Chromatic confocal microscopy (CCM) is a promising technology that enables high-speed three-dimensional surface profiling without mechanical depth scanning. However, the spectrometer, which measures depth information encoded by axial color, limits the speed of three-dimensional imaging. We present a novel method for chromatic confocal microscopy with transmittance detection. Depth information can be instantaneously obtained by the ratio of intensity signals from two photomultiplier tubes by detecting a peak wavelength using transmittance of a color filter. This non-destructive and high-speed surface profiling method might be useful in many fields, including the semiconductor and flat panel display industries, and in material science.
Abstract. A nonresonant, fiber-optic raster scanning endomicroscope was developed using a quarter-tubular piezoelectric (PZT) actuator. A fiber lever mechanism was utilized to enhance the small actuation range of the tubular PZT actuator and to increase its field-of-view. Finite element method simulation of the endoscopic probe was conducted for various conditions to maximize its scanning range. After fabricating the probe using a double clad fiber, we obtained two-photon fluorescence images using raster beam scanning of the fiber. The outer diameter of the probe was 3.5 mm and its rigid distal length was 30 mm including a high numerical aperture gradient index lens. These features are sufficient for input into the instrumental channel of a commercial colonoscope or gastroscope to obtain high resolution images in vivo.
Background and Objective The tethered spectrally‐encoded confocal endomicroscopy (SECM) capsule is an imaging device that once swallowed by an unsedated patient can visualize cellular morphologic changes associated with gastrointestinal (GI) tract diseases in vivo. Recently, we demonstrated a tethered SECM capsule for counting esophageal eosinophils in patients with eosinophilic esophagitis (EoE) in vivo. Yet, the current tethered SECM capsule is far too long to be widely utilized for imaging pediatric patients, who constitute a major portion of the EoE patient population. In this paper, we present a new tethered SECM capsule that is 33% shorter, has an easier and repeatable fabrication process, and produces images with reduced speckle noise. Materials and Methods The smaller SECM capsule utilized a miniature condenser to increase the fiber numerical aperture and reduce the capsule length. A custom 3D‐printed holder was developed to enable easy and repeatable device fabrication. A dual‐clad fiber (DCF) was used to reduce speckle noise. Results The fabricated SECM capsule (length = 20 mm; diameter = 7 mm) had a similar size and shape to a pediatric dietary supplement pill. The new capsule achieved optical sectioning thickness of 13.2 μm with a small performance variation between devices of 1.7 μm. Confocal images of human esophagus obtained in vivo showed the capability of this new device to clearly resolve microstructural epithelial details with reduced speckle noise. Conclusions We expect that the smaller size and better image performance of this new SECM capsule will greatly facilitate the clinical adoption of this technology in pediatric patients and will enable more accurate assessment of EoE‐suspected tissues. Lasers Surg. Med. 51:452–458, 2019. © 2019 Wiley Periodicals, Inc.
A simple structure of spectral fluorescence lifetime imaging microscope (SLIM) is designed with the use of tunable bandpass filter, a kind of Fabry-perot filter that transmission wavelength is varying according to incident angle of light. Feasibility tests of this angle-tuned bandpass filter (ATBF) are performed and it shows high transmission and constant spectral bandwidth (20 nm) with respect to angle of incidence. Furthermore, using two ATBFs in series, spectral bandwidth can be adjustable down to 4 nm. In this paper, dual ATBFs are implemented to the detection part of fluorescence lifetime imaging microscope (FLIM) system so that we obtained spectrally resolved FLIM images. We compare these SLIM images with an original FLIM image and confirm that the former case provides high accuracy to analyze lifetime distribution as well as high contrast of images. The proposed SLIM microscope with good wavelength selectivity has many opportunities to utilize to other applications such as FLIM-Föster resonant energy transfer and autofluorescence imaging.
We developed a multimodal microscopy based on an optical scanning system in order to obtain diverse optical information of the same area of a sample. Multimodal imaging researches have mostly depended on a commercial microscope platform, easy to use but restrictive to extend imaging modalities. In this work, the beam scanning optics, especially including a relay lens, was customized to transfer broadband (400-1000 nm) lights to a sample without any optical error or loss. The customized scanning optics guarantees the best performances of imaging techniques utilizing the lights within the design wavelength. Confocal reflection, confocal fluorescence, and two-photon excitation fluorescence images were obtained, through respective implemented imaging channels, to demonstrate imaging feasibility for near-UV, visible, near-IR continuous light, and pulsed light in the scanning optics. The imaging performances for spatial resolution and image contrast were verified experimentally; the results were satisfactory in comparison with theoretical results. The advantages of customization, containing low cost, outstanding combining ability and diverse applications, will contribute to vitalize multimodal imaging researches.
There exist microscopes that are able to obtain the chemical properties of a sample, because there are some cases in which it is difficult to find out causality of a phenomenon by using only the structural information of a sample. Obtaining the chemical properties of a sample is important in biomedical imaging, because most biological phenomena include changes in the chemical properties of the sample. Hyperspectral imaging (HSI) is one of the popular imaging methods for characterizing materials and biological samples by measuring the reflectance or emission spectrum of the sample. Because all materials have a unique reflectance spectrum, it is possible to analyze material properties and detect changes in the chemical properties of a sample by measuring the spectral changes with respect to the original spectrum. Because of its ability to measure the spectrum of a sample, HSI is widely used in materials identification applications such as aerial reconnaissance and is the subject of various studies in microscopy. Although there are many advantages to using the method, conventional HSI has some limitations because of its complex configuration and slow speed. In this research we propose a new type of multimodal confocal hyperspectral imaging microscopy with fast image acquisition and a simple configuration that is capable of both confocal and HSI microscopies.
Background and Objective Spectrally encoded endoscopy (SEE) is an optical imaging technology that uses spatial wavelength multiplexing to conduct endoscopy in miniature, small diameter probes. Contrary to the previous side‐viewing SEE devices, forward‐viewing SEE probes are advantageous as they provide a look ahead that facilitates navigation and surveillance. The objective of this work was to develop a miniature forward‐viewing SEE probe with a wide field of view and a high spatial resolution. Materials and Methods We designed and developed a forward‐viewing SEE device with an overall total diameter of 1.27 mm, which consists of a monolithic illumination probe with a length of 3.87 mm and a diameter of 500 µm, 8 multimode detection fibers that were polished at a 17° angle, a rotational scanning mechanism, and a sheath. The SEE device was evaluated using a USAF resolution target and was used for preclinical imaging of a swine joint ex vivo. Results This design resulted in a high resolution probe (best spatial resolution of 20.3 µm), a wide total angular field of view of 100°, and an effective number of imaging elements of ~344,000 pixels. The SEE probe performance was compared to a commercial color chip‐on‐the‐tip endoscope; while monochrome, results showed better spatial resolution and a wider field of view for the SEE device. Conclusion These results demonstrate the potential of this forward‐viewing SEE probe for visualization and navigation in medical imaging applications. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.
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