Spectrally-resolved Third Harmonic Generation Microscopy

I broadened the bandwidth of Cr:forsterite solid laser from 33nm to more than 80nm by optimizing the incorrect oscillator statement. Using the 80nm-broadband Cr:forsterite solid laser with a central wavelength around 1263nm and 48fs pulse width as excitation source, I first set up a third harmonic generation (THG) spectroscopy system for molecular analysis. This spectroscopy system was able to measure the THG spectra and analyze the corresponding nonlinear susceptibilities of the molecules commonly found within human skins, i.e. water, lipid, melanin, and hemoglobin by using one broadband ultrafast laser beam. Combining THG spectroscopy with THG microscopy, I then set up the spectrally-resolved THG microscope system, which could record 3-color THG images with 1024x1024 pixels 7 frames per second in real time. The broadband third harmonic signals were divided into 3 channels based on different wavelength sections to present the molecular spectral responses in different pseudo hues. By the spectrally-resolved THG images, it was able to provide detailed morphology with a submicron lateral resolution and visual molecular information of bio-tissues. Melanoma cells, zebrafishs, adipose tissues, erythrocytes, epidermal tissues, basal cell carcinoma, and dermal capillaries were as specimens ex vivo and in vivo to exhibit the sensitivity about molecular information of the spectrally-resolved THG microscope system.