Beam Delivery

Beam Delivery Devices

The successful implementation and use of OCT in clinical settings requires novel beam delivery systems that can address the wide range of applications for imaging different tissues. Portable beam delivery for clinical setting includes hand-held imaging probes, catheters, and imaging needles. The OCT imaging probes are to deliver and focus the optical light onto the tissue and collect the scattered radiation back to the interferometer of OCT system. In general, OCT imaging probe is comprised of three components: optical fiber, scanning mechanism and focusing lens. Optical light is delivered through the optical fiber while maintaining single mode and coherence, and then focused to a spot within the tissue specimen. Since OCT systems generate a single line of axial data through the sample at a time, a stationary focused beam in tissue enables single axial profile (1-D data set). In order to obtain a multi-dimensional OCT data set, it is necessary to steer the infrared beam laterally across the sample and compile the individual axial scan lines to form 2-D or 3-D images. In our laboratory, various optical beam delivery devices have been developed for real-time diagnosis of tissues, which provide tissue information as 1-D, 2-D and 3-D.

Beam delivery device for 1-D axial scan

(A) OCT needle probe to measure the refractive index of in vivo tissue and identify surgical margin in breast cancer rapidly. (B) Fiber-probe integrated into a video otoscope to perform simultaneous LCI depth-scanning into the middle ear and as well as CCD-based video imaging. (C) A LCI data from tympanic membrane and biofilm.

Beam delivery device for 2-D/3-D OCT images

(A) Modified surgical microscope incorporating scanners for simultaneous white-light and OCT imaging of tissue in the open surgical field. (B) Schematic and photograph of an OCT catheter. OCT catheters can be up to several meters in length, and less than a millimeter in diameter. Micro-optics at the distal end focus and re-direct the light out at a right angle. The inner fiber and micro-optics are rotated or translated within a stationary transparent sheath to perform radial or linear OCT imaging, respectively.

(A) OCT needle probe designs for forward-directed axial-scan acquisition and side-directed OCT imaging performed by either rotating or translating the needle within the tissue. (B) Prototype OCT needle control unit featuring both rotational and translational mechanical scanning. (C) A representative radial-OCT image from a needle probe.

(A) Photographs of handheld OCT scanner and lens mounts. In vitro 3D OCT images of a rat eye at (B) an angled view, and (C) a top view. (D-K) In vivo OCT and video images acquired from normal human tissue. (D) finger nail plate and fold, (E) uvula, (F) oral mucosa along gumline, (G) skin on arm, (H) cornea, (I) tympanic membrane in ear, (J) retina around fovea, (K) retina around optic nerve head. Abbreviations: NFL, nerve fiber layer; GCL, ganglion cell layer; INL, inner nuclear layer; ONL, outer nuclear layer; ELM, external limiting membrane; IS/OS, junction between the inner and outer segment of the photoreceptors; RPE, retinal pigment epithelium.

References

Zysk AM, Marks DL, Liu DY, Boppart SA. Needle-based reflection refractometry of scattering samples using coherence-gated detection. Optics Express, 15(8):4784-4794, 2007. n/a PDF
Boppart SA, Luo W, Marks DL, Singletary KW. Optical coherence tomography: feasibility for basic research and image-guided surgery of breast cancer. Breast Cancer Research and Treatment, 84:85-97 2004. PubMed
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