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Dual-Modality Imaging

GRIN Lens Based OCT-LIF Endoscope

Using a gradient-index lens optimized for 1300 nm, OCT light (red, below) is focused onto tissue after being reflected downwards by rod prism. Three LIF fibers (one for excitation, two for the collection of emitted light) bypass the GRIN lens and are also reflected downwards onto the tissue with the rod prism (blue, below). OCT channel shows lateral resolution of ~10 μm, while LIF light is unfocused.



Focused OCT-LIF Endoscope

The focused OCT-LIF endoscope is a high resolution endoscope that focuses both OCT and LIF beams. Using reflective as opposed to refractive optics, the endoscope is able to operate achromatically over a wavelength range from 325-1300 nm, though the OCT single-mode fiber must be optimized for center wavelength. In this endoscope, the OCT fiber and two LIF fibers (one excitation, one collection) are secured to the top of the endoscope, and all light undergoes TIR at two interfaces and is then reflected downwards onto the tissue by a third internal mirrored interface. The focused endoscope is capable of an OCT lateral resolution ~ 6 μm when used with 1300 nm, and an LIF lateral resolution of 152 μm (using a 220 μm core-diameter multi-mode fiber).





References

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Izatt, J. A., Kulkarni, M. D., Yazdanfar, S., Barton, J. K., and Welch, A. J., “In vivo biodirectional color Doppler flow imaging of picoliter blood volumes using optical coherence tomography,” Opt. Lett. 22, 1439-1441 (1997).

Hariri, L. P., Tumlinson, A. R., Besselsen, D. G., Utzinger, U., Gerner, E. W. and Barton, J. K., “Endoscopic optical coherence tomography and laser-induced fluorescence spectroscopy in a murine colon cancer model,” Lasers Surg. Med. 38, 305-313 (2006).

Barton, J. K., Guzman, F. and Tumlinson, A. R., “Dual modality instrument for simultaneous optical coherence tomography imaging and fluorescence spectroscopy,” J. Biomed. Opt. 9(3), 618-623 (2004).

Tumlinson, A. R., Hariri, L. P., Utzinger, U. and Barton, J. K., “Miniature endoscope for simultaneous optical coherence tomography and laser-induced fluorescence measurement,” Appl. Opt. 43(1), 113-121 (2004).