Week 7: Summer Placement

Day 1

The group meeting was cancelled this morning as my supervisor was busy with lots of meetings with the IFE (Inertial Fusion Energy) Network and CIFS (Centre for Inertial Fusion Studies). So instead I took this opportunity to clean up my lab space - it was so lovely to be back in the lab! I missed it so much. I then plotted all the data I had collected from my previous measurements of the spectra of a white light source passing through different optics - I had 22 graphs by the end of the day!

Clear skies

Sunny day

Plotted graphs

Treat from a PhD student :) mmmm...

My lab workspace 

 Day 2

My supervisor was very busy with the IFE Network conference and I couldn't meet him today - so instead I took the opportunity to have a science-y morning at the Science Museum. As Imperial College student I and a friend got to watch an IMAX film for free - we choseso I went with a friend to watch Robots 3D. It was so inspiring to see the work of scientists paying off to create incredible robots! My favourite was the robot that could catch balls almost as well as a human! The 3D effect was AMAZING! I've never experienced such a great 3D effect.

FUN FACT: The height of the IMAX screen is the size of four double-decker buses!!

It would be one of the most brilliant things if I could build something that everyone could use or  something that would increase the quality of life - maybe a career in bioengineering or a similar field would be something right up my street or even yours. Don't limit yourself to common career paths like medicine, law or dentistry - there are lots of exciting careers out there for you to consider and one of the is perfect for you!

If you are looking for a fun, science-y weekend then check out the science museum. The new cosmonauts exhibition is opening soon so don't miss out!

I got back into the lab in the afternoon and labeled my graphs with a description of the optic in question - such as orange with green tint. I also found some cool optics on the way - one of them looked like a standard mirror but when I looked through it it was like a red filter! See pictures below:

The lights without looking through an optic

Seeing red through the Al-mirror-looking optic

Seeing red

The Al-mirror-looking optic

Seeing purple through an Al mirror-looking optic

Looks like an Al mirror

Iris

The different optical pieces I worked with

One of the optics I characterised

Part of another experiment in the lab I was working with which I thought looked quite artistic

3D glasses

Cravings exhibition in Science Museum

Science Museum

Day 3

The group meeting this morning was very inspirational. I've missed so much science in the month that I was away! One of the PhD students had a sleepless night because of physics - he thought of a way to get rid of back scatter from a laser system. His supervisor was amazed and so, I too, was in awe - it was such a cool moment, the room went quiet as he spoke his intellectual mind. I couldn't have asked for a better return to the group. New experiments were underway and there was a lot of collaboration. After the meeting I worked with a PhD student to order the parts for the popomatic - this meant taking the popomatic down to the lab and taking it apart so we could identify the parts. :) After this, we had some lunch as a group and it was nice to be with the group again. We got back into the lab and the PhD student quickly identified the basic parts such as the cage you see in the popomatic, the posts, post-holders, lens mounts and other related objects. The lenses were cleaned using the drag method, I mentioned in a previous post, and we found that they weren't labeled so we had to find the focal lengths of the lenses ourselves in the only way we know - an experiment. In order to do this we needed to set up a collimated light beam (light that is in the same direction and all parallel to each other). I used my previous set up that I characterised optics with to set up a collimated white light beam but there was a lot of chromatic aberration (separation of different wavelengths) due to the spherical lens I was using to collimate the beam. Instead the PhD student set up a system which expanded a laser beam and then collimated it to a larger beam diameter. A waveplate and calcite cube was used in the system which were pieces of equipment I had learnt in my second year of undergraduate studies - it was so nice to relate what I had learnt to what I was doing in the lab! After having made the collimated laser beam of larger diameter, we put the optics in and measured the focal length (the distance from the centre of the lens to the point where the diameter of the laser/light beam is the smallest). We found that the lenses were planoconvex lenses (shaped like a half moon) with focal lengths of 15 and 20 cm. We found these lenses on Thorlabs (supplier of optical equipment) and I then put the part numbers, price and quantities of each item we wanted to purchase in a spreadsheet so that I could get a feel for the overall price. We found lots of aluminium optical rails that I could use as the backbone of the popomatic but needed to find out the names of the screws that we needed to mount the optics to the rail. This was a task for tomorrow.

