Toward development of a large field-of-view cancer screening patch (CASP) to detect cervical intraepithelial neoplasia.

Cervical cancers are primarily diagnosed via colposcopy, in which the tissue is visually assessed by a clinician for abnormalities, followed by directed biopsies and histologic analysis of excised tissue. Optical biopsy technologies offer a less invasive method of imaging such that subcellular features can be resolved without removing tissue. These techniques, however, are limited in field-of-view by the distal end of the probe. We present a prototype that incorporates a rigid, machinable waveguide that is in direct contact with a fluorescently-labeled sample paired with a scanning fluorescent microscope. The system is capable of imaging large areas of tissue without the need to re-position the tissue-probe interface. A mosaicing algorithm was developed to quantify scanning shifts and stitch neighboring frames together to increase the field-of-view. Our prototype can yield a maximum axial resolution of <5 µm for individual frames and can produce mosaiced images with a field-of-view greater than 15 mm x 15 mm without sacrificing resolution. We validated the system with a 1951 USAF resolution target, fluorescent in vitro standards, and a patient study where ex vivo conization samples of squamous cervical epithelium were imaged. The results of the patient study indicate that architectural features of subcellular components could be detected and differentiated between normal tissue and precancerous lesions.

3D printed fiber optic faceplates by custom controlled fused deposition modeling.

A 3D printing technique for manufacturing air-clad coherent fiber optic faceplates is presented. The custom G-code programming is implemented on a fused deposition modeling (FDM) desktop printer to additively draw optical fibers using high-transparency thermoplastic filaments. The 3D printed faceplate consists of 20000 fibers and achieves spatial resolution 1.78 LP/mm. Transmission loss and crosstalk are characterized and compared among the faceplates printed from four kinds of transparent filaments as well as different faceplate thicknesses. The printing temperature is verified by testing the transmission of the faceplates printed under different temperatures. Compared with the conventional stack-and-draw fabrication, the FDM 3D printing technique simplifies the fabrication procedure. The ability to draw fibers with arbitrary organization, structure and overall shape provides additional degree of freedom to opto-mechanical design. Our results indicate a promising capability of 3D printing as the manufacturing technology for fiber optical devices.

Quantitative evaluation of performance of 3D printed lenses.

We present an analysis of the shape, surface quality, and imaging capabilities of custom 3D printed lenses. 3D printing technology enables lens prototypes to be fabricated without restrictions on surface geometry. Thus, spherical, aspherical and rotationally non-symmetric lenses can be manufactured in an integrated production process. This technique serves as a noteworthy alternative to multistage, labor-intensive, abrasive processes such as grinding, polishing and diamond turning. Here, we evaluate the quality of lenses fabricated by Luxexcel using patented Printoptical© technology that is based on an inkjet printing technique by comparing them to lenses made with traditional glass processing technologies (grinding, polishing etc.). The surface geometry and roughness of the lenses were evaluated using white-light and Fizeau interferometers. We have compared peak-to-valley wavefront deviation, root-mean-squared wavefront error, radii of curvature and the arithmetic average of the roughness profile (Ra) of plastic and glass lenses. Additionally, the imaging performance of selected pairs of lenses was tested using 1951 USAF resolution target. The results indicate performance of 3D printed optics that could be manufactured with surface roughness comparable to that of injection molded lenses (Ra < 20 nm). The RMS wavefront error of 3D printed prototypes was at a minimum 18.8 times larger than equivalent glass prototypes for a lens with a 12.7 mm clear aperture, but when measured within 63% of its clear aperture, 3D printed components' RMS wavefront error was comparable to glass lenses.