R-3 Repository :: Browsing by Author "Wang, Ye"

Browsing by Author "Wang, Ye"

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3D printed fiber optic faceplates by custom controlled fused deposition modeling
(Optical Society of America, 2018) Wang, Ye; Gawedzinski, John; Pawlowski, Michal E.; Tkaczyk, Tomasz S.; Bioengineering; Electrical and Computer Engineering
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.
High spatial sampling light-guide snapshot spectrometer
(SPIE, 2017) Wang, Ye; Pawlowski, Michal E.; Tkaczyk, Tomasz S.; Bioengineering
A prototype fiber-based imaging spectrometer was developed to provide snapshot hyperspectral imaging tuned for biomedical applications. The system is designed for imaging in the visible spectral range from 400 to 700 nm for compatibility with molecular imaging applications as well as satellite and remote sensing. An 81×96 pixel spatial sampling density is achieved by using a custom-made fiber-optic bundle. The design considerations and fabrication aspects of the fiber bundle and imaging spectrometer are described in detail. Through the custom fiber bundle, the image of a scene of interest is collected and divided into discrete spatial groups, with spaces generated in between groups for spectral dispersion. This reorganized image is scaled down by an image taper for compatibility with following optical elements, dispersed by a prism, and is finally acquired by a CCD camera. To obtain an (x,y,λ) datacube from the snapshot measurement, a spectral calibration algorithm is executed for reconstruction of the spatial–spectral signatures of the observed scene. System characterization of throughput, resolution, and crosstalk was performed. Preliminary results illustrating changes in oxygen-saturation in an occluded human finger are presented to demonstrate the system’s capabilities.
Kagome fiber based ultrafast laser microsurgery probe delivering micro-Joule pulse energies
(The Optical Society, 2016) Subramanian, Kaushik; Gabay, Ilan; Ferhanoğlu, Onur; Shadfan, Adam; Pawlowski, Michal; Wang, Ye; Tkaczyk, Tomasz; Ben-Yakar, Adela; Bioengineering
We present the development of a 5 mm, piezo-actuated, ultrafast laser scalpel for fast tissue microsurgery. Delivery of micro-Joules level energies to the tissue was made possible by a large, 31 μm, air-cored inhibited-coupling Kagome fiber. We overcome the fiber’s low NA by using lenses made of high refractive index ZnS, which produced an optimal focusing condition with 0.23 NA objective. The optical design achieved a focused laser spot size of 4.5 μm diameter covering a 75 × 75 μm2 scan area in a miniaturized setting. The probe could deliver the maximum available laser power, achieving an average fluence of 7.8 J/cm2 on the tissue surface at 62% transmission efficiency. Such fluences could produce uninterrupted, 40 μm deep cuts at translational speeds of up to 5 mm/s along the tissue. We predicted that the best combination of speed and coverage exists at 8 mm/s for our conditions. The onset of nonlinear absorption in ZnS, however, limited the probe’s energy delivery capabilities to 1.4 μJ for linear operation at 1.5 picosecond pulse-widths of our fiber laser. Alternatives like broadband CaF2 crystals should mitigate such nonlinear limiting behavior. Improved opto-mechanical design and appropriate material selection should allow substantially higher fluence delivery and propel such Kagome fiber-based scalpels towards clinical translation.
Light-Guide Snapshot Imaging Spectrometer for Biomedical Applications
(2016-10-04) Wang, Ye; Tkaszyk, Tomasz
Fiber-based snapshot imaging spectrometer has found increasing potential of applications in the field of biomedical imaging these years. However, currently the technique’s spatial and spectral sampling still need improvement for most requirements in biomedical applications. In this thesis, I propose a strategy design and proof-of-principle prototype system of fiber-based snapshot imaging spectrometer to provide a solution for increasing the spatial and spectral sampling. Through a custom fabricated fiber bundle, the object image is collected with an 81 x 96 spatial sampling, then divided into 3 x 96 spatial groups with gaps in between for dispersion, and finally captured by a CCD camera. To extract the (x, y, λ) datacube from the raw image, a spectral calibration algorithm is implemented to locate each wavelength and obtain point spectrum. Then a phase-shifting spatial calibration procedure is performed to remap the fibers and reconstruct single channel images. The prototype system is designed for visible range from 400 nm to 700 nm and is able to record 71 spectral samples within the range. Preliminary results of oxygen-saturation in occluded finger are presented to show the system spectral and spatial resolving ability. The fibers are packed in an efficient way and the system could be scalable to larger formats with higher spatial sampling. The gaps between fiber groups are designed to be tunable to enable high spectral sampling which has advantage in medical devices such as optical coherence tomography (OCT) in the future.
Light-guide snapshot imaging spectrometer for remote sensing and environmental imaging applications
(2019-04-12) Wang, Ye; Tkaczyk, Tomasz S
Optical fibers provide a high degree of design freedom and enable the building of imaging spectrometers with optimized compactness. Moreover, the ability to arbitrarily reformat the fibers’ input/output configurations allows the tuning between spatial and spectral sampling to meet specific application requirements. However, currently the system’s spatial sampling is limited by the basic structure design of the fiber bundle, which confined its application in various scenarios. In this thesis, I aim to advance the current fiber-based snapshot imaging spectrometers by developing a compact system with >30000 spatial samplings. Specific aims include the system design, the fabrication of a compact light-guiding fiber bundle by both semi-manual assembling and fully automatic 3D printing, the development of a rapid calibration method, and the system performance assessment for environmental applications. As a result, a fiber-based snapshot imaging spectrometer was developed with a maximum of 31853 (~ 188 x 170) spatial sampling and 61 spectral channels in the 450nm-750nm range. A compact fiber bundle was fabricated with semi-manual assembling to sample the object image at the input and create void spaces between rows at the output for dispersion. 3D printing using custom controlled fused deposition modeling (FDM) is also explored as an alternative fabrication technique, with an air-clad fiber optic faceplate fabricated as a proof of concept. To calibrate the >30000 spatial samples of the system, a rapid spatial calibration method was developed based on Phase-Shifting Interferometry (PSI). Preliminary hyperspectral imaging results of the Rice University campus landscape is presented to demonstrate the system’s spectral imaging capability for distant scenes. The spectrum of different plant species with different health conditions were in accordance with reference instrument measurements. The Houston city traffic was also imaged to demonstrate the system’s snapshot hyperspectral imaging capability on dynamic scenes. Potential applications of the system include terrestrial monitoring land use, air pollution, water resources, and lightning spectroscopy and so on.
