ABSTRACT
We present a hand-held device aimed for reflectance-mode confocal imaging of biological tissues. The device consists of a light carrying optical fiber and a miniaturized raster scanner located at the distal end of the fiber. It is fabricated by mounting a polarization maintaining optical fiber on a cantilever beam that is attached to another beam such that their bending axes are perpendicular to each other. Fiber scanner is driven by electromagnetic forces and enables large fiber deflections with low driving currents. Optical resolutions of the system are 1.55 and 8.45 µm in the lateral and axial directions, respectively. Functionality of the system is demonstrated by obtaining confocal images of a fly wing and a human colon tissue sample.
Subject(s)
Fiber Optic Technology/instrumentation , Microscopy, Confocal , Optical Imaging , Animals , Colon/anatomy & histology , Diptera , Electromagnetic Fields , Humans , Lasers , Microscopy, Confocal/instrumentation , Microscopy, Confocal/methods , Miniaturization , Optical Fibers , Optical Imaging/instrumentation , Optical Imaging/methods , Wings, Animal/anatomy & histologyABSTRACT
A fiber optic confocal catheter with a micro scanning lens was developed for real-time and non-contact thickness measurement of biological tissue. The catheter has an outer diameter and rigid length of 4.75 mm and 30 mm respectively and is suitable for endoscopic applications. The catheter incorporates a lens actuator that is fabricated using microelectromechanical systems (MEMS) technology. The lens is mounted on a folded flexure made of nickel and is actuated by magnetic field. Thickness measurements are performed by positioning the catheter in front of the tissue and actuating the lens scanner in the out-of-plane direction. A single-mode optical fiber (SMF) is used to deliver a 785 nm laser beam to the tissue and relay back the reflected light from the tissue to a photomultiplier tube (PMT). When the focal point of the scanning lens passes tissue boundaries, intensity peaks are detected in the reflecting signal. Tissue thickness is calculated using its index of refraction and the lens displacement between intensity peaks. The utility of the confocal catheter was demonstrated by measuring the cornea and skin thicknesses of a mouse. Measurement uncertainty of 8.86 µm within 95% confidence interval has been achieved.
Subject(s)
Micro-Electrical-Mechanical Systems/instrumentation , Microscopy, Confocal/instrumentation , Microtechnology/methods , Animals , Catheters , Cornea/anatomy & histology , Endoscopy/methods , Equipment Design , Female , Lenses , Mice , Mice, Inbred C3H , Microscopy, Confocal/methods , Skin/anatomy & histologyABSTRACT
This paper presents a confocal microscanner for direct vertical optical sectioning of biological samples. Confocal imaging is performed by transverse (X-axis) and axial (Z-axis) scanning of a focused laser beam using an optical fiber and a microlens respectively. The actuators are fabricated by laser micromachining techniques and are driven by electromagnetic forces. Optical and mechanical performance of the system is predicted by simulation software packages and characterized by experimental measurements. The scanner has lateral resolution of 3.87 µm and axial resolution of 10.68 µm with a field of view of 145 µm in X and 190 µm in Z directions. Confocal imaging of a polymer layer deposited on a silicon wafer and onion epidermal cells is demonstrated.