Laser Light Imaging Research Articles

Motor Evoked Potential Monitoring and Novel Laser Light Imaging System to Simultaneously Visualize Light and Near-infrared Fluorescence Images in Aneurysm Surgery

Motor Evoked Potential Monitoring and Novel Laser Light Imaging System to Simultaneously Visualize Light and Near-infrared Fluorescence Images in Aneurysm Surgery

선형 레이저 광 영상기반 다면 3차원 스캐너

In light of recently developed 3D printers for rapid prototyping, there is increasing attention on the 3D scanner as a 3D data acquisition system for an existing object. This paper presents a prototypical 3D scanner based on a striped laser light image. In order to solve the problem of shadowy areas, the proposed 3D scanner has two cameras with one laser light source. By using a horizontal rotation table and a rotational arm rotating about the latitudinal axis, the scanner is able to scan in all directions. To remove an additional optical filter for laser light pixel extraction of an image, we have adopted a differential image method with laser light modulation. Experimental results show that the scanner’s 3D data acquisition performance exhibited less than 0.2 mm of measurement error. Therefore, this scanner has proven that it is possible to reconstruct an object’s 3D surface from point cloud data using a 3D scanner, enabling reproduction of the object using a commercially available 3D printer.

선택적 초음파 임프린팅을 사용한 복합 미세패턴의 복제기술

Ultrasonic imprinting is a micropattern replication technology for a thermoplastic polymer surface that uses ultrasonic vibration energy; it has the advantages of a short cycle time and low energy consumption. Recently, ultrasonic imprinting has been further developed to extend its functionality: (i) selective ultrasonic imprinting using mask films and (ii) repetitive ultrasonic imprinting for composite pattern development. In this study, selective ultrasonic imprinting was combined with repetitive imprinting in order to replicate versatile micropatterns. For this purpose, a repetitive imprinting technology was further extended to utilize mask films, which enabled versatile micropatterns to be replicated using a single mold with micro-prism patterns. The replicated hybrid micropatterns were optically evaluated through laser light images, which showed that versatile optical diffusion characteristics can be obtained from the hybrid micropatterns.

Effects of Leaflet Stiffness on In Vitro Dynamic Bioprosthetic Heart Valve Leaflet Shape

Advances in the development of replacement heart valves require a deeper understanding of the valve dynamics. In the present study, dynamic aortic valve (AV) leaflet geometries were quantified in vitro using a structured laser-light imaging system (Iyengar et al., ABME 29(11):963-973, 2001). Native AV leaflets were first imaged under simulated physiological flow conditions within a rigid glass conduit with simulated anatomic sinuses. Next, the valve/glass conduit combination was removed from the loop and immersed in a 0.625% aqueous glutaraldehyde solution at room temperature for 24 h to produce a bioprosthetic heart valve (BHV). The BHV leaflets were then re-imaged under identical flow conditions while kept in the same position in the glass conduit to minimize artifacts associated with removal/reinsertion of the valve. We observed that: (1) the native leaflet exhibited small, high frequency shifts in shape; (2) the BHV leaflet demonstrated a more stabile shape, as well as focal regions of prolonged, high curvature; (3) the BHV leaflet opened and closed faster by ~10 ms compared to native leaflet; (4) in both the BHV and native states, the AV opened from basal region leading to free edge (5) when closing, both the native and BHV close with both free edge and circumferential together. The high bending observed in the BHV leaflet correlated with known locations of tissue deterioration previously reported in our laboratory. Thus, in order to minimize leaflet tissue damage, methods of chemical modification utilized in BHVs that maintain leaflet flexibility are necessary to minimize the onset and progression of tissue damage. We conclude that leaflet stiffness can have a considerable effect on dynamic valve motion, and can induce deleterious bending behaviors that may be associated with tissue breakdown and valve failure. Moreover, these unique data can provide much needed quantitative information for computational simulation of heart valve leaflet stiffness on heart valve function.

Observing cross-sectional images and averaged optical patterns of photonic crystal fibers using partially incoherent laser light

We couple the coherent laser light and the partially incoherent laser light into the photonic crystal fibers, respectively, and compare the observed fiber cross-sectional images. Lower coherence light can indeed help us obtain higher-quality and uniform cross-sectional images on the fiber output endfaces. We have observed rather unique and clear averaged optical mode patterns within the microstructures of a silica-air index-guiding solid-core photonic crystal fiber, which might be due to the stress-induced refractive-index inhomogeneity formed therein during the fiber manufacturing process. The experimental results are also compared with those images taken by other light sources or imaging systems. Besides, we successfully achieve capturing consecutively the various near-field averaged optical patterns of the solid-core photonic crystal fiber using this single-wavelength partially incoherent laser light imaging system.

Observing cross-sectional images of various optical fibers using low coherence transformed laser light

When the laser light of high optical coherence is launched into various optical fibers, such as a single-mode fiber, a multimode fiber, and a polarization-maintaining fiber, the observed optical patterns exhibit fragmented speckles due to the field interference of higher-order modes. Hence, the coherent laser light imaging system cannot be exploited to observe high-quality fiber crosssectional images. By putting a rotating diffuser directly on the laser beam, the original coherent speckled light spots at the fiber output endfaces could be smeared out efficiently and easily. Using the low coherence transformed laser light, we can thus obtain uniform fiber cross-sectional images and clear information for the tiny index structures in the specialty optical fibers.

