Another Wavelength: Yanqi Zhang

Where are you from? 

I’m from Yantai, a city on the east coast of China.

What brought you to study optics? 

At first, I chose optics as my undergraduate major without thinking too much, only because that it seems like an interdisciplinary of physics, electrical engineering and mechanical engineering, which is cool! After four years study, I developed interests in optical metrology but also felt that I knew so little about this area. That’s why I decided to get into graduate program and learn optics more systematically and more in depth.

Who is your hero in science? 

There is no specific person but I would say people who can come up with elegant solutions or theories like a “magician”. Einstein and Maxwell are definitely two of them. Also, Richard Feynman is one among them. He is a physicist, an interesting person, and a great storyteller. The Feynman Lectures on Physics are still the best books I have ever read on explaining physics concepts to entry-level students.

Describe your research in 20 words or fewer. 

I am developing displacement interferometer for seismic opto-mechanical sensors that will be used in Laser Interferometer Gravitational-wave Observatory.

Describe your research in 200 words or fewer. 

By the end of last semester, I have been working on developing surface metrology systems. I started from building a two-wavelength interferometer for freeform surface measurement. The application of synthetic wavelength enlarges the dynamic range and makes measuring large surface slope possible. The intrinsic disadvantages of the synthetic wavelength come from the noise amplification and chromatic errors. Therefore, I worked on both algorithm and hardware modifications to reduce these errors. However, the accuracy is stilled limited by the quality of the reference surface. Then, I started looking into absolute surface metrology, using which the reference surface can also be evaluated.

Starting from this year, I switched gears from surface metrology to displacement metrology. Currently, I’m investigating on different types of displacement interferometer and possibilities of integrating them on opto-mechanical sensors that will be used in LIGO suspension systems. The interferometer is designed as the readout system to measure the displacement of the test mass on the opto-mechanical sensor, where eventually the displacement will be converted into acceleration noise.

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Name three neat facts about you. 

1. In Chinese, “Q” pronounces as “ch”. Therefore, my name sounds like “yan-chee” instead of “Yankee”.
2. The only thing I love more than travelling is to make travel plans.
3. I’m always open to try new thing: new restaurants, new hiking routes, new outdoor activities and so on!