• Additive Manufacturing of Glass
  • Scalable Nanomanufacturing of Visible and IR Metasurfaces
  • Digital Micromirror Device Modulated Thermography
  • Frequency-Selective Surface Strain Sensors
  • Modal Analysis as a Validation Technique for Additive Manufactured Parts
  • Frequency-Selective Surfaces Enabled Microbolometers

Additive Manufacturing of Glass


Additive Manufacturing of Glass

Dr. Edward Kinzel Project 1

 

INVESTIGATORS
Edward Kinzel, Douglas Bristow, Robert Landers
 

FUNDING SOURCE
NSF, AFRL, MRC
 

PROJECT DESCRIPTION
Additive manufacturing, or 3D printing, has been used for printing plastics, metals, and some ceramics.  However, comparatively little work has been performed on printing glass and other optical components aside from polymers.  Our work uses a CO2 laser is used to locally melt the glass and build 3D shapes. The λ=10.6 μm laser energy couples to phonon mode in glass and is well absorbed. An electrically heated build platform is moved relative to a stationary laser beam.  Material consolidated by the melting process, solidifies out of the melt pool as the part translates relative to the laser beam. Careful control of the process parameters, specifically the feed rate, scans speed and laser power, allows the deposition of optically transparent glass.  This forms the basis for creating lenses (including functionally graded, GRIN lenses), low coefficient of thermal expansion structures, integrated photonics, and glass/metal seals.
 

PUBLICATIONS 

1.   “Additive manufacturing of transparent soda-lime glass using a filament-fed process,” J. Luo, L.J. Gilbert, D.A. Bristow, R.G. Landers, E.C. Kinzel, accepted J. Mfct. Sci. Eng. (2016).

2.   “Selective Laser Sintering of Low Density, Low Coefficient of Thermal Expansion Silica Parts,” J.M. Hostetler, J.T. Goldstein, A.M. Urbas, R.E. Gutierrez, T.E. Bender, C.S. Wojnar, E.C. Kinzel, Solid Freeform Fabrication Symposium, Austin TX August (2016).

3.   “Bubble Formation in Additive Manufacturing of Borosilicate Glass,” J. Luo, T. Bender, D.A. Bristow, R.G. Landers, J.T. Goldstein, A.M. Urbas, E.C. Kinzel, Solid Freeform Fabrication Symposium, Austin TX August (2016).

4.   “Bubble formation in additive manufacturing of glass,” J. Luo, L.J. Gilbert, D.C. Peters, D.A. Bristow, R.G. Landers, J.T. Goldstein, A.M. Urbas, E.C. Kinzel, SPIE DCS, Baltimore MD April (2016).

5.   “Additive manufacturing of glass for optical applications,” J. Luo, L.J. Gilbert, D.A. Bristow, R.G. Landers, J.T. Goldstein, A.M. Urbas, E.C. Kinzel, SPIE Photonics West, San Francisco, Feb. (2016) (Best Paper Award).

6.   “Additive Manufacturing of Glass,” J. Luo, H. Pan, E. Kinzel, J. Mfct. Sci. Eng. 136 061024 (2014).

 

Scalable Nanomanufacturing of Visible and IR Metasurfaces


Scalable Nanomanufacturing of Visible and IR Metasurfaces

 Dr. Edward Kinzel Project 2

 

INVESTIGATORS
Edward Kinzel

FUNDING SOURCE
UMRB

PROJECT DESCRIPTION
Metasurfaces (2D metamaterials) allow the scattering response of a structure to be engineered.  This is particularly useful at IR wavelengths for specifying the absorptance, emittance and reflectance with respect to wavelength, polarization and angle of incidence.  Metasurfaces facilitate applications such as photon management, planar (diffractive) lenses, SERS/SEIRA sensors, as well as energy harvesting. While they can be realized in the laboratory using integrated circuit tools, metasurfaces are not finding practical applications because the manufacturing is cost prohibitive.  For example patterning a typical IR metasurface using e-beam lithography costs in excess of $5M/m2.  We are investigating the Microsphere Photolithography (MPL) process for the low-cost patterning of metasurfaces.  This uses a self-assembled hexagonal close packed array of microspheres as optical elements to focus photonic jets into photoresist.  The photonic jets are sub-diffraction limited and can be steered using off-normal illumination to achieve complicated patterns.


PUBLICATIONS
 

1.   “Polycrystalline metasurface perfect absorbers fabricated using microsphere photolithography,” C. Qu, E.C. Kinzel, Opt. Lett. 41(15) 3399-3402 (2016).

2.   “Scalable Nanomanufacturing of Metasurfaces,” J.S. Wilson, W. Pan, M. Gegel, M. Nath, E.C. Kinzel, IMECE 2014, Montreal (2014).

