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Research

ACES Methodology

The CHSLT develops and champions the ACES methodology which promotes unification of Analytical, Computational, and Experimental Solution methods in a complementary fashion to gain better understanding of the problems being studied than it would be possible otherwise. In this approach the CHSLT utilizes recent advances in analytical, computational, and experimental solution methodologies, emphasizes analogy between them, and points out cases where they can be merged to obtain solutions which may not be otherwise obtainable, to ease the existing in solution procedures, or to attain improvements in results.


Optical Metrology


Fringe Projection

Fringe projection is a holography technique used to measure shape and/or deformations of large objects. A sinusoidal image alternating light and dark is projected onto the object of interest. From acquiring a series of these images and running a series of algorithms on it, the shape or deformations of the object can be generated. From this, a 3-dimensional model can be produced.

Art Conservation

Art conservation measurements: (a) unwrapped image; and (b) 3D representation of sculpture.


Noninvasive techniques for surface measurements have become paramount for quality analysis in industrial applications, art conservation and restoration, as well as precision aid in medical procedures. The critical advantage of the fringe projection optical technique is the ability to provide full field-of-view information. Our team has developed and integrated novel techniques into a high-speed Fringe Projection system for real-time 3D shape measurements.


Road Surface Road Surface

Actual 3D road information


Topics: Art conservation, road surface inspection and forensics.

Optoelectronic Otoscope (OEHO)

The optoelectronic otoscope is a project being developed at the CHSLT in conjunction with Harvard Medical School and Massachusetts Eye and Ear Infirmary (MEEI).

Otologists are in need of quantitative methods to research and diagnose hearing loss. The current state of the art is single point measurements on the tympanic membrane (TM). The goal of this project is to bring live, full-field-of-view, 3-dimensional measurements to clinics and researchers to provide a better understanding of the tympanic membrane andhearing loss.

The system uses a custom-designed laser delivery system (laser diode, beam shifting hardware and other optics) and optical head (camera, otoscope) to observe the behaviorthe TMs as they are exposed to audible stimuli.

An experimental version is currently deployed at MEEI and further development is taking place at CHSLT.

Digital Optoelectronic Holographic System (DOEHS)

We are developing an advanced computer-controlled digital optoelectronic holographic system (DOEHS) with the ability to measure both shape and acoustically induced deformations of the tympanic membrane of several species, including humans.

MEMS

Microelectromechanical systems (MEMS) are micro- and nano-scale components with mechanical and electronic components embedded on a chip.

Flex joint on a MEMS component Courtesy of Sandia National Laboratories, SUMMiT(TM) Technologies, www.mems.sandia.gov

Because of the small size, the deformation of MEMS components is difficult to measure: non-destructive and non-contact measurement are critical. Using a microscope with laser interferometry, the nanometer-scale deformations of components can be measured accurately. These measurements are necessary to quantify theeffects that stimuli such as temperature or movement have on the device.

micro-mechaTronics

MEMS

Microelectromechanical systems (MEMS) are micro- and nano-scale components with mechanical and electronic components embedded on a chip.

Flex joint on a MEMS component Courtesy of Sandia National Laboratories, SUMMiT(TM) Technologies, www.mems.sandia.gov

Because of the small size, the deformation of MEMS components is difficult to measure: non-destructive and non-contact measurement are critical. Using a microscope with laser interferometry, the nanometer-scale deformations of components can be measured accurately. These measurements are necessary to quantify theeffects that stimuli such as temperature or movement have on the device.

Computational Mechanics

Decomposition of FEM solution corresponding to the first mode vibration of a conical latex membrane


Representative results of the DOEHS system in stroboscopic mode: Phase map (a) of the amplitude distribution of a copper foil membrane; a full-field-of-view displacement map (b) across the membrane indicates a 408nm p-p maximum amplitude; an isometric view (c) of the 3D shape of the displacement map.

Software

The CHSLT requires specialized software to perform many of its tasks, either to control hardware or automate complex tasks. Software is developed by the CHSLT staff.

LaserView

LaserView is custom platform for controlling holographic hardware, syncronizing cameras, and acquiring phase-shifted images.

HoloStudio

HoloStudio a post-processing companion to LaserView. It allows for processing of image and video files captured from LaserView, and output to various formats

PXHOLO

Written in IDL, PXHOLO is CHSLT program for applying filters, unwrapping phase maps, displaying 3D models, and performing other holography tasks. In conjunction with otherutilities it is used to process imagery acquired from LaserView.

Purpose of the CHSLT

The metrological applications at the CHSLT concentrate on holographic interferometry, laser speckle metrology, fiber optic sensors, analytical and computational modeling of structural behavior under static as well as dynamic loading conditions, and other areas of current interest. In these measurements, special effort is made to develop effective means for computer-aided quantitative analysis of experimental data and to relate these quantitative analyses to theoretical results.

In the area of holographic interferometry, the CHSLT concentrates on studies of fundamental phenomena governing recording, reconstruction, and quantitative interpretation of holograms with special emphasis on applications. More specifically, the CHSLT maintains holographic systems for studies of static as well as dynamic problems. These systems range from conventional double-exposure holography, to real-time and time-average holography, heterodyne holography, stroboscopic heterodyne holography, pulsed laser holography, and electro-optic holography (EOH). The EOH system allows for direct electronic acquisition and processing of interferometric data in real-time and sets a new standard for quantitative holographic analysis.

The CHSLT also conducts experimental and computational research in the field of nanoindentation studies in conjunction with a laboratory system which is uniquely suited to measure elastic, plastic, creep, and fracture properties of materials in sub-micron geometries.

In addition, the CHSLT is equipped with a complete laser vibrometer system, GHz frequency range storage oscilloscopes, a spectrum analyzer, a self-contained network of personal computers, UNIX based workstations and image processors, a host of supporting instrumentation, and a library of finite element analysis and general purpose software.

A well equipped electrical engineering and instrument development laboratory, a fiber optic preparation laboratory, an optical microscopy laboratory and a multifunctional dark room are also parts of the CHSLT. Sample preparation as well as electron microscope capabilities are available on the WPI campus and are heavily used by the CHSLT personnel.

The strengths of the CHSLT lie in a comprehensive utilization of laser technology, optics, computational methods, mechanical engineering, materials science and engineering, and computer data acquisition and processing. Building off of these strengths, greatly diversified projects in a number of areas of current interest are being conducted using the Center's own unique and innovative methods.