Light-guide snapshot imaging spectrometer for remote sensing applications
(The Optical Society, 2019) Wang, Ye; Pawlowski, Michal E.; Cheng, Shuna; Dwight, Jason G.; Stoian, Razvan I.; Lu, Jiawei; Alexander, David; Tkaczyk, Tomasz S.; Bioengineering; Electrical and Computer Engineering; Physics and Astronomy
A fiber-based snapshot imaging spectrometer was developed with a maximum of 31853 (~188 x 170) spatial sampling and 61 spectral channels in the 450nm-750nm range. A compact, custom-fabricated fiber bundle was used to sample the object image at the input and create void spaces between rows at the output for dispersion. The bundle was built using multicore 6x6 fiber block ribbons. To avoid overlap between the cores in the direction of dispersion, we selected a subset of cores using two alternative approaches; a lenslet array and a photomask. To calibrate the >30000 spatial samples of the system, a rapid spatial calibration method was developed based on phase-shifting interferometry (PSI). System crosstalk and spectral resolution were also characterized. Preliminary hyperspectral imaging results of the Rice University campus landscape, obtained with the spectrometer, are presented to demonstrate the system’s spectral imaging capability for distant scenes. The spectrum of different plant species with different health conditions, obtained with the spectrometer, was in accordance with reference instrument measurements. We also imaged Houston traffic to demonstrate the system’s snapshot hyperspectral imaging capability. Potential applications of the system include terrestrial monitoring, land use, air pollution, water resources, and lightning spectroscopy. The fiber-based system design potentially allows tuning between spatial and spectral sampling to meet specific imaging requirements.
Ultrafast laser surgery probe with a calcium fluoride miniaturized objective for bone ablation
(Optical Society of Americ, 2021) Subramanian, Kaushik; Subramanian, Kaushik; Andrus, Liam; Andrus, Liam; Pawlowski, Michal; Wang, Ye; Tkaczyk, Tomasz; Ben-Yakar, Adela; Ben-Yakar, Adela; Ben-Yakar, Adela; Bioengineering
We present a miniaturized ultrafast laser surgery probe with improved miniaturized optics to deliver higher peak powers and enable higher surgical speeds than previously possible. A custom-built miniaturized CaF2 objective showed no evidence of the strong multiphoton absorption observed in our previous ZnS-based probe, enabling higher laser power delivery to the tissue surface for ablation. A Kagome fiber delivered ultrashort pulses from a high repetition rate fiber laser to the objective, producing a focal beam radius of 1.96 μm and covering a 90×90 μm2 scan area. The probe delivered the maximum available fiber laser power, providing fluences >6 J/cm2 at the tissue surface at 53% transmission efficiency. We characterized the probe’s performance through a parametric ablation study on bovine cortical bone and defined optimal operating parameters for surgery using an experimental- and simulation-based approach. The entire opto-mechanical system, enclosed within a 5-mm diameter housing with a 2.6-mm diameter probe tip, achieved material removal rates >0.1 mm3/min, however removal rates were ultimately limited by the available laser power. Towards a next generation surgery probe, we simulated maximum material removal rates when using a higher power fiber laser and found that removal rates >2 mm3/min could be attained through appropriate selection of laser surgery parameters. With future development, the device presented here can serve as a precise surgical tool with clinically viable speeds for delicate applications such as spinal decompression surgeries.
Wavelets and the discrete ordinate method for the solution of radiative heat transfer through a participating medium
(1999) Wang, Ye; Bayazitoglu, Yildiz
Wavelet method is applied to the study of radiative heat transfer and combined conductive-radiative heat transfer through the gray and nongray participating medium in one- and two-dimensional (1-D and 2-D) geometries. The participating medium is assumed to have an index of refraction of unity and to be absorbing, emitting, and nonscattering. The surfaces of 1-D infinite parallel plates and 2-D rectangular enclosure are assumed to be black and isothermal. The governing equations are the radiative transfer equation (RTE) and energy equation. The wavelet expansion is used to evaluate the spectral dependence of radiative intensity in RTE. And a set of differential equations about the expansion coefficients are developed by applying Galerkin method and discrete ordinates method (DOM). For 1-D problem, these equations are solved by finite difference method, and for 2-D problem, they are solved by finite volume method. The energy equation is solved simultaneously by applying the modified quasi-linearization algorithm (MQA) to obtain the temperature distribution and heat flux. The results for the cases of radiative equilibrium, uniform internal heat generation, and combined conductive-radiative heat transfer with gray and nongray medium are given and compared with those obtained by other methods. The optical thickness of the medium ranges from optical thin to optical thick. The conduction-radiation parameter varies from radiation-dominated to conduction-dominated situations. The method is proved to be a powerful tool in analyzing the radiative heat transfer through the nongray participating media. The results of 2-D nongray problems are first presented.

Browsing by Author "Wang, Ye"

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