 

Digital Micromirror Device Modulated Thermography


Digital Micromirror Device Modulated Thermography

 

Dr. Edward Kinzel Project 3

 

INVESTIGATORS
Edward Kinzel
 

FUNDING SOURCE
ISC
 

PROJECT DESCRIPTION
Active thermography (radiometric imaging to map surface temperature) involves illuminating the target with a known heat flux provides more accurate detection of defects.  It have been widely studied and demonstrated for identifying features that impede the flow of heat away from the surface.  A typical example is the detection of delamination defects in composites. Several temporal modulation schemes have been studied intensively; notably a single short pulse and a sinusoidal modulation. Both involve uniform spatial illumination of the target.  While these are relatively simple to setup, neither technique produces thermal gradients tangential to the surface.  This renders the inspection blind to features normal to the surface such as cracks or broken fibers. We are investigating a system for actively illuminating the target by modulating a laser beam using a Digital Micromirror Device (DMD).  The DMD allows simultaneous control of both space and time dependence of the incident heat flux.  This approach permits multiple heat sources to be frequency multiplexed which is critical because a single heat source has a localized interrogation area. Modulating these heat sources at different know frequencies allows their influence to be recovered from a long (low-noise) temperature history for each point on the surface.  Beyond detecting cracks, the DMD technique has potential for measuring and mapping thermal properties such as thermal diffusivity.
 

PUBLICATIONS 

1.   “Toward DMD illuminated spatial-temporal modulated thermography,” J.D. Pribe, S.C. Thandu, Z. Yin, E.C. Kinzel,SPIE DCS, Baltimore MD April (2016).

 

Frequency-Selective Surface Strain Sensors


Frequency-Selective Surface Strain Sensors

 

Dr. Edward Kinzel Project 4

INVESTIGATORS
Edward Kinzel
 

FUNDING SOURCE
CTIS
 

PROJECT DESCRIPTION
Frequency Selective Surfaces (FSS) have long been used in the RF/microwave community to control radar cross-section. The scattering parameters of the FSS form a signature which is a function of the frequency, element size and spacing, as well as the local electromagnetic environment.  This paper considers a FSS as a strain sensor on the surface of a structural element.  By interrogating the FSS with a series of polarized far-field measurements in a bistatic configuration the biaxial plane strain, including shear, can be resolved.  This project has potential for remotely inspecting structures by embedding the FSS in structures that can be penetrated by microwaves such as GFRP composites or concrete.
 

PUBLICATIONS

1.   “Design of a Frequency-Selective Surface Strain Sensor,” E.C. Kinzel, IEEE Antennas and Propagation Conference, Memphis (2014).

 

Modal Analysis as a Validation Technique for Additive Manufactured Parts


Modal Analysis as a Validation Technique for Additive Manufactured Parts

 

Dr. Edward Kinzel Project 5

INVESTIGATORS
Edward Kinzel, Douglas Bristow, Robert Landers
 

FUNDING SOURCE
KC-NSC
 

PROJECT DESCRIPTION
This project investigates modal analysis as a validation technique for additively manufactured parts. The Frequency Response Function (FRF) is dependent on both the geometry and the material properties of the part as well as the presence of any defects. This allows the FRF to serve as a “fingerprint” for a given part of given quality.  Once established, the FRF can be used to qualify subsequently printed parts.  This approach is particularly attractive for metal parts, due to the lower damping as well as use in high-value applications where failure is unacceptable.  To evaluate the efficacy of the technique, tensile specimens are printed with a Renishaw AM250, the modal response of these parts is characterized prior to tensile testing, and the FRFs are compared to their engineering metrics for parts printed with both nominal and off-nominal parameters. Numerical modeling is used to understand the modal structure, and the possibility of defect prognosis is also explored by comparing the measured response to simulation results.
 

PUBLICATIONS 

1.   “Modal Response as a Validation Technique for Metal Parts Fabricated with Selective Laser Melting,” J.D. Pribe, B.M. West, M.L. Gegel, T. Hartwig, T. Lunn, B. Brown, D.A. Bristow, R.G. Landers, E.C. Kinzel, Solid Freeform Fabrication Symposium, Austin TX August (2016).

Frequency-Selective Surfaces Enabled Microbolometers


Frequency-Selective Surfaces Enabled Microbolometers

 

Dr. Edward Kinzel Project 6

 

INVESTIGATORS
Edward Kinzel, Mahmoud Almasri
 

FUNDING SOURCE
NSF
 

PROJECT DESCRIPTION
Frequency Selective Surfaces (FSS), also known as metasurfaces, are periodic array of sub-wavelength antenna elements. They allow the absorptance and reflectance of a surface to be engineered with respect to wavelength, polarization and angle-of-incidence. This project applies this technique to microbolometers for uncooled infrared sensing applications. Both narrowband and broadband near perfect absorbing surfaces are synthesized and applied engineer the response of microbolometers. The project focuses on simple FSS geometries (hexagonal close packed disk arrays) that can be fabricated using conventional lithographic tools for use at thermal infrared wavelengths (feature sizes > 1 µm). The affects of geometry and material selection for this geometry are explored. In the microbolometer application, the FSS controls the absorption rather than a conventional Fabry-Perot cavity and this permits an improved thermal design. A coupled full wave electromagnetic/transient thermal model of the entire microbolometer is presented and analyzed using the finite element method. The absence of the cavity also permits more flexibility in the design of the support arms/contacts. This combined modeling permits prediction of the overall device sensitivity, time-constant and the specific detectivity.

PUBLICATIONS 

1.   “Design and Analysis of Frequency-Selective Surface Enabled Microbolometers,” T. Liu, C. Qu, M. Almasri, E.C. Kinzel, SPIE DCS, Baltimore MD April (2016)