Scott Egbert

A Quick Introduction

Welcome to my personal website! I am a recent Ph.D. graduate from Greg Rieker's Precision Laser Diagnostics Lab at the University of Colorado Boulder. My specialization includes experimental optical diagnostics, laser system design and ruggedization, scientific computing, and optomechanical engineering. I am passionate about exploring ways to ruggedize groundbreaking optical technology so that it can move out of the optics lab and into the environments where it is needed the most.

This website is a platform for me to share cool pictures and videos that highlight my experiences, provide some links to connect, and (mostly) host my CV online. I am excited to continue my career in the field of optics. Thank you for visiting my website, I look forward to connecting with you!

Research Experience

My research focuses on optical measurements of real-world systems, specifically in three main areas:

• Designing and building portable mid-infrared frequency comb lasers
• Performing diagnostics on ramjets, atmospheric pollutants, etc.
• Developing a combustion-optimized spectral database of H₂O absorption

Designing Portable Frequency Comb Lasers

While at the University of Colorado, I have led the design, construction, and optimization of ultrashort pulsed laser systems from lab-based R&D efforts to robust, deployable products. After completing my Master's degree in passive IR sensing with an internship using Nd:YAG laser measurements at Sandia National Labs, I worked with Nazanin Hoghooghi, Scott Diddams, and Peter Chang at NIST, Boulder to develop a new frequency comb laser source for high-speed molecular spectroscopy. Shown above is the portable version of this laser that I designed in Solidworks. The enclosure is 19" rack-mountable and will hold all electrical and fiber components (oscillators, pump diodes, amplifiers, etc.) for each frequency comb laser. It is patterned after existing near-infrared dual comb spectrometers and generates light from 1-2 μm.

To convert the near-infrared light from each frequency comb to mid-infrared light spanning 3-5 μm, we use Intra-Pulse Difference Frequency Generation (IP-DFG), a technique developed by the Diddams group at CU. The generated beams are then combined and coupled into mid-infrared fibers that can be routed to the measurement. My SolidWorks design shrunk the footprint by over 40% and will enable these optics to escape the optics lab for the first time. The laser will soon enable the first broadband, mid-infrared dual comb spectroscopy measurements of hypersonic engines and wildfires.

Having a spectroscopy source simultaneously spanning 3-5 μm can measure the strong absorption of hydrocarbon fuels, combustion products, pollutants, and other chemical species in that region. To illustrate this, we obtained an example spectrum of some hydrocarbons using a GHz repetition rate laser, which is shown in the image above (filtered to highlight the absorption near 3 μm).

Optical diagnostics of ramjets

The Air Force Research Lab has funded the development of this mid-infrared laser to perform diagnostics on ramjet and other hypersonic engines. By comparing our measurement to absorption databases, we can calculate the temperature, pressure, and concentration of various gas species. Velocity is calculated from the Doppler shift by angling the laser beams, as shown above. Using these optically measured properties, we can calculate a total mass flux and species fluxes for the engine.

Combustion-Optimized Spectral Databases

Accurate spectral databases are crucial for calculating thermodynamic properties from spectral measurements. Dual comb spectroscopy is an ideal spectrometer for broadband, high-temperature database development, as it perfectly bridges the gap between low temperature (under 400 K), broadband (over 1000 cm^-1) FTIR measurements and high-temperature (over 1000 K), narrow (under 5 cm^-1) tunable diode laser measurements.

After optimizing our frequency comb lasers and high-temperature vacuum system to measure broadband H₂O absorption from 1.3-1.5 μm, I needed to automate the analysis of the over 20,000 spectral absorption parameters that I had measured. To solve this challenge, I created a simplified Python-based graphical user interface for exploring the data, enabling me to work almost 500 times faster than prior students without sacrificing database quality. This database improves our understanding of high-temperature H₂O absorption in the near-infrared. We have already seen a 23x reduction in measurement error when using this database for the hypersonics measurements we took with the AFRL and are excited to see other applications for this high-temperature database.

This video showcases the potential of dual comb spectroscopy to precisely and simultaneously measure broad spectra, starting with an individual frequency comb "tooth" before expanding to show the entire measurement. The data shown is from the same 1300 K measurement shown above.

In addition to improving our ability to calculate thermodynamic properties in combustion measurements, this database will help James Webb Space Telescope in its extraterrestrial search for water on exoplanets and in the inter-stellar medium.

Connect

Please reach out if you would like to connect. My email is scott.egbert@colorado.edu.

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