done very precisely and to a high degree of accuracy and gave me the opportunity to use equipment I had not used before. It was really interesting to work with lasers and learn about an area of physics that I have not had the opportunity to study before.




Day 2: I took measurements of the holes and collected data from the transmission of the light through the apertures from the experiment I set up the day before. It was great to gain a better understanding of how the experiment worked. I then analysed the data using a computer program 'Origin' that I had not used before. It was interesting to see how it worked and use the program to analyse my results. I produced graphs to display the data and show the location and size of the holes in the gold film.


The photo above shows the set up of lenses, beam splitters, detectors, irises, a telescope and a He-Ne laser to investigate the transmission of a He-Ne laser through apertures in a gold film.

Day 3: I realigned the lenses and detectors for the new sample and took note of the circular interference pattern that was produced. I took a video to show how the pattern changed with the focus. I then took measurements from the new sample and collected data about the properties of the holes - their location and their size. It was a great opportunity to use the equiptment again and learn more about the computer program I was using to collect the data.


Day 4: I took more measurements of the holes in the sample and produced graphs to show the holes using the computer program 'Origin'. I also began to plot the locations of the holes in the sample. This was more challenging than the first sample as the holes were much smaller and so the detectors were set to be more sensitive to ensure they recorded the smaller changes in voltage that were due to the hole being present.


Day 5: I finished plotting the locations of the holes in the sample and produced graphs to show where the holes were in the sample and how large they were. I then tried to trap polystyrene balls in the smaller holes by showering the gold with a solution containing the balls. However, as the solution was showered over the front of the gold it blocked the laser beam through the hole and so the balls were unable to be trapped because the transmission was too low. For the balls to be trapped the light must be shining through the hole so the balls gravitate to where there is the highest light intensity, in the hole. To solve this the gold needs to be flipped over to the other side of the slide and the balls showered onto the back of the slide so that the solution does not decrease the transmission of the He-Ne laser beam.

I also spent some time in the astromomy department looking at the projects there and finding out about the undergraduate physics with astromomy course and the study abroad opportunities.

Overall I have had a thoroughly enjoyable and interesting week. It has been great to work with new equipment and do experiments that I would otherwise not have had the opportunity to do. It has also been really useful to find out more about the university and what it is like to study here.

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