Prototyping a Laser Spectroscope

Materials are usually classified according to their physical and chemical properties. New technologies today are making the identification of materials increasingly simple, fast and reliable. Building on our earlier research in using spectroscopy and the physics of light to visually differentiate materials, we are now ready to ask: Can we make a laser-induced breakdown spectrometer, locally in Ghana?

Two physics teaching assistants from the University of Ghana signed on with AMP team to help us find out: Nutifafa Y. Doumon (who already participated in #ampqamp), with an MSc degree in Nanoscience from University of Groningen, in the Netherlands and Rodney Abugre, who recently graduated with an MPhil in Physics from University of Ghana.

Test experiment for material surface excitation with an incandescent light
Test experiment for material surface excitation with an incandescent light

We first reviewed existing technologies and later performed our own experiments. Materials were sourced from Agbogbloshie, since the device will be used to test scrap metal from that location.

The goal for our first three experiments was to investigate the laser excitation process of the material surfaces. Apparatus include: Laser light source, converging lens, sample holder and timer. In the laser excitation process we expect the electromagnetic energy of the laser light to be transformed into thermal energy inside the metal and this based on the amount of energy absorbed by the metal. In our experiment we tested this principle using red laser of power 1 mW & < 5 mW, and an incandescent light of power 100 W. From the test experiments, we conclude that due to low power output of the laser light available, we cannot obtain the desirable results from the experiment (See pre-lab here).

Test setup to study laser interaction with material's surface
Test setup to study laser interaction with material’s surface

The next step was to set up and calibrate the complete optical path with components such as, prism, diffraction grating,  laser source, lens, filters mirrors and a camera. In this optical system, our major need is to find a laser with high enough power output to help us obtain the correct spectrum through excitation process.

We will use this system to record the spectrum for the different materials, analyze them using MatLab software and compare results to literature.  In the latter stages, the Agbogbloshie community will be engaged in a workshop on spectroscopy.

The setup for laser alignment [top view]
The setup for laser alignment [top view]
The setup for laser alignment [view from laser source]
The setup for laser alignment [view from laser source]

STEAM workshop


For the past few months, the AMP team has engaged e-waste workers within Agbogbloshie. This time, on Saturday the 26th of April, the team organized its latest workshop intended to initiate the conversation with the STEAM world, who form a critical part of the AMP platform. Eventually, these professionals will come together with the e-waste workers and makers in Agbogbloshie to form the AMP makers collective. The knowledge that these professionals bring to the Agbogbloshie site will be useful for achieving AMP targets such as empowering makers to handle e-waste according to best practices and enabling makers to upcycle e-waste into value-added products.

The agenda was to:

  • Introduce AMP to the STEAM world, and invite them to apply for summer internships.
  • Engage students in hands-on projects that involved building a paper spectroscope, dis-assembly of a microwave oven, a printer and a fan.

The workshop took place at the lower lecture hall of the Physics department in the University of Ghana, Legon. Students from the host physics department, as well as chemistry, computer science and psychology students attended. There were also students from the architecture department of the Central University College. In all, there were 50 participants.

The workshop started with an introduction of the AMP team, followed by an interactive session, during which members of the AMP team engaged in conversation with the students.

After the interaction and lecture, participants were divided into four groups and made to work on the various projects. Each team documented the brand, the year of manufacture, and all other information they considered relevant. They were required to state to the best of their knowledge, which components were in the equipment and to what other uses these could be put.

We discovered that students from the physics department in particular had a fundamental awareness of the nature and uses of parts, as well as how these contributed to the total functioning of the equipment. After this session each team presented its findings to the larger group of participants.

Upon the completion of the workshop, participants by way of evaluation, passed on comments such as:

The program was insightful and inspirational. I am very happy I came and met other brilliant students and how they agitated minds to think critically. A great experience that will stay with me a long time.

A successful workshop in my opinion. I learned a lot and I am happy to know that such great ideas are being implemented. As I leave, my mind is racing through ways I can contribute to this positive revolution.

See photos on Flickr : STEAM Photos


Spectrascope test model
Spectrascope test model