Research and Techniques in Optical Imaging

When a fluorophore is excited, the emitted photon is released at a later (characteristic) time called the lifetime (tau).  The fluorescence lifetime of organic fluorophores is usually on the order of picoseconds (10^-12 seconds) to nanoseconds (10^-9 seconds).  The fluorescence lifetime is highly sensitive to the fluorophore microenvironment, including local changes in pH, O₂, temperature and molecular binding. For more information Click Here.

Multiphoton Microscopy is a three-dimensional fluorescence imaging technique that is useful for investigating optically thick samples such as tissue.  When two photons are simultaneously absorbed by a fluorophore (each with half the energy of the molecule's absorption band), the emission is the same as that in the single-photon case. For more information Click Here.

Photothermal Microscopy exploits optical changes induced by heat to pinpoint the location of molecular targets in biological samples.  Temperature changes in a sample result in a small shift in the index of refraction, which can be detected interferometrically. For more information Click Here.

Optical Coherence Tomography (OCT) is a three-dimensional tissue imaging technique.  Similar to ultrasound, OCT provides cross-sectional images of tissue, but does not require coupling media and provides cellular resolution (~1 to 10 micron isotropic resolution). For more information Click Here.

Optical spectra can be collected over a tissue volume with optical fibers that deliver light to the tissue surface and collect the diffusely back-scattered light.  This approach allows for rapid interrogation of macroscopic volumes of tissue. For more information Click Here.