Preparation and characterisation of a novel buoyancy and refractive index matched oil-in-water emulsion

We report a novel oil-in-water emulsion that is both buoyancy and refractive index matched. The dispersion is created using low-shear cross-flow membrane emulsification technology with a discrete phase comprising a mixture of n-hexane and the perfluorinated oil tetradecafluorohexane, in the form of FC-72. Three-dimensional confocal laser light imaging of a bulk-aggregated emulsion is demonstrated, showing explicit droplet-level detail of the emulsion interior. Magnetic resonance microscopy with a spatial resolution of tens of microns is also described. The proximity of a liquid–liquid binodal in the oil mixture can give rise to a ternary phase separation reminiscent of an O/O/W emulsion.

High Resolution Optical Imaging of Infarction in Intact Organs

We describe a method to visualize green fluorescent protein (GFP)-labeled cells in intact organs through combined confocal and reflected laser light imaging. This method allows us a three-dimensional (3-D) view of specific cell types in situ. Imaging of tissues from transgenic mice in which the endothelial cells are labeled with GFP under the control of endothelial-specific tyrosine receptor kinase 2 (TIE2) shows the spatial distribution of the GFP-labeled endothelial cells in intact organs. We have used this method to examine the tissue necrosis in the intact heart and kidney resulting from myocardial and renal infarction. In myocardial infarction produced by surgically occluding the left anterior descending coronary artery, the border of the infarct was highly cellular and showed a disrupted endothelial network and scar tissue appearing as a dense layer of reflection. The induced renal infarction produced by ligating the renal artery in the pedicle showed a clear infarct border in the affected kidney. The 3-D reconstruction of specific cell types in the context of the surrounding tissues should be useful for studying the overall organization and the relationship between different structures in the intact organ in normal and disease states.

Microplastic Lens Array Fabricated by a Hot Intrusion Process

A microplastic lens array has been successfully constructed on top of a 500-/spl mu/m-thick PC (Polycarbonate film) by using a micro hot intrusion process. A single-layer LIGA process is used to fabricate the high-aspect-ratio nickel mold insert that has circular hole patterns of 80 /spl mu/m in diameter and 200 /spl mu/m in depth. Under the hot intrusion process, plastic material can be intruded into these circular-shape holes and stopped at desired depth under elevated temperature and pressure to fabricate microlenses. By adjusting the embossing load, temperature and time, the curvature and height of the lens are controllable when the same mold insert is used. The optical properties of these microlenses have been characterized and the average radius of curvature is found as 41.4 /spl mu/m with a standard deviation of 1.05 /spl mu/m. Experimental characterization and theoretical model are conducted and developed for the micro-intrusion process in terms of the radius of curvature and height of the lenses and they correspond well with experimental data within 5% of variations. The focusing capability of the lenses is demonstrated by comparing the images of laser light with and without using the lenses. When the projection screen is placed 200 /spl mu/m away from the lens, the full-width at half-maximum (FWHM) for the lens is 110 /spl mu/m while the original FWHM of the optical fiber is 300 /spl mu/m.

Vision with a scanning laser display: comparison of flicker sensitivity to a CRT

Laser scanning displays allow for large depth-of-focus, reduced optical aberrations, and high luminance. However, scanned laser light images have no phosphor persistence. Psychophysical tests with a 3-color laser display showed that flicker thresholds were nearly equal with a laser display relative to the CRT when both were matched in luminance, resolution, frame rate, and similar chromaticity. The threshold ratio was 1.14 (range 0.7–1.6). Differences in flicker sensitivity between displays were significantly related to the absolute energy at the cornea irrespective of the subjective luminance match. Flicker sensitivity was not enhanced by a laser scanning display without image persistence.

Laser Light Based Machine System for Nondestructive Ripeness Sensing of Golden Apples

A laser light image on the apple surface was captured and digitized by a machine vision system to a 256 pixels x 256 pixels x 256 gray levels digital image. It was then smoothed by using a linear low pass filter, converted to a binary image at a threshold gray level of 15, and calculated for the size. The image size increases with the ripening of the apple. Measurements on 120 Golden apples showed a nonlinear negative relation between the image size and the firmness with a correlation coefficient (r) of 0.84. During shelf display, the image size increases linearly with time. This system can be used to evaluate the apple ripeness.

Droplet size characteristics for insecticide and herbicide spray atomizers

AbstractRotary atomizers and hydraulic nozzles used in forestry spraying were extensively tested with laser light scattering, laser light imaging, and photographic methods in a specially designed wind tunnel. Data on droplet size distribution and cumulative volume fraction versus droplet size are given. Correlations for reduced volume median diameter (Dv,0.5/d0) and reduced span ((Dv.0.9 – Dv.0.1)/d0) presented. Accuracy of prediction is of the order of 20% for hydraulic nozzle volume median diameter. Accuracy of prediction for high‐speed rotating wire mesh atomizers is of the order of 35% for the volume median diameter. When these accuracies are inadequate, a specific test of the device in question is recommended.

Fiber laser plate

In this paper a fiber laser plate, consisting of many fiber lasers in a form similar to an ordinary optical fiber plate, is described. The fiber laser plate, when end-pumped, can emit a laser light image corresponding to a 2-D transparency. The abrupt change of output intensity with excitation energy shows that the plate is attractive as an optical threshold device.

Image emission platelet laser for optical information processing

A laser light image corresponding to an image of an input transparency projected by a Rhodamine-6G dye laser has been emitted from an ultrathin GaAs crystal wafer. The image emission laser can be used as a new active device for optical parallel processings. Experimental results of image thresholding and wavelength converting are presented.