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Received October 14, 2005; revised January 7, 2006; accepted January 9, 2006; posted January 12, 2006 (Doc. ID 65391) The two-photon excitation action cross section of Hc-Red fluorescent proteins (Hc-RFPs) is measured and found to be of the same order as that of enhanced green fluorescent proteins. With a 618 nm emission wavelength in the far-red region and(More)
Harmonics-based optical microscopy has been widely applied in biomedical researches due to its noninvasiveness to the studied biomaterials. Due to momentum conservation consideration, most previous studies collect harmonics generation signals in a forward geometry, especially for third harmonic generation signals. However, the adopted forward transmission(More)
The first in vivo optical virtual biopsy based on epi-third-harmonic-generation (THG) microscopy is successfully demonstrated using Syrian hamster oral mucosa as a model system. Without complex physical biopsy procedures, epi-THG microscopy can provide high spatial resolution dynamic images of oral mucosa and sub-mucosa in all three dimensions. The(More)
Confocal and nonlinear optical microscopies have been applied for dermatological studies because of their capability to provide sub-surface three-dimensional images with sub-microm spatial resolutions. Optical signal degradation as the imaging plane being moved toward deeper regions in skin specimens is the key factor that limits the observation depth for(More)
Self-phase-modulation and group velocity dispersion of near IR femtosecond pulses in fibers restrict their use in two-photon fluorescence microscopy (TPFM). Here we demonstrate a hollow-core photonic crystal fiber based two-photon fluorescence microscope with low nonlinearity and dispersion effects. We use this fiber-based TPFM system to take two-photon(More)
We demonstrated that lipid-enclosed CdSe quantum dots (LEQDs) can function as versatile contrast agents in epi-detection third harmonic generation (THG) microscopy for biological applications in vivo. With epi-THG intensities 20 times stronger than corresponding fluorescence intensities from the same LEQDs under the same conditions of energy absorption,(More)
Simultaneous backward and forward second harmonic generations from isolated type-I collagen matrix are observed. Optical interference behaviors of these nonlinear optical signals are studied with accurately determined fibril thickness by an atomic force microscope. The nonlinear emission directions are strongly dependent on the coherent interaction within(More)
In recent years, nonlinear laser scanning microscopy has gained much attention due to its unique ability of deep optical sectioning. Based on our previous studies, a 1,200-1,300-nm femtosecond laser can provide superior penetration capability with minimized photodamage possibility. However, with the longer wavelength excitation, three-photon-fluorescence(More)
This paper reports a facile and effortless method to realize three-dimensional (3D) molecular third-harmonic-generation (THG) microscopy through the technique of resonance enhancement with absorbing dye. Hematoxylin, a popular absorbing stain, is applied as an example to verify the multiphoton resonant enhancement based on the 1230 nm excitation light and(More)