Return to in-person teaching and mentorship after COVID-19: hands-on photoacoustic demonstration apparatus

Abstract

In March 2020, the U.S. Naval Academy implemented policies for teaching midshipmen off the “yard” (campus) to finish out their spring semester online. Strategies and regulations were put in place so that after spring break midshipmen would go home to families, relatives or friends and establish a learning environment space for on-line synchronous or asynchronous classes. An online summer school served as a link into the fall of 2020— which was a mixture of online and very small in-class size environments. (Every other week half of a class was online.) During the spring of 2021, classes were hybrid. However, Instructors alternated between adjacent classrooms teaching online—but in-person in one of the rooms. During COVID, mentorship student LEB worked off the yard to develop apparatus for online acoustic demonstrations and future research projects. LEB designed and built a homemade pulsed 620 nm LED photoacoustic apparatus for imaging experiments in water. Components include an LED current pulse driver, two aspherical focusing lenses, a cuvette filled with green dye or India ink, an ultrasonic 1 MHz immersion transducer and 4 low noise amplifiers with 87 dB total gain. Photoacoustic signals were averaged (10 000 trials) producing a strong 20 mV seven cycle pulse.