Engineering Commons^™

Workspace Analysis Of A Linear Delta Robot: Calculating The Inscribed Radius, Michael Louis Pauly

Graduate Theses - Mechanical Engineering

One of the most important traits of a robotic manipulator is its work envelope, the space in which the robot can position its end effector. Parallel manipulators, while generally faster, are restricted by smaller work envelopes [1]. As such, understanding the parameters defining a physical robot’s work envelope is essential to the optimal design, selection, and use of robotic parallel manipulators. A Linear Delta Robot (LDR) is a type of parallel manipulator in which three prismatic joints move separate arms which connect to a single triangular end plate [2]. In this study, general inverse kinematics were derived for a linear …

Quantitative Data Extraction Using Spatial Fourier Transform In Inversion Shear Interferometer, Yanzeng Li

Graduate Theses - Physics and Optical Engineering

Currently there are many interferometers used for testing wavefront, measuring the quality of optical elements, and detecting refractive index changes in a certain medium. Each interferometer has been constructed for a specific objective. Inversion shear interferometer is one of them. Compared to other interferometers, it has its own advantages, such as only being sensitive to coma aberration, but it has some limitations as well. It does not allow use of phase shifting technique. A novel inversion shear interferometer was invented using holographic lenses. By using the spatial carrier method, phase information of the wavefront was extracted. The breakthrough of the …

Fabrication And Characterization Of Edge-Emitting Semiconductor Lasers, Junyeob Song

Graduate Theses - Physics and Optical Engineering

The semiconductor laser was invented in 1962, and has recently become ubiquitous in modern life. This thesis focuses on the development of a semiconductor laser fabricating process which utilizes semiconductor manufacturing technology in a cleanroom environment including photolithography, etching, deposition, and bonding processes. A photomask for patterning is designed, recipes of photolithography process and etching process are developed with experiments. This work gives how to develop the process of fabrication and determine the parameters for each processes. A series of semiconductor laser devices are then fabricated using the developed process and characterization is performed to assess device performance with industrial …

Calculation And Experimental Verification Of Longitudinal Spatial Hole Burning In High-Power Semiconductor Lasers, Ting Hao

Graduate Theses - Physics and Optical Engineering

Longitudinal spatial hole burning (LSHB) is believed to be one of the limiting factors in scaling the output power of high-power semiconductor lasers. In this work, a self-consistent simulation of LSHB was performed to investigate the non-uniform longitudinal photon density distribution, carrier density distribution, and gain distribution in a high-power semiconductor laser. The calculation is based on a modification to the semiconductor laser rate equations and solved using a finite difference approach, with Newton’s method employed to numerically solve the differential equations. The impact of LSHB on output power was analyzed with different parameters, including injection current, cavity length, and …

Emitter Localization And Compressed Sensing: A Low Cost Design Using Coarse Direction Finding Antennas, Andrew Raymond Wagner

Graduate Theses - Engineering Management

Research has been conducted to determine the location of uncooperative radio-frequency (RF) emitters, using low cost sensors employing broadband, low directivity antennas. Comparably lowered accuracy and longer response time may be appropriate trade-offs for size, weight, and power (SWAP). These sensors can then be deployed on numerous testbeds, and algorithms may take advantage of the reconfigurable, distributive network of sensors to precisely determine the location. To conduct this research, a network of three reconfigurable sensors, equipped for emitting and receiving RF signals, was designed based on Universal Software Radio Peripheral (USRP™) technology. This thesis details the experiments conducted and the …

Combining Monte Carlo Transport And Level Set Surface Evolution For Modeling Vapor Phase Deposition Of Thin Films Over Sub-Micron Features, John Lewis Smith

Graduate Theses - Chemical Engineering

A hybrid scheme is used to model the vapor phase deposition of thin films at the feature scale. The transport of the chemical species to the substrate surface is modeled with a Collisionless Direct Simulation Monte Carlo (DSMC) method. The Level Set Method is used to model the growth of the thin-film on the substrate. The convergence criteria for these methods were not found in literature.

The governing equations for the Level Set Method are, in general, non-linear partial differential equations. The coupling of the DSMC Method with the Level Set Method results in a set of non-Gaussian stochastic non-linear …