OSC Colloquium: Brandon Chalifoux, "Fabrication, Alignment and Testing of Ultralight Mirrors..."

Sept. 8, 2021
Brandon Chalifoux

Topic: Fabrication, Alignment and Testing of Ultralight Mirrors for Future X-ray Telescopes

Host: Dalziel Wilson 

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Abstract(s): 

Space telescopes may one day perform astronomical imaging with micro-arcsecond angular resolution in optical or even X-ray wave bands, if ultralight mirrors and structures can be fabricated and aligned with sufficient accuracy. My group’s research aims to fabricate, align, and test thin lightweight optical components for a range of applications on Earth and in space. 

I will present an optical design form for diffraction-limited X-ray telescopes that could in principle enable micro-arcsecond angular resolution without deployable optics, albeit with a detector flying in formation. I will enumerate the opto-mechanical tolerances that would be required for such an optical assembly, and our research activities to address key challenges with mirror figuring, alignment, and testing of these thin acylindrical optical surfaces. I will present recent experimental results from our lab that demonstrate two techniques critical to this effort: (1) lateral shift mapping interferometry and (2) ultrafast laser stress strain generation for figuring and alignment of X-ray mirrors. Lateral shift mapping is a self-referencing metrology technique that we expect to be capable of measuring X-ray mirrors with nanometer-level RMS uncertainty, and we have built a testbed for testing and improving this technique. We have also built a system to focus an ultrafast laser, with sub-picosecond pulse duration, to generate strain in glass to bend substrates for figure correction, or to create dimensional changes for permanently adjusting mirror-to-mirror alignment. I will share our recent experimental results demonstrating the value of these techniques for future lightweight optics. 

Speaker Bio(s): 

Dr. Brandon Chalifoux is an Assistant Professor in the James C. Wyant College of Optical Sciences at the University of Arizona. He received his PhD in Mechanical Engineering from MIT in 2019, and he was a postdoctoral associate in the Space Nanotechnology Laboratory at the MIT Kavli Institute for Astrophysics and Space Research. Prior to graduate school, he worked on concentrated solar energy generation as an engineer at a Vermont startup, Solaflect Energy. He earned a B.S. in Mechanical Engineering from Rice University.

 
 
 

 

 

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05
Donna Strickland Colloquium
OSC Colloquium: Donna Strickland, "High Intensity Fiber lasers for Nonlinear Optics"
3:30 – 5 p.m., Dec. 5, 2024

Ti:sapphire lasers offer the largest bandwidths and therefore the shortest pulses.   The highest laser intensities have been achieved using Chirped Pulse Amplification (CPA) of large diameter solid state lasers.  CPA was needed to avoid damage from the nonlinear process of self-focusing.  The disadvantage of solid-state lasers is the limited average power.  On the other hand, diode pumped fiber laser systems offer significantly higher average power than solid state lasers. Self-focusing is eliminated in single mode fibers by guiding and so nonlinear optics can be beneficial rather than detrimental and used to broaden the gain bandwidth.  Single fiber laser amplifiers will not reach the highest intensities offered by solid state lasers, but in this talk, I will discuss developing fiber laser amplifiers for nonlinear optical interactions such as mid-infrared generation and laser acceleration of electrons that require high intensity and benefit from high average power.

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