Ultrafast Spectroscopy and Microscopy for High-Throughput Biomedical Applications
Optical spectroscopy has been one of the most integral tools in scientific research, manufacturing, and medical practice. To investigate rapid transient phenomena such as chemical reactions, phase transitions of thermodynamic systems, and protein dynamics in living cells, fast real-time spectroscopy is highly desired. Unfortunately, conventional spectrometers, which usually rely on optical diffraction devices, such as prism or diffraction gratings, are often too slow to perform single-shot spectroscopic measurements due to the use of a moving component or a line camera with limited refresh rate (typically up to ~10 kHz).
Continuous running ultrafast real-time optical spectroscopy can be implemented based on dispersive Fourier transformation (DFT), which enables pulse-by-pulse spectroscopic measurement by mapping the spectrum of a broadband optical pulse into a time-domain waveform (frequency-to-time conversion) with the help of chromatic dispersion. Update rate of the spectrum measurement is same as the pulse repetition rate, which ranges from tens of MHz to a few GHz, at least four orders of magnitude higher than conventional spectrometers.
In addition, by encoding the spatial information (image) of an object into the optical spectrum of an ultrashort pulse using an optical diffraction device (space-to-time conversion), the real-time spectroscopy can be adapted, based on the two-fold conversions, to real-time microscopy for ultrafast and high-throughput optical imaging, which is a very powerful tool in various biomedical applications. For example, when combined with a microfluidic device, the ultrafast optical microscopy can act as an imaging-based flow-cytometer for ultrafast and high-throughput imaging of individual microparticles. This technique enables real-time screening of rare metastatic cancer cells in blood, hence holding great promise for non-invasive, low-cost, real-time diagnosis of cancer.
This project is supported by an EU Marie-Curie Career Integration Grant.