Abstract:An integrated microscope that combines different optical techniques for simultaneous imaging is demonstrated. The microscope enables spectral-domain optical coherence microscopy based on optical backscatter, and multi-photon microscopy for the detection of two-photon fluorescence and second harmonic generation signals. The unique configuration of this integrated microscope allows for the simultaneous acquisition of both anatomical (structural) and functional imaging information with particular emphasis for applications in the fields of tissue engineering and cell biology. In addition, the contemporary analysis of the spectroscopic features can enhance contrast by differentiating among different tissue components.

For optical coherence tomography (OCT), ultrasound, synthetic-aperture radar, and other coherent ranging methods, speckle can cause spurious detail that detracts from the utility of the image. It is a problem inherent to imaging densely scattering objects with limited bandwidth. Using a method of regularization by minimizing Csiszar's I-divergence measure, we derive a method of speckle minimization that produces an image that both is consistent with the known data and extrapolates additional detail based on constraints on the magnitude of the image. This method is demonstrated on a test image and on an OCT image of a Xenopus laevis tadpole.

We present a technique for maintaining phase stability in a three-dimensional optical coherence tomography system. When determining the inverse scattering solution, phase stable measurements are required to ensure proper object reconstruction. The proposed method uses a reference object placed above the specimen to facilitate the retrieval of accurate constant phase surfaces throughout the specimen. Our algorithm locates the reference object, determines the phase and group delay, and corrects the phase disturbance accordingly.

We present and experimentally demonstrate a novel dispersion compensation algorithm for Optical Coherence Tomography that can account for both material and delay-line induced dispersion. It is a Fast Fourier Transform based algorithm that simultaneously corrects for the dispersion at all depths in a material, so that longer scan ranges are possible than can be compensated by optically correcting the dispersion at a particular depth. Such an algorithm becomes necessary when large bandwidth illumination or a large scan range is employed. We validate the algorithm by correcting the OCT measurements of a multilayered transparent PDMS (polydimethyl siloxane) microfluidic device.