In this study, we have demonstrated by using time-lapsed two-photon fluorescence microscopy (2PFM), heat flow in
biological tissues can be monitored based on temperature-induced fluorescence change of endogenous molecules.
Compared to conventional infrared thermography or other thermal imaging tools, 2PFM provides not only sub-micrometer
spatial resolution, but also optical sectioning capability inside tissues. As a proof of principle, 2PFM was
used to monitor the fluorescence variation in a leaf of Eucalyptus Robusta Smith, which is placed on a home-made
heater. By heating the leaf asymmetrically, significant changes of chlorophyll fluorescence were observed in the
temperature range of 30°C to 60°C, leading to the visualization of heat conduction dynamics. From the analysis of
temporal variation in fluorescence, 0.5°C thermal resolution was demonstrated and detailed temperature distribution can
be quantized. Such a technique will be useful for the characterization of heat-related biophysical mechanisms with high
spatial and temperature resolution in a thick tissue.
In this study, we performed theoretical analysis and experimental measurement of third harmonic generation (THG) in
melanin solution with different concentrations. As predicted by theory, only THG at glass/solution interface was
observed due to Guoy phase shift effect. We have shown that this interfacial THG intensity is strongly affected by index
matching condition between the two media, leading to minimal THG at a certain melanin concentration. By fitting the
dependence of THG intensity versus melanin concentration, linear and nonlinear electric susceptibilities of melanin are
obtained, providing a valuable tool to characterize optical properties of biological molecules.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.