Feasibility studies of multimodal nonlinear endoscopy using multicore fiber bundles for remote scanning from tissue sections to bulk organs.

Here, we report on the development and application of a compact multi-core fiber optical probe for multimodal non-linear imaging, combining the label-free modalities of Coherent Anti-Stokes Raman Scattering, Second Harmonic Generation, and Two-Photon Excited Fluorescence. Probes of this multi-core fiber design avoid moving and voltage-carrying parts at the distal end, thus providing promising improved compatibility with clinical requirements over competing implementations. The performance characteristics of the probe are established using thin cryo-sections and artificial targets before the applicability to clinically relevant samples is evaluated using ex vivo bulk human and porcine intestine tissues.

Multimodal nonlinear endomicroscopic imaging probe using a double-core double-clad fiber and focus-combining micro-optical concept.

Multimodal non-linear microscopy combining coherent anti-Stokes Raman scattering, second harmonic generation, and two-photon excited fluorescence has proved to be a versatile and powerful tool enabling the label-free investigation of tissue structure, molecular composition, and correlation with function and disease status. For a routine medical application, the implementation of this approach into an in vivo imaging endoscope is required. However, this is a difficult task due to the requirements of a multicolour ultrashort laser delivery from a compact and robust laser source through a fiber with low losses and temporal synchronization, the efficient signal collection in epi-direction, the need for small-diameter but highly corrected endomicroobjectives of high numerical aperture and compact scanners.

Reliable profile reconstruction of GRIN lenses produced by ion-exchange processes.

We propose a method that allows for a fast and accurate reconstruction of the refractive index profile of radially symmetric gradient index lenses fabricated by ion-exchange processes. The presented method enables the reconstruction of the profile up to the 10th polynomial order without direct spatially resolved refractive index measurements. It requires as input a working distance measurement at the paraxial limit and an accurate wavefront aberration measurement at full aperture.

Chip-on-the-tip compact flexible endoscopic epifluorescence video-microscope for in-vivo imaging in medicine and biomedical research.

We demonstrate a 60 mg light video-endomicroscope with a cylindrical shape of the rigid tip of only 1.6 mm diameter and 6.7 mm length.

Design and evaluation of new color-corrected rigid endomicroscopic high NA GRIN-objectives with a sub-micron resolution and large field of view.

We demonstrate new GRIN-based endomicroscopic objectives for high resolution single photon fluorescence imaging modalities. Two endoscopic optical design approaches are presented in detail utilizing firstly diffractive and secondly refractive optical elements for the color correction in a spectral range from 488 nm to 550 nm. They are compared with their precursor device experimentally and by simulation.