The current version of the popomatic

Cage mount from the popomatic

Finding the lenses I need and putting the part details in a spreadsheet

My lab work space

The laser system I used to find the focal lengths of the lenses

Birefringent material

Waveplate - linearly polarises the light

Calcite cube

Finding the names of all the screws I needed was a bit of a challenge but a great learning experience

Day 4 and 5

Turns out the aluminium optical rail was too small for the popomatic so instead I found a thicker one on RS Components, a leading distributor of electronics, electrical and industrial components, and so ordered it from here. The PhD students were always willing to help me with part names and other questions I had. I am ever so grateful for their help. I continued with searching for the parts I needed for the four popomatics I shall be building in the coming weeks. I split the parts list into optics, housing and electronics and sent them to my supervisor for him to order them. I also got in contact with The Plastic Shop to get a quote for the housing for the popomatic, a plastic tube. Who knew it would cost £150 for a 1 m tube of acrylic! Over the weekend I plan to send my CAD drawings to another company recommended by my supervisor in order to get a quote for the acrylic tubes I need.

Aluminium profile I require but couldn't find a larger size at the time

Add caption

Finding the parts I need

Quick drawing of the slit in the popomatic casing (where balloons are inserted) - to be sent to companies for a quote on pricing for an acrylic tube with the slit cut

ABS box - electronics kept inside

Key switch for popomatic 

A lovely view of London from Imperial's Physics Department (Level 10)

The weather was great on Thursday so I shall end this blog with a lovely picture of the sunset I saw in Hyde Park after a game of frisbee with friends after work. Enjoy your weekend!

Hyde Park sunset

Sunset outside Physics Department

Lovely weather - clear skies

Week 6: Summer Placement

Day 1

At 10:30 we had the usual group meeting where everyone in the group got a chance to update everyone with their work. I spoke about the dispersion curves I was in the process of plotting and my supervisor advised me to start putting optics into my setup so that I could characterise them after I had plotted the dispersion curve. So after the meeting I managed to plot the dispersion curve (wavelength against pixel number) and got an approximately straight line. I also plotted marked wavelength (each interference filter had the wavelength marked on it) against the wavelength I measured from the spectrometer and its software. This gave a straight line which showed that the spectrometer was quite well calibrated.

I then had a quick meeting with my supervisor where we discussed the graphs and he said they looked good - which was such a relief because I was having doubts about my work. If there is one piece of advice I would give to someone taking a summer placement it would be ask questions! Ask lots of questions, not only does it help you to learn but it also shows others that you are keen to learn more - your supervisor might be your potential employer so this will definitely give you plus points! 

My supervisor then said that I could start characterising optics! He wanted me to measure the light transmitted through the optic at 0 and 45 degrees. So I went into the lab and set up my equipment in the following way:

Left to right: Spectrometer, optic in question, collimating lens and fibre-based white light source

Experimental set-up in the dark

Set-up

Orange optic

The same orange-y optic which has a green-blue tint.

Firstly, I took a measurement of the spectrum produced by the white light source so that I could use this to compare the spectra produced when the optic was placed in front of the light in order to see how the optic behaved. I took measurements for two optics before I called it a day. The software was pretty easy to use so taking measurements was very easy once I had a little practice. 

Day 2

This morning I had a chance to talk to a PhD student about her work and experience at Imperial College. It was great to see that you don't have to be a super-genius to do a PhD which made me feel like I could also do a PhD if I put my mind to it. This gave me some confidence to keep working hard and hopefully one day follow in her footsteps and do a PhD. Another piece of advice I would give to a summer student would be to get to know the person/people you are working with - they have been through everything you have gone through so far and so have the best advice to give you and who knows they may inspire you to follow a career path in something you never imagined yourself doing!

