SBIR-STTR Award

2-Dimensional Second-Harmonic Dispersion-Interferometer
Award last edited on: 1/23/2020

Sponsored Program
SBIR
Awarding Agency
DOE
Total Award Amount
$1,350,000
Award Phase
2
Solicitation Topic Code
24a
Principal Investigator
Frank Wessel

Company Information

L-Egant Solutions LLC

17165 Von Karman Avenue Nue Unit 102
Irvine, CA 92614
   (657) 210-2997?
   N/A
   N/A
Location: Single
Congr. District: 47
County: Orange

Phase I

Contract Number: DE-SC0019789
Start Date: 7/1/2019    Completed: 2/29/2020
Phase I year
2019
Phase I Amount
$200,000
Many applications in science, engineering, biology, and technology rely on interferometry to measure precisely the density of a plasma, gas, fluid, cellular structure, etc. Optical interferometry provides the highest sensitivity and resolution of all similar methods, yet designs are limited by mechanical vibrations, design complexity, and high maintenance. A Dispersion Interferometer (DI) alleviates these concerns, in a design that is stable, high bandwidth, and low cost. However, today?s DI systems provide only a 1-dimensional measurement, whereas a 2-dimensional measurement at cm2 transverse areas, and larger, is desired. Interferometers interfere two beams to make a measurement. Typically, separate paths are used for the reference-beam and the probe beam. In the DI both beams are co-linear, accounting for its design simplicity and high stability. DI?s presently use a continuous-wave (CW) laser to generate a primary beam that is then frequency-doubled in small, second-harmonic (SH) crystals. The resulting beam diameters are typically, ~ mm2 area. Instead, if a pulsed, high-intensity laser and beam optics were used to expand the beam to fully illuminate the sample, and then reduce it for the SH crystals, then 2-D interferometry would be feasible. However, methods must first be refined to demonstrate technical feasibility, by 1) characterizing precisely the instrument?s performance, and 2) re-constructing the phased-image data to represent accurately the sample. Extending this concept further, with a high- repetition-rate laser and fast camera, enables new imaging modalities in a 2-D cinematic recording of the sample?s evolution. The Phase I Project will assemble a 2DDI and characterize its performance in three configurations of increasing assembly: Configuration 1 is the basic instrument; Configuration 2 images a mm2 sample; Configuration 3 images a cm2 sample with beam optics. Digital methods are also needed to manipulate the phase-mapped interferometric data and allow the characteristics of the dispersive sample to be reconstructed. Feasibility demonstration is determined by successful results obtained from Configurations 1 & 2, enabling the 2DDI?s design to be scaled for larger- and smaller-size imaging applications, as a commercial product.The 2DDI is a superior approach to interferometry for measuring the characteristics of: plasma density in fusion, space physics, low-temperature physics, semiconductor processing; neutral-gas density in fluid dynamics, combustion dynamics, hydrodynamic compressors; structures at the nanometer scale, cellular function, microscopy in medicine and biology; quality-assurance testing in metrology. All of these are potential application areas for the commercial product.

Phase II

Contract Number: DE-SC0019789
Start Date: 8/24/2020    Completed: 8/23/2022
Phase II year
2020
Phase II Amount
$1,150,000
Interferometers are used for an incredible array of measurements in science, engineering, medicine, and technology, to quantify mass density and scale-lengths in a plasma, gas, liquid, etc. Interfer- ometers are often characterized by their high-cost, complex designs, and by the need for frequent maintenance. An interferometer lacking such downsides is appealing for many applications. Interferometers measure the phase difference between two electromagnetic beams. In transparent samples, such as plasma,gas,optical glass,the phase shift is due to chromatic dispersion thatis determined by the sample’s mass density, or similar physical quantities. A Second-Harmonic Dispersion-Interferometer (SHDI) may be used to measure the dispersive-phase shift. In the SHDI a primary beam is used to produce a second-harmonic (SH) beam both before, and after, the sam- ple. In this way all beams remain co-linear, allowing the primary beam to encode its phase directly into the second, SH beam. Thus, the phase difference between the two SH beams may be pre- cisely measured. The result is a design that is robustly stable, with fewer components, eliminating common-mode noise, and reducing routine maintenance. Until now, SHDIs have been constructed using beam diameters, d mm’s, which provides for a 1-dimensional, line-of-sight measurement. Most applications would benefit by having a 2-dimensional measurement, where the sample’s- transverse profile is imaged. This motivates the development of a 2D-SHDI, where d >> cm’s. During Phase I a 2D-SHDI prototype was assembled, using: a pulsed-high-power laser, fast- digital-cameras, and sophisticated-software algorithms. The prototype was used to measure the phase change produced in large-area samples, d cm, by increasing the beam diameter and ad- justing the laser intensity. These data verify that the 2D-SHDI’s phase coherence, image quality, and spatial resolution are suitable for 2-dimensional interferometric imaging. In Phase II the performance of the 2D-SHDI will be enhanced, then tested in collaborative experi- ments with members of the plasma-physics community, using their devices, that are representative of a broad range of existing-confinement concepts. The data produced in these collaborations will be disseminated in publications and at meetings, expositions, and trade shows. Commercialization of the instrument will focus on direct sales and licensing to established-instrumentation vendors. A 2D-SHDI is suitable for electron-density measurements in plasmas used in research, fusion en- ergy, space physics, materials processing, as well as the density of neutral gases, and for quantitative- phase microscopic imaging of structures. The 2D-SHDI provides a stable, cost-effective platform for measuring 2-dimensional phase interferometry with high-spatial and temporal resolution.