Zack Briesemeister

Zack Briesemeister is a third-year graduate student in the Astronomy and Astrophysics Department at University of California, Santa Cruz. He works on direct imaging of exoplanets in the mid-infrared with integral field spectroscopy. Zack is participating in PDP in order to develop teaching skills and strategies that are tailored towards equity and inclusion so that he can apply them both in teaching and outreach. He is a National Science Foundation Graduate Research Fellow and Eugene Cota-Robles Fellow.


Teaching Activity Summary

Name of Teaching Activity: Akamai PREP - Adaptive Optics

Teaching Venue & Date: Akamai PREP 2019, June 17-20 2019

Learners: 42 undergraduate students.

Reflection on the main learning outcome and how learners engaged with it during the inquiry:

Our content goal was that students would learn about sampling a continuous signal with discrete measurements, such that we preserve the information contained in the original signal in order to reconstruct the continuous signal. This is a fundamental concept in science, as instrument constraints place hard limits on our ability to analyze and recover the signal. A hands-on application of this concept is useful to convey how instruments are designed and used.

We approached this concept in terms of astronomical adaptive optics. Adaptive optics is a complex field encompassing many branches of physics. However, a core aspect of adaptive optics is the measurement of discrete samples of a continuous signal (atmosphere-distorted wavefront) that offers a unique opportunity to evaluate sampling in context of reconstructing and undoing atmosphere-induced wavefront distortion.

The activity tasked students with the task of identifying the performance requirements of an adaptive optic system to recover qualitatively sharper astrophysical images, constrained by the limitations of an evolving atmosphere, finite adaptive optic elements, and imperfect correction.

The first dimension and major 'eureka' moment for many students was discovering what a Shack-Hartmann wavefront sensor (SHWFS) actually measures (local average slope of a wavefront), and that this wavefront determines image quality. The second dimension of understanding adaptive optics is that the SHWFS takes discrete samples of a continuous wavefront as measurements that can be used to reconstruct the wavefront signal. The third dimension of understanding adaptive optics was that this reconstruction can be used to flatten the incoming wavefront using a deformable mirror to improve the image quality.

At the end of the activity, the students were given a price budget (equivalent to an error budget in real adaptive optics) to constrain the correction they can feasibly perform, and they chose, with justification, which corrections they would apply to improve their astrophysical image. They presented in groups on what they wanted scientifically out of the image, how adaptive optics works, and how the budget constrained them scientifically.