After this, I got back to work on characterising some more optics and managed to get through three more optics. I collected the data from the software onto a USB and then went to my office computer and transferred the data from Excel (which is what the software uses) to OriginLab, a graphing software that I use in my undergraduate studies. From there I quickly realised that not all my data was there :( - so I had to go back and re-take the measurements and again the same thing. I pondered about it for a while and couldn't figure out what was wrong - I went back to the lab and began troubleshooting. Whilst I was collecting data I scrolled down on the Excel spreadsheet as the data was being transferred to Excel and quickly realised that I was saving the data before the programme had time to transfer all the data to the Excel spreadsheet which is why I only got half the data. So tomorrow I shall need to retake all the data. 

Day 3

So I took the measurements again for the six optics which had the following appearances:

Optic 1: clear, no tint

Optic 2: slightly green tint

Optic 3: blue with pink tint

Optic 4: orange

Optic 5: green with pink tint

Optic 6: green with purple tint

I also noticed that with optic 3 and 4 there was a change in the wavelength (colour) of the reflected light at different angles, as seen in the following video on my Twitter account here - which was really cool!

After taking the measurements I plotted the data on OriginLab and got some pretty graphs:

I used the screen reader tool on OriginLab to find out the coordinates of the point of interest, for instance the wavelength at the point where there is not transmittance which I then labelled on the printed graphs. There were points on the graph were I noticed a range of wavelengths were absorbed by a particular optic - it was amazing to see how spectroscopy could tell so much about the optic. I then showed my supervisor the graphs and he liked them! :)  I also learned that optics labelled with AR were anti-reflective and HR were highly reflective.

Top two optics are interference filters and the bottom one is yet to be characterised fully

After a long day in the lab I attended the PG (postgraduate) BBQ which was the perfect opportunity for me to know the people in my group a lot better - I would definitely recommend any summer students out there to make the most of any socials so that you can learn more about the people you work with and what they do. The food was great and the people were so nice - I had a great time! There was also some music being played and an opportunity for the audience to get up and sing - I don't know what came over me but I got up and sang with an Outreach Officer that I knew, was a laugh!

Day 4

Today I went all out in the lab and got through 22 optics! Before I met my supervisor at 5 pm I got a chance to witness some cool science! I witnessed the dissection of a cockroach and a fly! I did not expect this in a laser lab! But once they explained what they were doing I understood why they were dissecting them! Turns out they were doing some x-ray imaging - where the x-rays were by-products of a laser-plasma interaction. This was so cool and right up my street, since the reason I took physics in the first place was because I was fascinated by medical imaging.

I then met up with my supervisor in the lab and he checked my method of measurement and it was fine. He then offered some improvements which included an iris which essentially just blocks some of my white light source so that I can have a nice clean beam without any chromatic aberration which was seen near the outer edges of the light beam. Chromatic aberration is where a lens fails to focus or in my case collimate all the wavelengths (colours) to the same place. He also suggested that I use a polariser so that I could check whether any of the optics I was characterising were polarisers - but this decreased the intensity of my light source so he recommended that I use a focusing lens to increase the intensity of my signal so that I could capture it on the spectrometer. We went into the lab upstairs to get these items so that I could make these improvements tomorrow.

Polariser

Iris

Day 5 

As soon as I got in I went straight into the lab and got to work on making the improvements. I had to get new posts and post-holders for the new items I was going to add to my set-up. My supervisor also wanted me to use up more of my bench space so I took all the apparatus apart and put them into their new positions. I then added the iris and the focusing lens to my set-up. This took a bit of time because I had to collimate the white light source again and put the focusing lens in the correct position for optimum results. 

Changing my set-up - unscrewing the equipment

New set-up

After lunch I caught up with those that were doing the x-ray imaging yesterday and they had the coolest image of a fly wing that I've ever seen been taken in a university laboratory! It made my mouth drop! At that moment I wanted their job!

Since one of the postdocs was leaving we had another social which was another great opportunity to get to know the people in the Plasma Group.

I am taking a break from my summer placement for a month but I shall return in September and more blog posts will come then. For now I shall say, why not try a summer placement, learn new things and have something great to talk about in an interview! Have a great summer! :)