Project - 2009

Optical Spectroscopy

Gökhan Özoğur, Sophomore, Koç University

Ali Serpengüzel, Professor of Physics, Koç University

I have spent almost two months in Koç University Summer Research Program. I have worked in liquid crystal based electrophotonics project in Microphotonics Research Laboratory. There was a fabrication plan that explains steps of liquid crystal and microsphere fabrication. In that purpose, I did the following;

Liquid Crystal Display - Electrode Characterization

In order to determine the correspondence of electrodes with different sections of a Liquid Crystal Display, I sent 5Hz, 30V square waves at -10V DC Offset to the LCD panel using a function generator. As a result, I figured out grounds and leads for corresponding sections of LCDs.

Figure1: I am modulating the LCD section. Figure2: I am storing the products in a clean box

Liquid Crystal Display Cutting

Due to the fact that some sections of the LCDs were not working significantly, I cut good-working small sections from the LCDs. First I cut the polarizers on the both sides of LCD using a knife and scratched the glasses using glass-cutter. Then, I broke the glasses in a uniform way. I did not take off the PCB, so the small sections could be still modulated after cutting process.


Figure3: I am cutting the polarizer of the LCD Figure4: The LCD section that I cut

Liquid Crystal Extraction

We need Liquid Crystal in our experiment in order to have a thicker LC layer. We need a thick LC layer because we will put smaller than 300 µm microspheres into that layer. In that purpose I extracted LC from not-working parts of LCDs. First of all, I separated edges of top and bottom glasses using heat gun. Then I put cylindrical sticks between two glasses and took off the top glass slowly. The LC just flowed to the lower side gradually. Then I scraped the LC using plastic sheet. After that I sucked the LC on the plastic sheet using a syringe. In the end I stored the LC that I gathered from LCD in a glass bottle. The amount of LC was less than one gram.

Figure5: Top glass that includes color filter Figure6: Bottom glass that includes TFT layer

In two months I learned how LCD works and the role of the optics in LCD technology. I realized that we frequently use products of optical science in our daily lives. I gained good experience from this research program, and it increased my research skill. I am really happy for spending two months in such a great place. I thank my professor since he gave me an opportunity to work in photonics laboratory.



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