April 2021 Issue
Feature Articles
Shedding Light on the Human Brain
The freedom of functional near-infrared spectroscopy opens a window into brain activity outside the confines of an MRI machine.
by Meeri KimCancer Holography for Personalized Medicine
Digital holography can measure the 3D physiology and motion of cancer cells, allowing identification of effective chemotherapies for patients.
by David D. NolteDepartments and Columns
Applications Engineering in Optics
Two AEs representing both the hardware and the software side of the optics industry highlight the virtues of an often-overlooked career path.
Setting COVID-19 Research Priorities
Sensors could help address many pandemic-related challenges. A team in Australia wants to pinpoint where the technology could have the greatest impact.
COVID-19 and the Biophotonics Industry
Even the biophotonics industry took a hit in 2020, although pandemic-related revenues point toward growth in 2021.
Also in this Issue
30, 20, and 10 Years Ago in OPN
Medical lasers; ocean optics; infrared imaging
Celebrating IDWGS / CLEO goes virtual / 2021 OSA Awardees / Kawata at OSK / Remembering A. David Buckingham / OSA Fellow stories / U.S. O&P Caucus / OIDA showacase / Thank you, editors and volunteers
Thank You, OSA Foundation Donors!
The OSA Foundation serves as the philanthropic arm for The Optical Society (OSA). Our mission is to inspire, reward and support students and early-career professionals in optics and photonics. Programs include professional development, schools, prizes, scholarships, fellowships, awards and honors. Each and every donation received is matched 100% by the OSA, doubling the impact of our donors. Additionally, all administrative fees are paid by OSA ensuring gifts directly support our programs. Learn more about our highlights from 2020 by checking out our annual report at www.osa.org/osafannualreport. To make a contribution to the foundation, visit www.osa.org/donate.

![Manual probe system with needles for test of semiconductor on silicon wafer. [A. Morozov / Getty]](https://opnmedia.blob.core.windows.net/$web/opn/media/images/articles/2025/1125/departments/202511-cover-web.jpg?ext=.jpg)
![Researcher Clara Saraceno in the lab. [Image by Carsten Behler Photography]](https://opnmedia.blob.core.windows.net/$web/opn/media/images/articles/2025/1025/departments/202510-cover-web.jpg?ext=.jpg)